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A Direct Link Between the Prompt Emission and the Afterglow: the Case of GRB 070311
Cristiano Guidorzi,Susanna D. Vergani 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.5
GRB 070311 was a long burst discovered by INTEGRAL. Here, we present prompt γ-ray, early near infrared (NIR)/optical, late optical, and X-ray data on this burst. We fitted the gamma-ray and the optical light curves and scaled the result to the late-time optical and X-radiation. The H-band light curve acquired by REM shows two pulses one at 80 and the other at 140 s after the peak of the γ-ray burst, with marginal evidence for a faint γ-ray tail. Notably, the late optical and X-ray afterglow experienced a rebrightening between 3 x 10⁴and 2 x 10⁵ s after the burst, with energy comparable to that of the prompt emission extrapolated to the X-ray band. We describe the time profile of the late rebrightening as a combination of a time-rescaled version of the prompt γ-ray pulse and an underlying power law. This result supports a common origin for both prompt and late X-ray/optical afterglow rebrightenings of GRB 070311 within the external shock scenario.
GRB Early Afterglow Observations with the REM Robotic Telescope
Susanna Diana Vergani,Stefano Covino,Daniele Malesani,Cristiano Guidorzi,Paolo D’Avanzo,Eliana Palazzi 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.56 No.5
Gamma-ray bursts (GRBs) are thought to be produced by highly relativistic outflows. Although upper and lower limits for the outflow initial Lorentz factor Γ₀ are available, observational efforts to derive a direct determination of Γ₀ have so far failed or have provided ambiguous results. As a matter of fact, the shape of the early-time afterglow light curve is very sensitive to Γ₀, which determines the time of the afterglow peak, i.e., when the outflow and the shocked circumburst material share a comparable amount of energy. We now comment on the early-time observations of the near-infrared afterglows of GRB060418 and GRB060607A performed by the (REM) robotic telescope. For both events, the afterglow peak was singled out, which allowed us to determine the initial fireball Lorentz, Γ₀ ~ 400.
THESEUS: A key space mission concept for Multi-Messenger Astrophysics
Stratta, G.,Ciolfi, R.,Amati, L.,Bozzo, E.,Ghirlanda, G.,Maiorano, E.,Nicastro, L.,Rossi, A.,Vinciguerra, S.,Frontera, F.,Gö,tz, D.,Guidorzi, C.,O’Brien, P.,Osborne, J.P.,Tanvir, N.,Branchesi, M. Elsevier 2018 ADVANCES IN SPACE RESEARCH Vol.62 No.3
<P><B>Abstract</B></P> <P>The recent discovery of the electromagnetic counterpart of the gravitational wave source GW170817, has demonstrated the huge informative power of multi-messenger observations. During the next decade the nascent field of multi-messenger astronomy will mature significantly. Around 2030 and beyond, third generation ground-based gravitational wave detectors will be roughly ten times more sensitive than the current ones. At the same time, neutrino detectors currently upgrading to multi km<SUP>3</SUP> telescopes, will include a 10 km<SUP>3</SUP> facility in the Southern hemisphere. In this review, we describe the most promising sources of high frequency gravitational waves and neutrinos that will be detected in the next two decades. In this context, we show the important role of the <I>Transient High Energy Sky and Early Universe Surveyor</I> (THESEUS), a mission concept accepted by ESA for phase A study and proposed by a large international collaboration in response to the call for the Cosmic Vision Programme M5 missions. THESEUS aims at providing a substantial advancement in early Universe science as well as in multi–messenger and time–domain astrophysics, operating in strong synergy with future gravitational wave and neutrino detectors as well as major ground- and space-based telescopes. This review is an extension of the THESEUS white paper (Amati et al., 2017), also in light of the discovery of GW170817/GRB170817A that was announced on October 16th, 2017.</P>