To APPEAR I" ApJ Preprint typeset using 1I"IE;X style cmulatcapj v. 8/13/10
SPECTRAL E~ERGY DISTRIBUTIO~ MODELS FOR LOW-LUMINOSITY ACTIVE GALACTIC NUCLEI IN LINERS
RODRIGO S. NEMMEN.1.2·:l THAISA STORCHI-BERGivlANN2 AND MICHAEL ERACLEOUS:J To appea'r in ApJ
ABSTRACT Low-luminosity active galactic nuclei (LLAGNs) represent the bulk of the AGN population in the present-day universe and they trace the low-level accreting supermassive black holes. In order to probe the accretion and jet physical properties in LLAGNs as a class, we model the broadband radio to X-rays spectral energy distributions (SEDs) of 21 LLAGNs in low-ionization nuclear emission-line regions (LINERs) with a coupled accretion-jet model. The accretion flow is modeled as an inner ADAF outside of which there is a truncated standard thin disk. We find that the radio emission is severely underpredicted by ADAF models and is explained by the relativistic jet. The origin of the X-ray radiation in most sources can be explained by three distinct scenarios: the X-rays can be dominated by emission from the ADAF, or the jet, or the X-rays can arise from a jet-ADAF combination in which both components contribute to the emission with similar importance. For 3 objects both the jet and ADAF fit equally well the X-ray spectrum and can be the dominant source of X-rays whereas for 11 LLAGNs a jet-dominated model accounts better than the ADAF-dominated model for the data. The individual and average SED models that we computed can be useful for different studies of the nuclear emission of LLAGNs. From the model fits, we estimate important parameters of the central engine powering LLAGNs in LINERs, such as the mass accretion rate and the mass-loss rate in the jet and the jet power - relevant for studies of the kinetic feedback from jets. Subject headings: accretion, accretion disks - black hole physics galaxies: active - galaxies: nuclei galaxies: jets - galaxies: Seyfert
1. INTRODUCTION (e.g., Osmer 2004; Silverman et al. 2005). One of the central paradigms in extragalactic astron In the present-day universe, 5MBHs are underfed com omy is that today's galaxies host supermassive black pared to the ones at high z and are "sleeping". Most holes (SMBHs) at their centers and have a symbiotic of 5MBH activity at low z is dominated by the weak evolution with them (Magorrian et al. 1998; Ferrarese end of the AGN luminosity function in the form of low & Ford 2005). The central black holes seeded in proto luminosity AGNs (LLAGNs; Ho, Filippenko & Sargent galaxies at high redshift grow in mass during cosmic 1995, 1997b; Nagar, Falcke & Wilson 2005; Ho 2008). history through a sequence of mergers of massive black Though the LLAGN phase dominates the time evolu holes and accretion episodes (e.g., Volonteri et al. 2005; tion of 5MBHs, it contributes little to their mass growth Fanidakis et al. 2011). The massive black holes grow in (Hopkins & Hernquist 2006; Sijacki et al. 2007; Merloni such a way that they co-evolve with the galactic bulges & Heinz 2008; Xu & Cao 2010). (Kormendy & Richstone 1995; Ferrarese & Merritt 2000; The bulk of the LLAGN population (;::;:; 2/3; Ho 2008. Gebhardt et al. 2000; Ferrarese & Ford 2005) but do not 2009) reside in low-ionization nuclear emission-line re seem to do so with the galaxy disks (Kormendy & Ben gions (LINERs; Heckman 1980; Ho, Filippenko & Sar der 2011) or dark matter haloes (Kormendy, Bender & gent 1997a). LLAGNs are extremely sub-Eddington sys Cornell 2011). tems which are many orders of magnitude less lumi The growth of 5MBHs is dominated by the quasar nous than quasars, with average bolometric luminosities (Lbol) ~ 1040 1041 erg and an average Eddington phase (Marconi et al. 2004; McLure & Dunlop 2004; Si 5 jacki et al. 2007; Merloni & Heinz 2008) during which ratio of LboI/ LEdd ~ 10- (Ho 2009) where L Edd is the they accrete from their large gas reservoir via geometri Eddington luminosity. The observational properties of callv thin accretion disks which are radiativelv efficient LLAGNs are quite different from those of more luminous (Sh~kura & Sunyaev 1973; Novikov & Thorn~ 1973) as AGNs. Regarding the broadband spectral energy distri ITITC,c+c,r/ by different lines of evidence 1978: Ko- butions (SEDs), LLAGNs seem not to have the thermal B1aes 1999: Shang et al. . The quasar continuum prominence in the ultraviolet - the "big has a strong with its blue bump" which is one of the of the press a factor ~ 2 - ence of an thin accretion reaches its disk Nemmen et al. Yuan &; Cao 2007: Ho 2008: 2010). Re- have weak 1 NASA Goddard Space Flight Center, Vlt.tllL'eH. ,\rm and narrow Fe Ka emission and Universidadc Federal do Rio Grande do a handful of LINERs display broad Ha RS. BraziL lines Storchi-Bergmann et al. 2003): ties emission-line spectrum are consistent 2 Nemmen et al. absence of a thin accretion disk. or a thin accretion disk ful outflows and jets, as suggested by theoretical stud whose inner radius is truncated at ;::; 100eM / c2 (Chen, ies including analytical theory (Narayan & Yi 1994; Halpern & Filippenko 1989; Chen & Halpern 1989). Last Meier 200l; Nemmen et al. 2007) and numerical sim but not least, with the typical fuel supply of hot diffuse ulations (McKinney & Gammie 2004; Hawley & Kro gas (via Bondi accretion) and cold dense gas (via stellar lik 2006; Tchekhovskoy, Narayan & McKinney 20l0)). mass loss) available in nearby galaxies, LLAGNs would This is in line with the different observational studies be expected to produce much higher luminosities than which demonstrate that LLAG~s are generally radio observed on the assumption of standard thin disks with loud (Ho 2002, 2008) and accompanied by powerful jets a 10% radiative efficiency (Ho 2009). Taken together, (e.g., Heinz, MerIoni & Schwab 2007; MerIoni & Heinz this set of observational properties favors the scenario 2008). In fact, the so-called "radio mode" of AGN feed in which the accretion flow in LLAGNs is advection back invoked in semi-analytic and hydrodynamic simula dominated or radiatively inefficient. tions of galaxy formation (e.g., Bower et al. 2006: Croton Advection-dominated accretion flows (ADAFs4; for re et al. 2006; Sijacki et al. 2007; Fanidakis et al. 2011) views see Narayan, Mahadevan & Quataert 1998: Yuan would presumably correspond to the ADAF accretion 2007; Narayan & McClintock 2008) are very hot, geo state actively producing jets as explicitly incorporated metrically thick, optically thin flows which are typified in some works (Sijacki et al. 2007; Okamoto, Nemmen & 2 by low radiative efficiencies (L « o.uli! c ) and occur Bower 2008). at low accretion rates (.i1 ;S 0.0l1lihdd)' SlVIBHs are It is clear that an understanding of the physical na thought to spend most of their lives in the ADAF state ture of LLAGNs in LINERs will shed light on the nature (Hopkins & Hernquist 2006; Xu & Cao 2010), the best of black hole accretion, outflows and consequently black studied individual case being Sgr A* (e.g., Yuan 2007). hole growth and AGN feedback in present-day galaxies. In many LLAGNs, another component in the accretion One of the best ways of exploring the astrophysics of flow besides the ADAF is required in order to account black hole accretion and outflows is by using multiwave for different observations, including a "red bump" in the length observations of black hole systems and compar SEDs (Lasota et al. 1996; Quataert et al. 1999; Nem ing the spectra predicted by specific models with the men et al. 2006: Yu, Yuan & Ho 2011) and as mentioned data. The goal of this work is therefore to probe the before the double-peaked Balmer emission lines (e.g., physics of accretion and ejection in the LLAGN popula Storchi-Bergmann et al. 2003; Eracleous, Lewis & Flohic tion, by modeling their nuclear, broadband, radio to X 2009): the emission from a thin accretion disk whose in rays SEDs which provide constraints on physical models ner radius is truncated at the outer radius of the ADAF. for the emission of the accretion flow and the jet. Fur In many LLAGNs the accretion flow may begin as a stan thermore, with a large enough sample of systems, we dard thin disk but somehow at a certain transition ra can derive from the fits to the data the parameters that dius the accretion flow abruptly switches from a cold to characterize the central engines and build a census of the a hot ADAF mode. The details of how this transition "astrophysical diet" of low-state AGNs. might happen are still not well understood (Manmoto In this work, we will present how the currently fa et al. 2000; Yuan & Narayan 2004; Narayan & McClin vored model for the central engines of weakly a~cret tock 2008), but it seems to be analogous to the transition ing black holes is able to account for the observed between the different spectral states in black hole binary SEDs of LLAGNs. We will also present the typical ac systems (Remillard & J\IcClintock 2006; Done, Gierliriski cretion/ejection - or feeding/feedback - properties of & Kubota 2007). LLAG~s in LINERs as inferred from our detailed SED Maoz (2007) challenged the scenario of the central en fits. With these