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Title: Starburst-driven Superwinds in Quasar Host Galaxies

Abstract

During the past five decades astronomers have been puzzled by the presence of strong absorption features including metal lines, observed in the optical and ultraviolet spectra of quasars, signaling inflowing and outflowing gas winds with relative velocities up to several thousands of km s{sup −1}. In particular, the location of these winds—close to the quasar, further out in its host galaxy, or in its direct environment—and the possible impact on their surroundings have been issues of intense discussion and uncertainty. Using our Herschel Space Observatory data, we report a tendency for this so-called associated metal absorption to occur along with prodigious star formation in the quasar host galaxy, indicating that the two phenomena are likely to be interrelated, that the gas winds likely occur on the kiloparsec scale and would then have a strong impact on the interstellar medium of the galaxy. This correlation moreover would imply that the unusually high cold dust luminosities in these quasars are connected with ongoing star formation. Given that we find no correlation with the AGN strength, the wind feedback that we establish in these radio-loud objects is most likely associated with their host star formation rather than with their black hole accretion.

Authors:
;  [1];  [2];  [3]
  1. Kapteyn Astronomical Institute, University of Groningen, Groningen (Netherlands)
  2. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
  3. Astronomisches Institut, Ruhr Universität, Bochum (Germany)
Publication Date:
OSTI Identifier:
22654447
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 843; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; BLACK HOLES; CORRELATIONS; DUSTS; GALAXIES; LUMINOSITY; METALS; QUASARS; RED SHIFT; SPACE; STARS; ULTRAVIOLET RADIATION; ULTRAVIOLET SPECTRA; VELOCITY

