arXiv subjects

Dorottya Szécsi

Publications and source records attributed to Dorottya Szécsi.

22 records · Page 2Linked to original sources

arXiv2017

Single and binary stellar progenitors of long-duration gamma-ray bursts

This review describes the most common theories behind long-duration gamma-ray burst progenitors. I discuss two astrophysical scenarios: the collapsar and the magnetar models. According to their requirements, the progenitor should be an envelope-free massive star with a fast rotating, collapsing iron core. Such an object, called a TWUIN star, may be produced by chemically homogeneous evolution either from a massive single star or a massive binary system. Various outcomes of this evolutionary path (e.g. supernova explosions and gravitational wave production) are also mentioned, and directions for future research are suggested. In the era of multi-messenger astronomy, my hope is to present a timely overview on how stellar astrophysicists are searching for progenitor models of long-duration gamma-ray bursts, and what they have found so far.

astro-ph.HE↗

arXiv2017

How may short-duration GRBs form? A review of progenitor theories

The origin of gamma-ray bursts (GRBs) is still a fascinating field of research nowadays. While we have been collecting more and more observationally constrained properties of GRB-physics, new theoretical results on the progenitor evolution (be it stellar or compact object) have also emerged. I review some of the most promising progenitor theories for forming a short-duration GRB. A special emphasis is put on the hypothetical case of forming a short-duration GRB through the double black hole merger scenario -- in which case we may expect to observe a gravitational wave emission too. The chemically homogeneous channel for forming a black hole binary is discussed, and the stellar progenitors (so called TWUIN stars) are introduced. The birth place of these short-duration GRBs with a gravitational wave counterpart may be low-metallicity, starforming dwarf galaxies.

astro-ph.HE↗

arXiv2013

Direction Dependent Background Fitting for the Fermi GBM Data

We present a method for determining the background of Fermi GBM GRBs using the satellite positional information and a physical model. Since the polynomial fitting method typically used for GRBs is generally only indicative of the background over relatively short timescales, this method is particularly useful in the cases of long GRBs or those which have Autonomous Repoint Request (ARR) and a background with much variability on short timescales. We give a Direction Dependent Background Fitting (DDBF) method for separating the motion effects from the real data and calculate the duration (T90 and T50, as well as confidence intervals) of the nine example bursts, from which two resulted an ARR. We also summarize the features of our method and compare it qualitatively with the official GBM Catalogue. Our background filtering method uses a model based on the physical information of the satellite position. Therefore, it has many advantages compared to previous methods. It can fit long background intervals, remove all the features caused by the rocking behaviour of the satellite, and search for long emissions or not-triggered events. Furthermore, many part of the fitting have now been automatised, and the method have been shown to work for both Sky Survey mode and ARR mode data. Future work will provide a burst catalogue with DDBF.

astro-ph.IM↗

arXiv2013

Background fitting of Fermi GBM observations

The Fermi Gamma-ray Burst Monitor (GBM) detects gamma-rays in the energy range 8 keV - 40 MeV. We developed a new background fitting process of these data, based on the motion of the satellite. Here we summarize this method, called Direction Dependent Background Fitting (DDBF), regarding the GBM triggered catalog. We also give some preliminary results and compare the duration parameters with the 2-years Fermi Burst Catalog.

astro-ph.HE↗