parameters, we will then be able to gines of LLAGNs consisting of ADAFs and truncated draw a connection between the 5MBHs in nearby active thin disks. J\laoz argues that LLAGNs in LINERs have galaxies and the one in the Milky Way, Sgr A *. "We will l)VIX-ray luminosity ratios similar on average to those also present the inferred production site of the continuum of brighter Seyfert Is and based on that observation he emission and other properties inferred from the fits. posits that thin disks extending all the way down to the The structure of this paper is as follows. In Section 2 radius of the innermost stable circular orbits (ISCO) per we describe the sample of 21 LLAGNs in LINERs that sist even for LLAGNs, despite their smaller accretion we used, the data and classifications. Section 3 describes rates. Yu, Yuan & Ho (2011) showed that the SEDs com the physical model that we adopted in order to interpret piled by J\laoz (2007) are naturally fitted by ADAF mod and fit the SEDs and derive the central engine parame els with the addition of a truncated thin disk and also dis- ters. In Section 4 we describe the model fits to the SEDs. cussed on theoretical grounds the ADAF model has explaining in more detail the SED models for 5 objects a explanation than the pure thin disk which we consider the "reference·' or fiducial LLAGN ex- The ADAF model that can nat- amples. Section 5 the model fits to the other 16 account for the set of observational of SEDs in our In Section 6 we describe the distri- within a self-contained butions of parameters resulting from our Hence. is the detailed model fits. the SED result- ADAFs are from our fits the emission back since wavebands which can be with future facilities such as ALMA and the James Webb and the inferred nature of the emission in each consider ADAFs inefficient to be the kind of ~.rrTPTmn flow so- in §7. We discuss in 8 which model is favored clarification regarding the terminology. Yu. Yuan our LLAG~ particular which com- ponent in the flow dominates the X-ray emission. \Ve SED Models for LLAGNs in LINERs 3
conclude by presenting a summary of our results in 9 Heinz & Di Matteo 2003). and comparing the 5MBH "diet" of massive black holes The optical-UV data of all objects were corrected for in LINER AGNs and Sgr A"'. extinction as discussed in EHF10. In order to compute the bolometric luminosities from the SEDs, EHFlO used 2. SAMPLE two methods. For the objects with the best sampled Eracleous, Hwang & Flohic (2010) (hereafter EHFlO) SEDs, they computed Lbol by integrating the SEDs di compiled a sample of 35 SEDs of LLAGNs found in LIN rectly, ignoring upper limit data points. The objects ERs which include high spatial resolution optical and UV with well-sampled SEDs are NGC 3031, NGC 3998, NGC observations with the Hubble Space Telescope (HST), as 4374, NGC 4486, NGC 4579 and NGC 4594. For these well as X-ray observations with Chandra. Most of the objects they assumed that pairs of neighboring points in SEDs studied by EHF10 have also high-resolution ra the SEDs defined a power law, integrated each segment dio (observed with the Very Large Array ~ VLA ~ or individually and summed the segments to obtain Lbo!. VLBAjVLBI) and infrared observations available. In or From this set of best sampled SEDs they estimated the der to select the best SEDs to be modelled from the sam average "bolometric correction" from the 2-10 keV lu ple of EHFlO, we applied the following selection criteria: minosity to the bolometric luminosity (Lbol 50Lx ), we selected only those objects for which their X-ray flux which they used to obtain Lbol for the remaining ob is not an upper limit. We also demand that there is a jects, for which the SEDs are not as well sampled. These determination of the black hole mass. These selection cri bolometric luminosities are listed in Table 1. teria leave us with 24 LINERs. In three of these objects (NGC 404, NGC 5055 and NGC 6500) the emission is 3. MODELS FOR THE ACCRETION FLOW AND likely to be dominated by a stellar population (EHFlO). JET Hence we discard these three LLAGNs and we are left We fit the observed broadband SEDs of the LLAGNs in with 21 objects which are listed in Table 1. This table our sample using a model which consists of three compo also lists their corresponding Hubble and LINER Types, nents: an inner ADAF, an outer truncated thin accretion black hole masses, bolometric luminosities and Edding disk and a jet. The components of the model are illus ton ratios. tratcd in Figure 1. We describe here the main features According to the quality of the available data, we can of this model. further classify our sample of LINERs in two groups. Group A contains the objects that have the data with the best quality available. For instance, the radio, op tical and UV bands have each at least one data point which is not an upper limit to the luminosity. Obviously, the objects in this group provide better constraints to the accretion-jet models. Group B comprises the sources that provide not as good contraints to the models, be cause they lack observational constraints in the radio to UV region of the spectrum. Some objects in this group have only upper limits to the flux in the UV, others have no data points or only upper limits in the radio band. All the objects in both groups have observations in the near IR band which are treated as upper limits. We take this approach because the observations in the near-IR were ADAF taken with lower spatial resolutions, i.e. larger apertures that include considerable contamination from the emis sion of the host galaxy. Therefore, near-IR observations can only be considered as upper limits to the nuclear emission. The masses of the 5MBHs were estimated from the Figure 1. Cartoon illustrating the model for the central engines of LLAGNs. It consists of three components: an inner ADAF, an lHBH (J stellar velocity dispersions using the relation outer truncated thin disk and a relativistic jet. ship (Ferrarese & Merritt 2000; Gebhardt et al. 2000: Tremaine et al. 2002), with the exception of NGC 266, whose black hole mass was estimated from the measured 5 GHz radio and the 2-10 keV X-ray luminosities the correlation of Heinz & Di i\latteo of black hole NGC 4486
mass determinations the estimated masses are consistent a factor of 2. Due to intrinsic scatter in the fundamental the mass estimated for NGC 266 is to an a factor of 10 4 Nemmen et al.
Table 1 Sample of galaxies and their basic propertiesa
b Galaxy Hubble Distance LINER Lx Lbol/LEdd SED Type (Mpc) Type (erg s-I)C typeC
42 4 NGC 266 SB(rs)ab 62.4 (1) 7.6f L1 7.4 X 1040 2.2 X 10 4 X 10- B NGC 1097 SB(rl)b 14.5 (1) 8.1 Ll 4.3 x 1040 8.5 X 1041 5 X 10,,5 A NGC 1553 SA(rl)O 17.2 (2) 7.9 L2/T2 1.3 x 1040 3.8 X 1041 4 X 10-5 B NGC 2681 SBA(rs)O/a 16.0 (2) 7.1 Ll 6.1 x 1038 1.8 X 1040 1 X 10-5 B 41 5 NGC 3031 (M81) SA(s)ab 3.6 (3) 7.8 S1.5/Ll 1.9 x 1040 2.1 X 10 3 X 10- A NGC 3169 SA(s)a 19.7 (1) 7.8 L2 1.1 x 1041 3.3 X 1042 4 X 10-4 B 4 NGC 3226 E2 21.9 (2) 8.1 Ll 5.0 x 1040 1.5 X 1042 1 X 10- B NGC 3379 (M105) El 9.8 (2) 8.2 L2/T2 1.7 x 1037 5.1 X 1038 3 X 10-8 B 41 43 4 NGC 3998 SA(r)O 13.1 (2) 8.9 Ll 2.6 x 10 1.4 X 10 1 X 10- A NGC 4143 SAB(s)O 14.8 (2) 8.3 L1 1.1 x 1040 3.2 X 1041 1 X 10-5 A NGC 4261 E2-3 31.6 (2) 8.7 L2 1.0 x 1041 6.8 X 1041 1 X 10-5 B NGC 4278 EI-2 14.9 (2) 8.6 L1 9.1 x 1039 2.7 X 1041 5 X 10-6 A NGC 4374 (M84, 3C 272.1) El 17.1 (2) 8.9 L2 3.5 x 1039 5.0 X 1041 5 X 10-6 A NGC 4457 SAB(s)O/a 10.7 (4) 6.9 L2 1.0 x 1039 3.0 X 1040 3 X 10-5 B NGC 4486 (M87, 3C 274) EO-l 14.9 (2) 9.8 L2 1.6 x 1040 9.8 X 1041 7 X 10-6 A 40 NGC 4494 EI-2 15.8 (2) 7.6 L2 9.2 x 1038 2.8 X 10 6 X 10-6 B 39 41 5 NGC 4548 (1\191) SBb(rs) 15.0 (3) 7.6 L2 5.4 x 10 1.6 X 10 3 X 10- B NGC 4552 (M89) E 14.3 (2) 8.2 T2 2.6 x 1039 7.8 X 1040 4 X 10-6 A NGC 4579 (M58) SAB(rs)b 21.0 (4) 7.8 L2 1.8 x 1041 1.0 X 1042 1 X 10-4 A NGC 4594 (MI04) SA(s)a 9.1 (2) 8.5 L2 1.6 x 1040 4.8 X 1041 1 X 10-5 A NGC 4736 (M94) (R)SA(r)ab 4.8 (2) 7.1 L2 5.9 x 1038 1.8 X 1040 1 X 10-5 A
The information in this table was obtained from EHF10. sec text. b The number in parenthesis gives the source and method of the distance as follows: (1) From the of Tully (19S8), determined from a model for pecuiiar velocities and assuming Ho 75 km From Tonry at al. (2001), used the surface on;gULllU," fiuctation method. Following Jensen et al. (2003), the distance modulus reported by Tonry et al. (2001) was corrected S1l[}u"cr,mQ' 0.16 mag; (3) From Freedman et al. (1994,2001), who used Cepheid variables; (4) From Gavazzi ct al. (2009) who used Tully-Fisher method. e Lx is the X-ray luminosity in the 2 - 10 keV range. d The bolometric luminosities of NGC 1097, NGC 3031, NGC 3998, NGC 4374, NGC 4486. NGC 4579 and NGC 4594 were estimated by integrating the SEDs. For all other galaxies Lbol was determined by scaling Lx as described in §2. C Classification of the SED depending on the quality of the data sampling (sec Section 2). f The mass estimate for NGC 266 is subject to a large uncertainty ("" 1 dex) since it is based on using the fundamental plane of MerIon;' Heinz & OJ Matteo (2003) (sec text).
