Time Evolution of Optical Darkness in GRB Afterglow: The Case of GRB 240825A

Abstract

Long-duration gamma-ray bursts (GRBs) are believed to occur in star-forming regions. The multiwavelength follow-up observations of the early afterglow of GRB 240825A provided insights into the evolution of the optical-to-X-ray spectral feature of the afterglow. We comprehensively investigate the evolution of X-ray spectral properties through time-resolved spectral analysis and calculate optical darkness (${\beta }_{\mathrm{OX}}$) to reveal the physical properties of the afterglow. The X-ray-to-optical SEDs of afterglow in different time intervals are fitted to derive the extinction curves. The ${\beta }_{\mathrm{OX}}$ exhibits a trend of decreasing and then increasing, reaching its minimum value at $\sim 1000\mathrm{s}$ post-trigger. However, at 11 hours post-trigger, ${\beta }_{\mathrm{OX}}$ does not meet the criteria for an optically dark burst. The extinction curves in different time intervals indicate that GRB 240825A occurred in a dust-obscured environment.

Accepted for publication in ApJ

References in corpus (25)

• Array Programming with NumPy
• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• The Physics of Gamma-Ray Bursts and Relativistic Jets
• An online repository of Swift/XRT light curves of GRBs
• An Analysis of the Shapes of Interstellar Extinction Curves. V. The IR-Through-UV Curve Morphology
• Swift Identification of Dark Gamma-Ray Bursts
• The Konus-Wind catalog of gamma-ray bursts with known redshifts. I. Bursts detected in the triggered mode
• X-ray Hardness Evolution in GRB Afterglows and Flares: Late Time GRB Activity Without N_H Variations
• Gaia Data Release 3: The Galaxy in your preferred colours. Synthetic photometry from Gaia low-resolution spectra
• The properties of the 2175AA extinction feature discovered in GRB afterglows
• A metal rich molecular cloud surrounds GRB 050904 at redshift 6.3
• A detailed study of the optical attenuation of gamma-ray bursts in the Swift era
• The History of GRB Outflows: Ejection Lorentz Factor and Radiation Location of X-Ray Flares
• Long Gamma-Ray Bursts and Their Host Galaxies at High Redshift
• Statistical studies of optically dark gamma-ray bursts in the Swift era
• Revealing nature of GRB 210205A, ZTF21aaeyldq (AT2021any), and follow-up observations with the 4K$\times$4K CCD Imager+3.6m DOT
• The variable absorption in the X-ray spectrum of GRB 190114C
• Spectral index-flux relation for investigating the origins of steep decay in $\gamma$-ray bursts
• On the dust properties of high redshift molecular clouds and the connection to the 2175 Å extinction bump
• Evolution of the afterglow optical spectral shape of GRB 201015A in the first hour: evidence for dust destruction
• Investigating time variability of X-ray absorption in Swift GRBs
• STDWeb: Simple Transient Detection pipeline for the Web
• Optical darkness in short-duration $\gamma$-ray bursts
• The Correlation Between Dust and Gas Contents in Molecular Clouds
• A simple model of dust extinction in gamma-ray burst host galaxies