DOCSLIB.ORG

Cosmologically Distant OH Megamasers: a Test of the Galaxy Merging Rate at Z Approximately 2 and a Contaminant of Blind HI Surveys in the 21Cm Line

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Cosmologically Distant OH Megamasers: a Test of the Galaxy Merging Rate at Z Approximately 2 and a Contaminant of Blind HI Surveys in the 21Cm Line A&A manuscript no. (will be inserted by hand later) ASTRONOMY AND Your thesaurus codes are: ASTROPHYSICS 03(11.01.2, 11.05.2, 11.09.2, 11.12.2, 13.09.1, 13.19.1) 18.11.2018 Cosmologically distant OH megamasers: A test of the galaxy merging rate at Z 2 and a contaminant of blind HI surveys in the 21cm line≈ F. H. Briggs Kapteyn Astronomical Institute, P.O. Box 800, 9700 AV Groningen, The Netherlands Received 30 September 1997; accepted 20 May 1998 Abstract. Bright OH megamaser galaxies, radiating 1. Introduction 1667/1665 MHz lines, could be detected at redshifts from z 1 to 3 in moderate integration times with existing The detectability of OH megamaser and gigamaser galax- radio≈ telescopes. The superluminous FIR galaxies that ies at cosmological distances has been noted by several host the megamasers are relatively rare at z 0, but authors (Baan 1989, Baan et al 1992a, Norman & Braun they may have been more common at high redshift,≈ if the 1996, Baan 1997). So far, the sample of known mega- galaxy merger rate increases steeply with redshift. There- masers has been assembled from targeted observations fore, blind radio spectroscopic surveys at frequencies of of luminous galaxies for which redshifts are known (cf. 400 to 1000 Mhz can form an independent test of the Baan et al 1992b, Martin et al 1989, Stavely-Smith et al galaxy merger rate as a function of time over the redshift 1992). The receiving systems are tuned to the predicted interval z = 4 to 0.7. frequencies of the redshifted OH lines whose rest frequen- The redshift range z =0.17 to 0.4 will be difficult to ∼ cies fall at 1665 and 1667 MHz. The greatest success survey for OH masers, since spectroscopic survey signals rate for discovery of megamasers occurs in galaxy sam- will be confused with HI emission from normal galaxies at ples that are selected for having the highest far infrared redshifts less than 0.3. In fact, the signals from OH masers (FIR) 60 µm luminosity, with the result that 50% of are likely to dominate over 21cm line emission from nor- 11.2 −2 ∼ galaxies with L60µ > 10 h L⊙ are strong OH masers mal galaxies at frequencies below 1200 MHz (i.e. large −1 (h = Ho/(100kms ). The odds decline to 5% for sam- redshifts zHI > 0.18 and zOH > 0.4). Surveyors of nearby 9 ∼ ples where L60µ 10 L⊙. There is a striking correlation galaxies in the 21cm line may find that OH masers form ≈ 2 between OH luminosity LOH and L60µ, with LOH L60µ a contaminant to deep, blind HI surveys for redshift ve- (Baan et al 1992a, Baan 1989, Martin et al 1989).∝ locities less than a few hundred kilometers per second. At frequencies just above 1420 MHz, sensitive sky surveys A picture explaining both the probability of detection might detect OH masers, which could be mistaken for a and the relative strengths of megamaser emission from ob- arXiv:astro-ph/9710143v2 12 Jun 1998 population of “infalling, compact High Velocity Clouds” jects of different L60µ has the maser strength depending but would ultimately be traced to luminous FIR back- on strength of the starburst activity in the galaxy (Baan ground galaxies at z 0.17 once optical and IR follow-up 1989, Henkel et al 1991). Major merger and interaction has been performed. ≈ events are the strongest stimulants of star formation and also produce the most turbulent interstellar gas distribu- tions; these conditions provide the strongest IR fluxes for pumping the