& Gammie 2004) and analytical work (l' (2000); Yuan, Quataert & Narayan (2003). Obtaining We adopt a jet model based on the internal shock sce the global solution of the differential equations for the nario which is used to interpret gamma-ray burst after structure of the accretion flow is a two-point boundary glows (e.g., Piran 1999; Spada et al. 2001; see Yuan, Cui value problem. This problem is solved numerically using & Narayan 2005 for more details). This model has been the shooting method, by varying the eigenvalue j (the adopted in previous works to understand the broadband specific angular momentum of the flow at the horizon) SEDs of X-ray binaries and AGNs (Spada et al. 2001; until the sonic point condition at the sonic radius Rs is Yuan, Cui & Narayan 2005; I\emmen et al. 2006; Wu, satisfied, in addition to the outer boundary conditions. Yuan & Cao 2007). According to this jet model, some There are three outer boundary conditions that the fraction of the material in the innermost regions of the ADAF solution must satisfy, specified in terms of the accretion flow is transferred to the jet producing an out three variables of the problem: the ion temperature Ti , flow rate Mjct and a standing shock wave in the region the electron temperature Te and the radial velocity v (or of the jet closest to the black hole is formed. This shock equivalently the angular velocity n). Following Yuan, wave is created from the bending of the supersonic ac Ma & I\arayan (2008), when the outer boundary of the cretion flow near the black hole in the direction of the ADAF is at the radius Rout 104 Rs (where Rs is jet. We calculate the shock jump (Rankine-Hugoniot) the Schwarzschild radius) we adopt the outer bound conditions to find the electron and ion temperatures of ary conditions Tout,i 0.2Tvir , Tout.e 0.19Tvir and the plasma (Te and T;). We find that the jet spectrum Aout = 0.2, where the virial temperature is given by is not very sensitive to changes in Te and Ti, since the 12 Tvir 3.6 x 10 (RsIR) K, A vlcs is the ]'v1ach emission is completely dominated by non-thermal elec number and Cs is the adiabatic sound speed. When trons (see below). We therefore adopt Ti 6.3 x 1011 K 2 9 the outer boundary is at Rout rv 10 Rs we adopt the and Te 10 K in our calculations of the jet emission. boundary conditions Tout,i 0.6Tvir , Tout,e 0.08Tvir The jet is modelled as having a conical geometry with and Aout 0.5. After the global solution is calculated, half-opening angle ¢ and a bulk Lorentz factor f j which the spectrum of the accretion flow is obtained (see e.g., are independent of the distance from the black hole. The Yuan, Quataert & Narayan 2003 for more details). We jet is along the axis of the ADAF and makes an angle i verified that if these boundary conditions are varied by with the line of sight. The internal shocks in the jet are a factor of a few, the resulting spectrum does not change presumably created by the collisions of shells of plasma much. with different velocities. These shocks accelerate a small fraction ~e of the electrons into a power-law energy dis 3.2. Thin disk component tribution with index p. The energy density of accelerated Outside the ADAF there is an outer thin accretion electrons and the amplified magnetic field are described disk with an inner radius truncated at Rtr Rout and by two free parameters, Ee and EB. Following Nemmen extending up to 105 Rs. Therefore, in practice the outer et al. (2006); Wu, Yuan & Cao (2007), we adopt in our radius of the ADAF corresponds to the transition radius calculations of the jet emission the values dJ 0.1 ra to the thin disk. The other parameters that describe dians, c'e 10% and fj 2.3, which corresponds to the thin disk solution are the inclination angle i, the vic;::::; 0.9 (except in the case of M87, which has an in fj black hole mass and the accretion rate A10ut (the same as dependent estimate of available). Unless otherwise the accretion rate at the outer boundary of the ADAF). noted, we adopt i 30°. Therefore, there are four free 4 p, Ee EB. In the cases where Rout rv 10 Rs we simply ignore the parameters in the jet model: l'vIjct, and In our contribution of the thin disk spectrum. calculations we consider the synchrotron emission of the The thin disk emits locally as a blackbody and we take jet, with the optically thick part of the synchrotron spec into account the reprocessing of the X-ray radiation from trum contributing mainly in the radio and the optically the ADAF. This reprocessing effect has only a little im thin part contributing mainly in the X-rays. pact on the spectrum of the thin disk though, with the resulting SED being almost identical to that of a stan 3.4. Free parameters and fit procedure dard thin disk (e.g., Frank, King & Raine 2002). When fitting the observed SEDs with our coupled 3.3. Jet component accretion-jet modeL we have eight free parameters. Four of these parameters describe the emission of the accretion The SEDs of LLAGNs are generally radio-loud (Ho flow: the accretion rate 1\;font, the transition radius be 1999: Ho & Peng 2001; Ho 2002: Terashima & \Vilson tween the inner ADAF and the outer truncated thin disk 2003: EHFlO): but see ~faoz 2007: Sikora, Stawarz & Rtr , the fraction of viscously dissipated energy that di Lasota .. The radio of these SEDs is rectly heats the electrons 8 and the of the wind from the ADAF s. The other four parameters character- ize the emission: the mass-loss rate in the electron energy index p, and the electron HW'bu.~V"L energy parameters and EB. and to be correlated, but mechanism of formation we vary 1l1UXjJeIHH:;U.GlY in our fits. We < 1. Since the ADAF it is also of interest to which the accretion 6 Nemmen et al. rate is calculated at the radius of the innermost stable corresponding reference from which mBondi was taken. circular orbit for a Schwarzschild black hole. lj~~s corresponds to the jet power estimated either from Throughout this paper we will use the dimension observations or using the correlation between jet power less mass accretion rates m IV1 I 1~1Edd, noting that and radio luminosity of Merloni & Heinz (2007). lj'::tO d the Eddington accretion rate is defined as 2V1Edd == represents the jet power resulting from our jet model, 9 1 2 22Ail(10 M 0 ) yr- assuming a 10% radiative effi calculated as flet Mjct f; c . ciency. We will also express the black hole mass in terms 4.1. The case of NGC of the mass of the sun, m Ai IAi0 , and the radius in 4594 terms of the Schwarzschild radius, r RI Rs. Pellegrini (2005) studied Chandra X-ray observations Our fitting procedure can be summarized as follows. of NGC 4594 and derived the Bondi accretion rate . 2+6 .8 10-3 We vary the free jet parameters in order to fit the radio mBondi -1.3 x . observations, since the radio is emitted predominantly by The SED of NGC 4594 is plotted in Figure 2, together the jet. Once we fit the radio band with the jet model, with two different spectral fits. The left panel of Figure we try to fit the truncated thin disk model to the IR 2 shows an ADAF-jet model in which the ADAF com optical data, in order to constrain the transition radius ponent (dashed line) completely dominates the emission and L~1out (keeping in mind that the theoretical spectrum from the 1R to the X-ray bands and is consistent with the should not exceed the observed luminosities). We then available optical-UV and X-ray data. In this model, the use the X-ray data to constrain the ADAF component jet (dot-dashed line) dominates the radio emission and in order to refine the estimates of R tr and lI;:fout, and contributes only weakly to the X-ray flux. The solid line to estimate sand 6. Depending on the combination of corresponds to the sum of the ADAF and jet emission. parameters that we use, the jet can have an important The parameters of the ADAF model are mout contribution to the emission not only in the radio, but 6.3 x 10-3 (consistent with the Bondi accretion rate es 4 also in the X-ray band. We sum the emission of the timated by Pellegrini 2005) , rout 10 , 6 0.01 and inner ADAF, outer thin disk and jet, and compare this s 0.3. The jet parameters are mjet 9 x 10-7 , P 2.3, 3 sum with the observed SEDs. Ee 5 X 10- and EB 0.03. The jet kinetic power is We explore the parameter space of the models consid flet! Lbol ~ 4. In other words, the kinetic power carried ering the many possible fits to the data. We search the by particles in the jet exceeds the overall radiative power. literature for independent constraints from other works The ratio of the mass-loss rate in the jet to the accretion on the values of the model parameters, such as the mass rate estimated at 3Rs ismjct!m{3Rs) ~ 1.6 x 10-3 . In accretion rate, inclination angle and the transition ra other words, only ~ 0.2% of the mass that is ultimately dius, as well as the jet power which is obtained from the accreted by the black hole is channeled into the jet. jet model. The dotted line in the left panel of Figure 2 shows an ADAF + truncated thin disk model for which rtr 300, 4 mout 9.1 x 10- , 6 0.01 and s 0.1. The thin disk emission corresponds to the "bump" at lO{1m. This model demonstrates that accretion flows with a much smaller transition radius are also consistent with the data. Since we have only upper limit points in the mid to near-IR for NGC 4594, the available data are not suf ficient to constrain the presence of a truncated thin disk in this source. The right panel of Fig. 2 shows a model for the SED of N GC 4594 in which the jet dominates the radio and X-ray emission. In fact, the right panel shows that the relaUvistic jet can account well for the entire observed SED. The jet parameters aremjct = 4.5 x 10-7 , P 2.01. 