Journal ArticleDOI
Rotating Nuclear Rings and Extreme Starbursts in Ultraluminous Galaxies
D. Downes,P. M. Solomon +1 more
TLDR
In this paper, a model of radiative transfer through subthermally excited CO in the molecular disks was proposed, which yields gas masses of ~5 × 109 M and a ratio M/L ≈ 0.8 MAbstract:
New CO interferometer data show that the molecular gas in infrared ultraluminous galaxies is in rotating nuclear disks or rings. The CO maps yield disk radii, kinematic major axes, rotation speeds, enclosed dynamical masses, and gas masses. The CO brightness temperatures, the double-peaked CO line profiles, the limits on thermal continuum flux from dust, and the constraint that the gas mass must be less than the dynamical mass all indicate that the CO lines are subthermally excited and moderately opaque (τ = 4 to 10). We fit kinematic models in which most of the CO flux comes from a moderate-density warm intercloud medium, rather than from self-gravitating clouds. Typical ring radii are 300 to 800 pc. We derive gas masses not from a standard CO-to-mass ratio, but from a model of radiative transfer through subthermally excited CO in the molecular disks. This model yields gas masses of ~5 × 109 M☉, ~5 times lower than the standard method, and a ratio M/L ≈ 0.8 M☉ (K km s-1 pc2)-1. In the nuclear disks, we derive a ratio of gas to dynamical mass of Mgas/Mdyn ≈ 1/6, and a maximum ratio of gas to total mass surface density, μ/μtot, of 1/3. For the galaxies VII Zw 31, Arp 193, and IRAS 10565+2448, the CO position-velocity diagrams provide good evidence for rotating molecular rings with a central gap. In addition to the rotating central rings or disks, a new class of star formation region is identified, which we call an extreme starburst. These have a characteristic sizes of only 100 pc, with about 109 M☉ of gas and an IR luminosity of ≈ 3 × 1011 L☉ from recently formed OB stars. Four extreme starbursts are identified in the 3 closest galaxies in the sample, including Arp 220, Arp 193, and Mrk 273. These are the most prodigious star formation events in the local universe, each representing about 1000 times as many OB stars as 30 Doradus. In Mrk 231, the CO (2-1) velocity diagram along the line of nodes shows a 12 diameter inner disk and a 3'' diameter outer disk. The narrow CO line width, the single-peak line profile, the equality of the major and minor axes, and the observed velocity gradients all imply that the molecular disk is nearly face-on, yielding low optical and UV extinction to the active galactic nucleus (AGN). Such a geometry means that the molecular disk cannot be heated by the AGN; the far-infrared (FIR) luminosity of Mrk 231 is powered by a starburst, not the AGN. In Mrk 273, the CO (1-0) maps show long streamers of radius 5 kpc (7'') with velocity gradients north-south, and a nuclear disk of radius 400 pc (06) with velocity gradients east-west. The nuclear disk contains a bright CO core of radius 120 pc (02). In Arp 220, the CO and 1.3 mm continuum maps show the two "nuclei" embedded in a central ring or disk at P.A. 50° and a fainter structure extending 7'' (3 kpc) to the east, normal to the nuclear disk. Models of the CO and dust flux indicate that the two K-band sources contain high-density gas, with n(H2) = 2 × 104 cm-3. There is no evidence that these sources really are the premerger nuclei. They are more likely to be compact extreme starburst regions, containing 109 M☉ of dense molecular gas and new stars, but no old stars. Most of the HCN emission arises in the two nuclei. The luminosity-to-mass ratios for the CO sources in Arp 220 are compatible with the early phases of compact starbursts. There is a large mass of molecular gas currently forming stars with plenty of ionizing photons, and no obvious AGN. The entire bolometric luminosity of Arp 220 comes from starbursts, not an AGN. The CO maps show that the gas in ultraluminous IR galaxies is in extended disks that cannot intercept all the power of central AGNs, even if they exist. We conclude that in ultraluminous IR galaxies—even in Mrk 231, which hosts a quasar—the FIR luminosity is powered by extreme starbursts in the molecular rings or disks, not by dust-enshrouded quasars.read more
Citations
More filters
Journal ArticleDOI
Extreme galactic wind and Wolf—Rayet features in infrared mergers and infrared quasi-stellar objects
Sebastian Lipari,Roberto Terlevich,Ruben Diaz,Yoshiaki Taniguchi,W. Zheng,Zlatan Tsvetanov,G. J. Carranza,Horacio Alberto Dottori +7 more
TL;DR: In this paper, the authors reported the presence of EVOF and Wolf-Rayet (WR) features in IR mergers and quasi-stellar objects (QSOs) in the IRAS 1-Jy Survey.
