SPATIALLY RESOLVED PROPERTIES OF THE GRB 060505 HOST: IMPLICATIONS FOR THE NATURE OF THE PROGENITOR

GRB 060505 was the first well-observed nearby possible long-duration gamma-ray burst ( GRB) that had no associated supernova. Here we present spatially resolved spectra of the host galaxy of GRB 060505, an Sbc spiral, at redshift z = 0.0889. The GRB occurred inside a star-forming region in the northern spiral arm at 6.5 kpc from the center. From the position of the emission lines, we determine a maximum rotational velocity for the galaxy of v similar to 212 km s(-1), corresponding to a mass of 1.14 x 10(11) M (circle dot) within 11 kpc from the center. By fitting single-age spectral synthesis models to the stellar continuum, we derive a very young age for the GRB site, confirmed by photometric and H alpha line measurements, of around similar to 6 Myr, which corresponds to the lifetime of a 32M(circle dot) star. The metallicity derived from several emission-line measurements varies throughout the galaxy and is lowest at the GRB site. Using the Two Degree Field Galaxy Redshift Survey we can locate the host galaxy in its large-scale (similar to Mpc) environment. The galaxy lies in the foreground of a filamentary overdensity, extending southwest from the galaxy cluster Abell 3837 at z = 0.0896. The properties of the GRB site are similar to those found for other long-duration GRB host galaxies with high specific star formation rate and low metallicity, which is an indication that GRB 060505 originated from a young, massive star that died without making a supernova.

[1]  R. Corradi,et al.  The metallicity gradient of M 33: chemical abundances of H ii regions , 2007, 0705.3116.

[2]  Alessandro Bressan,et al.  Modeling the Effects of Dust on Galactic Spectral Energy Distributions from the Ultraviolet to the Millimeter Band , 1998 .

[3]  M. Skrutskie,et al.  The Two Micron All Sky Survey (2MASS) , 2006 .

[4]  E. O. Ofek,et al.  A novel explosive process is required for the γ-ray burst GRB 060614 , 2006, Nature.

[5]  Nozomu Tominaga,et al.  The Connection between Gamma-Ray Bursts and Extremely Metal-poor Stars: Black Hole-forming Supernovae with Relativistic Jets , 2007, astro-ph/0702471.

[6]  P. Moller,et al.  The nature of the dwarf starforming galaxy associated with GRB 060218/SN 2006aj , 2007 .

[7]  Max Pettini,et al.  [O III] / [N II] as an abundance indicator at high redshift , 2004, astro-ph/0401128.

[8]  A. J. Levan,et al.  Long γ-ray bursts and core-collapse supernovae have different environments , 2006, Nature.

[9]  S. B. Cenko,et al.  The Afterglow, Energetics, and Host Galaxy of the Short-Hard Gamma-Ray Burst 051221a , 2006 .

[10]  Bernard E. J. Pagel,et al.  On the composition of H II regions in southern galaxies – I. NGC 300 and 1365 , 1979 .

[11]  Robert C. Kennicutt,et al.  The Integrated spectra of nearby galaxies: General properties and emission line spectra , 1992 .

[12]  et al,et al.  The Luminosity Function of Galaxies from SDSS Commissioning Data , 2000 .

[13]  S. B. Cenko,et al.  A New Population of High-Redshift Short-Duration Gamma-Ray Bursts , 2007 .

[14]  E. Ramirez-Ruiz,et al.  The Galaxy Hosts and Large-Scale Environments of Short-Hard Gamma-Ray Bursts , 2005, astro-ph/0510022.

[15]  L.Armus,et al.  Accepted for publication in The Astrophysical Journal Preprint typeset using L ATEX style emulateapj v. 6/22/04 PROBING THE COSMIC STAR FORMATION USING LONG GAMMA-RAY BURSTS: NEW CONSTRAINTS FROM THE SPITZER SPACE TELESCOPE ∗ , 2006 .

[16]  STAR FORMATION IN GALAXIES ALONG THE HUBBLE SEQUENCE , 1998, astro-ph/9807187.

[17]  A. Siebert,et al.  A model of spectral galaxy evolution including the effects of nebular emission , 2001, astro-ph/0107139.

[18]  Dynamical masses of two young globular clusters in the blue compact galaxy ESO 338–IG04 , 2006, astro-ph/0609774.

[19]  D. Schlegel,et al.  Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds , 1998 .

[20]  A. S. Fruchter,et al.  On the Lyalpha emission from gamma-ray burst host galaxies: Evidence for low metallicities , 2003, astro-ph/0306403.

[21]  E. Zackrisson,et al.  The temporal and spatial evolution of the starburst in ESO 338-IG04 as probed by its star clusters ? , 2003, astro-ph/0306522.

[22]  E. Bertin,et al.  SExtractor: Software for source extraction , 1996 .

[23]  Alan A. Wells,et al.  The Swift Gamma-Ray Burst Mission , 2004, astro-ph/0405233.

[24]  L. Kewley,et al.  The Host Galaxy of GRB 060505: Host ISM Properties , 2007, 0708.0833.

[25]  Peter Garnavich,et al.  Infrared and Optical Observations of GRB 030115 and its Extremely Red Host Galaxy: Implications for Dark Bursts , 2006, astro-ph/0608166.