maser levels, as well as the largest covering factors of the star forming regions, leading to the greatest probability that views from random directions will see OH Key words: Galaxies: active – Galaxies: evolution – maser activity. Galaxies with milder star formation have Galaxies: interaction – Galaxies: luminosity function, more placid disks, and maser emission is then observed mass function – Infrared: galaxies – Radio lines: galaxies only by observers who view the galaxies nearly edge-on to their planes. The strong association between the ultra- luminous FIR galaxies and strongly-interacting and merg- ing systems has been recently discussed by Clements et al Send offprint requests to: [email protected] (1996). 2 F.H. Briggs: OH MegaMasers At the present epoch, the superluminous FIR galax- tion, based on complete samples of galaxies from the IRAS ies that host the most luminous masers are relatively rare 60 µm survey. Their paper analyzes the sample in the con- galaxies. This means that radio spectroscopic surveys of text of several cosmological models; here, parameters for the sky would need to cover large solid angles before they the “p = 1” case, which is the conventional cosmology, would begin to detect OH masers at random from the lo- are adopted to describe the number density of luminous, cal galaxy population. On the other hand, this paper will FIR-selected galaxies. show that, since OH emission can be so very strong, it The 60 µm differential luminosity function is given by becomes probable that surveys with large spectral band- widths and covering large depths are likely to identify cos- α β Φ(L60)= + ∗ Ψ(L60) (1) mologically distant megamasers with moderate integra- L60 L60 + L60 tion times. The most luminous infrared sources known are the ob- with Ψ(L60), the cumulative luminosity function, defined jects detected at high redshifts, z 0.4 to 4.7, (Rowan- as ≈ 12 Robinson 1996, and references therein) with LFIR 10 −α −β 14 −2 ∼ L60 L60 to 10 h L⊙. There is general consensus that the merg- Ψ(L60)= C ∗ 1+ ∗ . (2) ing and interaction rate of galaxies was greater in the past L60 L60 m with merging rate rising in proportion to (1 + z) . Values For the case of conventional cosmology, Koranyi & Strauss for m as high as 4 (Carlberg 1992, Lavery et al 1996) are ∗ 9.68 fit values of α = 0.49, β = 1.81 and L60 = 10 L⊙. mentioned in the literature, although there is some obser- The normalization constant, C, is related to their pa- vational evidence pointing to m 1.2 for z < 1 in the rameter n = 0.058 Mpc−3, through the relation n = HST Medium Deep Survey (Neuschaefer≈ et al 1997) and 1 1 Ψ[Lmin(zs)], where Lmin(zs) is the minimum luminosity m = 2.8 0.9 from faint galaxy catalogs compiled from detectable in the sample, whose members are restricted CFHT surveys± (Patton et al 1997). The comoving number to lie at redshifts greater than zs. For Koranyi & Strauss’ density of bright QSOs (MB < 24.5 +5 log(h)) increases ∗ −3 6 − analysis, Lmin(zs)/L = 8.8 10 , which leads to C = as (1+ z) from z = 0 to 2 (Hewett et al 1993), and, if the −3 −3 × −1 −1 5.8 10 Mpc (Ho = 100 km s Mpc ). QSO phenomenon is tied to galaxy interactions, this steep × ∗ In the L >> L regime, which will characterize the evolution could point to a steep rise in the interaction rate. 60 60 hosts of the brightest OH line emitters, Φ(L60) may be Surveys in the range 400 to 1000 MHz may provide an approximated as independent measure of the merging rate by determining the density of merging galaxies as a function of redshift. ∗−1 ∗ −(α+β+1) Φ(L60) C(α + β)L60 (L60/L60) . (3) Since some of the currently most viable models of galaxy ≈ formation require the bulk of the construction of the larger 2.2. The effective OH luminosity function Θ(L ) galaxies