Special Issue "Gamma-Ray Bursts: Recent Theoretical Models and Observations"

A special issue of Galaxies (ISSN 2075-4434).

Deadline for manuscript submissions: closed (30 September 2016).

Special Issue Editors

Guest Editor
Dr. Ioannis Contopoulos E-Mail
Research Center for Astronomy, Academy of Athens, Athens, Greece
Guest Editor
Dr. Samantha Oates E-Mail
Instituto de Astrofísica de Andalucía (IAA-CSIC), Granada, Spain

Special Issue Information

Dear Colleagues,

Gamma-ray bursts (GRBs) are cosmic flashes of gamma-rays, and consist some of the most energetic events ever detected. They are powerful beacons of the early Universe, and extreme physical laboratories. They are intrinsically linked to the lifecycle of stars and galaxies and can, therefore, provide complementary insights into their evolution. Multi-wavelength observations of these enigmatic events allow us to go deeper into their underlying physics, but 40 years after their discovery their origin remains enigmatic. A great amount of theoretical work has been invested in order to understand what are their central engine and their emission mechanism. Obviously, any discussion of potential GRB models leads us to search for their signatures in GRB observations. In the modern era of multi messenger astronomy from various space missions and ground observatories, the study of these events and their afterglows is likely to intensify as we try to piece together information from the full electromagnetic spectrum, gravitational waves, and neutrinos.

This Special Issue of Galaxies is mainly based on the contributions presented during Symposium 11 at the European Week of Astronomy and Space Science (4­–5 July, 2016, Athens, Greece) that has been organized with the aim to discuss the physics and observations of GRBs, bringing together a number of theorists and observers from the already sizeable GRB community in Europe and worldwide.

Dr. Ioannis Contopoulos
Dr. Samantha Oates
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Galaxies is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (4 papers)

Order results
Result details
Select all
Export citation of selected articles as:

Research

Open AccessArticle
The Signature of the Blandford-Znajek Mechanism in GRB Light Curves
Galaxies 2017, 5(2), 21; https://doi.org/10.3390/galaxies5020021 - 12 Apr 2017
Cited by 1
Abstract
In 1977, Blandford and Znajek showed how the spin energy of a rotating black hole may be extracted electromagnetically through a magnetic field that threads the black hole horizon. A characteristic feature of this mechanism is that, under certain fairly general conditions, the [...] Read more.
In 1977, Blandford and Znajek showed how the spin energy of a rotating black hole may be extracted electromagnetically through a magnetic field that threads the black hole horizon. A characteristic feature of this mechanism is that, under certain fairly general conditions, the energy loss rate decays exponentially. We looked precisely for such behavior in the X-ray light curves of Long and Ultra Long duration Gamma-Ray Bursts (GRBs) observed with the XRT instrument on board the Swift satellite, and found that almost 30% of XRT light curves show an exponential decay before they reach the afterglow plateau. A similar behavior (Fast Rise Exponential Decay-FRED) was observed in γ -rays with the BATSE instrument aboard the CGRO satellite. We consider both of these findings as the signature of the Blandford-Znajek mechanism in action in the central engine of GRBs. Full article
(This article belongs to the Special Issue Gamma-Ray Bursts: Recent Theoretical Models and Observations)
Show Figures