[26]  Warren R. Brown,et al.  SDSS 0809+1729: Connections Between Extremely Metal-Poor Galaxies and Gamma-Ray Burst Hosts , 2007 .

[27]  P. Lundqvist,et al.  Supernova 1998bw - the final phases , 2002 .

[28]  S.Cole,et al.  The 2dF Galaxy Redshift Survey: spectra and redshifts , 2001, astro-ph/0106498.

[29]  Aimee L. Hungerford,et al.  Explosive Nucleosynthesis from Gamma-Ray Burst and Hypernova Progenitors: Direct Collapse versus Fallback , 2006, astro-ph/0604471.

[30]  D. Frail,et al.  The Radio Afterglow and Host Galaxy of the Dark GRB 020819 , 2005, astro-ph/0505035.

[31]  J. Mathis,et al.  The relationship between infrared, optical, and ultraviolet extinction , 1989 .

[32]  D. Fugazza,et al.  An enigmatic long-lasting γ-ray burst not accompanied by a bright supernova , 2006, Nature.

[33]  D. Kiselman,et al.  Line formation in solar granulation IV. (O I), O I and OH lines and the photospheric O abundance , 2003, astro-ph/0312290.

[34]  C. Carollo,et al.  The Metallicities of Star-forming Galaxies at Intermediate Redshifts 0.47 < z < 0.92 , 2003, astro-ph/0307300.

[35]  Abundances of Metal-rich H II Regions in M51 , 2004, astro-ph/0407065.

[36]  Melvyn B. Davies,et al.  A new type of long gamma-ray burst , 2007 .

[37]  Warren R. Brown,et al.  Spectroscopic Discovery of the Supernova 2003dh Associated with GRB 030329 , 2003, astro-ph/0304173.

[38]  C. Leitherer,et al.  O VI + Lyβ + C II from Starburst and Poststarburst Galaxies. I. Stellar Library and Evolutionary Synthesis Profiles , 1997 .

[39]  N. R. Butler.  Refined Astrometry and Positions for 179 Swift X-Ray Afterglows , 2007 .

[40]  M. J. Michalowski,et al.  The Nature of GRB-selected Submillimeter Galaxies: Hot and Young , 2007, 0708.3850.

[41]  S. Mereghetti,et al.  Are the hosts of gamma-ray bursts sub-luminous and blue galaxies? , 2003, astro-ph/0301149.

[42]  J. P. U. Fynbo,et al.  On the nature of nearby GRB/SN host galaxies ⋆ , 2005 .

[43]  M. M. Kasliwal,et al.  The afterglow of GRB 050709 and the nature of the short-hard γ-ray bursts , 2005, Nature.

[44]  K. Pedersen,et al.  A very energetic supernova associated with the γ-ray burst of 29 March 2003 , 2003, Nature.

[45]  D. Bersier,et al.  Evidence for a Supernova Associated with the X-Ray Flash 020903 , 2006, astro-ph/0602163.

[46]  S. Smartt,et al.  The Galactic Oxygen Abundance Gradient , 1997 .

[47]  France.,et al.  The Galaxy Density Environment of Gamma-Ray Burst Host Galaxies , 2004, astro-ph/0402576.

[48]  D. Osterbrock,et al.  Astrophysics of Gaseous Nebulae , 1976 .

[49]  S. Klose,et al.  A Systematic Analysis of Supernova Light in Gamma-Ray Burst Afterglows , 2003, astro-ph/0311610.

[50]  K. Stanek,et al.  The Fate of the Most Massive Stars , 2005 .

[51]  J. Gorosabel,et al.  The galaxies in the field of the nearby GRB 980425/SN 1998bw , 2005, astro-ph/0510813.

[52]  Donald Q. Lamb,et al.  A study of compact object mergers as short gamma-ray burst progenitors , 2006 .

[53]  E. O. Ofek,et al.  A Spectacular Radio Flare from XRF 050416a at 40 Days and Implications for the Nature of X-Ray Flashes , 2006, astro-ph/0607511.

[54]  Norbert Langer,et al.  Evolution of rapidly rotating metal-poor massive stars towards gamma-ray bursts , 2005 .

[55]  D. Schlegel,et al.  Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds , 1997, astro-ph/9710327.

[56]  R. Kennicutt.  A spectrophotometric atlas of galaxies , 1992 .

[57]  Bing Zhang,et al.  Making a Short Gamma-Ray Burst from a Long one: Implications for the Nature of GRB 060614 , 2007 .

[58]  Takashi Ichikawa,et al.  GALAXY COLORS IN VARIOUS PHOTOMETRIC BAND SYSTEMS , 1995 .

[59]  E. O. Ofek,et al.  GRB 060505: A Possible Short-Duration Gamma-Ray Burst in a Star-forming Region at a Redshift of 0.09 , 2007 .

[60]  IAA-CSIC,et al.  UV star-formation rates of GRB host galaxies , 2004, astro-ph/0407066.

[61]  Jesper Sollerman,et al.  No supernovae associated with two long-duration γ-ray bursts , 2006, Nature.

[62]  D. Osterbrock,et al.  Astrophysics of Gaseous Nebulae and Active Galactic Nuclei , 1989 .

[63]  S. R. Kulkarni,et al.  A Redshift Determination for XRF 020903: First Spectroscopic Observations of an X-Ray Flash , 2003, astro-ph/0311050.