to occur by merging throughout this range of red- OH shift (z 0.5 to 3), surveys for OH masers will form an The strong correlation between OH and 60µm luminosity, ≈ 2 important test of the principal processes of galaxy forma- LOH L60 (cf. Baan et al, 1992a) provides a way to recast tion. the 60∝µm luminosity function for luminous FIR galaxies to obtain an OH megamaser luminosity function Θ(LOH ) as 2. Detection rate of cosmologically distant OH shown in Fig. 1. In this paper, this has been accomplished Masers in two complementary ways: one by numerical integration of Φ(L60) to obtain the number of OH sources falling in The detection rate for OH megamasers can be estimated logarithmically spaced bins of LOH , and the second by by combining 1) knowledge of the density of prospective noting that the masers that are detectable at cosmological FIR luminous host galaxies, 2) the probability that galax- distances inhabit host galaxies that are far more luminous ∗ ies of each luminosity will be seen as megamaser emitters, than L60 and then using the approximation in Eq.(3) to 3) the dependence of megamaser strength on FIR lumi- derive an analytic expression. nosity, and 4) the sensitivity of radio telescope receiving The advantages of computing Θ(LOH ) numerically are systems. The steps in the estimation of the detection rate that it (1) simplifies inclusion of the spread of OH lumi- ±0.7 2 are outlined in the following subsections. A parallel line of nosities in a band of width 10 about the LOH L60 reasoning applies to the detectability of normal galaxies relation (Baan et al 1992a),∼ and (2) allows for varying∝ the in the 21cm line of neutral hydrogen, as discussed in Sect. probability fm that luminous FIR galaxies will appear to 2.5. be megamasers as a function of L60. Here, the range of FIR luminosities that are considered to contribute OH megamasers is conservatively restricted to the range where 2.1. The FIR luminosity function Φ(L60µ) strong OH emission has actually been detected (cf.
Load more

Recommended publications
  • An Embedded Active Nucleus in the OH Megamaser Galaxy IRAS16399−0937 Dinalva A
    University of Kentucky UKnowledge Physics and Astronomy Faculty Publications Physics and Astronomy 1-13-2015 An Embedded Active Nucleus in the OH Megamaser Galaxy IRAS16399−0937 Dinalva A. Sales Universidade Federal do Rio Grande do Sul, Brazil A. Robinson Rochester Institute of Technology D. J. Axon Rochester Institute of Technology J. Gallimore Bucknell University P. Kharb Indian Institute of Astrophysics, India See next page for additional authors Right click to open a feedback form in a new tab to let us know how this document benefits oy u. Follow this and additional works at: https://uknowledge.uky.edu/physastron_facpub Part of the Astrophysics and Astronomy Commons, and the Physics Commons Repository Citation Sales, Dinalva A.; Robinson, A.; Axon, D. J.; Gallimore, J.; Kharb, P.; Curran, R. L.; O'Dea, C.; Baum, S.; Elitzur, Moshe; and Mittal, R., "An Embedded Active Nucleus in the OH Megamaser Galaxy IRAS16399−0937" (2015). Physics and Astronomy Faculty Publications. 260. https://uknowledge.uky.edu/physastron_facpub/260 This Article is brought to you for free and open access by the Physics and Astronomy at UKnowledge. It has been accepted for inclusion in Physics and Astronomy Faculty Publications by an authorized administrator of UKnowledge. For more information, please contact [email protected]. Authors Dinalva A. Sales, A. Robinson, D. J. Axon, J. Gallimore, P. Kharb, R. L. Curran, C. O'Dea, S. Baum, Moshe Elitzur, and R. Mittal An Embedded Active Nucleus in the OH Megamaser Galaxy IRAS16399−0937 Notes/Citation Information Published in The Astrophysical Journal, v. 799, no. 1, 25, p. 1-28. © 2015.
