T. Kruehler

GRB 161219B/SN 2016jca: A low-redshift gamma-ray burst supernova powered by radioactive heating

Since the first discovery of a broad-lined type Ic supernova (SN) with a long-duration gamma-ray burst (GRB) in 1998, fewer than fifty GRB-supernovae (SNe) have been discovered. The intermediate-luminosity Swift GRB 161219B and its associated supernova SN 2016jca, which occurred at a redshift of z = 0.1475, represents only the seventh GRB-SN to have been discovered within 1 Gpc, and hence provides an excellent opportunity to investigate the observational and physical properties of these very elusive and rare type of SN. As such, we present optical to near-infrared photometry and optical spectroscopy of GRB 161219B and SN 2016jca, spanning the first three months since its discovery. GRB 161219B exploded in the disk of an edge-on spiral galaxy at a projected distance of 3.4 kpc from the galactic centre. GRB 161219B itself is an outlier in the E p,i − E γ, iso plane, while SN 2016jca had a rest-frame, peak absolute V -band magnitude of M V = − 19.0 ± 0.1, which it reached after 12.3 ± 0.7 rest-frame days. We find that the bolometric properties of SN 2016jca are inconsistent with being powered solely by a magnetar central engine, and demonstrate that it was likely powered exclusively by energy deposited by the radioactive decay of nickel and cobalt into their daughter products, which were nucleosynthesised when its progenitor underwent core collapse. We find that 0.22 ± 0.08 M ⊙ of nickel is required to reproducethe peak luminosity of SN 2016jca, and we constrain an ejecta mass of 5.8 ± 0.3 M ⊙ and a kinetic energy of 5.1 ± 0.8 × 10 52 erg. Finally, we report on a chromatic, pre-maximum bump in the g -band light curve, and discuss its possible origin.

The properties of GRB 120923A at a spectroscopic redshift of z=7.8

Gamma-ray bursts (GRBs) are powerful probes of early stars and galaxies, during and potentially even before the era of reionization. Although the number of GRBs identified at z gsim 6 remains small, they provide a unique window on typical star-forming galaxies at that time, and thus are complementary to deep field observations. We report the identification of the optical drop-out afterglow of Swift GRB 120923A in near-infrared Gemini-North imaging, and derive a redshift of

The luminous host galaxy, faint supernova and rapid afterglow rebrightening of GRB 100418A

z={7.84}_{-0.12}^{+0.06}

GRB091109A: VLT/FORS2 spectroscopic redshift.

from Very Large Telescope/X-shooter spectroscopy. At this redshift the peak 15–150 keV luminosity of the burst was 3.2 × 1052 erg s−1, and in this sense it was a rather typical long-duration GRB in terms of rest frame luminosity. This burst was close to the Swift/Burst Alert Telescope detection threshold, and the X-ray and near-infrared afterglow were also faint. We present ground- and space-based follow-up observations spanning from X-ray to radio, and find that a standard external shock model with a constant-density circumburst environment of density n ≈ 4 × 10−2 cm−3 gives a good fit to the data. The near-infrared light curve exhibits a sharp break at t ≈ 3.4 days in the observer frame which, if interpreted as being due to a jet, corresponds to an opening angle of

The fraction of ionizing radiation from massive stars that escapes to the intergalactic medium

{\theta }_{\mathrm{jet}}\approx 5^\circ

No variation in the Crab pulsar in the near-infrared J and H bands

. The beaming-corrected γ-ray energy is then

GRB 090510: GROND observations.

{E}_{\gamma }\approx 2\times {10}^{50}

GRB 080913: VLT/FORS spectrum.

erg, while the beaming-corrected kinetic energy is lower,

GRB 081028: GROND confirmation of the Optical/NIR afterglow.

{E}_{{\rm{K}}}\approx {10}^{49}

Four GRB-Supernovae at Redshifts between 0.4 and 0.8.

erg, suggesting that GRB 120923A was a comparatively low kinetic energy event. We discuss the implications of this event for our understanding of the high-redshift population of GRBs and their identification.