PoS(RTS2012)030 http://pos.sissa.it/ h starbursts and AGN are fre- y, being relevant for accreting upernova factory) in coexistence ct components (Radio Supernovae ssential contribution of Richard T. some of them (Arp 299A, IC883, e of the European VLBI Network site AGN-starburst scenario. These ecent bursts of formation. The ndi clear and nuclear regions of (Ultra- Future -RTS2012 e Commons Attribution-NonCommercial-ShareAlike Licence. [email protected] , and M. A. Pérez-Torres † ∗ [email protected] quently associated phenomena in mergers, favouring a compo NGC 7469, between others) the presence of non-thermaland compa Supernova Remnants, constituting in somewith a of Low the Luminosity cases AGN. a These s findings may suggest that bot findings may have an impact in the evolution of the AGN activit )Luminous Infrared ((U-)LIRGs) have revealed for models in the central regions ofobservations galaxies we in show the in presence this of contribution r make extensive us High angular resolution radio observations of the circumnu (EVN), a facility which was created and developped with the e Schilizzi. Speaker. Other collaborators: C.Romero-Cañizales, R. Herrero-Illana, M. Bo ∗ † Copyright owned by the author(s) under the terms of the Creativ c April 17-20, 2012 Manchester, UK Resolving the Sky - Radio Interferometry: Past, Present and

Instituto de Astrofísica de Andalucía, IAA-CSIC E-mail: Antxon Alberdi High angular radio observations of (U-)LIRGs PoS(RTS2012)030 ⊙ ⊙ L M 11 5 ∼ 10 × K) central –. 3 tar formation of 0.8 SN/yr– Antxon Alberdi ing six epochs 10 f 6.7 ive than entral 150 pc, 26 ≥ died in our group, urce (AGN), or by b efore, the detection sty environments of ns emitted by young T e compact, centrally ntrated in two nuclei: stellar luminosity and w in Fig 1, an image hown that its compact ; on the other hand, it n ongoing burst of star /or interaction between ply of gas to the central ies (LIRGs) in our local ism in their nuclear (using pond to (U-)LIRGs at dif- idates for starburst activity n the fact that a significant rburst or a combination of va Rate (CCSN) both locally for ULIRGs) is thought to be rnovae (RSNe) is a useful tool ⊙ L 12 10 years, short compared with the typical ≥ 8 -10 7 2 150 pc), high surface brightness ( for LIRGs and ⊙ ≤ L 11 10 ≥ /yr and lifetimes of 10 ⊙ Arp 299 is an early stage merger at a distance of 45 Mpc and a total luminosity o We have observed the nuclear region of Arp 299A with the EVN at 6cm dur In the following, we will discuss different scientific cases that we have stu High resolution radio observations of nearby starburst galaxies have s (Ultra-)Luminous Infrared Galaxies ((U-)LIRGs) are excellent cand Starbursts are intense periods of star formation within a , with typical s [13]. When observed at radioArp 299A wavelenghts, –which most emits of 40% the ofand luminosity the Arp is total 299B conce –which luminosity, corresponding emits to 20% of a the CCSN total rate luminosity andbetween a CCSN April rate 2008 of 0.4 and SN/yr which November is 2010 the (Bondi result of et the al.2012 stacking [2]). of the 6 We epochs sho of the eEVN images. In the c making extensive use of the EVNferent stage and mergers. eMERLIN. These sources corres 2.1 Arp 299 radio source inmersed inlocated a radio low emission in surface these brightnessthe starbursts circumnuclear might combined be halo. effect generated of by multiple Th seems a radio well point-like established so supernovae that and the supernova circumnuclearformation. remnants region Radio of interferometric those observations objects of host LuminousUniverse a Infrared are Galax a powerful tool tothe probe EVN, the VLBA) dominant and dust circumnuclear heating (using mechan eMERLIN, EVLA) regions. 