2 42 Ee = 0.8 and EB = 3 X 10- , with flet 8.4 X 10 erg flet!Lbol ~ 4 and mjct/m(3Rs) ~ 0.009. \Ve display in the right panel of Figure 2 one illustra tive ADAF model which is consistent with the possibility that the emission dominates in this source. i.e. the ADAF contribution in all bands (except at 1 . is very small to the The ADAF parameters are , 6 0.01 and s 0.3. \,ie can that result from type of models. We list whenever available Bondi accretion rate and the SED Models for LLAGNs in LINERs 7 44 1m lOem lem Imm lOO"m lO"m l"m loooA .1keV lkeV lOkeVIOOkeV 44 1m lOem lem Imm lOO"m lO"m l"m loooA .1keV lkeV lOkeVIOOkeV NGC4594 NGC4594 43 43 42 42 ::- 41 ::- 41 I I III III E' 40 E' 40 Q) Q) I \ ~" 39 ~" 39 I \ I \ ---- 0; 0; \ ..Q I 38 ..Q 38 ! ! I 37 36 35 10 12 14 16 18 20 8 10 12 14 16 18 20 log(v/ Hz) log(v/ Hz) Figure 2. Models for the SED of NGe 4594 (Sombrero). The dashed and dot-dashed lines show respectively the emission from the ADAF and jet, while the solid line shows the sum of the radiation from these components. Left: model in which the ADAF dominates the observed X-ray emission. The dotted line shows for comparison an ADAF + thin disk model in which the transition radius is 300Rs. Right: model in which the jet dominates the X-ray output. See the text for the parameters. this section. In the first type. the emission from the the jet power estimated by MerIoni & Heinz (2007) based ADAF dominates the observed X-rays; in the second type on the calorimetry of the X-ray cavities observed with of model, the jet emission dominates the X-rays. We Chandra (3.9 x 1042 erg S-l). The ratio injct /in{3Rs ) is will hereafter use the abbreviations AD (as in ADAF 1.5 x 10-3 . dominated) and JD (as in jet-dominated) when referring The right panel of Fig 3 shows a model in which the to the former and latter types of models, respectively. A jet dominates the radio and the 1-100 keY X-ray band. third type of model is also possible in which the jet and The emission in the region between 1000 A and 1 ke V is the ADAF contribute with similar intensities to the high dominated by the Compton peak of the ADAF spectrum. energy emission. These results apply not only to the five As was the case for the previous model, the IR emission LINERs discussed in more detail in this section but also is dominated by a truncated thin disk with a small tran to the other sources in our sample with a few exceptions. sition radius (rtr 30) which is even smaller than the AD fit. At v > 100 keY the bremmstrahlung emission of 4.2. NGC 4314 the ADAF is the dominant radiation process. The pa 4 A prominent jet resolved with the VLA is observed rameters of ADAF areinout 1.5 x 10- (in agreement to create cavities in the X-ray emitting gas (Allen et al. with the Bondi rate) and 6' .5 0.3. The jet parame- 6 3 2006; Finoguenov et al. 2008). The Bondi accretion rate ters are injct 1.6 x 10- , P 2.2, Le 9 X 10- and 4 3 42 isli~Bondi = 4 X 10- (Pellegrini 2005; Allen et al. 2006). EB 8 x 10- , with /let 8.4 X 10 erg ;:::::: 17 L bol' The left panel of Figure 3 shows an ADAF-jet model The ratio injctlin(3Rs) is injct/in(3Rs) ;:::::: 0.02. There (dashed line) in which the ADAF completely dominates are no data available to constrain the predicted ADAF the emission from the near-IR to the X-ray bands and bumps at soft and hard X-rays in this modeL Notice explains well the available optical-UV and X-ray data, that. similarlv to the JD fit to the SED of NGC 4594. the as was the case for NGC 4594. The synchrotron peak shape of X-r~y spectrum from the ADAF with <5 . 0.3 of the ADAF also dominates the emission in the range (dashed line) does not agree with the data. '" 1 mm 100 pm. The jet (dot-dashed dominates the radio emission, but contributes weakly to the X-ray 4.3. NGC flux. The thin disk dominates the IR emission and its Di ~latteo et a1. (2003) previously calculated the Bondi contribution peaks at A cv 10 pm. a "red accretion rate using Chandra X-ray data and found it the SED as to the "big blue to be '" 0.1 ;:::::: 7 x &. Blaes 1999; of M87 The parameters of the accretion flow 3.95 6' 0.0l and.5 0.1. mass-loss case for NGC ·i594. the mid to near-IR data and fonnd are insufficient to make case of a truncated thin disk SED. and similar models with much values observations of of are not ruled out the available IR data. and lOG < The 4 x Le & Macchetto mod- 0.01 power 2.1 and i 10°. kinetic which is in excellent agreement with estimated to be in the range 8 Nemmen et al. 1m IOem Iem Imm lOOjlm lOp:m Ipm 1000A .1keV 1keV 10keV100keV 1m IOem Iem 1mm 100"m 10"m 1"m 1000A .lkev 1keV 10keVlOOkeV 44 44 NGC4374 NGC4374 43 rr 43 rr 42 42 ::- 41 ::- 41 I I Vl Vl e' 40 e' 40 (l) • (l) / ? . ~' 39 ' 39 I / ~ j 0; ! 0; / j \ / ..2 38 ..2 38 , / I I j T I T ! \1 37 / 37 I I I I 36 I 36 I 35 35 8 10 12 14 16 18 20 8 10 12 14 16 18 20 log(v/ Hz) log(v/ Hz) Figure 3. Models for the SED of NGC 4374/M84 showing the emission of the ADAF (dashed), jet (dot-dashed), truncated thin disk (dotted) and the total emission (solid). Left: model in which the ADAF dominates the observed X-ray emission ("AD model"). Right: model in which the jet dominates the X-ray output ("JD model"). 1043 1044 erg (e.g., Bicknell & Begelman 1999; Yu & Ho (2009) instead successfully fit the data with a Owen, Eilek & Kassim 2000; Allen et al. 2006; Merloni JD model using p 0.5. & Heinz 2007), therefore the jet power resulting from fitting our jet model must be within this range. 4.4. NGG 3031 The left panel of Figure 4 shows an ADAF-jet model in which the ADAF dominates the optical-UV (OUV) This source is among the brightest LLAGNs known and X-ray emission (i.e. AD-type model), while the jet since it is the nearest AGN besides Centaurus A and dominates the radio band. The parameters of the ac- has been the subject of a broadband multiwavelength monitoring campaign (Markoff et al. 2008; Miller et al. cretion flow are mout 5.5 x 10-4 (in agreement with 4 2010). Due to the many available observational con the Bondi rate), rout 10 , 8 0.01 and s 0.1. 8 straints, accretion-jet models can be well constrained for The jet parameters are mjet 5 x 10- , P 2.6. this LLAGN. For illustrative purposes, here we will re 3 3 Ee 10- and EB 8 x 10- . The jet power is given port our modelling results using the data compiled by 42 by ?jet 6 X 10 erg S-l, with ?jet/ Lbol ~ 6 and EHFlO. 5 Tnjct/m(3Rs) ~ 9 x 10- . Devereux & Shearer (2007) modeled the profile of the The right panel in Fig 4 shows a jet model which ex broad double-peaked Hoc line with a relativistic thin disk plains quite well the radio and X-ray observations (JD model. They were able to explain the profile with an type model), although it underpredicts the OUV data inclination angle of 50°. Such a high inclination angle is by a factor of a few. The jet parameters are r1Ljet supported by radio observations of the jet (Bietenholtz, 8 3 3 3 X 10- , P 2.3, Ee 10- and EB 8 x 10- , with Bartel & Rupen 2000). The Hoc line profile of M81 is 42 ?jet 9 X 10 erg s-l and ?jet/ Lbol ~ 9. consistent with an inner radius of ~ 280 - 360Rs for the The SED of M87 was previously fitted using ADAF line-emitting thin disk (Devereux & Shearer 2007). In and/or jet models (Di Matteo et al. 2003; Yuan, Yu & Ho our models for the SED, we therefore adopt an inclination 2009; Li et al. 2009). Di Matteo et al. (2003) modelled the angle i 50° and we impose the constraint on the models SED of M87 with an ADAF model using different values that rtr .:S 360. of 8 but not including mass-loss sO). The model The left panel of Figure 5 shows the AD fit model for by Li et al. (2009) is quite similar to that of the SED of ~I81. In this model, the synchrotron radi Di et al. (2003) although the former incorporate ation from the jet is the dominant mechanism of radio general relativistic corrections. Di ;\latteo et al. (2003); emission. In the wavelength range between ~ 10 (.lm and Li et al. (2009) obtained that the ADAF emission with no ~ 1 (.lm a "red can be seen which corresponds to mass-loss the SED and results emission of the truncated thin disk. The thin disk in accretion rates consistent with Bondi rate. Our dominates the emission in this band. In the interval be- AD model is similar to that of Di ;\fatteo al. l and ~ 100 the ADAF is the UV'H'HCHH but also effect of The ADAF also the flow numerical simulations. UVHHHCLv"O the emission for less 1 Ii un- Yuan, Yu & Ho tried to model the SED The sum the radiation of all components is an ADAF model 0.5 but failed to fit to data as the solid line. The accretion flow with an AD model. The reason is that for 3 ,rtr 360 8 (8 > 0.1) and small accretion rates t5 0.01 and s param- 13 ADAF spectrum is harder than 2 10- • p 2.2, Ee 0.1 and ICB 0.01. SED Models for LLAGNs in LINERs 9 44 1m 10em 1em lmm 100~m lO~m l~m loooA .1keV lkeV lOkeV100keV 44 1m 10em 1cm 1mm lOOl'm lO"m 11'm 1000A .lkev 1keV 10keV100keV NGC4486 NGC4486 43 43 42 T 42 .::- 41 .::- 41 I I VI VI • e' 40 e' 40 Qj • Qj • / I f ',if 39 T ./ \ / ~. 39 • ~ • CI • C; .Q 38 .Q 38· 37 37 36 36 10 12 14 16 18 20 358~----1~0~--~1~2-----1~4~--~1~6----~1~8~--~20 log(v/ Hz) log(v/ Hz) Figure 4. Same as Figure 3 for M87 !NGC 4486. 44 1m 10em 1em 1mm 100~m lO~m l~m loooA .1keV 1keV 10keV100keV 44 1m lOem 1cm 1mm lOO"m 10~m l"m lOocA .lkev IkeV lOkeV100keV NGC3031 NGC3031 43 43 42 42 .::- 41 .::- 41 I I VI VI e' 40 e' 40 Qj Qj ·39 ~ , C; \ .Q 38 • 37 I 37 I / I 36 i 36 I I i I / 35 358~----~10~--~1~2----~14~--~1~6----~~--~18 20 8 10 12 14 16 18 20 log(v/ Hz) log(v/ Hz) Figure 5. Same as Figure 3 for M81. The jet power is given by ~ct 8 X lO41 erg with rameters of the accretion flow are lnout 8 x lO-4. ~ct!Lbol;:::: 4 and TnjctFn(3Rs);:::: lO-3. 50. 