Dorottya Szécsi

Dorottya Szécsi
Nicolaus Copernicus University | umk

PhD

About

65
Publications
3,435
Reads
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1,005
Citations
Education
September 2010 - June 2012
Eötvös Loránd University
Field of study
  • Physics
September 2007 - June 2010
Eötvös Loránd University
Field of study
  • Physics

Publications

Publications (65)
Article
Massive rotating single stars with an initial metal composition appropriate for the dwarf galaxy I Zw 18 ([Fe/H]=$-$1.7) are modelled during hydrogen burning for initial masses of 9-300 M$_{\odot}$ and rotational velocities of 0-900 km s$^{-1}$. Internal mixing processes in these models were calibrated based on an observed sample of OB-type stars i...
Article
Full-text available
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...
Preprint
Full-text available
We present 3-D hydrodynamical models of the evolution of superbubbles powered by stellar winds and supernovae from young coeval massive star clusters within low metallicity ($Z = 0.02$Z$_{\odot}$), clumpy molecular clouds. We explore the initial stages of the superbubble evolution, including the occurrence of pair-instability and core-collapse supe...
Article
The evolution of massive stars is the basis of several astrophysical investigations, from predicting gravitational-wave event rates to studying star-formation and stellar populations in clusters. However, uncertainties in massive star evolution present a significant challenge when accounting for these models’ behaviour in stellar population studies...
Article
Inspired by the excess soft X-ray emission recently detected in Green Pea galaxies, we model the soft X-ray emission (0.5–2.0 keV) of hot gas from star-cluster winds. By combining individual star clusters, we estimate the soft X-ray emission expected from the typically unresolved diffuse hot gas in starburst galaxies, devoid of competing emission f...
Preprint
Full-text available
Inspired by the excess soft X-ray emission recently detected in Green Pea galaxies, we model the soft X-ray emission (0.5 - 2.0 keV) of hot gas from star cluster winds. By combining individual star clusters, we estimate the soft X-ray emission expected from the typically unresolved diffuse hot gas in starburst galaxies, devoid of competing emission...
Preprint
Full-text available
The evolution of massive stars is the basis of several astrophysical investigations, from predicting gravitational-wave event rates to studying star-formation and stellar populations in clusters. However, uncertainties in massive star evolution present a significant challenge when accounting for these models' behaviour in stellar population studies...
Preprint
Full-text available
Proximity to the Eddington luminosity has been attributed as the cause of several observed effects in massive stars. Computationally, if the luminosity carried through radiation exceeds the local Eddington luminosity in the low-density envelopes of massive stars, it can result in numerical difficulties, inhibiting further computation of stellar mod...
Article
Full-text available
At peak, long-duration gamma-ray bursts are the most luminous sources of electromagnetic radiation known. Since their progenitors are massive stars, they provide a tracer of star formation and star-forming galaxies over the whole of cosmic history. Their bright power-law afterglows provide ideal backlights for absorption studies of the interstellar...
Article
The majority of close massive binary stars with initial periods of a few days experience a contact phase, in which both stars overflow their Roche lobes simultaneously. We perform the first dedicated study of the evolution of massive contact binaries and provide a comprehensive prediction of their observed properties. We compute 2790 detailed binar...
Article
Full-text available
Cosmic history has witnessed the lives and deaths of multiple generations of massive stars, all of them invigorating their host galaxies with ionizing photons, kinetic energy, fresh material, and stellar-mass black holes. Ubiquitous engines as they are, astrophysics needs a good understanding of their formation, evolution, properties and yields thr...
Preprint
At peak, long-duration gamma-ray bursts are the most luminous sources of electromagnetic radiation known. Since their progenitors are massive stars, they provide a tracer of star formation and star-forming galaxies over the whole of cosmic history. Their bright power-law afterglows provide ideal backlights for absorption studies of the interstellar...
Preprint
Full-text available
The majority of massive stars are born in close binary systems, where often both stars overfill their Roche lobes simultaneously and the systems experience contact. Here, we aim at a comprehensive prediction of the observable properties of such massive contact binaries and their fates. We present the first set of detailed binary evolution models fo...
Article
In the era of advanced electromagnetic and gravitational wave detectors, it has become increasingly important to effectively combine and study the impact of stellar evolution on binaries and dynamical systems of stars. Systematic studies dedicated to exploring uncertain parameters in stellar evolution are required to account for the recent observat...
Article
The Hercules–Corona Borealis Great Wall is a statistically significant clustering of gamma-ray bursts (GRBs) around redshift 2. Motivated by recent theoretical results indicating that a maximal Universal structure size may indeed coincide with its estimated size (2–3 Gpc), we reexamine the question of this Great Wall’s existence from both observati...
Preprint
Full-text available
The Hercules--Corona Borealis Great Wall is a statistically significant clustering of gamma-ray bursts around redshift 2. Motivated by recent theoretical results indicating that a maximal Universal structure size may indeed coincide with its estimated size (2$-$3\,Gpc), we reexamine the question of this Great Wall's existence from both observationa...
Preprint