2. Some Scientific Cases radio structure consists of a compact ( from the Far Infrared Luminosity, assuming is that used most for of heating theend the energy their dust. in lives photo as These supernovae. massive Therefore, starsfor the dominate the detection the understanding of overall radio of supe thethe physics central regions of of star galaxies. formation, Thefraction in importance of of particular (U-)LIRGs the in is Star the based Formation du o of at radio supernovae high is crucial takes forand place revising at the in high Core them . Collapse [6]. Superno Ther [12]. The high IR luminosity ( caused by dust grains thatboth. are heated Indeed, by it is the possible presence to of estimate an the AGN, star a formation sta rate for stars more mass galaxy lifetime. The presence of aregions starburst of is the associated galaxy, with a a process violentgalaxies. sup which is usually triggered by merging and rates of around 10-100 M High angular radio observations of (U-)LIRGs 1. Starburst Galaxies: the case of (U-)LIRGs PoS(RTS2012)030 A3 A15 -200 Antxon Alberdi suggesting that es with previous AGN (LLAGN). 150 pc [2]. nuclear starburst of ) EVN observations 5.0 GHz. Moreover, ave obtained the first w CCSNe within our tral index and ratio of ed by the diffuse, low- mage plane six observing ee Fig. 2). Pérez-Torres -100 bjects are consistent with d (2009) [15], identifying s, the so called A1, previ- derstand their nature [10]. A26 A5 A18 A1 A19 A6 0.80 SN/yr, suggesting that the 0 A2 A0 ≤ est image ever of the central 150 pc of A28 A7 A8 A9 A29 A30 A22 100 A10 A11 3 8 mas, at a Position Angle of 25 deg, corresponding to MilliARC SEC Jy/beam, and corresponds to the AGN candidate. Image × A31 µ 200 A12 A4 A13 A25 300 400 A14 EVN image at 5.0 GHz of Arp299-A, obtained by stacking in the i 0 50

-50 200 150 100 300 250

-100 -150 -200 MilliARC SEC MilliARC We have performed quasi-simultaneous dual frequency (5.0 and 1.7 GHz epochs between April 2008 andArp299-A at December 5 2010. GHz. The Thisa angular is linear resolution resolution the is of 10 deep about 2 pc. The peak is 907 taken from Bondi et al.(2012) [2]. Figure 1: High angular radio observations of (U-)LIRGs compact sources are detected, showing5.0 a GHz linear radio size light-curve smaller (spanning thanArp 2 2.5 299-A. pc. yr) The of We all properties h compact (spectralthem components index, being in a variability) the mixed of population all of CCSNeobservations detected and at o SNRs. 8.4 We GHz have compared performed our8 by imag Neff new et components; al.(2004) from [7]observing and those, Ulvesta period, we implying find a clear lower evidence limit for to at the least CCSN two rate ne of of the inner 150 ofWe the have nuclear found region that of the Arp brightest 299-Aously source in detected order of at to all 5.0 un the GHz compactour and VLBI 1.7 8.4 source GHz GHz, EVN has image a showssurface flat that brightness spectrum A1 emission between displays a 1.7 extending core-jet and westwardset structure, from as al. A1 trac towards (2010) A5 [10] (s radio-to-X-ray have emission shown of that the the A1-A5 region morphology,We is radio concluded consistent luminosity, that with spec a the low-luminosity complex A1-A5 is the long-sought AGN in Arp 299-A, bulk of the current star formation in Arp 299-A is taking place in the innermost PoS(RTS2012)030 Antxon Alberdi , suggesting that Mpc, containing a the presence of an AGN Arp 299-A, displaying a large 1 kpc in size. NGC 7469 is a at 1.7 and 5.0 GHz. The morphology, ggestive of a core-jet structure. Image taken ddle and bottom: blow-ups of the inner 8 parsec were 2/3 of the luminosity is emitted by the central black hole coming from reverberation ⊙ ⊙ L M 11 7 4 = 5 x 10 FIR L Top: 5.0 GHz full EVN image of the central 150 parsec region of NGC 7469 is a well known barred spiral galaxy located at a distance of 70 number of bright, compact, nonthermal emitting sources.of Mi the nuclear regionspectral of index Arp and 299-A, luminosity as of imaged the with A1-A5 region the are full very EVN su 2.2 NGC 7469 from Pérez-Torres et al.