5 0.3 and s 0.6. The parameters of In this AD modeL a low value of 5 0.01 is required in 1.2 x lO-5, P = 2.05, Ee = 0.6 and order to reproduce the X-ray spectral shape character 4.8 x lO42 erg S-l, ;:::: 23 and ized bv r = 1.88. As was the case for M87. if we increase ;:::: 3 x the v~lue to 5 0.3 keeping the other parameters fixed two different transition radii in the fits except s OA the predicted value of the photon index is 5. The accretion flow model with reduced and the ADAF spectrum becomes harder than the UV data panel of the smaller transition radius of rt.r 50 on the The 5 shows a JD model does better overall of the U~HUHU\LO the radio. data. Such transition radius seems also to be fa- In the vored of the Fe Ka emission line the ADAF is et al. note however that with the no observa- near-IR data it is not constraints to the in this Between constraint on of truncated thin disk. ;:::: lO 11m and 6000 A the truncated thin disk dominates Tv181 has been of several efforts the emission as is case for the AD model. The pa- et al. 1999: et al. 2008: Yll & 10 N emmen et al. Ho 2009). Our goal here is not to discuss extensively this UV data. The parameters of the jet are mjet 3.5 x 6 5 particular LINER since this was done elsewhere (Miller 10- , P 2.01. Ee 0.75 and EB 3 x 10- (!let 43 et al. 2010), but rather put the general features of our 1.8 X 10 erg ,!let/Lbol ~ 1.3 and mjct/m(3Rs ) ~ AD and JD models for M81 in context with the results 0.025). For illustration, we also show in the right panel found by other authors. an ADAF model computed with parameters such that 4 Quataert et al. (1999) did not consider the jet contribu its contribution in X-rays is weak (rhout 4 x 10- , tion and favored an AD scenario for the origin of the SED rtr 100, 8 0.3 and s 0.3). Note that, as for (they used an "old" ADAF model assuming IS 0.01 and the cases discussed in the previous section, for values of s 0, i.e. no winds). l\Iarkoff et al. (2008): Yuan, Yu & IS ~ 0.3 the ADAF X-ray spectrum is harder than the Ho (2009) on the other hand were also able to explain the data. observations, but in the context of a JD model. Yuan, The SED of this NGC 3998 was modelled before by Yu & Ho (2009) also considered the simultaneous contri Ptak et al. (2004). Here we confirm the main results of bution of the ADAF and jet but restricted themselves to their work, namely that both AD and JD models are able IS 0.5 in their fits. Mainly for this reason, Yuan, Yu & to account well for the broadband SED. Ho (2009) were unable to find an AD model for the SED, since as we mentioned before, ADAF X-ray spectra with 5. FITS TO SPARSELY SAMPLED SEDS such values of IS are quite hard. It should be noted that Quataert et al. (1999) esti We present in this section the model fits to the 16 SEDs mated a transition radius which is twice (rtr 100) the that were not discussed in the previous section. value favored in the present work and a much higher The SED fits are shown in Figures 7-12. In the sub accretion rate. The reason for this is that these authors sections below, we briefly describe the details of the fits previously fitted the SED of M81 using an outdated value to the SED of each object. The model parameters are of the black hole mass, which was fifteen times smaller summarized in Table 2. and more uncertain than the value we use (estimated via spatially resolved gas and stellar kinematics, see EHFI0). 5.1. NCG 0266 As a consequence, the multicolor blackbody radiated by The AD model accounts slightly better for the best-fit their thin disk for the same accretion rate and transition X-ray slope, but note the pronnounced uncertainty on radius that we use is considerably hotter and fainter. As the value of observed photon index. The JD model re a consequence, they needed to increase rtr and m. quires p < 2 which is below the usual range 2 < p < 3 suggested by relativistic shock theory (Bednarz Os 4.5. NCG 3998 & trowski 1998; Kirk et al. 2000). The shortest wavelength (1750 A) UV data point in the SED of NGC 3998 presented in EHFlO is anoma 5.2. NCG 1097 lously high because of variability (Devereux 2011). As discussed by Devereux this data point was obtained many Note that even though the SED of NGC 1097 is as years before all the other observations, when the source well sampled as many of the LLAGNs in Section 4, we was much brighter. For this reason, we exclude this lTV chose to include it in this section rather than discussing measurement from our analysis and plots. it in more detail in §4 because its SED was already well The left panel of Figure 6 shows an AD model in which studied by Nemmen et al. (2006). the ADAF dominates the emission from the IR to the We take into account here the HST lTV spectrum which X-ray bands and explains well the available optical-lTV was not included in EHFlO because it contains contri and X-ray data. As usual, the jet dominates the radio butions from an obscured nuclear starburst in addition to the AGN. This spectrum was obtained from Storchi emission. The ADAF parameters are 7.2 x 10-3 • 4 Bergmann et al. (2005) who studied and modeled it in rout 10 , IS 0.1 and s 0.4. The jet parameters are 6 3 detail. 1. 7 x 10- , P 2.2, Ee 0.01 and 10- . Our models do not take into account the contribution FOr the resulting jet power from this model 9 x 42 3 of the nuclear starburst. Therefore. the AD and JD mod 10 erg , mjet/m(3Rs) 6 x 10- ), the jet kinetic ~ els do not reproduce the "UV bump" between 1000 energy is quite modest compared to the radiative output ~ A and ~ 7000 A Fig. 3 in Storchi-Bergmann et al. (!let.! Lbol ~ 0.6). In the AD model abo\'e we adopted a large outer radius 2005). for the ADAF, but smaller radii are not ruled out the The AD model displayed in Figure 7 corresponds to data. For instance. we are able to obtain a reasonable the model obtained by Nemmen et al. (2006). The JD 3 model is also able to account for the whole SED, though fit to the SED with = 500. = 10- and 5 IS 0.01. This model is consistent with the IR it does not reproduce the slope of the X-ray spectrum limits and accounts the data. The as well as the AD model. the JD fit. radius cannot be much smaller this otherwise the available data there is no need to the emission of truncated thin disk would exceed the contribution of ADAF. Hence we do IR limits. Furthermore, noted Ptak ADAF model in the of 7. the lack of Fe Ka line emission also suggests of not so small. 5.3. NCG 1553 of 6 shows The Bondi accretion rate was estimated Pellegrini UVlllllldLt;:, the emission. Note that accounts Even the JD model accounts for the es the X-rays. it somewhat underestimates timated fails to fit the the X-ray spectrum SED IVlodels for LLAGNs in LINERs 11 44 1m lOem 1em 1mm lOO~m lOMm l~m loOoA.1keV 1keV lOkeV100keV 44 1m lOem Iem 1mm lOOMm lO~m 1Mm lOOoA.lkeV IkeV lOkeVIOOkeV NGC3998 NGC3998 43 43 42 42 ::- 41 I III e' 40 Q} \ / I • \ / I I 10 12 14 16 18 20 12 14 16 18 20 log(v/ Hz) log(v/ Hz) Figure 6. Same as Figure 3 for NGC 3998. even with a small value of p. vVe take this as evidence with the findings of Soria et al. (2006a,b) for a sample of that this source is unlikely to be JD. The estimated mO\lt quiescent early-type galaxies. is consistent with the lower limit on mBondi obtained by Pellegrini (2005). 5.8. NGC 4143 The contribution of the truncated thin disk is required 5.4. NGC 2681 in order to account for the optical emission. The required For this LLAGN, there are not enough optical obser transition radius in particular is rtr 70. vations to fit the truncated thin disk model and estimate The JD model requires a value of p smaller than the the transition radius. usual values suggested by relativistic shock theory. as was the case of NGC 266. 5.5. NGC 3169 As was the case of ;\IGC 2681, for this LLAGN there are 5.9. NGC 4261 not enough optical observations to fit the truncated thin For this object, estimates of the Bondi rate, inclination disk model and estimate the transition radius. The JD angle and jet power are available (Gliozzi. Sambruna & model accounts well for the available data. The inferred Brandt 2003; Merloni & Heinz 2007). There are two in extreme values of Ee and EB imply that essentially all the dependent estimates of the jet power. The first is based energy in the post-shock region of the jet is carried by on energetic considerations and the VLBA observations the particles. of the pc-scale jet, which yield a lower limit to the jet power (Gliozzi, Sambruna & Brandt 2003). In the sec 5.6. NGC 3226 ond method we use the 5 GHz specific luminosity and The SED of this LLAGN is well fitted by both an AD the lVIerloni & Heinz (2007) correlation obtaining a much and JD type of models. As is the case of NGC 2681, there higher jet power estimate. are no good optical band constraints on the emission of Note that the accretion rate that we obtain from the the truncated thin disk. AD fit is somewhat smaller than This AGN is likely to be strongly affected by extinction in the OUV 5.7. NGC 3379 band (EHFlO). Hence, the OUV measurements probably This source has only two data points outside the X-ray do not capture the emission of the central engine. For band. one in the radio and the other in the both this reason, it is not surprising that the models overpre of which to upper limits. dict the OUV emission by almost one order of HW,,,,".,"L'U,," the in 9. rate was estimated David 9 shows that the AD 5.10. NGC SED the few constraints available. The radio emission of NGC 4278 was but there are no data to constrain the model ied in the context of ADAF models 111 case so we don't include it. The data & Fabian who found that s are not to constrain well the transition radius. order for enllSSlon The accretion rate the AD model is more not to overestimate the flux. Di .Matteo. Carilli than an order of than. One & Fabian (2001) also estimated that the Bondi rate is this result is that the accretion rv 0.001 0.01. Giroletti et al. found a gas released stars. This is in line two-sided radio structure for the data. 12 Nemmen et al. lOcm lcm Imm lOO~m lOpm l~m loooA .1keV lkeV lOkeVIOOkeV 1m lOem lem lmm lOOpm lOMm lpm loooA .1keV lkeV lOkeVlOOkeV 44 1m 44 NGC0266 NGC0266 43 43 42 42 ., 41 41 I III III E' 40 E' 40 Q) Q) I I • 39 ! ~ I ~' 39 0; I 0; .E 38 .E 38 • 37 f 37 I ! ! I 10 12 14 16 18 20 10 12 14 16 18 20 10g(lI/ Hz} 10g(lI/ Hz} 1m lOem lem Imm lOOMm lOpm Ipm loooA .1keV lkeV lOkeVIOOkeV lOem lem Imm lOOpm lOpm Ipm loooA .1keV lkeV lOkeVIOOkeV 44 44 1m NGCI097 NGC1097 43 43 42 42 11 t~ ., 41 ., 41 III III E' 40 E' 40 Q) Q) ~. 39 ~. 39 0; 0; .E 38 38 ! .E J 37 37 36 1// 36 35 35 8 10 12 14 16 18 20 8 10 12 14 16 18 20 10g(lI/ Hz} 10g(lI/ Hz} lOem lcm Imm IOOMm IO~m lpm loooA .1keV lkeV lOkeVIOOkeV lOem lem Imm lOOpm lOpm lpm looOA.lkeV lkeV lOkeVIOOkeV ,. ::[ NGelSS3i NGC1553 42' 42 .::- 41 .::- 41 I I III I '" E' 40 I E' Q) Q) I I 10g(lI/ Hz) 10g(lI/ Hz) Figure 7. SEDs and coupled accretion-jet models for NGC 0266. NGC 1097 and NGC 1553. The left panel shows the AD models for each object wbile the panel displays the JD models. The dashed, dotted and dot-dashed lines to the emission from the ADAF. truncated thin and jet, respectively. The solid line when present represents the sum of the from all components. SED Models for LLAGNs in LINERs 13 1m lOcm lcm Imm lOO~m lO"m l~m loooA .1keV lkeV lOkeVIOOkeV 1m lOcm lcm Imm lOOl'm lOl'm ll'm loooA .1keV lkeV lOkeVIOOkeV 44 44 NGC2681 NGC2681 43 43 42 42 ;:- 41 ;:- 41 I I III III e' 40 e' 40 Q) Q) , 39 ~. 