Swift and XMM-Newton Observations of the Extraordinary GRB 060729: An afterglow with a more than 100 days X-ray light curve

Abstract

We report the results of the Swift and XMM observations of the Swift-discovered long Gamma-Ray Burst GRB 060729 ($T_{90}$=115s). The afterglow of this burst was exceptionally bright in X-rays as well as at UV/Optical wavelengths showing an unusually long slow decay phase ($\alpha$=0.14\plm0.02) suggesting a larger energy injection phase at early times than in other bursts. The X-ray light curve displays a break at about 60 ks after the burst. The X-ray decay slope after the break is $\alpha$=1.29\plm0.03. Up to 125 days after the burst we do not detect a jet break, suggesting that the jet opening angle is larger than 28 degrees. In the first 2 minutes after the burst (rest frame) the X-ray spectrum of the burst changed dramatically from a hard X-ray spectrum to a very soft one. We find that the X-ray spectra at this early phase can all be fitted by an absorbed single power law model or alternatively by a blackbody plus power law model. The power law fits show that the X-ray spectrum becomes steeper while the absorption column density decreases. In Swift's UV/Optical telescope the afterglow was clearly detected up to 9 days after the burst in all 6 filters and even longer in some of the UV filters with the latest detection in the UVW1 31 days after the burst. A break at about 50 ks is clearly detected in all 6 UVOT filters from a shallow decay slope of about 0.3 and a steeper decay slope of 1.3. In addition to the \swift observations we also present and discuss the results from a 61 ks ToO observation by XMM. (Abriviated)

Accepted to be published in the Astrophysical Journal, 28 pages, 10 figures

References in corpus (17)

• The shock break-out of GRB 060218/SN 2006aj
• Swift detects a remarkable gamma-ray burst, GRB 060614, that introduces a new classification scheme
• The early X-ray emission from GRBs
• X-Ray Flares from Postmerger Millisecond Pulsars
• GRB Radiative Efficiencies Derived from the Swift Data: GRBs vs. XRFs, Long vs. Short
• Panchromatic study of GRB 060124: from precursor to afterglow
• Testing the Curvature Effect and Internal Origin of Gamma-Ray Burst Prompt Emissions and X-ray Flares with Swift Data
• The Giant X-ray Flare of GRB 050502B: Evidence for Late-Time Internal Engine Activity
• Jet Breaks in Short Gamma-Ray Bursts. II: The Collimated Afterglow of GRB 051221A
• Short-living supermassive magnetar model for the early X-ray flares following short GRBs
• X-ray flares and the duration of engine activity in gamma-ray bursts
• GeV-TeV and X-ray flares from gamma-ray bursts
• Radiation from an expanding cocoon as an explanation of the steep decay observed in GRB early afterglow light curves
• Gamma-Ray Burst Spectral Correlations: Photospheric and Injection Effects
• Swift Discovery of Gamma-Ray Bursts without Jet Break Feature in their X-Ray Afterglows
• The Swift X-ray flaring afterglow of GRB 050607
• Swift observations of GRB050712

Cited by in corpus (83)

