EXTREME FEEDBACK AND THE EPOCH OF REIONIZATION: CLUES IN THE LOCAL UNIVERSE

The source responsible for reionizing the universe at z > 6 remains uncertain. While an energetically adequate population of star-forming galaxies may be in place, it is unknown whether a large enough fraction of their ionizing radiation can escape into the intergalactic medium. Attempts to measure this escape fraction in intensely star-forming galaxies at lower redshifts have largely yielded upper limits. In this paper, we present new Hubble Space Telescope Cosmic Origins Spectrograph and archival Far-Ultraviolet Spectroscopic Explorer (FUSE) far-UV spectroscopy of a sample of 11 Lyman Break Analogs (LBAs), a rare population of local galaxies that strongly resemble the high-z Lyman Break galaxies. We combine these data with Sloan Digital Sky Survey optical spectra and Spitzer photometry. We also analyze archival FUSE observations of 15 typical UV-bright local starbursts. We find evidence of small covering factors for optically thick neutral gas in three cases. This is based on two independent pieces of evidence: a significant residual intensity in the cores of the strongest interstellar absorption-lines tracing neutral gas and a small ratio of extinction-corrected Hα to UV plus far-IR luminosities. These objects represent three of the four LBAs that contain a young, very compact (~10^2 pc), and highly massive (~10^9 M_⊙) dominant central object (DCO). These three objects also differ from the other galaxies in showing a significant amount of blueshifted Lyα emission, which may be related to the low covering factor of neutral gas. All four LBAs with DCOs in our sample show extremely high velocity outflows of interstellar gas, with line centroids blueshifted by about 700 km s^(–1) and maximum outflow velocities reaching at least 1500 km s^(–1). We show that these properties are consistent with an outflow driven by a powerful starburst that is exceptionally compact. We speculate that such extreme feedback may be required to enable the escape of ionizing radiation from star-forming galaxies.

[1]  Hsiao-Wen Chen,et al.  Escape of Ionizing Radiation from High-Redshift Galaxies , 2007, 0707.0879.

[2]  A. Szalay,et al.  The Properties of Ultraviolet-luminous Galaxies at the Current Epoch , 2004, astro-ph/0412577.

[3]  C. Leitherer,et al.  AN ULTRAVIOLET SPECTROSCOPIC ATLAS OF LOCAL STARBURSTS AND STAR-FORMING GALAXIES: THE LEGACY OF FOS AND GHRS , 2010, 1011.0385.

[4]  R. Chevalier,et al.  Wind from a starburst galaxy nucleus , 1985, Nature.

[5]  C. Steidel,et al.  THE STRUCTURE AND KINEMATICS OF THE CIRCUMGALACTIC MEDIUM FROM FAR-ULTRAVIOLET SPECTRA OF z ≃ 2–3 GALAXIES , 2010, 1003.0679.

[6]  Tom Abel,et al.  The Influence of Supershells and Galactic Outflows on the Escape of Ionizing Radiation from Dwarf Starburst Galaxies , 2002 .

[7]  D.Lutz,et al.  A study of the gas–star formation relation over cosmic time , 2010 .

[8]  A. Szalay,et al.  The Diverse Properties of the Most Ultraviolet-Luminous Galaxies Discovered by GALEX , 2006, astro-ph/0609415.

[9]  S. Veilleux,et al.  Galactic Winds , 2005, astro-ph/0504435.

[10]  D. Schiminovich,et al.  MORPHOLOGIES OF LOCAL LYMAN BREAK GALAXY ANALOGS. II. A COMPARISON WITH GALAXIES AT z ≃ 2–4 IN ACS AND WFC3 IMAGES OF THE HUBBLE ULTRA DEEP FIELD , 2009, 0911.1279.

[11]  Jonathan P. Williams,et al.  AN ACCURATE POSITION FOR HDF 850.1: THE BRIGHTEST SUBMILLIMETER SOURCE IN THE HUBBLE DEEP FIELD-NORTH , 2009, 0905.1946.