    [Show full text]
  • Interstellar Scintillation and Scattering of Micro-Arc-Second AGN
    galaxies Review Interstellar Scintillation and Scattering of Micro-arc-second AGN David L. Jauncey 1,2,*, Hayley E. Bignall 3, Lucyna Kedziora-Chudczer 4,5, Jun Yi Koay 6, James E. J. Lovell 7, Jean-Pierre Macquart 8,9, Roopesh Ojha 10,11,12, Tapio Pursimo 13, Cormac Reynolds 3 and Barney J. Rickett 14 1 CSIRO Astronomy and Space Science, Epping 1710, Australia 2 Research School of Astronomy and Astrophysics, Australian National University, Canberra 2611, Australia 3 CSIRO Astronomy and Space Science, Kensington 6151, Australia; [email protected] (H.E.B.); [email protected] (C.R.) 4 School of Physics, The University of New South Wales, Sydney 2052, Australia; [email protected] 5 Australian Centre for Astrobiology, The University of New South Wales, Sydney 2052, Australia 6 Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen Ø, Denmark; [email protected] 7 University of Tasmania, School of Physical Sciences, Private Bag 37, Hobart 7001, Australia; [email protected] 8 ICRAR/Curtin University, Curtin Institute of Radio Astronomy, Perth 6845, Australia; [email protected] 9 ARC Centre of Excellence for All-Sky Astrophysics (CAASTRO), The University of Sydney, Sydney 2006, Australia 10 NASA Goddard Space Flight Center, 8800 Greenbelt Rd, Greenbelt, MD 20771, USA; [email protected] 11 Center for Space Science and Technology, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA 12 Department of Physics, The Catholic University of America, 620 Michigan Ave NE, Washington, DC 20064, USA 13 Nordic Optical Telescope, La Palma, Canary Islands 3537, Spain; [email protected] 14 ECE Department, University of California San Diego, La Jolla, CA 92093, USA; [email protected] * Correspondence: [email protected] Academic Editors: Jose.
    [Show full text]
  • Megamasers in Active Galactic Nuclei R. J. Cohen
    MEGAMASERS IN ACTIVE GALACTIC NUCLEI R. J. COHEN University of Manchester Jodrell Bank, Macclesfield, Cheshire SK11 9DL, UK 1. Introduction Extragalactic masers were discovered more than 20 years ago (Whiteoak & Gardner 1973). It soon became apparent that those extragalactic masers we can detect are intrinsically very powerful and are located in galactic nuclei. The term Megamaser was coined to describe the most luminous OH masers, which are a million times more powerful than any OH masers within our own Galaxy (Baan & Haschick 1984). The same word is nowadays applied to any powerful maser associated with an active galactic nucleus (AGN). Whereas normal Galactic masers would be barely detectable outside the Local Group, megamasers are detectable in principle out to redshifts of z ~ 2 (Baan 1997). The galaxies hosting megamasers in their nuclei are invariably active in some degree: they include ultraluminous infrared galaxies, starbursts and Seyfert galaxies. Masers occur in a wide variety of environments in the Galaxy, from comets and circumstellar envelopes to star-forming regions. Molecular masers amplify the natural line emission or a con­ tinuum background, along paths where there is frequency resonance or velocity-coherence. The requirement for a long amplification path in a megamaser provides a natural link with the optical appearance of the associated galaxy. Maser emission from a molecular torus or disk surrounding an AGN will be beamed in the plane of the disc, where the amplification path is longest. Thus the disc orientation relative to our line-of-sight will influence both the detectability of the maser emission and the optical appearance of the galaxy.
