A NEARBY GAMMA-RAY BURST HOST PROTOTYPE FOR z {approx} 7 LYMAN-BREAK GALAXIES: SPITZER-IRS AND X-SHOOTER SPECTROSCOPY OF THE HOST GALAXY OF GRB 031203

Journal Article · Tue Nov 01 00:00:00 EDT 2011 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/741/1/58; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)· OSTI ID:21612732

Watson, D; French, J; Hjorth, J; Malesani, D; Fynbo, J P. U.; Castro Ceron, J M ^[1]; Christensen, L ^[2]; O'Halloran, B ^[3]; Michalowski, M ^[4]; Gordon, K D ^[5]; Covino, S ^[6]

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1. Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen O (Denmark)
2. Excellence Cluster Universe, Technische Universitaet Muenchen, 85748 Garching (Germany)
3. Astrophysics Group, Imperial College, Blackett Laboratory, London SW7 2AZ (United Kingdom)
4. Scottish Universities Physics Alliance, Institute for Astronomy, University of Edinburgh, Royal Observatory, Edinburgh EH9 3HJ (United Kingdom)
5. Space Telescope Science Institute, Baltimore, MD 21218 (United States)
6. INAF/Osservatorio Astronomico di Brera, 23807 Merate (Saint Lucia) (Italy)

Gamma-ray burst (GRB) host galaxies have been studied extensively in optical photometry and spectroscopy. Here we present the first mid-infrared spectrum of a GRB host, HG 031203. It is one of the nearest GRB hosts at z = 0.1055, allowing both low- and high-resolution spectroscopy with the Spitzer Infrared Spectrograph (IRS). Medium-resolution UV to K-band spectroscopy with the X-shooter spectrograph on the Very Large Telescope is also presented, along with Spitzer IRAC and MIPS photometry, as well as radio and submillimeter observations. These data allow us to construct a UV to radio spectral energy distribution with almost complete spectroscopic coverage from 0.3 to 35 {mu}m of a GRB host galaxy for the first time, potentially valuable as a template for future model comparisons. The IRS spectra show strong, high-ionization fine structure line emission indicative of a hard radiation field in the galaxy-in particular the [S IV]/[S III] and [Ne III]/[Ne II] ratios-suggestive of strong ongoing star formation and a very young stellar population. The absence of any polycyclic aromatic hydrocarbon emission supports these conclusions, as does the probable hot peak dust temperature, making HG 031203 similar to the prototypical blue compact dwarf galaxy (BCD), II Zw 40. The selection of HG 031203 via the presence of a GRB suggests that it might be a useful analog of very young star-forming galaxies in the early universe, and hints that local BCDs may be used as more reliable analogs of star formation in the early universe than typical local starbursts. We look at the current debate on the ages of the dominant stellar populations in z {approx} 7 and z {approx} 8 galaxies in this context. The nebular line emission is so strong in HG 031203 that at z {approx} 7, it can reproduce the spectral energy distributions of z-band dropout galaxies with elevated IRAC 3.6 and 4.5 {mu}m fluxes without the need to invoke a 4000 A break. Indeed, photometry of HG 031203 shows elevation of the broadband V-magnitude at a level similar to the IRAC elevation in stacked z-band dropouts, solely due to its strong [O III] line emission.

• OSTI ID: 21612732
• Journal Information: Astrophysical Journal, Vol. 741, Issue 1; Other Information: DOI: 10.1088/0004-637X/741/1/58; Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
COSMIC GAMMA BURSTS
DUSTS
EMISSION
ENERGY SPECTRA
GALAXIES
INFRARED SPECTRA
IONIZATION
PHOTOMETRY
POLYCYCLIC AROMATIC HYDROCARBONS
SPECTROSCOPY
STARS
TELESCOPES
UNIVERSE
AROMATICS
COSMIC RADIATION
HYDROCARBONS
IONIZING RADIATIONS
ORGANIC COMPOUNDS
PRIMARY COSMIC RADIATION
RADIATIONS
SPECTRA