28th Texas Symposium on Relativistic Astrophysics

Session

13 - Gamma-ray bursts

.GRB

14 Dec 2015, 14:00

International Conference Centre Geneva

Conveners

13 - Gamma-ray bursts

• Luigi Piro (National Institute for Astrophysics - INAF)

13 - Gamma-ray bursts

• Luigi Piro (National Institute for Astrophysics - INAF)

13 - Gamma-ray bursts

• Luigi Piro (National Institute for Astrophysics - INAF)

206. Thermal emission in GRB 101219B

Dr Josefin Larsson (KTH Royal Institute of Technology)

14/12/2015, 14:00

Talk

In recent years there has been growing evidence that emission from the photosphere of the jet contributes to the prompt emission in many GRBs. The photospheric emission is usually seen to coexist with a dominant non-thermal component. In this talk I will present an analysis of GRB 101219B, the second burst observed by Fermi GBM that is well described by pure blackbody emission. This burst also...

306. Fitting gamma-ray burst prompt emission spectra with a model for subphotospheric dissipation

Björn Ahlgren (KTH Royal Institute of Technology)

14/12/2015, 14:21

Talk

The prompt emission mechanism of gamma-ray bursts (GRBs) is still unknown. While GRB spectra are usually well fitted by the Band function, an empirically motivated, smoothly broken power law, this gives little understanding of the underlying radiation mechanism. In this talk I will present results from fitting a physical model to prompt GRB spectra observed by Fermi. The model simulates the...

318. Signs of magnetic acceleration and multi-zone emission in GRB 080825C

Elena Moretti (MPI Munich)

14/12/2015, 14:42

Talk

The era of the Band function paradigm is ending, due in large part to the high-quality data provided by the Fermi Gamma-ray Space Telescope. Practically all bright GRBs detected by Fermi-LAT and GBM data show deviations from a pure Band function, most often due to extra spectral features being present. Understanding the physics of these components is necessary to reveal the acceleration and...

486. A new intrinsic intrinsic 3 parameter correlation in Gamma Ray Bursts

Maria Dainotti (Stanford University)

14/12/2015, 15:03

Talk

An analysis of 176 GRBs with known redshift observed by Swift which present afterglow plateau revealed a new tri-parameter correlation (Lpeak,Lx,T*a) where Lpeak is the peak luminosity in the prompt emission, Lx is the luminosity at the end of the plateau emission and T*a is the rest frame time at the end of the plateau emission. We have already proven the intrinsic nature of the Lx- T*a...

63. GRB polarization with the POLAR detector.

Dr Nicolas Produit (Universite de Geneve (CH))

14/12/2015, 15:24

Talk

The POLAR detector will be launched together with the Tiangong 2 Chinese space station in the Summer of 2016 from Jiuquan Launch center. POLAR is a GRB polarimeter that will be able to measure GRB polarization degree with 10% precision for 10 GRB per year. POLAR detector has been build by a Chinese-Swiss-Polish collaboration. POLAR flight spare model has passed all qualification tests...

474. Using Gamma-Ray Bursts as Cosmological Probes

Rob Preece (University of Alabama in Huntsville)

14/12/2015, 16:15

Talk

Although they are not standard candles, gamma-ray bursts (GRBs) are quite definitely cosmological objects, with some of the highest redshifts observed. The problem remains how to use GRB observables to construct a usable Hubble diagram. Several correlations between observables and the energetics have been noted, e.g. Amati et al. (2002) and Yonetoku et al. (2004), but it is not clear whether...

92. Shedding light on the early Universe with THESEUS

Lorenzo Amati (INAF - IASF Bologna)

14/12/2015, 16:35

Talk

The Transient High Energy Sky and Early Universe Surveyor (THESEUS) is a mission concept developed by a large international collaboration aimed at exploiting Gamma-Ray Bursts for investigating the early Universe. The main scientific objectives of THESEUS include: investigating the star formation rate and metallicity evolution of the ISM and IGM up to redshift 10, detecting the first generation...

79. An External Shock Origin of GRB 141028A

Dr J. Michael Burgess (KTH Royal Institute of Technology)

14/12/2015, 16:55

Talk

The prompt emission of the long, smooth, and single-pulsed gamma-ray burst, GRB 141028A, is analyzed under the guise of an external shock model. First, we fit the gamma-ray spectrum with a two-component photon model, namely synchrotron+blackbody, and then fit the recovered evolution of the synchrotron vFv peak to an analytic model derived considering the emission of a...