• The Physics of Gamma-Ray Bursts and Relativistic Jets
• Gamma-Ray Bursts in the Swift Era
• Discerning the physical origins of cosmological Gamma-ray bursts based on multiple observational criteria: the cases of z=6.7 GRB 080913, z=8.3 GRB 090423, and some short/hard GRBs
• The Afterglows of Swift-era Gamma-Ray Bursts. I. Comparing pre-Swift and Swift era Long/Soft (Type II) GRB Optical Afterglows
• The Observer's Guide to the Gamma-Ray Burst-Supernova Connection
• A Comprehensive Analysis of the Swift/XRT Data: II. Diverse Physical Origins of the Shallow Decay Segment
• The optically unbiased GRB host (TOUGH) survey. I. Survey design and catalogs
• Afterglow Observations of Fermi-LAT Gamma-Ray Bursts and the Emerging Class of Hyper-Energetic Events
• A test of the millisecond magnetar central engine model of GRBs with Swift data
• The Swift Burst Analyser I: BAT and XRT spectral and flux evolution of Gamma Ray Bursts
• A new method for estimating the bolometric properties of Ibc SNe
• GRB Afterglows with Energy Injection from a spinning down NS
• The prompt-afterglow connection in Gamma-Ray Bursts: a comprehensive statistical analysis of Swift X-ray light-curves
• Open Questions in GRB Physics
• The extinction curves of star-forming regions from z=0.1 to 6.7 using GRB afterglow spectroscopy
• A Comprehensive Study of Gamma-Ray Burst Optical Emission: II. Afterglow Onset and Late Re-Brightening Components
• Correlations of Prompt and Afterglow Emission in Swift Long and Short Gamma Ray Bursts
• Looking Into the Fireball: ROTSE-III and Swift Observations of Early GRB Afterglows
• Taxonomy of GRB optical light-curves: identification of a salient class of early afterglows
• A unifying view of Gamma Ray Burst Afterglows
• A New Paradigm for Gamma Ray Bursts: Long Term Accretion Rate Modulation by an External Accretion Disk
• Gamma-ray burst jet breaks revisited
• Prior Emission Model for X-ray Plateau Phase of Gamma-Ray Burst Afterglows
• A tale of two GRB-SNe at a common redshift of z = 0.54
• A Study of the Gamma-Ray Burst Fundamental Plane
• Testing the Epeak - Eiso relation for GRBs detected by Swift and Suzaku-WAM
• Phenomenology of Reverse-Shock Emission in the Optical Afterglows of Gamma Ray Bursts
• The faster the narrower: characteristic bulk velocities and jet opening angles of Gamma Ray Bursts
• Superluminous X-rays from a superluminous supernova
• Identification of a Local Sample of Gamma-Ray Bursts Consistent with a Magnetar Giant Flare Origin
• GRB 071003: Broadband Follow-up Observations of a Very Bright Gamma-Ray Burst in a Galactic Halo
• Gamma-ray burst optical light-curve zoo: comparison with X-ray observations
• Multi-color observations of short GRB afterglows: 20 events observed between 2007 and 2010
• Fall-Back Disks in Long and Short GRBs
• Spin Evolution of Millisecond Magnetars with Hyperaccreting Fallback Disks: Implications for Early Afterglows of Gamma-Ray Bursts
• Photometry and spectroscopy of GRB 060526: A detailed study of the afterglow and host galaxy of a z=3.2 gamma-ray burst
• A morphological analysis of gamma-ray burst early optical afterglows
• High latitude emission from structured jet of Gamma-Ray Bursts observed off-axis
• Variability and spectral energy distributions of low-luminosity active galactic nuclei: a simultaneous X-ray/UV look with Swift
• GRB 060605: multi-wavelength analysis of the first GRB observed using integral field spectroscopy
• A Correlated Study of Optical and X-ray Afterglows of GRBs
• X-ray flares, plateaus, and chromatic breaks of GRB afterglows from up-scattered forward-shock emission
• GRB 120711A: an intense INTEGRAL burst with long-lasting soft gamma-ray emission and a powerful optical flash
• On Binary Driven Hypernovae and their nested late X-ray emission
• GRB jet structure and the jet break
• Estimating Redshifts for Long Gamma-Ray Bursts
• Constraining the energy budget of GRB 080721
• A Trio of GRB-SNe: GRB 120729A, GRB 130215A / SN 2013ez and GRB 130831A / SN 2013fu
• The Two-Component Afterglow of Swift GRB 050802
• Late-time detections of the X-ray afterglow of GRB 060729 with Chandra - the latest detections ever of an X-ray afterglow
• GRB 090727 and gamma-ray bursts with early time optical emission
• GRB 130427A and SN 2013cq: A Multi-wavelength Analysis of An Induced Gravitational Collapse Event
• Is GRB afterglow emission intrinsically anisotropic ?
• The diverse broad-band light-curves of Swift GRBs reproduced with the cannonball model
• Novel distance indicator for gamma-ray bursts associated with supernovae
• GRB 170817A as a Refreshed Shock Afterglow viewed off-axis
• A Large Catalogue of Multi-wavelength GRB Afterglows I: Color Evolution And Its Physical Implication
• The prompt-early afterglow connection in gamma-ray bursts: implications for the early afterglow physics
• Central Engine of Late-Time X-ray Flares with Internal Origin
• Optical afterglow luminosities in the Swift epoch: confirming clustering and bimodality
• Testing a new view of Gamma Ray Burst Afterglows
• Determining the Dust Extinction of Gamma-ray Burst Host Galaxies: A Direct Method Based on Optical and X-ray Photometry
• A Correlation Between the Intrinsic Brightness and Average Decay Rate of Gamma-ray Burst X-ray Afterglow Light Curves
• Radio observations of GRB 100418a: Test of an energy injection model explaining long-lasting GRB afterglows
• A Large Catalog of Homogeneous Ultra-Violet/Optical GRB Afterglows: Temporal and Spectral Evolution
• 'Jet breaks' and 'missing breaks' in the X-Ray afterglow of Gamma Ray Bursts
• Testing Blandford-Znajek mechanism in black hole hyperaccretion flows for long-duration gamma-ray bursts
• GRB 191016A: A Long Gamma-Ray Burst Detected by TESS
• Constraining Properties of GRB Central Engines with X-ray flares
• Signature of a spin-up magnetar from multi-band afterglow rebrightening of GRB 100814A
• Effective absorbing column density in the gamma-ray burst afterglow X-ray spectra
• Searching for narrow absorption and emission lines in XMM-Newton spectra of gamma-ray bursts
• Long-term Continuous Energy Injection in the Afterglow of GRB 060729
• Swift/UVOT: 18 Years of Long GRB Discoveries and Advances
• Investigating time variability of X-ray absorption in Swift GRBs
• GRB Timing: Decoding the Hidden Slow Jets in GRB 060729
• The shallow-decay phase in both optical and x-ray afterglows of Swift GRB 090529A: Energy injection into a wind-type medium?
• Observational constraints on the external shock prior emission hypothesis of GRBs
• Optimal Coaddition of Imaging Data for Rapidly Fading Gamma-Ray Burst Afterglows
• Examining the evidence for dust destruction in GRB 980703
• Afterglows after Swift
• The Swift satellite lives up to its name, revealing cosmic explosions as they happen
• United classification of cosmic gamma-ray bursts and their counterparts