39 ~ Oi Oi .2 38 I .2 38 . i " I 37 I 37 T I 36 I 36 l I 35 10 12 14 16 18 20 8 10 12 14 16 18 20 log(v I Hz) log(v/ Hz) Imm lOOl'm 1OI'm l"m loooA .1keV Imm lOO"m lO"m ll'm loooA .1keV 44 1m lOcm Iem lkeV lOkeVIOOkeV 44 1m lOcm lcm lkev lOkeVIOOkeV NGC3169 NGC3169 43 43 42 42 ;:- 41 ;:- 41 I I III III e' 40 e' 40 Q) Q) ~. 39 ~ "/~ ~' 39 I Oi Oi .2 38 .2 38 37 T 37 • 36 I 36 ( I 35 35 8 10 12 14 16 18 20 8 10 12 14 16 18 20 log(v/ Hz) log(v/ Hz) lOcm lcm Imm lOOl'm lO"m ll'm loooA .1keV lkeV lOkeVIOOkeV 1m lOcm lcm Imm lOOl'm lO"m l"m loooA .1keV lkeV lOkeVIOOkeV 441 1m 44 NGC3226I NGC3226 43[[ 43 42 42 ;:- 41 ;:- 41 [ I III , i III e' 40 f e' Q) Q) -.., -.. ~ ~' Oi Oi .2 .2 log(v / Hz) log(v I Hz) Figure 8. Same as 7 for NGe 2681. Nee 3169 and NGe 322(). 14 Nemmen et al. Imm lOO~m lO~m l~m loooA, lkeV 1m lOem lem Imm loOOA,lkeV lkeV lOkeVIOOkeV 44 1m lOcm Icm lkeV lOkeVIOOkeV 44 lOO~m lO~m l~m NGC3379 NGC3379 43 43 42 42 ::::- 41 ::::- 41 , I III III e' 40 e' 40 CII CII ~' 39 ~' 39 Oi Oi .2 38 .2 38 f 37 \ 37 36 T 36 I/~- 35 8 10 12 14 16 18 20 358~----~10~~~1~2----~1~4~--~1~6-----1~8~---720 log(v/ Hz) log(v/ Hz) 44 1m lOem lem Imm lOO~m lO~m l~m loooA ,1keV lkeV lOkeVIOOkeV NGC4143 43 42 ::::- 41 I III e' 40 CII \ \ f 'I• 1 I •• I 37 ! I 36 358~--~~10~--~1~2-----1~4~--~1~6~---1~8~---720 log(v/ Hz) 1m IOem lem Imm lOO~m lO~m l~m loooA ,1keV lkeV lOkeVIOOkeV NGC4261 43 , III e' CII • ~f ~' Oi .2 log{vl Hz) Figure 9. Same as Figure 7 for NGC 3379. :\GC 4143 and :\GC SED Models for LLAGNs in LINERs 15 and estimated that the jet is oriented close to the line of emission. The truncated thin disk in our fits is some sight (2° :.s i :.s and mildly relativistic (fj ~ 1.5). In what hotter than the thin disk modeled by Quataert et our jet models we therefore adopt i 3° and f j 1.5. al. (1999), since their adopted black hole mass is out Both the AD and JD models require a truncated thin dated and is ~ 10 smaller than the value we use in this disk with a small transition radius ~ 30 40) in work. The transition radius can be chosen to be some order to account for the near-IR data. The values of the what smaller if the accretion rate is lower and still be transition radius that we used in the models presented consistent with the data. above (rtr 30 - 40) are not unique and models with We show together with the JD model an ADAF model larger radii can also reproduce the SED. For instance, which is the same as the one calculated for the AD fit an accretion model with rtr 100, mout 4 x 10-3 , except for the higher value of s. 5 0.1 and s 0.77 is able to explain the optical and X-ray observations. 5.16. NeG 4736 The jet emission by itself under predicts the 1 mm radio As was the case of NGC 1097, NGC 4143 and NGC observation, therefore the ADAF contribution is required 4278, this LINER requires a small transition radius in even in the JD case. In the JD fit, a small value of s is order to explain the OCV data. favored by the observations as is the case of the JD fit for NGC 4143. 6. THE DISTRIBUTION OF THE ACCRETION-JET PARAMETERS FOR LLAGNS IN LINERS 5.11. NeG 4457 Since there are only upper limits in the radio band, Our detailed SED modeling allows us to place indepen the jet power for this object was estimated using the dent constraints on the mass accretion rate onto the black hole, the jet mass-loss rate and jet kinetic power for the observation at lJ 1.5 x 1010 Hz and the Merloni & LLAGNs in our sample. These quantities are of direct Heinz (2007) correlation. relevance to studies of the feeding and feedback of the 5.12. NeG 4494 underfed supermassive black holes in nearby galaxies. It is therefore prudent to study the resulting distributions Same as NGC 4457. of the central engine parameters from our models. 5.13. NeG 4548 6.1. Accretion rates Same as NGC 4457. Given the large uncertainty in the In the previous section we showed that essentially two photon index, the X-ray spectrum does not provide good types of models (AD and JD) are able to account for the constraints for the models. SEDs, depending on the combination of parameters that 5.14. NeG 4552 we choose. We found that in most of the JD fits, the con tribution of an underlying ADAF is not required at all The Bondi accretion rate was estimated by Merloni & (cf. the JD models for NGC 4594, M87 and NGC 4579). Heinz (2007) (see also Allen et a1. 2006) from the X-ray Since the estimate of the accretion rate relies on fitting profiles of density and temperature. The kinetic power the ADAF-thin disk model to the data, in those cases no carried by the jet was estimated by Merloni & Heinz robust TiL constraint is available. We therefore show in (2007) (see also Allen et al. 2006) from the energy de the left and right panels of Figure 13 the histograms dis posited in the X-ray cavities. playing the distribution of values of mout (dimensionless) Since the X-ray spectrum is quite soft, AD models are and (in units of Al0 year-I) respectively, consider unable to account for the X-ray emission. The JD model Afout ing only the AD models. For one object (NGC 4552) we in Fig. 11 is roughly consistent with the radio observa are unable to find a suitable AD model, therefore we do tions and explains quite well the X-ray data, but overpre not include this object in the histogram. dicts the optical data. The resulting jet power is roughly Most of the objects have accretion rates in the range consistent with the value estimated by Allen et a1. (2006); Til ;:::::: 0.003 - 0.01. The mean accretion rate for the sam Merloni & Heinz (2007). ple, in the case of the AD fits, is (logrh) -2.5 or 5.15. NeG 4579 (lOg eM /M0 year-I) ) - 2 with standard deviations NGC 4579 shares many characteristics with NGC 3031 of 0.5 and 0.6, respectively. and NGC 1097: its nucleus features broad double Not all gas supplied at the outer radius of the accre Balmer emission lines (Barth et a1. 200l) and a tion flow ends up being accreted onto the black hole due of the iron Kn line emission (Eracleous et a1. 2002). to mass-loss via winds produced in the ADAF. From Quataert et a1. modeled the SED of our derived we can estimate the fraction of NGC 4579 the "old" ADAF the gas that falls into the event horizon. ure 14 shows the Barth et estimate of the inner radius of of the accretion disk ~ 160. SED models rtr :.s 160 and the continuum data a transition radius since it can be either the (JD or ADAF (AD 16 Nemmen et al. 1m 10em lem Imm 100pm 10pm Ipm loooA .1keV lkeV lOkeVIOOkeV 1m lOem lem Imm lOOpm lOpm Ipm loOOA.1keV 1keV lOkeV100keV 44 44 NGC4278 NGC4278 43 43 42 42 41 41 I' I III III e' 40 e' 40 Q) Q) , I \ / , 39 ~' 39 ~ / ! \ ! 0; I • en ! \ ! .2 38 .2 38 , ! / ! 37 37 I I I I I 10 12 14 16 18 20 10 12 14 16 18 20 log(v/ Hz) log(v I Hz) 1m lOem lem Imm lOOpm lOpm Ipm lOooA .1keV 1keV lOkeVIOOkeV 1m lOem lem Imm lOOpm 1OI'm 1pm loooA .1keV 1keV lOkeV100keV 44 44 NGC4457 NGC4457 43 43 42 42 ::- 41 41 I I' III III e' 40 e' 40 Q) Q) ~' 39 ~' 39 t en 0; .2 38 .2 38 37 37 36 t T 36 ,r 35 35 8 10 12 14 16 18 20 8 10 12 14 16 18 20 log(v / Hz) log(v/ Hz) 1m lOem lem Imm lOOpm lOpm Ipm 1000A.lkeV lkeV lOkeVIOOkeV 44 NGC4494 43 42 I' 41 I III III e' e' Q) Q) --~' en .2 log(v I Hz) !og(v / Hz) Figure 10. Same Figure 7 for :"iGC 4278. :"iGC and :"iGC SED Models for LLAGNs in LINERs 17 lmm IOO#m loooA .1keV lmm lOO#m lO~m l~m lOonA .1keV 44 1m lOcm lcm lO~m l~m IkeV IOkeVIOOkeV 44 1m lOem lcm 1keV lOkeV1OOkeV NGC4548 NGC4548 43 43 42 42 ::::- 41 ::::- 41 I I III III E' 40 E' 40 (l) (l) , 39 ~ ~' 39 0; I 0; .Q 38 ! .Q 38 I 37 37 I f ! 36 I 36 35 35 8 10 12 14 16 18 20 8 10 12 14 16 18 20 log(v / Hz) log(v/ Hz) 44 1m IOem 1em 1mm lOO!,m 1OI'm 1! 42 ::::- 41 I II> E' 40 (l) • • • f 37 10 12 14 16 18 20 log(v/ Hz) lOem lem Imm lOOl'm lOl'm loooA .1keV 44 1m I~m IkeV lOkeV100keV 43 ! NGC4579j 42 ::::- 41 I II> E' 40 (l) ~ ::t " . T "1 ~ r ~ 38~ / 37~ Y ~ t / 1 36L( i 35~11------~I~----~----~~----~~----.~~----~j8 10 12 14 16 18 20 log{v / Hz) log(v! Hz) Figure 11. Figure 7 for r;GC r;GC and r;GC 11579. 18 Nemmen et al. 44 1m IOem Iem 1mm lOO~m 10Mm l~m loooA .lkeV IkeV IOkeVIOOkeV 44 1m IOem Iem 1mm IOO~m 10~m l~m loooA .1keV 1keV 10keV100keV NGC4736 NGC4736 43 43 42 42 ::-- 41 ::--, 41 '", e' 40 //\ '"e' 40 OJ OJ ~' 39- ;:. ~' 39 0; 0; .2 38 .2 38 37 37 I I 36 36 35 35 8 12 14 16 18 20 8 12 14 16 18 20 lag(v / Hz) lag(v/ Hz) Figure 12. Same as Figure 7 for :-.rGC 4736. " 5 logM(Me yr') Figure 13. Distribution of accretion rates at the outer radius of the ADAF obtained from our AD SED fits. a, left: Accretion rate in Eddington units. b, right: Accretion rate in physical units. 2 6.2. Jet powers defined as T)jet Flct/(1V1c ). The choice of accretion Especially relevant for studies of the feedback of mas rate in the definition of the "jet kinetic efficiency" is ar sive black holes in the local universe is the amount of bitrary and we could choose to use either the accretion energy that the jets deposit in their environment. Fig rate 1V1out at the outer radius of the ADAF or the one at ure 15 shows the distribution of kinetic powers ob the innermost stable circular orbit (ISCO), 1\;1i8co (note tained via both the AD and .JD type of SED fits. As we that }v1isco < iiout given the mass-loss through winds in noted above, we were not able to estimate a jet for the ADAF). The ISCO radius in this ease corresponds to the AD model fit to NGC 4552. The HVf'nU!e 3Rs, appropriate for a Schwarzschild black hole. Figure (log (Flet! erg ) is 41.8 and 42.2 16 shows the distribution of the jet kinetic efficiency de- AD and JD each with a ;OCO.1lU''''' fined and 1 dex. we can say that the for the case since erg . The distributions in are no reliable estimates of the agreement \vith the distribution erage values of are -2.9 estimated Falcke & Wilson these averages have of r::::: 0.7 the latter efficiencv is relevant studies of the kinetic AGN feedback order to be consistent with the smaller IS'CO accretion is what fraction of the rest mass associated with rates. the mass accretion rate is central We are also able to the fraction of the mass and converted into the power, which can be accretion rate that escapes attraction of the black SED l\lodels for LLAGNs in LINERs 19 .... Q) ..0 E ::l Z logP;et!