Journal ArticleDOI
Mid-infrared diagnostics of starburst galaxies : Clumpy, dense structures in star-forming regions in the antennae (NGC 4038/4039)
TL;DR: In this article, the authors used the stellar population synthesis code Starburst 99 with the photoionization code Mappings to model stellar clusters and their surrounding interstellar medium, focusing on the evolution of emission lines in the N- and Q-band atmospheric windows (8 − 13 and 16.5 µm respectively) and those in the near infrared.
Journal ArticleDOI
Evidence for feedback in action from the molecular gas content in the z ~ 1.6 outflowing QSO XID2028
Marcella Brusa,Chiara Feruglio,Giovanni Cresci,V. Mainieri,Mark Sargent,Michele Perna,Michele Perna,Paola Santini,Fabio Vito,Fabio Vito,Alessandro Marconi,Andrea Merloni,Dieter Lutz,Enrico Piconcelli,Giorgio Lanzuisi,Giorgio Lanzuisi,Roberto Maiolino,David J. Rosario,E. Daddi,Angela Bongiorno,Fabrizio Fiore,Elisabeta Lusso +21 more
TL;DR: In this paper, an obscured quasar at z~1.5, XID2028 was observed with the Plateau de Bure Interferometer and the detection of CO(3-2) emission in this source allows us to infer the molecular gas content and compare it to the ISM mass derived from the dust emission.
Journal ArticleDOI
Dark Matter Substructure Detection Using Spatially Resolved Spectroscopy of Lensed Dusty Galaxies
Yashar D. Hezaveh,Neal Dalal,Gilbert Holder,Michael Kuhlen,Daniel P. Marrone,Norman Murray,Joaquin Vieira +6 more
TL;DR: In this article, the authors investigate how strong lensing of dusty, star-forming galaxies by foreground galaxies can be used as a probe of dark matter halo substructure, and they find that spatially resolved spectroscopy of lensed sources allows dramatic improvements to measurements of lens parameters.
Journal ArticleDOI
High-Resolution Radio Continuum Measurements of the Nuclear Disks of Arp 220
L. Barcos-Muñoz,Adam K. Leroy,Aaron S. Evans,Aaron S. Evans,George C. Privon,Lee Armus,James J. Condon,Joseph M. Mazzarella,David S. Meier,David S. Meier,Emmanuel Momjian,Eric J. Murphy,J. Ott,Ashely Reichardt,Kazushi Sakamoto,David B. Sanders,Eva Schinnerer,S. Stierwalt,Jason Surace,Todd A. Thompson,Fabian Walter +20 more
TL;DR: In this article, the authors present new Karl G. Jansky Very Large Array radio continuum images of the nuclei of Arp 220, the nearest ultra-luminous infrared galaxy, and conclude that the radio emission surrounding both nuclei is mostly synchrotron in nature.
References
More filters
Journal ArticleDOI
What Powers Ultraluminous IRAS Galaxies
Reinhard Genzel,Dieter Lutz,Eckhard Sturm,E. Egami,D. Kunze,A. F. M. Moorwood,D. Rigopoulou,Henrik Spoon,Amiel Sternberg,Lowell E. Tacconi-Garman,Linda J. Tacconi,Niranjan Thatte +11 more
TL;DR: In this paper, the authors present an ISO SWS and ISOPHOT-S, mid-infrared spectroscopic survey of 15 ultraluminous IRAS galaxies (LIR ≥ 1012 L ).
Journal ArticleDOI
What Powers Ultra-luminous IRAS Galaxies?
R. Genzel,Dieter Lutz,Eckhard Sturm,E. Egami,D. Kunze,A. F. M. Moorwood,D. Rigopoulou,Henrik Spoon,Amiel Sternberg,Lowell E. Tacconi-Garman,Linda J. Tacconi,Niranjan Thatte +11 more
TL;DR: In this paper, the authors present an ISO SWS and ISOPHOT-S, mid-infrared spectroscopic survey of 15 ultra-luminous IRAS galaxies.
Journal ArticleDOI
The molecular interstellar medium in ultraluminous infrared galaxies
TL;DR: In this article, the authors used the IRAM 30 m telescope of CO in a large sample of ultraluminous IR galaxies out to redshift z = 0.3 to derive the sizes of the FIR- and CO-emitting regions and the enclosed dynamical masses.
Journal ArticleDOI