    [Show full text]
  • AN EXPANDED VERY LARGE ARRAY SEARCH for WATER MEGAMASER EMISSION in the SUBMM GALAXY SMM J16359+6612 at Z = 2.5
    The Astronomical Journal, 137:3293–3296, 2009 February doi:10.1088/0004-6256/137/2/3293 c 2009. The American Astronomical Society. All rights reserved. Printed in the U.S.A. AN EXPANDED VERY LARGE ARRAY SEARCH FOR WATER MEGAMASER EMISSION IN THE SUBMM GALAXY SMM J16359+6612 AT z = 2.5 R. Edmonds1, J. Wagg1, E. Momjian1, C. L. Carilli1,D.J.Wilner2, E. M. L. Humphreys2, K. M. Menten3,and D. H. Hughes4 1 National Radio Astronomy Observatory, P.O. Box 0, Socorro, NM 87801, USA; [email protected] 2 Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA 3 Max-Planck Institut fur¨ Radioastronomie, Auf dem Hugel¨ 69, D-53121 Bonn, Germany 4 Instituto Nacional de Astrof´ısica, Optica´ y Electronica´ (INAOE), Aptdo. Postal 51 y 216, Puebla, Mexico Received 2008 August 14; accepted 2008 November 5; published 2009 January 28 ABSTRACT Using the Expanded Very Large Array, we have conducted a search for 22.2 GHz H2O megamaser emission in the strongly lensed submm galaxy, SMM J16359+6612 at z = 2.517. This object is lensed into three components, and after a correction for magnification is applied to its submm-wavelength flux density, it is typical of the bulk of the high-redshift, submm galaxy population responsible for the 850 μm extragalactic background (S850 μm ∼ 1 mJy). We do not detect any H2O megamaser emission, but the lensing allows us to place an interesting con- −1 straint on the luminosity of any megamasers present, LH2O < 5305 L for an assumed linewidth of 80 km s .
    [Show full text]
  • Near-Infrared Study of OH Megamaser Galaxies Walas Silva-Oliveira1, Dinalva A
    Boletim da Sociedade Astronômica Brasileira, 31, no. 1, 122-125 c SAB 2020 Near-infrared study of OH megamaser galaxies Walas Silva-Oliveira1, Dinalva A. Sales1, Andrew Robinson2, Luis Colina3, Alberto Rodriguez-Ardila4, Miguel Pereira- Santaella3, Jack Gallimore5, Rogemar A. Riffel6, Thaisa Storchi-Bergmann7, Christopher O’Dea2;8, & Stefi Baum8;9 1 Instituto de Matemática, Estatística e Física, Universidade Federal do Rio Grande, Rio Grande 96203-900, Brazil; e-mail: [email protected], [email protected] 2 School of Physics and Astronomy, Rochester Institute of Technology, 84 Lomb Memorial Drive, Rochester, NY 14623, USA e-mail: [email protected] 3 Centro de Astrobiología (CAB, CSIC-INTA), Carretera de Ajalvir, 28850 Torrejón de Ardoz, Madrid, Spain; e-mail: [email protected], [email protected] 4 Laboratório Nacional de Astrofísica, Rua dos Estados Unidos 154, 37504-364, Itajubá, MG, Brazil e-mail: [email protected] 5 Department of Physics, Bucknell University, Lewisburg, PA 17837, USA e-mail: [email protected] 6 Departamento de Física, CCNE, Universidade Federal de Santa Maria, 97105-900, Santa Maria, RS, Brazil e-mail: [email protected] 7 Departamento de Astronomia, Universidade Federal do Rio Grande do Sul. 9500, Porto Alegre, 91501-970, Brazil e-mail: [email protected] 8 University of Manitoba, Winnipeg, Canada, e-mail: [email protected],[email protected] 9 Carlson Center for Imaging Science, Rochester Institute of Technology, 54 Lomb Memorial Dr. Rochester, NY 14623 Abstract. OH megamaser galaxies (OHMGs), a subset of Ultra-Luminous Infrared Galaxies (ULIRGs), are of particular interest because they may represent a critical short-lived transition phase connected to the onset of rapid nuclear fueling, which in turn leads to the development of a circum-nuclear gas disk and the initiation of Active Galactic Nuclei (AGN) or starburst winds.