(2010) [10]. Figure 2: High angular radio observations of (U-)LIRGs Arp 299A has a composite AGN-Starburstat nature. a We mere also distance suggested of that 8the parsec star from formation a processes stellar could cluster could be explain hindering its the low AGN luminoity activity. luminous Seyfert 1 nucleus surrounded byvery a luminous dusty infrared starburst galaxy of with about starburst [5]. Moreover, there is evidence for a 10 PoS(RTS2012)030 Antxon Alberdi ed environment, istant RSNe ever cm). Some of the consists of at least egions of NGC 7469 r diffuse emission or a ontained within an area image of NGC 7469 ever VLA in A-configuration, yfert 1, luminous infrared re and flux/structural time s (Colina et al.2001 [3]). It the circumnuclear starburst 1]; Pérez-Torres et al. 2009 1 kpc). SN 2000ft is a CCSNe that ∼ in its circumnuclear starburst. Image taken of . R1, R2 and R3 correspond to star-forming regions 5 1 − Jy beam µ data for epochs 1998 through 2006. This is the deepest 8.4 GHZ v Total intensity image of NGC 7469 obtained at 8.4 GHZ with the − u We have performed quasi-simultaneous EVN observations of the nuclear r at 6cm and 18cm (seefive Fig. compact 4). sources located The alongjet-like image an structure shows connecting east-west that the line, compact the sources with NGCof between no them. 150 7469 evidence mas They nucleus (50pc) are fo c with acomponents total are flux unresolved, density of while 15 othersvariability mJy show (for (at example, evidence 18cm) the for and westernmost 10 substructu one). mJy (at 6 exploded at a distance offrom 600 Pérez-Torres et pc al.(2009) from [9]. the galaxy nucleus, with within the circumnuclear starburst of NGC 7469 (linear size using all Figure 3: High angular radio observations of (U-)LIRGs mapping [8]. In 2000, we detected aof new NGC radio 7469 supernova, SN (see 2000ft, Fig. in 1), atis a the distance first of radio 600 supernova pc ever from detectedgalaxy. the in galaxy the At nucleu circumnuclear a ring of distance adetected. of Se 70 Although Mpc, it has SN exploded 2000ftit in is behaves a like one radiation-dominated a of and normal the highly type-II[9]). most magnetiz radio luminous supernova (Alberdi and et d al. 2006 [ produced, with an off-source rms of 10 PoS(RTS2012)030 50 ∼ Antxon Alberdi ove reasons, we t structure of an f two disc galaxies could be associated ate for NGC 7469 is gest also that the core infrared luminosities) dio supernovae are ex- t all the VLBI sources ds still to be confirmed d orientation consistent eported by Davies et al. nmost component is the e of the components has ith values between -1 and C 7469. urrently exploding–, and/or g more than in the Seyfert 1 or the overall structure is of at a distance of 100 Mpc [13]. ⊙ L 11 central black hole from reverberation 10 ⊙ × M 7 6 EVN images of the nuclear region of NGC 7469 (the linear size f IC 883 is a LIRG with an IR luminosity of about 4.7 It is still unclear whether these components are tracing i) the typical core-je This LIRG is an advanced(Smith stage et al. member, 1995) probably [14] the as result suggested by of its the associated merger tidal o tails. mapping [8]. Moreover, the MERLINbetween and them: VLBI the structures MERLIN have core-jet a structureAGN core; size [1] in an suggests the that VLBI the images, wester theis structural located and at flux-density the variability western sug sidevia of multi-epoch the multi-frequency VLBI structure, observations. although Additionally, thisa result the factor nee supernova of r 5 lowerand than one for would expect the radio archetype supernovaenucleus, ULIRG to which be Arp found should 220 in be (based the coincident on starburstfavour with rin a their compact composite AGN Starburst-AGN scenario emission. for Due the nuclear to region the of ab NG 2.3 IC 883 AGN, ii) compact starforming regions where individualsploding, and/or or clumps iii) of an ra starburst-AGN composite scenario:a on flat/inverted spectrum the (all one the hand, nuclear non components-0.3), show steep which spectra, favours w the interpretationwith that, young at starforming