[12]  M. Pettini,et al.  The ultraviolet spectrum of the gravitationally lensed galaxy ‘the Cosmic Horseshoe’: a close-up of a star-forming galaxy at z∼ 2 , 2009, 0906.2412.

[13]  M. O’Hara,et al.  Summary and Implications , 1995 .

[14]  NOAO,et al.  New Constraints on the Lyman Continuum Escape Fraction at z ~ 1.3 , 2007, 0706.4093.

[15]  M. Asplund,et al.  The chemical composition of the Sun , 2009, 0909.0948.

[16]  T. Heckman,et al.  The dynamics and high-energy emission of conductive gas clouds in supernova-driven galactic superwinds , 2005, astro-ph/0506645.

[17]  Boqi Wang.  Cooling gas outflows from galaxies , 1994, astro-ph/9412033.

[18]  Jr.,et al.  The Global Schmidt law in star forming galaxies , 1997, astro-ph/9712213.

[19]  P. Jelinsky,et al.  Reexamining the Lyman Continuum in Starburst Galaxies Observed with the Hopkins Ultraviolet Telescope , 1997, astro-ph/9703041.

[20]  C. Conselice,et al.  A DEEP HUBBLE SPACE TELESCOPE SEARCH FOR ESCAPING LYMAN CONTINUUM FLUX AT z ∼ 1.3: EVIDENCE FOR AN EVOLVING IONIZING EMISSIVITY , 2010, 1001.3412.

[21]  C. Leitherer,et al.  Synthetic UV Lines of SI iv, C iv, and He II from a Population of Massive Stars in Starburst Galaxies , 1993 .

[22]  E. Bell,et al.  Stellar mass-to-light ratios and the Tully-Fisher relation , 2000, astro-ph/0011493.

[23]  E. Quataert,et al.  On the Maximum Luminosity of Galaxies and Their Central Black Holes: Feedback from Momentum-driven Winds , 2004, astro-ph/0406070.

[24]  Denis Foo Kune,et al.  Starburst99: Synthesis Models for Galaxies with Active Star Formation , 1999, astro-ph/9902334.

[25]  M. Franx,et al.  ULTRAVIOLET LUMINOSITY FUNCTIONS FROM 132 z ∼ 7 AND z ∼ 8 LYMAN-BREAK GALAXIES IN THE ULTRA-DEEP HUDF09 AND WIDE-AREA EARLY RELEASE SCIENCE WFC3/IR OBSERVATIONS , 2010, 1006.4360.

[26]  C. Leitherer,et al.  Kinematics of Interstellar Gas in Nearby UV-selected Galaxies Measured with HST STIS Spectroscopy , 2006, astro-ph/0605215.

[27]  Jing Wang,et al.  DUST ATTENUATION IN UV-SELECTED STARBURSTS AT HIGH REDSHIFT AND THEIR LOCAL COUNTERPARTS: IMPLICATIONS FOR THE COSMIC STAR FORMATION RATE DENSITY , 2010, 1011.6098.

[28]  M. Pettini,et al.  Rest-Frame Ultraviolet Spectra of z ∼ 3 Lyman Break Galaxies , 2003, astro-ph/0301230.

[29]  C. Steidel,et al.  New Observations of the Interstellar Medium in the Lyman Break Galaxy MS 1512–cB58 , 2001, astro-ph/0110637.

[30]  C. Leitherer,et al.  Synthetic High-Resolution Line Spectra of Star-forming Galaxies below 1200 Å , 2002, astro-ph/0209481.

[31]  V. Brun,et al.  Constraints on the Lyman continuum radiation from galaxies: First results with FUSE on Mrk 54 , 2001, astro-ph/0106306.

[32]  C. Steidel,et al.  PHYSICAL CONDITIONS IN A YOUNG, UNREDDENED, LOW-METALLICITY GALAXY AT HIGH REDSHIFT , 2010, 1006.5456.

[33]  Robert H. Becker,et al.  Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z ∼ 6 Quasars. II. A Sample of 19 Quasars , 2005, astro-ph/0512082.

