GCN Circular 25677
Subject
GRB 190829A: GTC confirmation of an associated Type Ic-BL Supernova
Date
2019-09-06T14:47:37Z (5 years ago)
From
Alexander Kann at IAA-CSIC <kann@iaa.es>
A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), L. Izzo (DARK/NBI), C. C
Thoene, M. Blazek, K. Bensch, J. F. Agui, D. A. Kann (all
HETH/IAA-CSIC), A. L. Cabrera Lavers, N. Castro-Rodriguez (both IAC,
Grantecan), and A. Tejero Caro (Grantecan) report:
We obtained spectroscopy of GRB 190829A (Fermi GBM team, GCN #25551;
Dichiara et al., GCN #25552) with OSIRIS on the 10.4 m Gran Telescopio
Canarias on La Palma, Spain, based on Director's Discretionary Time
proposal GTC02-19BDDT. We obtained 3 x 600 s exposures each in two
grisms, R1000B and R1000R, yielding a total wavelength coverage from
3700 to 10000 AA. Observations began at 03:57 UT on 06 September 2019,
7.35 days after the trigger.
After correcting for the large amount of host-galaxy reddening, using
A_V = 1.5 mag and an SMC-like extinction curve, we find a spectrum
showing broad undulations. An excellent match is obtained vs. an
X-shooter spectrum of SN 2010bh at a similar epoch (Bufano et al., ApJ,
753, 67), especially above 5000 AA (see
https://www.iaa.csic.es/~deugarte/GRBs/190829A/GRB190829A_SN.png). We
further find a good match to a spectrum of SN 1998bw (Patat et al. 2001,
ApJ, 555, 900) taken 6.6 days before peak light (and ~ 8 days post-GRB),
but a less good match for SN 2006aj at a similar time after the GRB.
We find evidence for broad absorption lines of SiII 6355, OI 7775, and
CaII 8490, with the expansion speed of SiII being ~ 30,000 km/s, very
similar to SN 1998bw at this time after trigger. This fully confirms the
results of Terreran et al. (GCN #25664) that this rising source (Perley & Cockerma,
GCN 25623, Bolmer et al., GCN 25651) is indeed the SN accompanying GRB
190829A, and we unambiguously identify it as a broad-lined Type Ic SN
similar to other SNe accompanying GRBs.
Comparison spectra were obtained from WISeREP
(https://wiserep.weizmann.ac.il, Yaron & Gal-Yam, 2012, PASP, 124, 66.)
[GCN OPS NOTE(07sep19): Per author's request, "(GCN #25664)" was added
in the 4th paragraph.]