least, regions some –where ofolder core-collapse the regions, supernova components are formed c by chainsare within of an supernova area remnants. of 50(2004) We pc, [4]; also which on note is the tha also other the hand, size there of is the evidence nuclear for starburst a r 10 pc) obtained at 5.0 (colour) and 1.6 GHz (contours). Figure 4: High angular radio observations of (U-)LIRGs PoS(RTS2012)030 Antxon Alberdi needed. One of requencies with sensitivity are ex- scales; in addition, its nucleus, and the y Project “LIRGI - Jy/beam, respectively. region of IC883: the and test the IMF for µ st regions. Our obser- sociated with a warped ted a lower limit to the ) [11]; see Fig. 5). The n radio searches of large ast four non-thermal com- y likely an AGN. Thus, we obably CCSNe candidates- ) and at 5 GHz with the e-EVN es is 44 and 66 12) [11]. nated by a compact source seen at mas-scales 0.6 SNe/yr based on the detection of three radio 7 ∼ erg/s/Hz. 27 10 × IC 883 contour images at 6.9 GHz obtained with e-MERLIN (left Radio Observations of (U-)LIRGs at the highest angular resolution and We have imaged the circumnuclear and nuclear regions of IC 883 at radio f 3. Summary Note that the brightest component atwith e-MERLIN scales the is e-EVN. domi Image taken from Romero-Cañizales et al.(20 (right) performed in March 2011. The rms noise in the two imag Figure 5: High angular radio observations of (U-)LIRGs tremely useful to discern starburst fromvations AGN could driven also activity in contribute the tomassive innermo determine stars. the In core-collapse order supernovasamples to rate –making get extensive meaningful use results, of highthe instruments angular like co-authors resolutio eMERLIN of and this the contribution EVN– (MAPT) are is co-PI of the eMERLIN Legac eMERLIN and the e-EVN, respectivelye-MERLIN (Romero-Cañizales observations trace et a al. double-sideddisc/ring. structure, (2012 On which the other is hand, likely the nuclearponents: as region three of IC of 883 these consists are ofand at transient the le sources fourth within one a is 100 aare long-lived, pc variable facing region compact a -pr source, situation which with is starburstAGN ver and candidate AGN powers driven activity the in radio theIC emission innermost 883 on displays both very nuclear active and starcircumnuclear formation circumnuclear regions. both within the Romero-Cañizales innermost et 100CCSN al. pc rate of in (2012) the [11] innermost have nuclear estima regions of SNe above a luminosity threshold of 4 PoS(RTS2012)030 Antxon Alberdi etermination of nificant uniformly phenomenological se- L19 s. A134 553 , A72 en granted observations with 539 543 1641 129 2001 ApJ 12 A&A 399 444 012 A&A 1607 57 623 938 148 126 L5 496 439 638 186 602 749 8 519 611 34 L13 540 1529 138 [1] Alberdi A, Colina L, Torrelles J M et al.2006 ApJ [6] Magnelli B, Elbaz D, Chary R R et al.2009, A&A [2] Bondi M, Pérez-Torres M A, Herrero-Illana R, Alberdi A 20 [7] Neff S, Ulvestad J S and Teng S H 2004, ApJ [3] Colina L, Alberdi A, Torrelles J M, Panagia N and Wilson A S [8] Peterson B M and Wandel A 2000, ApJ [4] Davies R L, Tacconi L J and Genzel R 2004 ApJ [9] Pérez-Torres M A, Alberdi A, Colina L et al.2009 MNRAS [5] Genzel R, Weitzel L and Tacconi-Garman L et al.1995 ApJ High angular radio observations of (U-)LIRGs Luminous Infrared Galaxies Inventory": this project willquence allow and to timescale establish for a theobserved evolution sample of of nuclear (U-)LIRGs starbursts in the in Local athe Universe. statistically EVN We have for sig also the be LIRGI sample,the which AGN will and provide Starburst additional energy information contribution on in the the d nuclear regions of LIRG References [10] Pérez-Torres M A, Alberdi A et al.2010 A&A [11] Romero-Cañizales C, Pérez-Torres MA, Alberdi A et al.2 [12] Sanders D B and Mirabel J F 1996 ARA&A [13] Sanders D B, Mazzarella J M, Kim D. et al.2003 AJ [14] Smith D A, Herter T, Haynes, M P et al.1995 ApJ [15] Ulvestad J S 2009 AJ