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21.
The rise and fall of the nuclear transient PS16dtm
Tanja Petrushevska, 2022, published scientific conference contribution abstract

Abstract: Thanks to the advent of large-scale optical surveys, a diverse set of flares from the nuclear regions of galaxies has recently been discovered. These include the disruption of stars by supermassive black holes at the centres of galaxies - nuclear transients known as tidal disruption events (TDEs). Active galactic nuclei (AGN) can show extreme changes in the brightness and emission line intensities, often referred to as changing-look AGN (CLAGN).  Given the physical and observational similarities, the interpretation and distinction of nuclear transients as CLAGN or TDEs remains difficult. One of the obstacles of making progress in the field is the lack of well-sampled data of long-lived nuclear outbursts in AGN. I will present PS16dtm, a nuclear transient in a Narrow Line Seyfert 1 (NLSy1) galaxy which has been proposed to be a TDE candidate. I will show our multi-year spectroscopic and photometric study of PS16dtm, which can help us to better understand the outbursts originating in NLSy1 galaxies.
Keywords: supermassive black holes, tidal disruption events, active galactic nucleus
Published in RUNG: 09.11.2022; Views: 1024; Downloads: 5
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Extending the sample of core-collapse supernovae forsearches of axion-like-particle induced gamma-ray burstswith the Fermi LAT
Manuel Meyer, Tanja Petrushevska, 2021, published scientific conference contribution

Keywords: dark matter, axions, supernovae
Published in RUNG: 06.07.2021; Views: 1847; Downloads: 3
.pdf Full text (2,32 MB)

26.
Strongly Lensed Supernovae in Well-Studied Galaxy Clusters with the Vera C. Rubin Observatory
Tanja Petrushevska, 2020, original scientific article

Abstract: Strong lensing by galaxy clusters can be used to significantly expand the survey reach, thus allowing observation of magnified high-redshift supernovae that otherwise would remain undetected. Strong lensing can also provide multiple images of the galaxies that lie behind the clusters. Detection of strongly lensed Type Ia supernovae (SNe Ia) is especially useful because of their standardizable brightness, as they can be used to improve either cluster lensing models or independent measurements of cosmological parameters. The cosmological parameter, the Hubble constant, is of particular interest given the discrepancy regarding its value from measurements with different approaches. Here, we explore the feasibility of the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) of detecting strongly lensed SNe in the field of five galaxy clusters (Abell 1689 and Hubble Frontier Fields clusters) that have well-studied lensing models. Considering the 88 systems composed of 268 individual multiple images in the five cluster fields, we find that the LSST will be sensitive to SNe Ia (SNe IIP) exploding in 41 (23) galaxy images. The range of redshift of these galaxies is between 1.01 < z < 3.05. During its 10 years of operation, LSST is expected to detect 0.2 ± 0.1 SN Ia and 0.9 ± 0.3 core collapse SNe. However, as LSST will observe many more massive galaxy clusters, it is likely that the expectations are higher. We stress the importance of having an additional observing program for photometric and spectroscopic follow-up of the strongly lensed SNe detected by LSST.
Keywords: supernovae, strong gravitational lensing, galaxy clusters
Published in RUNG: 28.11.2020; Views: 2335; Downloads: 91
.pdf Full text (863,97 KB)

27.
Iskanje narave temne snovi
Tanja Petrushevska, 2020, popular article

Keywords: temno snov, supernova
Published in RUNG: 15.06.2020; Views: 2175; Downloads: 0
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28.
Search for Axionlike-Particle-Induced Prompt γ -Ray Emission from Extragalactic Core-Collapse Supernovae with the Fermi Large Area Telescope
Manuel Meyer, Tanja Petrushevska, 2020, original scientific article

Abstract: During a core-collapse supernova (SN), axionlike particles (ALPs) could be produced through the Primakoff process and subsequently convert into γ rays in the magnetic field of the Milky Way. We do not find evidence for such a γ-ray burst in observations of extragalactic SNe with the Fermi Large Area Telescope (LAT). The SN explosion times are estimated from optical light curves and we find a probability of about ∼90% that the LAT observed at least one SN at the time of the core collapse. Under the assumption that at least one SN was contained within the LAT field of view, we exclude photon-ALP couplings ≳2.6×10−12 GeV−1 for ALP masses ma≲3×10−10 eV, improving previous limits from SN1987A by a factor of 2.
Keywords: darn matter, axions, axion-like particles, core-collapse supernovae
Published in RUNG: 15.06.2020; Views: 2477; Downloads: 77
.pdf Full text (30,47 MB)

29.
Black holes, gravitational waves and fundamental physics: a roadmap
Leor Barack, Tanja Petrushevska, Andreja Gomboc, Katja Bricman, 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.
Keywords: black holes, gwverse
Published in RUNG: 24.06.2019; Views: 3456; Downloads: 0
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30.
First attempt to start fighting light pollution in Macedonia
Tanja Petrushevska, Andrej Mohar, 2018, published scientific conference contribution abstract (invited lecture)

Keywords: light pollution, Macedonia
Published in RUNG: 14.01.2019; Views: 2960; Downloads: 14
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