1 / 13

Study on Gamma-Ray Burst host galaxies in the TMT era

Study on Gamma-Ray Burst host galaxies in the TMT era. Tetsuya Hashimoto (NAOJ). Imaginary picture of Gamma-Ray Burst (GRB) – death of massive star–. that is, supernova explosion. Gamma-Ray Burst (GRB).

tejana
Download Presentation

Study on Gamma-Ray Burst host galaxies in the TMT era

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Study on Gamma-Ray Burst host galaxies in the TMT era Tetsuya Hashimoto (NAOJ)

  2. Imaginary picture of Gamma-Ray Burst (GRB) –death of massive star– that is, supernova explosion

  3. Gamma-Ray Burst (GRB) Among the most energetic explosions in the universe, GRBs are bright flashes of enormous gamma rays that appear suddenly in the sky and usually last only several to a few tens of seconds Swift (gamma- and X-ray) Light curve GRB ``Afterglow’’ The afterglow of a GRB can be observed in the X-ray, optical, and near-infrared wavelengths for several hours to several days Afterglows quickly fade after the burst Afterglow brightness GRB 080319B Racusin et al.2008, Nature 1day 1hour time after the burst (s)

  4. Cosmic star formation history ∝ production rate of GRB (e.g., Kistler et al. 2009) Advantages: GRBs are ・bright enough to be detected at redshift > 10 ・expected to be observable even if obscured by dust Gamma Ray is not attenuated by dust Problem to be solved: ・What kind of galaxies or star forming regions are traced by GRBs? GRB is really unbiased tracer of cosmic star formation history?

  5. GRB and metallicity (Theory) e.g., Woosley & Bloom 2006, Yoon et al. 2006 (single-star explosion scenario) Before massive star explodes, stellar wind carries the rotating momentum (spin angular momentum) of the progenitor away rapidly rotating progenitor becomes GRB slowly rotating progenitor does not become GRB

  6. Direct metallicity measurements of GRB host galaxies by spectroscopic observations Theory + Observation 超新星のみ Supernova (w/o GRB) 9.0 ガンマ線バースト+超新星 GRB+Supernova GRBs occur in 8.5 Low-metallicity environment Metallicity 8.0 It is widely accepted that star forming activity traced by GRBs is biased toward low-metallicity 7.5 Modjaz 他 2008, AJ Modjaz et al. 2008 However.... Brightness of host galaxies

  7. Small sample of GRB hosts GRB event rate ~1 event / 3 day  totally ~1140 eventsat the present time But... ``well explored’’ GRB hosts ~ 50 – 160 (Savaglio et al. 2009, Perley+2013) This is because majority of GRBs is at redshift = 1~2 Wanderman & Piran 2010 Detection of faint GRB host galaxies at redshifts around 1~2 is not easy even if 8m-class telescope is used “Dark” GRB (shows unusually optical faint afterglow) makes it difficult to discover and identify their hosts Jochen Greiner, 14-Oct-2013 Significant numbers of dark GRBs Properties of Dark GRB hosts remains a mystery

  8. Dark GRB -Spectroscopic follow up with Subaru– GRB site Whole South part Hα Hashimoto et al. 2013 in prep. Hashimoto et al. 2010 Hα GRB 080325 host [NII]6584 GRB 080325 host [NII]6584 Relative flux density 6520 Angstrom 6600 6520 6600 Angstrom

  9. High-metal host!? Hashimoto et al. 2013 in prep. 080325 (z=1.78) Niino+ T. H. et al. 2012 100418A (z=0.624) (KK04) ★ (dark GRB) Whole ★ South part DEEP2 Survey (0.4 < z < 1.0) Abraham et al. 2004 ★ GRB site (dark GRB) critical metallicity Erb et al. 2006 (z ～ 2) levesque et al. 2010

  10. TMT Era -Completedark and non-dark GRBs- Dark GRB Kann et al. 2010

  11. Search for GRBs occurred in SF region obscured by dust Hatsukade, T.H. et al. 2012 “Extreme Case” of obscured star formation is very rare?

  12. TMT Era –Origin of GRB– ・GRB productionrequires low-metallicityenvironment suggested by theoretical simulations (MacFadyen& Woosley1999; Woosley & Heger2006; Yoon et al. 2006; Niinoet al. 2009) ・ManyGRB hosts are less massive and low metallicity, But… Another origin of GRBs? ・High metallicity environment of dark GRBs (Graham et al. 2009; Levesque et al. 2010; Hashimoto et al. 2010) Spectroscopy Spectroscopy Redshift ~2 Dark GRB 020819 host at redshift=0.41 (Jakobsson et al. 2005) Current 8m-class telescope TMT Era Metallicitymeasurement at GRB position is the key to reveal the origin of GRBs TMT/IFU_specwith AO is best

  13. Summary Recent studies on missing dark GRBs suggests possible high-metallicity environment in contrast to low metallicity prediction by theoretical simulations. High sensitivity of TMT would promise to complete dark GRB hosts and clarify the traceability of cosmic star formation history with GRBs. TMT/IFU spectroscopy is best suited to understanding the origin of GRB.

More Related