    [Show full text]
  • Black Holes in Active Galactic Nuclei
    SLAC-PUB-9702 March 2003 Black Holes in Active Galactic Nuclei Greg Madejski Stanford Linear Accelerator Center, 2575 Sand Hill Rd, Menlo Park, CA USA Abstract. The most viable scenario for modellingof active galactic nuclei includes a supermassive black hole (with the mass of 106 −109 Solar masses) accretingthe galaxian matter from its vicinity. The release of the gravitational energy of the infalling matter is ultimately responsible for the large radiative output of those objects, and in some cases, for formation and acceleration of powerful relativistic jets. This paper outlines our current understandingof the structure of AGN, and summarizes the observational evidence for black holes in those objects. 1 Introduction What are Active Galactic Nuclei? These celestial objects, originally found in the early sixties as point-like radio emitters, were identified with apparently stellar sources, possessing somewhat unusual spectra, with prominent emission lines. The identification of these line series as redshifted systems by Schmidt (1963) implied that quasars are distant and extremely luminous, commonly producing radiation at a rate of 1046 erg s−1; this is a hundred times or more in excess of the total luminosity of all the stars in a galaxy. Subsequent sensitive imaging of the nebulosities which often surround themimpliedthat quasars are nuclei of galaxies, and thus are higher-luminosity counterparts of the compact nuclei of the so-called Seyfert galaxies (studied some twenty years before the discov- ery of quasars) as unusual emission line objects. We currently believe that they represent respectively the lower and higher luminosity end of the same popula- tion. Sensitive optical searches for point-like, blue objects revealed that quasars are quite numerous.
    [Show full text]
  • Going Deep with ALFA
    Going Deep with ALFA E-ALFA Ultra-deep field group ABSTRACT The improved spatial and spectral survey capabilities available with ALFA will open a new era of high sensitivity observations for the Arecibo telescope. In principle, it is possible to achieve noise of less than 50 µJy per with integration times of about 8 100 hours, which translates into a 1σ HI mass sensitivity of a few 10 M at a redshift of 0.16. Surveys of such sensitivity could be used to, e.g. investigate the evolution of HI gas in the universe, directly detect Lyman-limit systems, explore the low-density gas around the edges of galaxies and search for OH megamasers. Enabling ultra- sensitive observations at Arecibo would therefore open whole new fields of research to the observatory. In this proposal, we request observing time for a set of precursor observation to test the feasibility of such very deep ALFA observations and find the limitations of such observations. The proposed strategy is to obtain multiple drift scans over a field with known late-type disk galaxies close to the redshift limit and close to the optimal Arecibo declination at night. The total time request is 70 hours of observing time. The target field for this precursor proposal includes the low redshift target NGC 7523. The observations will serve as a technical test for high redshift observations and simultaneously search for extended HI emission around NGC 7523. If successful, this search will lead to the first detection of the unionized fraction of the low column-density hydrogen in emission outside the Local Group.
    [Show full text]
  • Science with the Square Kilometer Array
    Science with the Square Kilometer Array edited by: A.R. Taylor and R. Braun March 1999 Cover image: The Hubble Deep Field Courtesy of R. Williams and the HDF Team (ST ScI) and NASA. Contents Executive Summary 6 1 Introduction 10 1.1 ANextGenerationRadioObservatory . 10 1.2 The Square Kilometre Array Concept . 12 1.3 Instrumental Sensitivity . 15 1.4 Contributors................................ 18 2 Formation and Evolution of Galaxies 20 2.1 TheDawnofGalaxies .......................... 20 2.1.1 21-cm Emission and Absorption Mechanisms . 22 2.1.2 PreheatingtheIGM ....................... 24 2.1.3 Scenarios: SKA Imaging of Cosmological H I .......... 25 2.2 LargeScale Structure and GalaxyEvolution . ... 28 2.2.1 A Deep SKA H I Pencil Beam Survey . 29 2.2.2 Large scale structure studies from a shallow, wide area survey 31 2.2.3 The Lyα forest seen in the 21-cm H I line............ 32 2.2.4 HighRedshiftCO......................... 33 2.3 DeepContinuumFields. .. .. 38 2.3.1 ExtragalacticRadioSources . 38 2.3.2 The SubmicroJansky Sky . 40 2.4 Probing Dark Matter with Gravitational Lensing . .... 42 2.5 ActivityinGalacticNuclei . 46 2.5.1 The SKA and Active Galactic Nuclei . 47 2.5.2 Sensitivity of the SKA in VLBI Arrays . 52 2.6 Circum-nuclearMegaMasers . 53 2.6.1 H2Omegamasers ......................... 54 2.6.2 OHMegamasers.......................... 55 2.6.3 FormaldehydeMegamasers. 55 2.6.4 The Impact of the SKA on Megamaser Studies . 56 2.7 TheStarburstPhenomenon . 57 2.7.1 TheimportanceofStarbursts . 58 2.7.2 CurrentRadioStudies . 58 2.7.3 The Potential of SKA for Starburst Studies . 61 3 4 CONTENTS 2.8 InterstellarProcesses .