Figure 1

Open AccessArticle
Black Hole Accretion in Gamma Ray Bursts
Galaxies 2017, 5(1), 15; https://doi.org/10.3390/galaxies5010015 - 13 Feb 2017
Cited by 2
Abstract
We study the structure and evolution of the hyperaccreting disks and outflows in the gamma ray bursts central engines. The torus around a stellar mass black hole is composed of free nucleons, Helium, electron-positron pairs, and is cooled by neutrino emission. Accretion of [...] Read more.
We study the structure and evolution of the hyperaccreting disks and outflows in the gamma ray bursts central engines. The torus around a stellar mass black hole is composed of free nucleons, Helium, electron-positron pairs, and is cooled by neutrino emission. Accretion of matter powers the relativistic jets, responsible for the gamma ray prompt emission. The significant number density of neutrons in the disk and outflowing material will cause subsequent formation of heavier nuclei. We study the process of nucleosynthesis and its possible observational consequences. We also apply our scenario to the recent observation of the gravitational wave signal, detected on 14 September 2015 by the two Advanced LIGO detectors, and related to an inspiral and merger of a binary black hole system. A gamma ray burst that could possibly be related with the GW150914 event was observed by the Fermi satellite. It had a duration of about 1 s and appeared about 0.4 s after the gravitational-wave signal. We propose that a collapsing massive star and a black hole in a close binary could lead to the event. The gamma ray burst was powered by a weak neutrino flux produced in the star remnant’s matter. Low spin and kick velocity of the merged black hole are reproduced in our simulations. Coincident gravitational-wave emission originates from the merger of the collapsed core and the companion black hole. Full article
(This article belongs to the Special Issue Gamma-Ray Bursts: Recent Theoretical Models and Observations)
Show Figures

Figure 1

Open AccessArticle
Challenging the Forward Shock Model with the 80 Ms Follow up of the X-ray Afterglow of Gamma-Ray Burst 130427A
Galaxies 2017, 5(1), 6; https://doi.org/10.3390/galaxies5010006 - 16 Jan 2017
Cited by 1
Abstract
GRB 130427A was the most luminous gamma-ray burst detected in the last 30 years. With an isotropic energy output of 8.5×1053 erg and redshift of 0.34, it combined very high energetics with a relative proximity to Earth in an unprecedented [...] Read more.
GRB 130427A was the most luminous gamma-ray burst detected in the last 30 years. With an isotropic energy output of 8.5 × 10 53 erg and redshift of 0.34, it combined very high energetics with a relative proximity to Earth in an unprecedented way. Sensitive X-ray observatories such as XMM-Newton and Chandra have detected the afterglow of this event for a record-breaking baseline longer than 80 million seconds. The light curve displays a simple power-law over more than three decades in time. In this presentation, we explore the consequences of this result for a few models put forward so far to interpret GRB 130427A, and more in general the implication of this outcome in the context of the standard forward shock model. Full article
(This article belongs to the Special Issue Gamma-Ray Bursts: Recent Theoretical Models and Observations)
Show Figures

Figure 1

Open AccessArticle
Exploring the Behaviour of Long Gamma-Ray Bursts with Intrinsic Afterglow Correlations: log L200s−α>200s
Galaxies 2017, 5(1), 4; https://doi.org/10.3390/galaxies5010004 - 10 Jan 2017
Abstract
In these proceedings, we summarise the exploration so far of the relationship between the afterglow luminosity (measured at rest frame 200s; logL200s) and average afterglow decay rate (measured from rest frame 200s onwards, α>200s) of [...] Read more.
In these proceedings, we summarise the exploration so far of the relationship between the afterglow luminosity (measured at rest frame 200s; log L 200 s ) and average afterglow decay rate (measured from rest frame 200s onwards, α > 200 s ) of long duration Gamma-ray Bursts (GRBs), first reported in the optical/UV light curves of GRB afterglows. We show that this correlation is also present in the X-ray afterglows of GRBs as observed by Swift-XRT. We explore how the parameters of the correlation observed in both the X-ray and optical/UV light curves relate to each other and the prompt emission phase and whether these correlations are consistent with predictions of the standard afterglow model. We find that the observed correlations are consistent with a common underlying physical mechanism producing GRBs and their afterglows regardless of the detailed temporal behaviour. However, a basic afterglow model has difficulty explaining all the observed correlations. This leads us to briefly discuss alternative more complex models. Full article
(This article belongs to the Special Issue Gamma-Ray Bursts: Recent Theoretical Models and Observations)
Show Figures

Figure 1

Back to TopTop