Multi-wavelength afterglow observations of the high redshift GRB 050730

Abstract

GRB 050730 is a long duration high-redshift burst (z=3.967) discovered by Swift. The afterglow shows variability and is well monitored over a wide wavelength range. We present comprehensive temporal and spectral analysis of the afterglow of GRB 050730 including observations from the millimeter to X-rays. We use multi-wavelength afterglow data to understand the temporal and spectral decay properties with superimposed variability of this high redshift burst. Five telescopes were used to study the decaying afterglow of GRB 050730 in the B, V, r', R, i', I, J and K photometric pass bands. A spectral energy distribution was constructed at 2.9 hours post-burst in the K, J, I, R, V and B bands. X-ray data from the satellites Swift and XMM-Newton were used to study the afterglow evolution at higher energies. The early afterglow shows variability at early times and shows a steepening at ~0.1 days (8.6 ks) in the B, V, r', R, i', I, J and K passbands. The early afterglow light curve decayed with alpha_1 = -0.60+/-0.07 and alpha_2 = -1.71+/-0.06 based on R and I band data. A millimeter detection of the afterglow around 3 days after the burst shows an excess in comparison to predictions. The early X-ray light curve observed by Swift is complex and contains flares. At late times the X-ray light curve can be fit by a powerlaw alpha_x = -2.5+/-0.15 which is steeper than the optical light curve. A spectral energy distribution (SED) was constructed at \~2.9 hours after the burst. An electron energy index, p, of ~ 2.3 was calculated using the SED and the photon index from the X-ray afterglow spectra and indicates that the synchrotron cooling frequency nu_c is above observed frequencies.

12 pages, 10 figures, Accepted for publication in A&A. Typo corrected in revision

References in corpus (2)

• The Afterglow of GRB010222: A Case of Continuous Energy Injection
• Outshining the quasars at reionisation: The X-ray spectrum and lightcurve of the redshift 6.29 Gamma-Ray Burst GRB050904

Cited by in corpus (14)

• REM observations of GRB 060418 and GRB 060607A: the onset of the afterglow and the initial fireball Lorentz factor determination
• Correlations of Prompt and Afterglow Emission in Swift Long and Short Gamma Ray Bursts
• Taxonomy of GRB optical light-curves: identification of a salient class of early afterglows
• A unifying view of Gamma Ray Burst Afterglows
• The Early-time Optical Properties of Gamma-Ray Burst Afterglows
• Swift GRB Afterglows and the Forward-Shock Model
• The extreme, red afterglow of GRB 060923A: Distance or dust?
• Line Searches in Swift X-ray Spectra
• High energy afterglows and flares from Gamma-Ray Burst by Inverse Compton emission
• Spectroscopy and multiband photometry of the afterglow of intermediate duration gamma-ray burst 040924 and its host galaxy
• Optical afterglow luminosities in the Swift epoch: confirming clustering and bimodality
• An Estimation of the Gamma-Ray Burst Afterglow Apparent Optical Brightness Distribution Function
• The exceptionally extended flaring activity in the X-ray afterglow of GRB 050730 observed with Swift and XMM-Newton
• Statistical studies of optically dark gamma-ray bursts in the Swift era