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Start Over Author "Niino, Y." Topic gamma-ray burst
2 results on '"Niino, Y."'

1. Metallicity of Gamma-Ray Burst Progenitors: Connection between Star Formation and Gamma-Ray Burst Production.

Author

Niino, Y., Choi, J.-H., Kobayashi, M. A. R., Nagamine, K., Totani, T., and Zhang, B.

Subjects
*GAMMA ray bursts, *STAR formation, *REDSHIFT, *SUPERGIANT stars, *STELLAR evolution, *GALAXIES
Abstract

Long Gamma-Ray Bursts (GRBs) are the brightest astronomical transient events which provide us clues to study high redshift universe. It is broadly accepted that at least some of the long GRBs originate from dying massive stars. Therefore GRBs can be used as a tracer of star formation which are detectable to very high redshift (z>10). However, studies using stellar evolution models suggest that GRBs do not simply trace star formation, but preferentially occur in low-metallicity environment. The observational evidence is still controversial. We need to understand the low-metallicity preference of long GRBs before using them as a tracer of star formation. Using cosmological smoothed particle hydrodynamic simulations, we compute the UV luminosity distribution of GRB host galaxies for two different cases: (i) GRBs simply trace star formation, and (ii) GRBs preferentially occur in low-metallicity environment. We compare the simulation with observations, and discuss the low-metallicity preference of GRBs. We reproduce the observed luminosity probability distribution function of GRB host galaxies when we assume that GRBs originate from stars with metallicities Z<=O.1Z⊙, supporting the suggestion from the theoretical studies. [ABSTRACT FROM AUTHOR]

Published
2010
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2. The Star Formation Rate and Metallicity of the Host Galaxy of the Dark GRB 080325 at z=1.78

Author

Hashimoto, T, Perley, D.~A., Ohta, K, Aoki, K, Tanaka, I, Niino, Y, Yabe, K, and Kawai, Nobuyuki

Subjects
Physics, Infrared, Star formation, Metallicity, Astrophysics::High Energy Astrophysical Phenomena, Astronomy, Astronomy and Astrophysics, Astrophysics, Astrophysics::Cosmology and Extragalactic Astrophysics, Galaxy, Redshift, Space and Planetary Science, Astrophysics::Solar and Stellar Astrophysics, galaxies: abundances, Astrophysics::Earth and Planetary Astrophysics, gamma-ray burst: individual: GRB 080325, Gamma-ray burst, Spectroscopy, Astrophysics::Galaxy Astrophysics, QC, QB
Abstract

We present near-infrared spectroscopy of the host galaxy of the dark gamma-ray burst (GRB) 080325 using Subaru/Multi-Object Infrared Camera and Spectrograph. The obtained spectrum provides a clear detection of H emission and marginal [Nii]λ6584. The host is a massive (M∗ ∼ 1011 Mȯ), dusty (Av ∼ 1.2) star-forming galaxy at z = 1.78. The extinction-corrected star formation rate (SFR) calculated from the H luminosity (35.6-47.0 Mȯ yr-1) is typical among GRB host galaxies (and star-forming galaxies generally) at z > 1; however, the specific SFR is lower than for normal star-forming galaxies at redshift ∼1.6, in contrast to the high specific SFR measured for many of other GRB hosts. The metallicity of the host is estimated to be 12 + log(O/H)KK04 = 8.88. We emphasize that this is one of the most massive host galaxies at z > for which metallicity is measured with emission-line diagnostics. The metallicity is fairly high among GRB hosts, however, this is still lower than the metallicity of normal star-forming galaxies of the same mass at z ∼ 1.6. The metallicity offset from normal star-forming galaxies is close to a typical value of other GRB hosts and indicates that GRB host galaxies are uniformly biased toward low metallicity over a wide range of redshifts and stellar masses. The low-metallicity nature of the GRB 080325 host likely cannot be attributed to the fundamental metallicity relation of star-forming galaxies because it is a metal-poor outlier from the relation and has a low specific star formation rate. Thus, we conclude that metallicity is important to the mechanism that produced this GRB. © 2015. The American Astronomical Society. All rights reserved.

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