    [Show full text]
  • O Masers in Seyfert and FIR Bright Galaxies
    A&A 436, 75–90 (2005) Astronomy DOI: 10.1051/0004-6361:20042175 & c ESO 2005 Astrophysics New H2O masers in Seyfert and FIR bright galaxies C. Henkel1,A.B.Peck2, A. Tarchi3,4,N.M.Nagar5,6,7,J.A.Braatz8, P. Castangia4,9, and L. Moscadelli4 1 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany e-mail: [email protected] 2 Harvard-Smithsonian Center for Astrophysics, SAO/SMA Project, 654 N. A’ohoku Pl., Hilo, HI 96720, USA 3 Istituto di Radioastronomia, CNR, via Gobetti 101, 40129-Bologna, Italy 4 INAF - Osservatorio Astronomico di Cagliari, Loc. Poggio dei Pini, Strada 54, 09012 Capoterra (CA), Italy 5 INAF, Arcetri Observatory, Largo E. Fermi 5, 50125 Florence, Italy 6 Kapteyn Instituut, Postbus 800, 9700 AV Groningen, The Netherlands 7 Astronomy Group, Departamento de Física, Universidad de Concepción, Casilla 160-C, Concepción, Chile 8 National Radio Astronomy Observatory, PO Box 2, Green Bank, WV 24944, USA 9 Universitá di Cagliari, Dipartimento di Fisica, Cittadella Universitaria, 09012 Capoterra (CA), Italy Received 14 October 2004 / Accepted 16 February 2005 Abstract. Using the Effelsberg 100-m telescope, detections of four extragalactic water vapor masers are reported. Isotropic luminosities are ∼50, 1000, 1 and 230 L for Mrk 1066 (UGC 2456), Mrk 34, NGC 3556 and Arp 299, respectively. Mrk 34 contains by far the most distant and one of the most luminous water vapor megamasers so far reported in a Seyfert galaxy. The interacting system Arp 299 appears to show two maser hotspots separated by approximately 20. With these new results and even more recent data from Braatz et al.
    [Show full text]
  • OH Megamasers As Extragalactic Diagnostics Ylva M
    Astrophysical Masers and their Environments Proceedings IAU Symposium No. 242, 2007 c 2008 International Astronomical Union J.M. Chapman & W.A. Baan, eds. doi:10.1017/S1743921307013579 OH megamasers as extragalactic diagnostics Ylva M. Pihlstr¨om Department of Physics and Astronomy, 800 Yale Blvd. NE, 1 University of New Mexico, Albuquerque, NM 87131, USA email: [email protected] Abstract. Luminous, extragalactic OH masers are excellent tracers of merger triggered, intense star formation in Ultra Luminous Infrared Galaxies (ULIRGs). As such, they are tracers of high density regions in the centers of active galaxies. From high resolution imaging of the 1667 MHz emission in a small sample of OH megamaser galaxies, the general consensus is that most of the maser emission arises in thick, circumnuclear structures. Here we summarize the current work on OH megamasers, and present the preliminary results on VLA observations of the 1720 MHz satellite line in III Zw 35, Mrk 231 and Arp 220. We also briefly mention ongoing work on inves- tigating the nature of the high molecular gas density environment in a sample of ULIRGs, using CO (J=3–2) observations. A subset of the ULIRG sample harbors OH megamaser emission, and is therefore suited for comparing gas properties between ULIRGs with and without OH megamaser emission. Keywords. masers, galaxies:starburst, radio lines: galaxies, instrumentation: high angular res- olution 1. Introduction The extremely luminous 1667 MHz OH maser emission detected in extragalactic sources has been shown to be associated with the most central regions of Ultraluminous Infrared Galaxies (ULIRGs). ULIRGs are known to be merging systems (e.g.