In the era of advanced electromagnetic and gravitational wave detectors, it has become increasingly important to effectively combine and study the impact of stellar evolution on binaries and dynamical systems of stars. Systematic studies dedicated to exploring uncertain parameters in stellar evolution are required to account for the recent observat...
Preprint
Massive and very massive stars can play important roles in stellar populations by ejecting strong stellar winds and exploding in energetic phenomena. It is therefore of high importance that their behaviour is properly accounted for in synthetic model populations. Here we present nine grids of stellar evolutionary model sequences, together with fine...
Article
We investigate the impact of uncertainty in the metallicity-specific star formation rate over cosmic time on predictions of the rates and masses of double compact object mergers observable through gravitational waves. We find that this uncertainty can change the predicted detectable merger rate by more than an order of magnitude, comparable to cont...
Preprint
Full-text available
Cosmic History has witnessed the lives and deaths of multiple generations of massive stars, all of them invigorating their host galaxies with ionizing photons, kinetic energy, fresh material and stellar-mass black holes. Ubiquitous engines as they are, Astrophysics needs a good understanding of their formation, evolution, properties and yields thro...
Preprint
We investigate the impact of uncertainty in the metallicity-specific star formation rate over cosmic time on predictions of the rates and masses of double compact object mergers observable through gravitational waves. We find that this uncertainty can change the predicted detectable merger rate by more than an order of magnitude, comparable to cont...
Preprint
A population of binary black hole mergers has now been observed in gravitational waves by Advanced LIGO and Virgo. The masses of these black holes appear to show evidence for a pile-up between $30$--$45$\,\Msol{} and a cut-off above $\sim 45$\,\Msol. One possible explanation for such a pile-up and subsequent cut-off are pulsational pair-instability...
Article
Full-text available
Context . Metal-poor massive stars are assumed to be progenitors of certain supernovae, gamma-ray bursts, and compact object mergers that might contribute to the early epochs of the Universe with their strong ionizing radiation. However, this assumption remains mainly theoretical because individual spectroscopic observations of such objects have ra...
Article
Full-text available
Multiple stellar populations are observed in almost all globular clusters, but the origin of this phenomenon is still debated. We investigate the role cool supergiants may have played. To do this, we combine two investigative methods: state-of-the-art massive stellar evolution and calculations of the hydrodynamic structure of the cluster gas. This...
Article
Double neutron stars (DNSs) have been observed as Galactic radio pulsars, and the recent discovery of gravitational waves from the DNS merger GW170817 adds to the known DNS population. We perform rapid population synthesis of massive binary stars and discuss model predictions, including DNS formation rates, mass distributions, and delay time distri...
Preprint
Full-text available
Context. Metal-poor massive stars are supposed to be progenitors of certain supernovae, gamma-ray bursts and compact object mergers, potentially contributing to the early epochs of the Universe with their strong ionizing radiation. However, they remain mainly theoretical as individual spectroscopic observations of such objects have rarely been carr...
Preprint
Multiple stellar populations have been observed in almost all globular clusters, but the origin of this phenomenon is still debated. Here we investigate the role cool supergiants may have played. To do this, we combine two investigative methods: state-of-the-art massive stellar evolution and calculations of the hydrodynamic structure of the cluster...
Preprint
Double neutron stars (DNS) have been observed as Galactic radio pulsars, and the recent discovery of gravitational waves from the DNS merger GW170817 adds to the known DNS population. We perform rapid population synthesis of massive binary stars and discuss model predictions, including formation rates, mass distributions, and delay time distributio...
Article
THESEUS is a space mission concept aimed at exploiting Gamma-Ray Bursts for investigating the early Universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics. These goals will be achieved through a unique combination of instruments allowing GRB and X-ray transient detection over a broad field of view (more...
Article
Full-text available
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. In 2030s, third generation gravitational wave detectors will be roughly ten t...
Conference Paper
With the detection of gravitational wave emissions from from merging compact objects, it is now more important than ever to effectively mine the data-set of gamma-satellites for non-triggered, short-duration transients. Hence we developed a new method called the Automatized Detector Weight Optimization (ADWO), applicable for space-borne detectors s...
Article
Context. Anomalous surface abundances are observed in a fraction of the low-mass stars of Galactic globular clusters, that may originate from hot-hydrogen-burning products ejected by a previous generation of massive stars. Aims. We aim to present and investigate a scenario in which the second generation of polluted low-mass stars can form in shells...
Article
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...
Article
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 f...
Article
Full-text available
THESEUS is a space mission concept aimed at exploiting Gamma-Ray Bursts for investigating the early Universe and at providing a substantial advancement of multi-messenger and time-domain astrophysics. These goals will be achieved through a unique combination of instruments allowing GRBs and X-ray transients detection over a broad FOV (more than 1sr...
Article
We present the method called Automatized Detector Weight Optimization (ADWO). This method searches for non-triggered, short-duration transients in the data-set of the Fermi's Gamma-ray Burst Monitor. The data of all available detectors and energy channels are combined. Therefore, ADWO is ideal to search for electromagnetic counterparts of gravitati...
