2023A&A...671A.112C


Query : 2023A&A...671A.112C

2023A&A...671A.112C - Astronomy and Astrophysics, volume 671A, 112 (2023/3-1)

GRB minimum variability timescale with Insight-HXMT and Swift Implications for progenitor models, dissipation physics, and GRB classifications.

CAMISASCA A.E., GUIDORZI C., AMATI L., FRONTERA F., SONG X.Y., XIAO S., XIONG S.L., ZHANG S.N., MARGUTTI R., KOBAYASHI S., MUNDELL C.G., GE M.Y., GOMBOC A., JIA S.M., JORDANA-MITJANS N., LI C.K., LI X.B., MACCARY R., SHRESTHA M., XUE W.C. and ZHANG S.

Abstract (from CDS):

Context. There has been significant technological and scientific progress in our ability to detect, monitor, and model the physics of γ-ray bursts (GRBs) over the 50 years since their first discovery. However, the dissipation process thought to be responsible for their defining prompt emission is still unknown. Recent efforts have focused on investigating how the ultrarelativistic jet of the GRB propagates through the progenitor's stellar envelope for different initial composition shapes, jet structures, magnetisation, and, consequently, possible energy dissipation processes. Study of the temporal variability - in particular the shortest duration of an independent emission episode within a GRB - may provide a unique way to distinguish the imprint of the inner engine activity from geometry and propagation related effects. The advent of new high-energy detectors with exquisite time resolution now makes this possible.
Aims. We aim to characterise the minimum variability timescale (MVT) defined as the shortest duration of individual pulses that shape a light curve for a sample of GRBs in the keV-MeV energy range and test correlations with other key observables such as the peak luminosity, the Lorentz factor, and the jet opening angle. We compare these correlations with predictions from recent numerical simulations for a relativistic structured - possibly wobbling - jet and assess the value of temporal variability studies as probes of prompt-emission dissipation physics.
Methods. We used the peak detection algorithm MEPSA to identify the shortest pulse within a GRB time history and preliminarily calibrated MEPSA to estimate the full width at half maximum duration. We then applied this framework to two sets of GRBs: Swift GRBs (from 2005 to July 2022) and Insight Hard Modulation X-ray Telescope (Insight-HXMT) GRBs (from June 2017 to July 2021, including the exceptional 221009A). We then selected 401 GRBs with measured redshift to test for correlations.
Results. We confirm that, on average, short GRBs have significantly shorter MVTs than long GRBs. The MVT distribution of short GRBs with extended emission such as 060614 and 211211A is compatible only with that of short GRBs. This is important because it provides a new clue concerning the progenitor's nature. The MVT for long GRBs with measured redshift anti-correlates with peak luminosity; our analysis includes careful evaluation of selection effects. We confirm the anti-correlation with the Lorentz factor and find a correlation with the jet opening angle as estimated from the afterglow light curve, along with an inverse correlation with the number of pulses.
Conclusions. The MVT can identify the emerging putative new class of long GRBs that are suggested to be produced by compact binary mergers. For otherwise typical long GRBs, the different correlations between MVT and peak luminosity, Lorentz factor, jet opening angle, and number of pulses can be explained within the context of structured, possibly wobbling, weakly magnetised relativistic jets.

Abstract Copyright: © The Authors 2023

Journal keyword(s): radiation mechanisms: non-thermal - relativistic processes - gamma-ray burst: general - stars: jets

VizieR on-line data: <Available at CDS (J/A+A/671/A112): table1.dat table2.dat table5.dat>

Status at CDS : Tables of objects will be appraised for possible ingestion in SIMBAD.

Simbad objects: 19

goto Full paper

goto View the references in ADS

Number of rows : 19
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 GRB 170802A gB 03 29 -39.2           ~ 10 0
2 GRB 050219B gB 05 25 15.990 -57 45 28.70   21.38 20.40     ~ 56 0
3 Fermi bn170626401 gB 11 02 +56.5           ~ 21 0
4 GRB 050219A gB 11 05 38.990 -40 41 03.00           ~ 91 0
5 GRB 050215B gB 11 37 48.030 +40 47 43.39           ~ 70 0
6 Fermi bn170705115 gB 12 46 50 +18 18.0           ~ 43 0
7 GRB 050124 gB 12 51 30.560 +13 02 39.50           ~ 61 0
8 GRB 050128 gB 14 38 17.750 -34 45 55.61           ~ 67 0
9 Fermi bn170728961 gB 15 51 55.45 +70 07 21.3           ~ 41 0
10 GRB 050223 gB 18 05 32.200 -62 28 20.40           ~ 106 0
11 GRB 050126 gB 18 32 27.22 +42 22 14.2           ~ 125 0
12 GRB 050202 gB 19 22 18.0 -38 44 06           ~ 34 0
13 GRB 170726A gB 19 51 +06.6           ~ 8 0
14 Fermi bn170708046 gB 22 23 +19.8           ~ 8 0
15 GRB 050215A gB 23 13 32 +49 19.3           ~ 20 0
16 GRB 050117A gB 23 53 47.24 +65 56 00.2           ~ 64 0
17 GRB 170712A gB ~ ~           ~ 3 0
18 GRB 170801A gB ~ ~           ~ 2 0
19 GRB 170626B gB ~ ~           ~ 5 0

To bookmark this query, right click on this link: simbad:objects in 2023A&A...671A.112C and select 'bookmark this link' or equivalent in the popup menu