GRB 090727 and gamma-ray bursts with early time optical emission

Abstract

We present a multi-wavelength analysis of gamma-ray burst GRB 090727, for which optical emission was detected during the prompt gamma-ray emission by the 2-m autonomous robotic Liverpool Telescope and subsequently monitored for a further two days with the Liverpool and Faulkes telescopes. Within the context of the standard fireball model, we rule out a reverse shock origin for the early time optical emission in GRB 090727 and instead conclude that the early time optical flash likely corresponds to emission from an internal dissipation processes. Putting GRB 090727 into a broader observational and theoretical context, we build a sample of 36 gamma-ray bursts (GRBs) with contemporaneous early time optical and gamma-ray detections. From these GRBs, we extract a sub-sample of 18 GRBs, which show optical peaks during prompt gamma-ray emission, and perform detailed temporal and spectral analysis in gamma-ray, X-ray, and optical bands. We find that in most cases early time optical emission shows sharp and steep behaviour, and notice a rich diversity of spectral properties. Using a simple internal shock dissipation model, we show that the emission during prompt GRB phase can occur at very different frequencies via synchrotron radiation. Based on the results obtained from observations and simulation, we conclude that the standard external shock interpretation for early time optical emission is disfavoured in most cases due to sharp peaks ($\Delta t/t<1$) and steep rise/decay indices, and that internal dissipation can explain the properties of GRBs with optical peaks during gamma-ray emission.

21 pages, 12 figures, accepted for publication in ApJ

References in corpus (35)

• The Internal-Collision-Induced Magnetic Reconnection and Turbulence (ICMART) Model of Gamma-Ray Bursts
• Empirical Color Transformations Between SDSS Photometry and Other Photometric Systems
• REM observations of GRB 060418 and GRB 060607A: the onset of the afterglow and the initial fireball Lorentz factor determination
• Prompt GRB emission from gradual energy dissipation
• Observations of the Naked-Eye GRB 080319B: Implications of Nature's Brightest Explosion
• Ten per cent polarized optical emission from GRB 090102
• Energy input and response from prompt and early optical afterglow emission in gamma-ray bursts
• The Epeak-Eiso plane of long Gamma Ray Bursts and selection effects
• 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
• The Remarkable Afterglow of GRB 061007: Implications for Optical Flashes and GRB Fireballs
• Multiwavelength analysis of the intriguing GRB 061126: the reverse shock scenario and magnetization
• Early Optical Polarization of a Gamma Ray Burst Afterglow
• Expected high energy emission from GRB 080319B and origins of the GeV emission of GRBs 080514B, 080916C and 081024B
• Observational Limits on Inverse Compton Processes in GRBs
• GRB 071003: Broadband Follow-up Observations of a Very Bright Gamma-Ray Burst in a Galactic Halo
• Detection of GRB 060927 at z = 5.47: Implications for the Use of Gamma-Ray Bursts as Probes of the End of the Dark Ages
• Rise and fall of the X-ray flash 080330: an off-axis jet?
• Prompt, early, and afterglow optical observations of five gamma-ray bursts (GRBs 100901A, 100902A, 100905A, 100906A, and 101020A)
• Optical and X-Ray Observations of GRB 060526: A Complex Afterglow Consistent with An Achromatic Jet Break
• Panchromatic observations of the textbook GRB 110205A: constraining physical mechanisms of prompt emission and afterglow
• GRB 060605: multi-wavelength analysis of the first GRB observed using integral field spectroscopy
• Swift-UVOT captures the earliest ultraviolet spectrum of a Gamma Ray Burst
• The updated spectral catalogue of INTEGRAL Gamma-Ray Bursts
• The Dark Side of ROTSE-III Prompt GRB Observations
• The prompt to late-time multiwavelength analysis of GRB 060210
• GRB 110205A: Anatomy of a long gamma-ray burst
• Early emission of rising optical afterglows: The case of GRB 060904B and GRB 070420
• Clues from the prompt emission of GRB 080319B
• The GRB early optical flashes from internal shocks: application to GRB990123, GRB041219a and GRB060111b
• A unified picture for the gamma-ray and prompt optical emissions of GRB 990123
• The origin of the early time optical emission of Swift GRB 080310
• The rise of the afterglow in GRB 050820a
• A Comptonization Model for the Prompt Optical and Infrared Emission of GRB 041219A
• Prompt GeV emission in the synchrotron self-Compton model for Gamma-Ray Bursts

Cited by in corpus (25)

• The Physics of Gamma-Ray Bursts and Relativistic Jets
• Physics of Gamma-Ray Bursts Prompt Emission
• GRB 091024A and the nature of ultra-long gamma-ray bursts
• Prompt optical emission as a signature of synchrotron radiation in gamma-ray bursts
• Phenomenology of Reverse-Shock Emission in the Optical Afterglows of Gamma Ray Bursts
• A Reverse Shock and Unusual Radio Properties in GRB 160625B
• A Correlated Study of Optical and X-ray Afterglows of GRBs
• A comprehensive statistical study on gamma-ray bursts
• New constraints on GRB jet geometry and relativistic shock physics
• Polarimetry and Photometry of Gamma-Ray Bursts with RINGO2
• The nature of the late achromatic bump in GRB 120326A
• Very Bright Prompt and Reverse Shock Emission of GRB 140512A
• Prompt emission of GRB 121217A from gamma-rays to the NIR
• Limits on optical polarization during the prompt phase of GRB 140430A
• GRB 140102A: Insight into Prompt Spectral Evolution and Early Optical Afterglow Emission
• A blast from the infant Universe: the very high-z GRB 210905A
• The optical rebrightening of GRB100814A: an interplay of forward and reverse shocks?
• Swift/UVOT: 18 Years of Long GRB Discoveries and Advances
• Photospheric Prompt Emission From Long Gamma Ray Burst Simulations -- I. Optical Emission
• Possible correlations between gamma-ray burst and its host galaxy offset
• Photometric and Spectroscopic Observations of GRB 210104A: Bright Reverse shock Emission and Dense Circumburst Environment
• GRB X-ray plateaus as evidence that the afterglow begins before the prompt gamma-ray emission
• Detecting the early optical flashes of gamma-ray bursts with small telescope arrays
• Prompt Optical Emission from Gamma-ray Bursts with Non-single Timescale Variability of Central Engine Activities
• Broad-band Spectral Modeling of Prompt Emission from Gamma-Ray Bursts Observed by the Transiting Exoplanet Survey Satellite