    [Show full text]
  • Hubble Gazes at a Cosmic Megamaser 29 December 2016, by Karl Hille
    Hubble gazes at a cosmic megamaser 29 December 2016, by Karl Hille This megamaser galaxy is named IRAS 16399-0937 and is located over 370 million light-years from Earth. This NASA/ESA Hubble Space Telescope image belies the galaxy's energetic nature, instead painting it as a beautiful and serene cosmic rosebud. The image comprises observations captured across various wavelengths by two of Hubble's instruments: the Advanced Camera for Surveys (ACS), and the Near Infrared Camera and Multi-Object Spectrometer (NICMOS). NICMOS's superb sensitivity, resolution, and field of view gave astronomers the unique opportunity to observe the structure of IRAS 16399-0937 in detail. They found it hosts a double nucleus—the galaxy's core is thought to be formed of two separate cores in the process of merging. The two components, named IRAS 16399N and IRAS 16399S for the This megamaser galaxy is named IRAS 16399-0937 and northern and southern parts respectively, sit over is located over 370 million light-years from Earth. This 11,000 light-years apart. However, they are both NASA/ESA Hubble Space Telescope image belies the buried deep within the same swirl of cosmic gas galaxy's energetic nature, instead painting it as a and dust and are interacting, giving the galaxy its beautiful and serene cosmic rosebud. The image comprises observations captured across various peculiar structure. wavelengths by two of Hubble's instruments: the Advanced Camera for Surveys (ACS), and the Near The nuclei are very different. IRAS 16399S appears Infrared Camera and Multi-Object Spectrometer to be a starburst region, where new stars are (NICMOS).
    [Show full text]
  • Nustar Observations of Water Megamaser AGN
    A&A 589, A59 (2016) Astronomy DOI: 10.1051/0004-6361/201527689 & c ESO 2016 Astrophysics NuSTAR observations of water megamaser AGN A. Masini1;2, A. Comastri1, M. Balokovic´3, I. Zaw4;5, S. Puccetti6;7, D. R. Ballantyne8, F. E. Bauer9;10;11;12, S. E. Boggs13, W. N. Brandt14;15;16, M. Brightman3, F. E. Christensen17, W. W. Craig13;18, P. Gandhi19;20, C. J. Hailey21, F. A. Harrison3, M. J. Koss22;26, G. Madejski23, C. Ricci9;12, E. Rivers3, D. Stern24, and W. W. Zhang25 1 INAF–Osservatorio Astronomico di Bologna, via Ranzani 1, 40127 Bologna, Italy e-mail: [email protected] 2 Dipartimento di Fisica e Astronomia (DIFA), Università di Bologna, viale Berti Pichat 6/2, 40127 Bologna, Italy 3 Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125, USA 4 New York University Abu Dhabi, PO Box 129188, Abu Dhabi, UAE 5 Center for Cosmology and Particle Physics, Department of Physics, New York University – Affiliate Member, 4 Washington Place, New York, NY 10003, USA 6 ASDC-ASI, via del Politecnico, 00133 Roma, Italy 7 INAF–Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio Catone, Italy 8 Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA 9 Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, 306 Santiago 22, Chile 10 Millennium Institute of Astrophysics, MAS, Nuncio Monseñor Sótero Sanz 100, Providencia, Santiago de Chile 11 Space Science Institute, 4750 Walnut Street, Suite 205, Boulder,
    [Show full text]