Article
Recently it has been found that models of massive stars reach the Eddington limit in their interior, which leads to dilute extended envelopes. We perform a comparative study of the envelope properties of massive stars at different metallicities, with the aim to establish the impact of the stellar metallicity on the effect of envelope inflation. We...
Article
The recently detected gravitational wave signals (GW150914 and GW151226) of the merger event of a pair of relatively massive stellar-mass black holes (BHs) calls for an investigation of the formation of such progenitor systems in general. We analyse the common envelope (CE) stage of the "traditional" formation channel in binaries where the first-fo...
Article
Full-text available
The Fermi collaboration identified a possible electromagnetic counterpart of the GW event of September 14, 2015. Our goal is to work out an unsupervised data analysis algorithm to identify similar events in the Fermi's Gamma-ray Burst Monitor CTTE data stream. In a typical case the signal is very weak and can be only found by a careful analysis of...
Article
Full-text available
Short and long bursts were identified by the BATSE team in the early 90s. A decade ago there were some suggestions about the intermediate duration type of bursts. We are going to summarize recent analyses of the duration distributions of the Beppo-Sax and Swift data. Our conclusion is all the three satellites (CGRO, Swift, Beppo-Sax) can see the th...
Article
The first stellar generation in galactic globular clusters contained massive low-metallicity stars (Charbonnel et al. 2014). We modelled the evolution of this massive stellar population and found that such stars with masses 100-600 M ⊙ evolve into cool RSGs (Szécsi et al. 2015). These RSGs spend not only the core-He-burning phase but even the last...
Article
Massive stars at low metallicity are strong candidates for two of the most energetic explosions in the Universe: long duration gamma-ray bursts and superluminous supernovae. But what is the reason these explosions prefer low metallicity environments? To answer this question, we investigate how massive stellar evolution proceeds in low metallicity e...
Article
The evolution of massive stars is strongly influenced by their initial chemical composition. We have computed rapidly-rotating massive star models with low metallicity (∼1/50 Z⊙) that evolve chemically homogeneously and have optically-thin winds during the main sequence evolution. These luminous and hot stars are predicted to emit intense mid- and...
Article
Full-text available
The Swift satellite made a real break through with measuring simultaneously the gamma X-ray and optical data of GRBs, effectively. Although, the satellite measures the gamma, X-ray and optical properties almost in the same time a significant fractions of GRBs remain undetected in the optical domain. In a large number of cases only an upper bound is...
Article
Full-text available
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 resu...
Article
There are number of evidences that the gamma-ray bursts (GRBs) have a third group beside the short and long ones: The intermediate group. Although at this time, no reasonable physical explanation is known for them. We use discriminant analysis to confirm the former classification and give some further physical properties for the intermediate GRBs.
Conference Paper
Full-text available
Up to 24 Feb 2012 Swift has triggered on 638 GRBs. In this work we use the pattern of the missing gamma, X-ray and optical data measured by BAT, XRT, UVOT and ground based measurements of the redshift, collected for the Swift GRBs ([1]). Using the Boolean factor analysis of multivariate statistical methods we studied the missing data patterns of th...
Article
Full-text available
The Fermi satellite has a particular motion during its flight which enables it to catch the gamma-ray bursts mostly well. The side-effect of this favourable feature is that the lightcurves of the GBM detectors are stressed by rapidly and extremely varying background. Before this data is processed, it needs to be separated from the background. The c...
Article
Full-text available
The Fermi Gamma-ray Space Telescope is programmed to have a proper motion during its flight: if a gamma-ray burst occures, the satellite changes its orientation toward the burst. This rapid rotation has a contribution to the measured data, therefore, the background of a lightcurve varies in time. In order to get the statistical parameters of a burs...
Article
Full-text available
Fermi Gamma-ray Burst Monitor (GBM) detects gamma-rays in the energy range 8 keV – 40 MeV. Background fitting of the Fermi data is not trivial in some cases, especially when an Autonomous Repoint Request (ARR) is received. One good example is the burst 091030613 measured by the GBM, which cannot be fitted properly by a third-order polynomial of tim...
Article
There are number of evidences that the gamma-ray bursts (GRBs) have a third group beside the short and long ones: The intermediate group. Although at this time, no reasonable physical explanation is known for them. We use discriminant analysis to confirm the former classification and give some further physical properties for the intermediate GRBs.
Article
We've analyzed the Fermi high time resolution GRB light curves' autocorrelation function looking for gravitational lens effects. The theoretical amplification-time delay function was applied with a photon count S/N approximation to determine the optimal photon binning. We conclude that during the lens signal search among the Fermi data the usual li...
Article
There are accumulating evidences that GRBs have an intermediate group, beside the short and long classes. Based on the observational data available in the Swift table we compared the observational gamma and X ray properties of GRBs making use the discriminant analysis of the multivariate mathematical statistics. The analysis resulted in two canonic...

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