228. Signs of Blandford & Znajek mechanism in GRB afterglow lightcurves.

Antonio Nathanail

14/12/2015, 17:15

Talk

According to Blandford & Znajek (1977), the spin energy of a rotating black hole can be extracted electromagnetically, should the hole be endowed with a magnetic field supported by electric currents in a surrounding disk. We argue that this can be the case for the central engines of GRBs and we show that the duration of the burst depends on the magnetic flux accumulated on the event horizon of...

315. Constraining emission mechanisms in gamma-ray bursts using spectral width

Magnus Axelsson

14/12/2015, 17:35

Talk

The emission processes active in the highly relativistic jets of gamma-ray bursts (GRBs) remain unknown. The spectra are usually well-fit by the Band function, an empirically motivated smoothly-broken power law, yet this gives little understanding of the underlying radiation mechanisms. In this talk we propose a new measure to describe spectra: the width of the EFE spectrum, a quantity...

219. Study of GRB light curve decay indices in the afterglow phase

Mrs Roberta Del Vecchio (Astronomical Observatory of the Jagiellonian University)

14/12/2015, 17:55

Poster

In this work we study the distribution of temporal power-law decay indices, $\alpha$, in the Gamma Ray Burst (GRB) afterglow phase, fitted for a sample of $164$ long GRBs with known redshifts using a power-law form. These indices are compared to the values of characteristic afterglow luminosity, $L_a$, the time, $T_a^{\ast }$, and the analogous decay index, ${\alpha }_W$, derived with global...

484. Observed properties of high redshift Gamma-Ray Bursts

Graziella Pizzichini (INAF)

14/12/2015, 17:58

Poster

I shall compare the observed properties of high redshift long Gamma-Ray Bursts with those at lower redshifts

375. Moving observed Short GRBs both off-axis and into the local Universe

Dr Giovanni De Cesare (IASF-Bologna), Giulia Stratta (Urbino University), Dr Giuseppe Greco (Urbino University), Dr Marica Branchesi (Urbino University)

14/12/2015, 18:01

Poster

Short Gamma Ray Bursts (SGRBs) are among the best source candidates of simultaneous electromagnetic radiation and gravitational waves (GWs) in the frequency range covered by the imminent second generation laser interferometer detectors Advanced LIGO and Advanced Virgo. SGRB afterglow properties in the electromagnetic spectrum (e.g. photon flux intensity, variability time scale) can be very...

209. Short gamma-ray bursts from binary neutron star mergers: the time-reversal scenario

Dr Riccardo Ciolfi (University of Trento and INFN-TIFPA)

15/12/2015, 14:00

Talk

Leading models relate short gamma-ray bursts (SGRBs) to a relativistic jet launched by the black hole (BH)-accretion torus system that can be formed in a binary neutron star (BNS) or a NS-BH binary merger. However, recent observations by Swift have revealed a large fraction of SGRB events accompanied by X-ray afterglows with durations $\sim {10}^2-{10}^5$ s, suggesting continuous energy injection...

210. Electromagnetic emission from long-lived binary neutron star merger remnants

Mr Daniel Siegel (Max Planck Institute for Gravitational Physics (Albert Einstein Institute))

15/12/2015, 14:21

Talk

Recent observations indicate that in a large fraction of binary neutron star (BNS) mergers a long-lived neutron star (NS) may be formed rather than a black hole. Unambiguous electromagnetic (EM) signatures of such a scenario would strongly impact our knowledge on how short gamma-ray bursts (SGRBs) and their afterglow radiation are generated. Furthermore, such EM signals would have...

286. Dynamical mass ejection from black hole-neutron star binaries

Dr Koutarou Kyutoku (RIKEN)

15/12/2015, 14:42

Talk

In recent years, mass ejection from compact binary coalescences has been getting a lot more attention. Neutron-rich material ejected from neutron stars during such a coalescence event are increasingly recognized as the most promising site of the rapid process (r-process) nucleosynthesis. Mass ejection will also be the primary agent for driving electromagnetic radiation from compact binary...

287. Fast luminous blue transients from newborn black holes

Dr Kazumi Kashiyama (University of California, Berkeley)

15/12/2015, 15:03

Talk

Newborn black holes in collapsing massive stars can be accompanied by a fallback disc. The accretion rate is typically super-Eddington and strong disc outflows are expected. Such outflows could be directly observed in some failed explosions of compact (blue supergiants or Wolf-Rayet stars) progenitors, and may be more common than long-duration gamma-ray bursts. Using an analytical model, we...