A comprehensive view of blackbody components in the X-ray spectra of GRBs

Abstract

A small fraction of gamma-ray bursts (GRBs) exhibit blackbody emission in the X-ray spectra, the origin of which is debated. In order to gain a more complete understanding of this phenomenon, we present a search for blackbody components in 116 GRBs with known redshifts observed by {\it Swift}~XRT. A time-resolved spectral analysis is carried out and the significance of the blackbody is assessed with respect to an absorbed power-law model. We report nine new detections and confirm the previously reported blackbody in GRB~171205A. Together with our previous results, there are a total of 19 GRBs with significant blackbody emission in a sample of 199 GRBs observed by {\it Swift} over 13 years. The detections include one short GRB and two low-luminosity GRBs. We estimate fireball parameters from the blackbody components and note that the blackbody luminosity is correlated with the temperature and inferred Lorentz factor. There is a large spread in the properties of the blackbody components and the light curves, which points to different origins for the emission. In about a third of the GRBs, the blackbody is clearly associated with late prompt emission from the jet. The rest of the sample includes cases that are fully consistent with the expectations from a cocoon, as well cases that may be explained by high-latitude emission or more energetic cocoons. These results indicate that thermal emission is associated with all parts of the jet.

Accepted for publication in MNRAS

References in corpus (25)

• The Physics of Gamma-Ray Bursts and Relativistic Jets
• GRB Radiative Efficiencies Derived from the Swift Data: GRBs vs. XRFs, Long vs. Short
• Discovery of the nearby long, soft GRB 100316D with an associated supernova
• The Galactic WC stars: Stellar parameters from spectral analyses indicate a new evolutionary sequence
• Jet collimation in the ejecta of double neutron star merger: new canonical picture of short gamma-ray bursts
• The Observable Signatures of GRB Cocoons
• GRB110721A: An extreme peak energy and signatures of the photosphere
• The First Survey of X-ray Flares from Gamma Ray Bursts Observed by Swift: Spectral Properties and Energetics
• A new method of determining the initial size and Lorentz factor of gamma-ray burst fireballs using a thermal emission component
• A comprehensive analysis of Swift/XRT data: I. Apparent spectral evolution of GRB X-ray tails
• A unified picture for low-luminosity and long gamma-ray bursts based on the extended progenitor of llgrb 060218/SN 2006aj
• Signatures of a jet cocoon in early spectra of a supernova associated with a $\gamma$-ray burst
• Bulk Lorentz factors of Gamma-Ray Bursts
• Peak energy of the prompt emission of long Gamma Ray Bursts vs their fluence and peak flux
• Detection of Low-energy Breaks in Gamma-Ray Burst Prompt Emission Spectra
• Uncovering the Intrinsic Variability of Gamma-ray Bursts
• Curvature Effect of a Non-Power-Law Spectrum and Spectral Evolution of GRB X-Ray Tails
• The photospheric radiation model for the prompt emission of Gamma-ray Bursts: Interpreting four observed correlations
• Did we observe the supernova shock breakout in GRB 060218?
• Photosphere emission in the X-Ray Flares of Swift Gamma-Ray Bursts and Implications for the Fireball Properties
• An Observed Correlation Between Thermal and Non-Thermal Emission in Gamma-Ray Bursts
• Testing a model for subphotospheric dissipation in GRBs: fits to Fermi data constrain the dissipation scenario
• Probing the Structure of Gamma-Ray Burst Jets with Steep Decay Phase of their Early X-ray Afterglows
• Thermal components in the early X-ray afterglows of GRBs: likely cocoon emission and constraints on the progenitors
• Diffusive photospheres in gamma-ray bursts

Cited by in corpus (4)

• A wind environment and Lorentz factors of tens explain gamma-ray bursts X-ray plateau
• Chemical stratification in a long gamma-ray burst cocoon and early-time spectral signatures of supernovae associated with gamma-ray bursts
• Investigating time variability of X-ray absorption in Swift GRBs
• The Double-Burst Nature and Early Afterglow Evolution of Long GRB 110801A