[34]  C. Martin.  Mapping Large-Scale Gaseous Outflows in Ultraluminous Galaxies with Keck II ESI Spectra: Variations in Outflow Velocity with Galactic Mass , 2004, astro-ph/0410247.

[35]  G. Chabrier.  Galactic Stellar and Substellar Initial Mass Function , 2003, astro-ph/0304382.

[36]  S. Veilleux,et al.  NEUTRAL GAS OUTFLOWS AND INFLOWS IN INFRARED-FAINT SEYFERT GALAXIES , 2009, 0911.3897.

[37]  D. Schiminovich,et al.  THE KINEMATICS OF IONIZED GAS IN LYMAN-BREAK ANALOGS AT z ∼ 0.2 , 2010, 1009.4934.

[38]  T. Heckman,et al.  Far-Ultraviolet and X-Ray Observations of VV 114: Feedback in a Local Analog to Lyman Break Galaxies , 2006, astro-ph/0605241.

[39]  D. Calzetti.  The Dust Opacity of Star‐forming Galaxies , 2001, astro-ph/0109035.

[40]  S. Veilleux,et al.  Outflows in Active Galactic Nucleus/Starburst-Composite Ultraluminous Infrared Galaxies , 2005, astro-ph/0507037.

[41]  D. Schaerer,et al.  3D Lyα radiation transfer III. Constraints on gas and stellar properties of z ∼ 3 Lyman break galaxies (LBG) and implications for high-z LBGs and Lyα emitters , 2008, 0805.3601.

[42]  T. Heckman,et al.  Absorption-Line Probes of Gas and Dust in Galactic Superwinds , 2000, astro-ph/0002526.

[43]  David Schiminovich,et al.  Hubble Space Telescope Morphologies of Local Lyman Break Galaxy Analogs. I. Evidence for Starbursts Triggered by Merging , 2007, 0709.3304.

[44]  D. Calzetti,et al.  On the escape of ionizing radiation from starbursts , 2001 .

[45]  A. Modigliani,et al.  Rest-frame ultraviolet spectrum of the gravitationally lensed galaxy "the 8 o'clock arc": stellar and interstellar medium properties , 2009, 0912.4384.

[46]  C. Leitherer,et al.  Global Far-Ultraviolet (912-1800 Å) Properties of Star-forming Galaxies , 2002 .

[47]  Timothy M. Heckman,et al.  Synthetic properties of starburst galaxies , 1995 .

[48]  D. Schiminovich,et al.  AN OSIRIS STUDY OF THE GAS KINEMATICS IN A SAMPLE OF UV-SELECTED GALAXIES: EVIDENCE OF “HOT AND BOTHERED” STARBURSTS IN THE LOCAL UNIVERSE , 2009, 0906.1012.

[49]  C. Leitherer,et al.  The Ultraviolet Spectroscopic Properties of Local Starbursts: Implications at High Redshift , 1998, astro-ph/9803185.

[50]  T. Heckman,et al.  Feedback in the Local Lyman-break Galaxy Analog Haro 11 as Probed by Far-Ultraviolet and X-Ray Observations , 2007, 0707.0693.

[51]  A. Fernandez-Soto,et al.  Mission: impossible (escape from the Lyman limit) , 2003 .

[52]  Max Pettini,et al.  The Direct Detection of Lyman Continuum Emission from Star-forming Galaxies at z~3 , 2006, astro-ph/0606635.

[53]  B. M'enard,et al.  RADIATION PRESSURE FROM MASSIVE STAR CLUSTERS AS A LAUNCHING MECHANISM FOR SUPER-GALACTIC WINDS , 2010, 1005.4419.

[54]  A. Fontana,et al.  THE GREAT OBSERVATORIES ORIGINS DEEP SURVEY: CONSTRAINTS ON THE LYMAN CONTINUUM ESCAPE FRACTION DISTRIBUTION OF LYMAN-BREAK GALAXIES AT 3.4 < z < 4.5 , 2010, 1009.1140.

[55]  S. Peng Oh,et al.  Lyman α radiative transfer in a multiphase medium , 2005 .

