GRB 201015A and the nature of low-luminosity soft gamma-ray bursts

Abstract

GRB 201015A is a peculiarly low luminosity, spectrally soft gamma-ray burst (GRB), with $T_{90}=9.8\pm 3.5$ s (time interval of detection of 90\% of photons from the GRB), and an associated supernova (likely to be type Ic or Ic-BL). GRB 201015A has an isotropic energy $E_{\gamma ,\mathrm{iso}}=1.75_{-0.53}^{+0.60}\times 10^{50}$ erg, and photon index $\Gamma =3.00_{-0.42}^{+0.50}$ (15-150 keV). It follows the Amati relation, a correlation between $E_{\gamma ,\mathrm{iso}}$ and spectral peak energy $E_{\mathrm{p}}$ followed by long GRBs. It appears exceptionally soft based on $\Gamma$, the hardness ratio of HR = $0.47\pm 0.24$, and low-$E_{\mathrm{p}}$, so we have compared it to other GRBs sharing these properties. These events can be explained by shock breakout, poorly collimated jets, and off-axis viewing. Follow-up observations of the afterglow taken in the X-ray, optical, and radio, reveal a surprisingly late flattening in the X-ray from $t=(2.61\pm 1.27)\times 10^4$ s to $t=1.67_{-0.65}^{+1.14}\times 10^6$ s. We fit the data to closure relations describing the synchrotron emission, finding the electron spectral index to be $p=2.42_{-0.30}^{+0.44}$, and evidence of late-time energy injection with coefficient $q=0.24_{-0.18}^{+0.24}$. The jet half opening angle lower limit (${\theta }_j\ge 16^{\circ }$) is inferred from the non-detection of a jet break. The launch of SVOM and Einstein Probe in 2023, should enable detection of more low luminosity events like this, providing a fuller picture of the variety of GRBs.

15 pages, 4 figures

References in corpus (34)

• Gravitational Waves and Gamma-rays from a Binary Neutron Star Merger: GW170817 and GRB 170817A
• An online repository of Swift/XRT light curves of GRBs
• The X-ray counterpart to the gravitational wave event GW 170817
• Long gamma-ray bursts and core-collapse supernovae have different environments
• Gamma-Ray Bursts: Progress, Problems & Prospects
• A Kilonova Following a Long-Duration Gamma-Ray Burst at 350 Mpc
• The Millisecond Magnetar Central Engine in short GRBs
• Discovery of the nearby long, soft GRB 100316D with an associated supernova
• Early-time light curves of Type Ib/c supernovae from the SDSS-II Supernova Survey
• Hyper-accreting black hole as GRB central engine. I: Baryon loading in GRB jets
• A unified picture for low-luminosity and long gamma-ray bursts based on the extended progenitor of llgrb 060218/SN 2006aj
• Investigating the properties of stripped-envelope supernovae, what are the implications for their progenitors?
• The Ep,i - Eiso correlation: type I gamma-ray bursts and the new classification method
• Low-Luminosity Gamma-Ray Bursts as a Distinct GRB Population:A Firmer Case from Multiple Criteria Constraints
• A complete sample of bright Swift short Gamma-Ray Bursts
• Short GRB Host Galaxies I: Photometric and Spectroscopic Catalogs, Host Associations, and Galactocentric Offsets
• Correlations of Prompt and Afterglow Emission in Swift Long and Short Gamma Ray Bursts
• Accurate early positions for Swift GRBS: enhancing X-ray positions with UVOT astrometry
• The case for a minute-long merger-driven gamma-ray burst from fast-cooling synchrotron emission
• A Peculiarly Short-duration Gamma-Ray Burst from Massive Star Core Collapse
• Gamma-ray burst progenitors
• Electrons' energy in GRB afterglows implied by radio peaks
• An Unambiguous Separation of Gamma-Ray Bursts into Two Classes from Prompt Emission Alone
• Signature of a New-Born Black Hole from the Collapse of a Supra-massive Millisecond Magnetar
• GRB jet structure and the jet break
• Off-axis jet scenario for early afterglow emission of low-luminosity gamma-ray burst GRB 190829A
• GRB 170817A as a Refreshed Shock Afterglow viewed off-axis
• Revisiting the Redshift Distribution of Gamma Ray Bursts in the Swift Era
• GRB Observational Properties
• On Spectral Peak Energy of Swift Gamma-Ray Bursts
• Gamma-Ray Bursts with Extended Emission: Classifications, Energy Correlations and Radiation Properties
• Gamma-Ray Bursts: To be Short or Long is not the Question
• VLBI observations of GRB 201015A, a relatively faint GRB with a hint of Very High Energy gamma-ray emission
• ALMA Host galaxy observation of the off-axis Gamma-Ray Burst XRF020903

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• The host of GRB 171205A in 3D -- A resolved multiwavelength study of a rare grand-design spiral GRB host
• Revisiting GRB 060218: new insights into low-luminosity gamma-ray bursts from a revised shock breakout model
• The soft X-ray transient EP241021a: A cosmic explosion with a complex off-axis jet and cocoon from a massive progenitor
• GRB 241105A: A test case for GRB classification and rapid r-process nucleosynthesis channels