(M"z ) Figure 14. Distribution of accretion rates at the radius corre 2 sponding to the ISCO of a Schwarzschild black hole, estimated Figure 16. Distribution of jet kinetic efficiencies Ilct/(1\;fc ) con- from the AD fits. sidering 1'v1 Misco and M Mout for the AD models. .... Q) ..0 E ::l .... Z Q) ..0 E ::l Z Figure 15. Distribution of jet powers. Figure 17. Distribution of hole and is channeled into the the distribution of values of to the AD scenario we obtain the average value of fits. As it turns out, the average value of the ratio is (log (LboJ/ erg S-1) 41.5 with a standard deviation (log -2.9, i.e. on average 0.4% of the of ~ 1 dex. For the SED fits computed according to \ the JD scenario we find a corresponding average of 41.3 the ISeQ is channeled in the jet. with a similar standard deviation, which gives the same The corresponding uncertainty in this estimate is 0.6 dex. average as the one computed using the bolometric lu minosities estimated by EHFlO. Figure 18 displays the 6.3. Bolometric luminosities and radiative distribution of values of resulting from the models compared with the one estimated EHFlO. Defining the X-ray bolometric correction as KX we calculated the bolometric correc- from as 1.45 and l.35 to the AD and JD scenarios with of 0.36 dex (AD) and tiOll means of In our case. we the mean values are 43 the 21 SEDs. UH"'.HCH'" are 22 and 14 calculated result in values of KX this out those estimated EHFlO. 20 Nemmen et al. _ AD .... .aOJ - JD E :l Z .0 !ogFjetl Lhol Figure 18. Distribution of bolometric luminosities inferred from Figure 19. Distribution of the ratio of jet power to bolometric the models compared with the ones estimated by EHFlO. luminosity. "Csing our SED models we can calculate what is the interpolations between the data, usually a linear interpo typical fraction of the accreted matter that is converted lation in log-log space (Ho 1999; EHFlO) , which might into the combined radiation of the accretion flow and not reflect the actual physical processes involved in the 2 the jet, i.e. the radiative efficiency 1Jrad Lbot! Oifoutc ) emission. The average from the AD and JD scenarios (note that the accretion rate in the definition of this ef that we obtained can hence serve as guidelines - with a ficiency is the one at the outer radius of the ADAF). physical justification - to the typical shape of the SEDs We obtained the average value (log 1Jrad) -3.25 with a in the bands which have not been constrained yet. standard deviation of 0.75 dex. Hence, the typical radia Motivated by the reasons above, we show in Fig. 20a 4 tive efficiency is 5 x 10- . the average SEDs computed separately for the AD and We estimated how the jet kinetic power compares to JD scenarios. We first normalized the individual SEDs the total radiative output of the central engine, i.e. we to the same X-ray luminosity of 1040 erg S-l in the band calculate the ratio ?jet! Lbo! where ?jet is obtained from 2-10 keV. This value is approximately the average X-ray the jet model and Lbo! from integrating the modeled luminosity for the LINERs in our sample. After normal SEDs. We obtain (log (?jet! Lbo!)) ~ 0.2 for the AD-type izing the SEDs. for each frequency bin we computed the of fits and 0.9 for the JD models (there is a ~ 0.5 dex geometric mean of the model SEDs corresponding to the uncertainty in both values). The reason for the smaller particular model class as (log vLv). Following EHFlO we jet powers in the AD fits compared to the JD ones is choose to compute the average of the logarithm of the lu that the mass-loss rates required in the former fits are minosities instead of using the values of vLI/ themselves systematically smaller than in the ones in which the jet in order to reduce the effect of outliers in the resulting has a higher degree of contribution in the X-rays. Based average. on our results and given the degeneracy in the fits, we The different bumps in the average model SEDs reflect can say that the typical kinetic to radiative power ratio the different physical processes that operate in the flows. of LLAGNs is ~ 5 (i.e. the average of the value from In the average AD model SED, the different bands are the AD and JD fits). This is in agreement with the find dominated by different radiative processes in the flow as ings of Nagar, Falcke & Wilson (2005) that the accretion described below: power output in LLAGNs is dominated by the jet power. Figure 19 shows the distribution of values of ?jet! Lbo! 1 m 1 mm: jet optically thick synchrotron emission. ";">'AlL.llll". from the models. 1 mm ~ 100/Lm: the first bump and usually the 7. THE AVERAGE SED strongest one in the average AD SED is due to the ADAF emission. It is of interest to compute the "v,pr'~IOf-' from the AD and JD These ~ lOtLm are for purposes. First and mal CilU""O'Vil since the observed SEDs are main observables that use to derive the central check the first inverse the average SED rin·Df"".· from UllUL\Jll~ in the the observed ones. SEDs obtained from observed data 0.1 keY 100 keY: the last in limited the bands. Out the second inverse Compton different authors ad-hoc IJH\JLV'W in the ADAF. SED Models for LLAGNs in LINERs 21 The average JD SED is more simple and has only one ties and the explored model parameter space: NGC 1553 bump in the IR between a few x lOflm - a few x 1flm (§5.3) and NGC 4552 (§5.14). For NGC 1553, the JD which is due to the truncated thin disk. The rest of model does not reproduce the hardness of the X-ray spec the emission is due to synchrotron photons from the jet. trum whereas for NGC 4552 the AD model is not able Overall, the spectral shapes of the average JD and AD to account for the corresponding X-ray softness. For the SEDs are quite similar in the radio and X-rays above remaining objects, by inspecting the SED fits we can see 1 ke V. In between these bands the shapes are slightly that both the AD and the JD models are able to repro dissimilar. The bumps in the average SEDs are much duce with varying degrees of success the whole SED from less pronounced than the bumps in the individual SEDs. radio to X-rays, in particular the X-ray portion. This occurs because the bumps in the individual SEDs In order to quantify which model systematically fits do not peak at the same place and when the SEDs are better the broadband SEDs we use as a goodness-of-fit averaged these bumps are smoothed out. For this reason, parameter a modified X2. We define this modified X2 the average model SEDs will not resemble anyone of the simply as individual SEDs. (2) Figure 20a also displays the average data points com puted from the observed SEDs in a similar way by EHFlO where the error bars represent the uncertainty in the where y log v Lv and the sum is carried over the ob emission due to the uncertainty affecting the amount served data points. We sample the X-ray continuum us of extinction correction involved. The shaded region ing 3 data points from 0.5 ke V to 10 ke V and we do not around the average best-fit X-ray power-law represents take into account upper limit data points. The values of the standard deviation in the value of the LINER pho X2 for each model are displayed in Table 2. ton index. In order to illustrate the wide diversity of the Considering the 20 objects for which we were able to individual SEDs, we show in Figure 20b the 10" scatter obtain both JD and AD fits, we find that X2(JD) < affecting the model SEDs (where we show only the AD X2(AD) for 9 objects and X2(JD) > X2(AD) for the average SED for simplicity) and the observed ones. remaining 8. In other words, for 9 objects (10 including As expected, the average model SEDs agree well with NGC 4552 for which we did not find an appropriate AD the observed constraints. There are some details that fit) the JD results in better SED fits as opposed to 8 for are worth mentioning. The shape of the X-ray spectrum which the AD model is a better fit. The results from of the average JD SED is slightly softer than the corre this goodness-of-fit test show that 52% of the SEDs in sponding shape of the average AD SED. Both are within our sample are better fitted by the JD model whereas the 10" uncertainty in the photon index of the average ob 38% are better reproduced by the AD scenario. For the served SED. In the OUV, even though the model SEDs 3 objects with X2(JD)/X2(AD) ;:::; 1 (NGC 1097, NGC agree with the observed constraints they are quite dif 3998 and NGC 4374) it is hard to tell based on the ferent from each other. For instance, the red bump is broadband SED alone which model provides a better stronger in the average JD SED. The average JD SED fit. predicts a lower level of UV flux. In the radio band, the We should point out a number of caveats involved when model SEDs are quite similar to each other. considering which scenario better accounts for the nature Figure 21 shows the average AD and JD SEDs com of the X-ray emission. From an observational point of pared to the average ones of radio-loud and radio-quiet view, even though we are carrying the largest systematic quasars computed by Shang et al. (2011). The average analysis of the SEDs of LLAGNs in LINERs done up to quasar SEDs computed by Shang et al. (2011) are very date, the size of our sample is limited. We need to extend similar to the ones of Elvis (1994) but the former in our modeling to a larger number of LLAGNs in order to clude more detailed features, and are based on more re increase the statistics and draw further conclusions. Sec cent data obtained with improved instrumentation. As ondly, for many sources we only have a few data points in Fig. 20a, the SEDs were normalized such that they available to fit, so clearly for these objects we need to all have the same X-ray luminosity in the 2-10 keY band obtain more measurements to better constrain the mod of 1040 erg . The UV excess in the quasar SEDs (the els. In addition, in our modeling we find that one of blue bump) is clearly apparent in comparison to the the main observables that help to pinpoint the dominant LLAGN ones. It is also interesting that for v > 10 17 Hz source of X-rays is the hardness of the X-ray spectrum. the average AD. average JD and the radio-loud quasar ADAF models tend to predict harder X-ray spectra while SEDs are similar. jet models predict softer ones. In most of the LLAGNs in our sample there is a significant observational uncer- 8. DISCUSSION: THE NATURE OF X-RAY in the hardness derived from the Chandra EMISSION observations make it difficult to determine which whether the AD or JD is favored based on the X-ray 22 ~emmen et al. Imm lOO?,m lOjlm ll'm Imm lOOj.tm lOjlm ll'm loooA 44 1m IOem lem loOoA.lkeV lkeV lOkeV lOOkeV lem AD mean 43 JD mean 42 :::- 41 :::- 'VI In ~ 40 ~ OJ , ;.