Spectroscopy of the short-hard GRB 130603B

Abstract

Context. Short duration gamma-ray bursts (SGRBs) are thought to be related to the violent merger of compact objects, such as neutron stars or black holes, which makes them promising sources of gravitational waves. The detection of a "kilonova"-like signature associated to the Swift-detected GRB 130603B has suggested that this event is the result of a compact object merger. Aims. Our knowledge on SGRB has been, until now, mostly based on the absence of supernova signatures and the analysis of the host galaxies to which they cannot always be securely associated. Further progress has been significantly hampered by the faintness and rapid fading of their optical counterparts (afterglows), which has so far precluded spectroscopy of such events. Afterglow spectroscopy is the key tool to firmly determine the distance at which the burst was produced, crucial to understand its physics, and study its local environment. Methods. Here we present the first spectra of a prototypical SGRB afterglow in which both absorption and emission features are clearly detected. Together with multi-wavelength photometry we study the host and environment of GRB 130603B. Results. From these spectra we determine the redshift of the burst to be z = 0.3565±0.0002, measure rich dynamics both in absorption and emission, and a substantial line of sight extinction of A V = 0.86 ± 0.15 mag. The GRB was located at the edge of a disrupted arm of a moderately star forming galaxy with near-solar metallicity. Unlike for most long GRBs (LGRBs), N H X /A V is consistent with the Galactic ratio, indicating that the explosion site differs from those found in LGRBs. Conclusions. The merger is not associated with the most star-forming region of the galaxy; however, it did occur in a dense region, implying a rapid merger or a low natal kick velocity for the compact object binary. Key words. gamma-ray burst: individual: GRB 130603B -galaxies: distances and redshifts -galaxies: stellar contentgalaxies: spiral Appendices are available in electronic form at http://www.aanda.orgArticle published by EDP Sciences A62, page 1 of 17 A&A 563, A62 (2014)

Molecfit: A general tool for telluric absorption correction

“…For this purpose, we used a spectrum of the γ-ray burst GRB 130606A (Xu et al 2013;Ukwatta et al 2013;Castro-Tirado et al 2013;de Ugarte Postigo et al 2014) at redshift z ∼ 5.913 (Hartoog et al 2014) P.I. : Holt).…”

Models of Kilonova/Macronova Emission From Black Hole–neutron Star Mergers

“…The Galactic extinction in the direction to GRB 130603B is negligible (A H ∼ 0.01 mag). The extinction in the host galaxy is estimated to be A V ∼ 0.8-1.0 mag (de Ugarte Postigo et al 2014;Fong et al 2014) and, thus, according to the Galactic extinction law (A J /A V ∼ 0.282; Cardelli et al 1989), the extinction in the J-band can be estimated as A J ≈ 0.23-0.28 mag. Figure 9 shows that a BH-NS merger with a small spin χ eff 0.3 is disfavored for all EOS cases.…”

Detectability of compact binary merger macronovae

“…The best case for a macronova so far comes from (Tanvir et al 2013). The detection of the short GRB 130603B is currently the best macronova candidate, the GRB had a fast decaying optical afterglow and was well placed within the host galaxy (de Ugarte Postigo et al 2014) at redshift z = 0.356. The Hubble Space Telescope (HST) imaging of (Tanvir et al 2013) detected an H-band candidate at 25.73 ± 0.20 (F160W) at 7 rest-frame days (9.5 in observer frame) past GRB.…”