[56]  C. Leitherer,et al.  OBSERVATIONS OF STARBURST GALAXIES WITH FAR-ULTRAVIOLET SPECTROGRAPHIC EXPLORER: GALACTIC FEEDBACK IN THE LOCAL UNIVERSE , 2009 .

[57]  D. Burgarella,et al.  DETECTIONS OF LYMAN CONTINUUM FROM STAR-FORMING GALAXIES AT z ∼ 3 THROUGH SUBARU/SUPRIME-CAM NARROW-BAND IMAGING , 2008, 0805.4012.

[58]  P. Hopkins,et al.  DISSIPATION AND EXTRA LIGHT IN GALACTIC NUCLEI. IV. EVOLUTION IN THE SCALING RELATIONS OF SPHEROIDS , 2008, 0807.2868.

[59]  C. Steidel,et al.  THE RELATIONSHIP BETWEEN STELLAR POPULATIONS AND Lyα EMISSION IN LYMAN BREAK GALAXIES , 2009, 0911.2000.

[60]  B. Gibson,et al.  Hα Emission from High-Velocity Clouds and Their Distances , 2003, astro-ph/0307509.

[61]  M. Pettini,et al.  Lyman-Continuum Emission from Galaxies at z ≃ 3.4 * , 2001 .

[62]  First detection of Lyman continuum escape from a local starburst galaxy. I. Observations of the lumi , 2006, astro-ph/0601608.

[63]  Astronomy,et al.  A study of interstellar gas and stars in the gravitationally lensed galaxy 'the Cosmic Eye' from rest-frame ultraviolet spectroscopy , 2009, 0910.0840.

[64]  R. Cen,et al.  IONIZING PHOTON ESCAPE FRACTIONS FROM HIGH-REDSHIFT DWARF GALAXIES , 2008, 0808.2477.

[65]  D. Morton,et al.  Atomic Data for Resonance Absorption Lines. III. Wavelengths Longward of the Lyman Limit for the Elements Hydrogen to Gallium , 2003 .

[66]  H. Ford,et al.  LOCAL LYMAN BREAK GALAXY ANALOGS: THE IMPACT OF MASSIVE STAR-FORMING CLUMPS ON THE INTERSTELLAR MEDIUM AND THE GLOBAL STRUCTURE OF YOUNG, FORMING GALAXIES , 2009, 0910.1352.

[67]  Henry C. Ferguson,et al.  The Lyman Continuum in Starburst Galaxies Observed with the Hopkins Ultraviolet Telescope , 1995 .

[68]  Cynthia S. Froning,et al.  The cosmic origins spectrograph: capabilities and prelaunch performance , 2009 .

[69]  J. Sommer-Larsen,et al.  IONIZING RADIATION FROM z = 4–10 GALAXIES , 2009, 0903.2045.

[70]  VLT narrow-band photometry in the Lyman continuum of two galaxies at z ∼ 3 : Limits to the escape of ionizing flux , 2005, astro-ph/0501382.

[71]  Q. Konopacky,et al.  A Hubble Space Telescope Search for Lyman Continuum Emission from Galaxies at 1.1 < z < 1.4 , 2003, astro-ph/0310237.

[72]  George K. Miley,et al.  On the nature and implications of starburst-driven galactic superwinds , 1990 .

[73]  T. Heckman,et al.  Ionized gas in the halos of edge-on starburst galaxies: Evidence for supernova-driven superwinds , 1996 .

[74]  Benjamin D. Johnson,et al.  The Young and the Dustless: Interpreting Radio Observations of Ultraviolet-Luminous Galaxies , 2007, 0707.1878.

[75]  A. F. Casa,et al.  The Escape of Ionizing Photons from OB Associations in Disk Galaxies: Radiation Transfer through Superbubbles , 1999, astro-ph/9903331.

[76]  M. Halpern,et al.  FIVE-YEAR WILKINSON MICROWAVE ANISOTROPY PROBE OBSERVATIONS: LIKELIHOODS AND PARAMETERS FROM THE WMAP DATA , 2008, 0803.0586.