~,,7':o''h.:- OJ 39 ~' ,.,z" " ~' 0. 0. ..2 38 '!> ..2 e 37 --1' .', e ,je 36 35 8 10 12 14 16 18 20 log (v / Hz) log(v/ Hz) Figure 20. a, left: The average SEDs (geometrie mean) computed separately for the AD and JD models (dashed and dotted lines respectively). The data points correspond to the geometric mean computed by EHFlO. b, right: 10" scatter around the average (model and observed) SEDs illustrating the diversity of individual SEDs. The solid line shows the average AD SED and the shaded region corresponds to the standard deviation from the AD models. The points correspond to the mean computed by EHFIO and the error bars show the scatter in the measurements. In the OUV, the filled circles correspond to measurements without any reddening correction whereas the open circles correspond to the maximal extinction correction. The nature of the X-ray emission in LLAGNs has been 44 1m lOem lem Imm lOOl'm 1OI'm ll'm loooA .lkeV lkeV lOkeVIOOkeV debated in the last few years by several authors favoring in some cases the AD or JD models based on the analysis AD mean 43 of individual sources (e.g., Falcke & Markoff 2000; Y~an, JD mean Markoff & Falcke 2002; Yuan et aL 2002; Yuan, Quataert 42 Radio-quiet & ~arayan 2003; Wu, Yuan & Cao 2007; 1\1arkoff et al. Radio-loud 2008; Miller et aL 20l0) or in a statistical sense based on the fundamental plane of black hole actiyity (Mer loni, Heinz & Di Matteo 2003; Falcke, Kording & Markoff 2004; Yuan & Cui 2005; Yuan, Yu & Ho 2009; Plotkin et aL 2011). We suggest different routes to clarify this ~' 39 issue in the future. 0. The AD and JD models should predict different charac ..2 38 teristic radio and X-ray variability timescales (e.g., Ptak 37 et al. 1998), hence we should be able to test which com ponent is dominant in X-rays by carrying out a simul 36 taneous monitoring of the variability of radio and X rays. By comparing the variability pattern predicted by 358~~--710~--~1~2~---714~--~1~6~--~178-----=20 jet/ ADAF models we could pinpoint the X-ray dominant log(v / Hz) component. This promising strategy is quite similar to what the observational campaigns carried out for M81 Figure 21. The average JD and AD model SEDs compared to (Nlarkoff et aL 2008; Miller et al. 20l0) and the radio the radio-loud and radio-quiet quasar SEDs computed by quiet Seyfert 1 NGC 4051 (King et al. 2011) and could be (2011). applied to many other LLAGNs. We note that in the case of M81, Miller et al. (2010) favor a scenario in which the sible values of these parameters despite recent rmr>rrra"" X-rays in the transition between the thin Sharma et al. 2007' 1\ledvedev 2006). disk and ADAF: ~GC 4051 is a different case since ([oodne~os-'Jt-tit of the AD and JD H1U'UI:::J.;O. AGN at the ~ model is "'(10H.. o.Ll.) et into account these caveats, it is still premature parameters that we derived in our to favor one model over the other based on SED. SED Models for LLAGNs in LI:'-JERs 23 42 should be able to predict the I-ray spectrum (Mahade and JD scenarios is rv 10 erg ranging from 40 44 van, :'-Jarayan & Krolik 1997; Takami 2011) and compare rv 10 to rv 10 erg S-l. with future Fermi detections. In this way we should be able to compare AD I JD predictions and through I-ray Jet production efficiencies: The typical efficiency observations place further constraints on the production with which the rest mass energy associated with site responsible for the high-energy emission and the jet gas supplied to the accretion flow is converted into disk connection in LLAGNs. jet kinetic power is estimated to be rv 0.001 (range 4 Observations in the mm and sub-mm are also very rv 10- - 0.01). The efficiency is ten times larger if helpful because they constrain the ADAF synchrotron we consider the gas that reaches a few gravitational emission and hence also the X-ray emission. This fol radii only. lows because the synchrotron photons in the ADAF are inverse-Compton-scattered to X-rays. Fraction of material ejected in the jet: On aver Finally, further refinements and a better understand age, a fraction of 0.4% of the gas that reaches a few ing of the fundamental plane of black hole activity (Mer gravitational radii is chanelled in the relativistic loni, Heinz & Di Matteo 2003; Falcke, Kording & Markoff jet (range 0.01 - 1%). 2004; Gultekin et aL 2009: Yuan, Yu & Ho 2009; Plotkin et aL 2011) should make the fundamental plane a better Radiative efficiencies: The typical efficiency of con tool for constraining the radiative processes shaping the version of rest mass energy associated with gas sup radio and X-ray emission in sub-Eddington black hole plied to the accretion flow into disk+jet radiation is source and by consequence LLAGNs. ~ 5x 10-4 (dispersion of 0.8 dex) , producing an av 41 erage bolometric luminosity of a few x10 erg S-l. 9. SU~1MARY We performed detailed modeling of the broadband - Kinetic to radiative output ratio: LLAGNs typi radio-to-X-rays spectral energy distributions of a sam cally release ~ 5 times more kinetic power in the ple of 21 low-luminosity AGNs in LINERs selected from jets than the total energy radiated away. EHF10. With this exploratory modeling, our goal is to constrain the general properties of the central engines of Transition radii between thin disk and ADAF: A the dominant population of AGNs at z ~ o. Our coupled truncated thin disk is required to fit the available accretion-jet model consists of an accretion flow which is mid and near-IR data for only 4 sources - NGC radiatively inefficient in the inner parts and becomes a 1097 (see also Nemmen et aI.' 2006), NGC 4143, thin disk outside a certain transition radius. The rela NGC 4278 and :'-JGC 4736 with the resulting tivistic jet is modeled in the framework of the internal transition radii in the range 30 225Rs. shock scenario. We demonstrated that there are two classes of mod The values that we derived from our SED models above els that can explain the majority of the observed SEDs. provide useful indicators of the feeding and feedback We call the first one AD which stands for "ADAF properties of LLAGNs in LINERs, and by extension of dominated" since the ADAF dominates most of the the whole LLAGN population. broadband emission, particularly the X-rays. In the sec Even though we used the physical scenario that is fa ond class of models, the jet component dominates the vored to account for the combined set of observational majority of the continuum emission and for this reason properties of LLAGNs (Ho 2008; :'-Jarayan & McClintock we call this scenario JD as in "jet-dominated". The SEDs 2008), the inferred values of the parameters are model de predicted by the AD models have a more complex shape pendent. There are theoretical and observational sources than the JD ones, given the richer variety of radiative of uncertainty in the values of the derived parameters. processes involved in ADAFs. For both scenarios though, For instance, there are degeneracies between the effect of the radio band is almost always dominated by the syn the model parameters on the resulting SEDs (Quataert & chrotron emission from the jet and the near IR to optical :'-Jarayan 1999b; Nemmen et al. 2006). The uncertainty in band is dominated by the truncated thin disk thermal the OUV - due to uncertain degree of extinction correc emission. tion and the X-ray data also contribute to uncertainty From our exploratory modeling of the SEDs we are able in the estimated parameters. Furthermore, our sample is to constrain important parameters that characterize the currently limited to 21 objects. In spite of these caveats, central engines of LLAGNs, as summarized below. the estimates \ve obtained for the properties of central GHi';HL<~" of LI:'-JER AG:'-Js should be illustrative of the gen- Mass accretion rates: based on the AD the behavior of the class. values of the accretion rates JUlnHKU We can draw a link between the tion flow lie in the holes in LINERs and the UH'F-LVU units with A* This value is two orders of accretion rate of LINERs that we est i- we could that in order to A * outflows. become a LLAGN, it needs to accrete at a rate ~ 100 times than the present Jet powers: the power from the AD one. 24 Nemmen et al. The individual and average SED models can be useful Eracleous, M., Lewis, K T" & Flohic, H. M. 1. G. 2009, New for a different number of applications. They provide a li Astron. Rev., 53, 133 Eracleous, M., Hwang, J. A" & Flohic, H. M. L. 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C. 2011, ApJ, 726, 87 Galaxy Model rh out rtr b mjet p fCc cn i(0) Hds. 8 x 10 ~a ~ +" (j) ;:::1 (j) S S (j) Z 2.2 X lOa 5.5 10'4 104 0.01 0.1 6.5 x 10' s 104 0.3 2 10 Notes: (a) Black hole mass estimated from the fundamental plane of black holes (Merloni, Heinz & Di Matteo 2(03), using the X-ray and radio Imninositips. (b) Observed jet power estimated using the radio data and the Merloni & Heinz (2007) correlation. (c) For NGC 1097, r 10 (for consistency with the work of Nemmen et aL 2(06). (d) 5 GHz luminosity estimated using the Merloni, Heinz & Di Matteo (2003) correlation. (e) The lower limit on Pj~~S was derived by Gliozzi, Sambrnna & Brandt (2003) and the upper limit results from using the radio data and the Merloni & Ileinz (2007) correlation. inclination angle is from Gliozzi, Sambruna & Brandt (2003). (2005), 2. David et al. (2005), 3. Gliozzi, Sambruna & Brandt (2003), 1. Di Carilli & Fabian (20(H), 5. Giroletti a!. (2005), Allen Ill. (2007), 8. Biretta, Sparks & MaccheUo (1999), 9. Di Matteo et al. (200:~), 10. et al. (2001) Table 2 Model paran1ctcrs reslllting frOl11 the SED fits. The Ilwaning of the pararnctcrs is described in Section :L r..o C'l Cf2 M 2 U rhout rt.r Ii rr~jct p ( c (B i (0) rhBlIudi x Refs, o~ 0. ('I) Ul ...,0' r r >(1 Z Ul S' r Table 3 ;-< Model parameters resulting from the SED fits (continued), Z t:rl &? t,,;) -J