GRB 100418A: a Long GRB without a Bright Supernova in a High-Metallicity Host Galaxy
Abstract
We present results of a search for a supernova (SN) component associated with GRB 100418A at a redshift of 0.624. The field of GRB 100418A was observed with FOCAS on the Subaru 8.2 m telescope under a photometric condition (seeing 0.3"-0.4") on 2010 May 14 (UT). The date corresponds to 25.6 days after the burst trigger (15.8 days in the restframe). We made imaging observations in the V, Rc , and Ic bands, and two hours of spectrophotometric observations. We obtained a resolved host galaxy image that is elongated 1.6" (= 11 kpc) from north to south. No point source was detected on the host galaxy. The time variation of the Rc -band magnitude shows that the afterglow of GRB 100418A has faded to Rc ≳; 24 without any SN-like rebrightening, when we compare our measurement to reports in GCN circulars. We could not identify any SN feature, such as broad emission-lines or bumps in our spectrum. Assuming the SN is fainter than the 3 σ noise spectrum of our observation, we estimated the upper limit on the SN absolute magnitude to be MIc , obs > -17.2 in the observer frame Ic -band. This magnitude is comparable to the faintest type Ic SNe. We also estimated the host galaxy properties from the spectrum. The host galaxy of GRB 100418A is relatively massive (log M*/M⊙ = 9.54) compared to typical long GRB host galaxies, and has 12 + log (O/H) = 8.75.
- Publication:
-
Publications of the Astronomical Society of Japan
- Pub Date:
- October 2012
- DOI:
- 10.1093/pasj/64.5.115
- arXiv:
- arXiv:1204.0583
- Bibcode:
- 2012PASJ...64..115N
- Keywords:
-
- galaxies: abundances;
- gamma-ray burst: individual;
- stars: supernovae: individual;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 8 pages, 8 figures, accepted for publication in PASJ, changed figure 8 and related text