Citation Formats

Barthel, Peter, Podigachoski, Pece, Wilkes, Belinda, and Haas, Martin, E-mail: pdb@astro.rug.nl, E-mail: podigachoski@astro.rug.nl. Starburst-driven Superwinds in Quasar Host Galaxies. United States: N. p., 2017. Web. doi:10.3847/2041-8213/AA7631.
Barthel, Peter, Podigachoski, Pece, Wilkes, Belinda, & Haas, Martin, E-mail: pdb@astro.rug.nl, E-mail: podigachoski@astro.rug.nl. Starburst-driven Superwinds in Quasar Host Galaxies. United States. doi:10.3847/2041-8213/AA7631.
Barthel, Peter, Podigachoski, Pece, Wilkes, Belinda, and Haas, Martin, E-mail: pdb@astro.rug.nl, E-mail: podigachoski@astro.rug.nl. Sat . "Starburst-driven Superwinds in Quasar Host Galaxies". United States. doi:10.3847/2041-8213/AA7631.
@article{osti_22654447,
title = {Starburst-driven Superwinds in Quasar Host Galaxies},
author = {Barthel, Peter and Podigachoski, Pece and Wilkes, Belinda and Haas, Martin, E-mail: pdb@astro.rug.nl, E-mail: podigachoski@astro.rug.nl},
abstractNote = {During the past five decades astronomers have been puzzled by the presence of strong absorption features including metal lines, observed in the optical and ultraviolet spectra of quasars, signaling inflowing and outflowing gas winds with relative velocities up to several thousands of km s{sup −1}. In particular, the location of these winds—close to the quasar, further out in its host galaxy, or in its direct environment—and the possible impact on their surroundings have been issues of intense discussion and uncertainty. Using our Herschel Space Observatory data, we report a tendency for this so-called associated metal absorption to occur along with prodigious star formation in the quasar host galaxy, indicating that the two phenomena are likely to be interrelated, that the gas winds likely occur on the kiloparsec scale and would then have a strong impact on the interstellar medium of the galaxy. This correlation moreover would imply that the unusually high cold dust luminosities in these quasars are connected with ongoing star formation. Given that we find no correlation with the AGN strength, the wind feedback that we establish in these radio-loud objects is most likely associated with their host star formation rather than with their black hole accretion.},
doi = {10.3847/2041-8213/AA7631},
journal = {Astrophysical Journal Letters},
number = 1,
volume = 843,
place = {United States},
year = {Sat Jul 01 00:00:00 EDT 2017},
month = {Sat Jul 01 00:00:00 EDT 2017}
}
  • Supernova-driven galactic winds ({open_quote}{open_quote}superwinds{close_quote}{close_quote}) have been invoked to explain many aspects of galaxy formation and evolution. Such winds should arise when the supernova rate is high enough to create a cavity of very hot shock-heated gas within a galaxy. This gas can then expand outward as a high-speed wind that can accelerate and heat ambient interstellar or circum-galactic gas causing it to emit optical line radiation and/or thermal X-rays. Theory suggests that such winds should be common in starburst galaxies and that the nature of the winds should depend on the star formation rate and distribution. In order to systematizemore » our observational understanding of superwinds (determine their incidence rate and the dependence of their properties on the star formation that drives them) and to make quantitative comparisons with the theory of superwinds, we have analyzed data from an optical spectroscopic and narrow-band imaging survey of an infrared flux-limited ({ital S}{sub 60 {mu}m}{ge}5.4 Jy) sample of about 50 IR-warm ({ital S}{sub 60 {mu}m}/{ital S}{sub 100 {mu}m}{approx_gt}0.4), starburst galaxies whose stellar disks are viewed nearly edge-on ({ital b}/{ital a}{approx_gt}2). This sample contains galaxies with infrared luminosities from {approx_equal}10{sup 10}{endash}10{sup 12} {ital L}{sub {circle_dot}} and allows us to determine the properties of superwinds over a wide range of star formation rates. We have found that extraplanar emission-line gas is a very common feature of these edge-on, IR-bright galaxies and the properties of the extended emission-line gas are qualitatively and quantitatively consistent with the superwind theory. We can summarize these properties as morphological, ionization, dynamical, and physical. {copyright} {ital 1996 The American Astronomical Society.}« less
  • Optical spectroscopic data are presented on the ionized nebulae associated with 14 galaxies that are strong far-IR emitters. It is found that the data provide both qualitative and quantitative support for the superwind model in which the kinetic energy provided by SNe and winds from massive stars in a central starburst drives a large-scale outflow that can shock heat and accelerate ambient interstellar and circumgalactic gas. Clear kinematic signatures of an outflow along the galaxy's minor axis are found for the three nearest far-IR galaxies (FIRGs). The FIRG nebulae are highly overpressured relative to the Galactic ISM, with the pressuremore » dropping systematically with distance from the nucleus. Superwinds are energetically adequate to power both the observed optical and X-ray nebulae, and the relative emission-line intensities and their radial variations are consistent with ionization by wind-driven shocks, but not with photoionization by normal O stars or an AGN. The possible astrophysical implications of superwinds are discussed. 158 refs.« less
  • We have imaged CO(J = 7 -> 6) and C I({sup 3} P {sub 2} -> {sup 3} P {sub 1}) emission in the host galaxy of the z = 6.42 quasar SDSS J114816.64+525150.3 (hereafter J1148+5251) through observations with the Plateau de Bure Interferometer. The region showing CO(J = 7 -> 6) emission is spatially resolved, and its size of 5 kpc is in good agreement with earlier CO(J = 3 -> 2) observations. In combination with a revised model of the collisional line excitation in this source, this indicates that the highly excited molecular gas traced by the COmore » J = 7 -> 6 line is subthermally excited (showing only 58% +- 8% of the CO J = 3 -> 2 luminosity), but not more centrally concentrated. We also detect C I({sup 3} P {sub 2} -> {sup 3} P {sub 1}) emission in the host galaxy of J1148+5251, but the line is too faint to enable a reliable size measurement. From the C I({sup 3} P {sub 2} -> {sup 3} P {sub 1}) line flux, we derive a total atomic carbon mass of M{sub CI} = 1.1 x10{sup 7} M {sub sun}, which corresponds to approx5 x 10{sup -4} times the total molecular gas mass. We also searched for H{sub 2}O(J{sub K{sub aK{sub c}}} = 2{sub 12} -> 1{sub 01}) emission, and obtained a sensitive line luminosity limit of L{sup '}{sub H{sub 2O}}< 4.4 x 10{sup 9} K km s{sup -1} pc{sup 2}, i.e., <15% of the CO(J = 3 -> 2) luminosity. The warm, highly excited molecular gas, atomic gas and dust in this quasar host at the end of cosmic reionization maintain an intense starburst that reaches surface densities as high as predicted by (dust opacity) Eddington limited star formation over kiloparsec scales.« less
  • We present Keck/LRIS-B spectra for a sample of 10 AEGIS X-ray active galactic nucleus (AGN) host galaxies and 13 post-starburst galaxies from SDSS and DEEP2 at 0.2 < z < 0.8 in order to investigate the presence, properties, and influence of outflowing galactic winds at intermediate redshifts. We focus on galaxies that either host a low-luminosity AGN or have recently had their star formation quenched to test whether these galaxies have winds of sufficient velocity to potentially clear gas from the galaxy. We find, using absorption features of Fe II, Mg II, and Mg I, that six of the tenmore » (60%) X-ray AGN host galaxies and four of the thirteen (31%) post-starburst galaxies have outflowing galactic winds, with typical velocities of {approx}200 km s{sup -1}. We additionally find that most of the galaxies in our sample show line emission, possibly from the wind, in either Fe II* or Mg II. A total of 100% of our X-ray AGN host sample (including four red sequence galaxies) and 77% of our post-starburst sample has either blueshifted absorption or line emission. Several K+A galaxies have small amounts of cool gas absorption at the systemic velocity, indicating that not all of the cool gas has been expelled. We conclude that while outflowing galactic winds are common in both X-ray low-luminosity AGN host galaxies and post-starburst galaxies at intermediate redshifts, the winds are likely driven by supernovae (as opposed to AGNs) and do not appear to have sufficiently high velocities to quench star formation in these galaxies.« less
  • We constrain the recent star formation histories of the host galaxies of eight optical/UV-detected tidal disruption events (TDEs). Six hosts had quick starbursts of <200 Myr duration that ended 10–1000 Myr ago, indicating that TDEs arise at different times in their hosts’ post-starburst evolution. If the disrupted star formed in the burst or before, the post-burst age constrains its mass, generally excluding O, most B, and highly massive A stars. If the starburst arose from a galaxy merger, the time since the starburst began limits the coalescence timescale and thus the merger mass ratio to more equal than 12:1 inmore » most hosts. This uncommon ratio, if also that of the central supermassive black hole (SMBH) binary, disfavors the scenario in which the TDE rate is boosted by the binary but is insensitive to its mass ratio. The stellar mass fraction created in the burst is 0.5%–10% for most hosts, not enough to explain the observed 30–200× boost in TDE rates, suggesting that the host’s core stellar concentration is more important. TDE hosts have stellar masses 10{sup 9.4}–10{sup 10.3} M {sub ☉}, consistent with the Sloan Digital Sky Survey volume-corrected, quiescent Balmer-strong comparison sample and implying SMBH masses of 10{sup 5.5}–10{sup 7.5} M {sub ☉}. Subtracting the host absorption line spectrum, we uncover emission lines; at least five hosts have ionization sources inconsistent with star formation that instead may be related to circumnuclear gas, merger shocks, or post-AGB stars.« less