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1.
A study on tidal disruption event dynamics around an Sgr A*-like massive black hole
Aurora Clerici, Andreja Gomboc, 2020, original scientific article

Found in: osebi
Keywords: astronomija, črne luknje, plimsko raztrganje zvezd
Published: 05.11.2020; Views: 123; Downloads: 0
.pdf Fulltext (689,20 KB)

2.
A search for Galactic transients disguised as gamma-ray bursts
Valentina La Parola, Cristiano Guidorzi, Aurora Clerici, 2015, original scientific article

Abstract: A significant fraction of cosmological gamma-ray bursts (GRBs) are characterised by a fast rise and exponential decay (FRED) temporal structure. This is not a distinctive feature of this class, since it is observed in many Galactic transients and is likely descriptive of a sudden release of energy followed by a diffusion process. Possible evidence has recently been reported by Tello et al. (2012) for a Galactic contamination in the sample of FRED GRBs discovered with Swift. We searched for possible Galactic intruders disguised as FRED GRBs in the Swift catalogue up to September 2014. We selected 181 FRED GRBs (2/3 with unknown redshift) and considered different subsamples. We tested the degree of isotropy through the dipole and the quadrupole moment distributions, both with reference to the Galaxy and in a coordinate-system-independent way, as well as with the two-point angular autocovariance function. In addition, we searched for possible indicators of a Galactic origin among the spectral and temporal properties of individual GRBs. We found marginal (~3 sigma) evidence for an excess of FREDs with unknown redshift towards the Galactic plane compared with what is expected for an isotropic distribution corrected for the non-uniform sky exposure. However, when we account for the observational bias against optical follow-up observations of low-Galactic latitude GRBs, the evidence for anisotropy decreases to ~2 sigma. In addition, we found no statistical evidence for different spectral or temporal properties from the bulk of cosmological GRBs. We found marginal evidence for the presence of a disguised Galactic population among Swift GRBs with unknown redshift. The estimated fraction is f=(19 +- 11)%, with an upper limit of 34% (90% confidence).
Found in: osebi
Keywords: gamma-ray burst, statistical, Galactic transient
Published: 03.02.2016; Views: 2013; Downloads: 0
.pdf Fulltext (173,64 KB)

3.
Tidal disruption events from different kinds of astrophysical objects
Andreja Gomboc, Aurora Clerici, published scientific conference contribution abstract

Found in: osebi
Keywords: astronomija, črne luknje, plima
Published: 11.10.2016; Views: 1823; Downloads: 0
.pdf Fulltext (579,63 KB)

4.
Tidal disruption events from different kinds of astrophysical objects: a preliminary analysis
Aurora Clerici, Andreja Gomboc, 2017, published scientific conference contribution abstract

Found in: osebi
Keywords: astronomy, tidal disruption events, black holes
Published: 17.08.2017; Views: 1784; Downloads: 0
.pdf Fulltext (221,17 KB)

5.
Tidal Disruption Events from different kinds of astrophysical objects: a preliminary analysis
Aurora Clerici, Andreja Gomboc, 2016, published scientific conference contribution abstract

Found in: osebi
Keywords: črne luknje, zvezde, plimska sila
Published: 17.11.2016; Views: 1933; Downloads: 0
.pdf Fulltext (18,27 MB)

6.
7.
Black holes, gravitational waves and fundamental physics: a roadmap
Katja Bricman, Andreja Gomboc, Tanja Petrushevska, Leor Barack, Aurora Clerici, Christopher Eckner, Nada Ihanec, Gabrijela Zaharijas, 2019, review article

Abstract: The grand challenges of contemporary fundamental physics—dark matter, dark energy, vacuum energy, inflation and early universe cosmology, singularities and the hierarchy problem—all involve gravity as a key component. And of all gravitational phenomena, black holes stand out in their elegant simplicity, while harbouring some of the most remarkable predictions of General Relativity: event horizons, singularities and ergoregions. The hitherto invisible landscape of the gravitational Universe is being unveiled before our eyes: the historical direct detection of gravitational waves by the LIGO-Virgo collaboration marks the dawn of a new era of scientific exploration. Gravitational-wave astronomy will allow us to test models of black hole formation, growth and evolution, as well as models of gravitational-wave generation and propagation. It will provide evidence for event horizons and ergoregions, test the theory of General Relativity itself, and may reveal the existence of new fundamental fields. The synthesis of these results has the potential to radically reshape our understanding of the cosmos and of the laws of Nature. The purpose of this work is to present a concise, yet comprehensive overview of the state of the art in the relevant fields of research, summarize important open problems, and lay out a roadmap for future progress. This write-up is an initiative taken within the framework of the European Action on 'Black holes, Gravitational waves and Fundamental Physics.
Found in: osebi
Keywords: black holes, gwverse
Published: 24.06.2019; Views: 829; Downloads: 0
.pdf Fulltext (7,00 MB)

8.
9.
A study of stellar debris dynamics during a tidal disruption event
Aurora Clerici, 2020, doctoral dissertation

Abstract: The number of observed tidal disruption events is increasing rapidly with the advent of new surveys. Thus, it is becoming increasingly important to improve TDE models using different stellar and orbital parameters. We study the dynamical behaviour of tidal disruption events produced by a massive black hole like Sgr A* by changing different initial orbital parameters, taking into account the observed orbits of S stars. Investigating different types of orbits and penetration factors is important since their variations lead to different timescales of the tidal disruption event debris dynamics, making mechanisms such as self-crossing and pancaking act strongly or weakly, thus affecting the circularisation and accretion disk formation. We have performed smoothed particle hydrodynamics simulations. Each simulation consists in modelling the star with $10^5$ particles, and the density profile is described by a polytrope with $\gamma$ = 5/3. The massive black hole is modelled with a generalised post-Newtonian potential, which takes into account relativistic effects of the Schwarzschild space-time. Our analyses find that mass return rate distributions of solar-like stars and S-like stars with same eccentricity have similar durations, but S-like stars have higher mass return rate, as expected due to their larger mass. Regarding debris circularisation, we identify four types of evolution, related to the mechanisms and processes involved during circularisation: in type 1 the debris does not circularise efficiently, hence a disk is not formed or is formed after relatively long time; in type 2 the debris slowly circularises and eventually forms a disk with no debris falling back; in type 3 the debris relatively quickly circularises and forms a disk while there is still debris falling back; finally, in type 4 the debris quickly and efficiently circularises, mainly through self-crossings and shocks, and forms a disk with no debris falling back. Finally, we find that the standard relation of circularisation radius $r_{\rm circ} = 2r_{\rm t}$ holds only for $\beta = 1$ and eccentricities close to parabolic.
Found in: osebi
Keywords: 07.05.Tp Computer modeling and simulation, 95.30.Lz Hydrodynamics, 98.35.Jk Galactic center, bar, circumnuclear matter, and bulge, 98.62.Js Galactic nuclei (including black holes), circumnuclear matter, and bulges, 98.62.Mw Infall, accretion, and accretion disks
Published: 29.09.2020; Views: 173; Downloads: 12
.pdf Fulltext (37,55 MB)

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