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61.
Searching for supernovae in the multiply-imaged galaxies behind the gravitational telescope A370
Tanja Petrushevska, Ariel Goobar, D. J. Lagattuta, R. Amanullah, Laura Hangard, S. Fabbro, C. Lindman, K. Paech, J. Richard, J.P. Kneib, 2017, izvirni znanstveni članek

Opis: Aims. Strong lensing by massive galaxy clusters can provide magnification of the flux and even multiple images of the galaxies that lie behind them. This phenomenon facilitates observations of high-redshift supernovae (SNe) that would otherwise remain undetected. Type Ia supernovae (SNe Ia) detections are of particular interest because of their standard brightness, since they can be used to improve either cluster lensing models or cosmological parameter measurements. Methods. We present a ground-based, near-infrared search for lensed SNe behind the galaxy cluster Abell 370. Our survey was based on 15 epochs of J-band observations with the HAWK-I instrument on the Very Large Telescope (VLT). We use Hubble Space Telescope (HST) photometry to infer the global properties of the multiply-imaged galaxies. Using a recently published lensing model of Abell 370, we also present the predicted magnifications and time delays between the images. Results. In our survey, we did not discover any live SNe from the 13 lensed galaxies with 47 multiple images behind Abell 370. This is consistent with the expectation of 0.09 ± 0.02 SNe calculated based on the measured star formation rate. We compare the expectations of discovering strongly lensed SNe in our survey and that performed with HST during the Hubble Frontier Fields (HFF) programme. We also show the expectations of search campaigns that can be conducted with future facilities, such as the James Webb Space Telescope (JWST) or the Wide-Field Infrared Survey Telescope (WFIRST). We show that the NIRCam instrument aboard the JWST will be sensitive to most SN multiple images in the strongly lensed galaxies and thus will be able to measure their time delays if observations are scheduled accordingly.
Najdeno v: ključnih besedah
Ključne besede: gravitational lensing: strong / supernovae: general / galaxies: clusters: individual: A 370
Objavljeno: 28.06.2018; Ogledov: 2401; Prenosov: 115
.pdf Polno besedilo (4,14 MB)

62.
Prospects for lensed supernovae behind galaxy clusters with the James Webb Space Telescope
Tanja Petrushevska, 2018, objavljeni povzetek znanstvenega prispevka na konferenci

Opis: Galaxies, and clusters of galaxies, can act as gravitational lenses and magnify the light of objects behind them. The effect enables observations of very distant supernovae, that otherwise would be too faint to be detected by existing telescopes, and allows studies of the frequency and properties of these rare phenomena when the universe was young. Under the right circumstances, multiple images of the lensed supernovae can be observed, and due to the variable nature of the objects, the difference between the arrival times of the images can be measured. Since the images have taken different paths through space before reaching us, the time-differences are sensitive to the expansion rate of the universe. One class of supernovae, Type Ia, are of particular interest to detect. Their well known brightness can be used to determine the magnification, which can be used to understand the lensing systems. I will also report our discovery of the first resolved multiply-imaged gravitationally lensed supernova Type Ia. I will also show the expectations of search campaigns that can be conducted with future facilities, such as the James Webb Space Telescope (JWST) or the Wide-Field Infrared Survey Telescope (WFIRST).
Najdeno v: ključnih besedah
Ključne besede: Strong lensing, Hubble constant, measuring expansion history with time delays, lensed supernovae
Objavljeno: 09.07.2018; Ogledov: 2407; Prenosov: 115
.pdf Polno besedilo (4,14 MB)

63.
Prospects for observing lensed supernovae behind galaxy clusters with JWST
Tanja Petrushevska, 2018, prispevek na konferenci brez natisa

Opis: Contributed talk at the international conference "The Universe as a telescope: probing the cosmos at all scales with strong lensing" in Milan 3-7 September 2018
Najdeno v: ključnih besedah
Ključne besede: strong lensing, supernovae, JWST, LSST
Objavljeno: 12.09.2018; Ogledov: 1748; Prenosov: 0
.pdf Polno besedilo (48,18 KB)
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64.
Flares from the centers of galaxies with Gaia and OGLE surveys
Nada Ihanec, 2018, magistrsko delo

Opis: Modern wide-field-of-view and all-sky satellites (e.g. Gaia) and ground based surveys (e.g. OGLE) repeatedly cover a large part of the sky and are detecting new, transient astrophysical sources on daily basis. In this thesis I analyzed the data from Gaia and OGLE transient surveys, with special focus on transients located near the centres of galaxies to detect possible Tidal Disruption Events. These occur when a star gets too close to a Super-Massive Black Hole, which lurks in the centres of most galaxies, and gets disrupted due to the black hole's gravitational tidal forces. The goal of my research was to detect possible Tidal Disruption Events and eliminate false candidates, such as supernovae. The work involved daily inspection of new alerts, identified with Gaia and OGLE Transient Detection System. I searched for potential transients in galactic nuclei and in case there was such a transient detected, follow-up spectroscopic observations were initiated in order to help classify the object. During the course of my work I analyzed spectra obtained with the largest telescopes in the world (SALT, VLT) and performed the spectral template matching, recognition of spectral features related to known classes of transients, determination of redshift etc.
Najdeno v: ključnih besedah
Povzetek najdenega: ...Events and eliminate false candidates, such as supernovae. The work involved daily inspection of new...
Ključne besede: Flares, transients, Gaia, OGLE, supernovae, tidal disruption events, nuclear transients
Objavljeno: 14.05.2019; Ogledov: 2690; Prenosov: 99
.pdf Polno besedilo (8,11 MB)

65.
Exploring the Universe with supernovae
Tanja Petrushevska, objavljeni povzetek znanstvenega prispevka na konferenci (vabljeno predavanje)

Opis: Supernovae have proven to be exquisite tools for a variety of astrophysics and cosmology topics. In this lecture, I will highlight a selection of dedicated tele- scopic surveys for detecting supernovae and I will report some of our interesting discoveries during the past few years. I will dedicate special attention to strongly lensed supernovae by galaxies and galaxy clusters. Under the right circumstances, multiple images of the lensed supernovae can be observed, and due to the variable nature of the objects, the difference between the arrival times of the images can be measured. Since the images have taken different paths through space before reaching us, the time-differences are sensitive to the expansion rate of the universe. Therefore, measuring time delays from strongly lensed supernovae is emerging as a novel and independent tool for estimating the Hubble constant (H0). This is very important given the recent discord in the value of H0 from two methods that probe different distance ranges: the ESA mission Planck value corresponds to 67.74 ± 0.46 km s−1 Mpc−1; [1], while a reanalysis of the local distance scale gives 73.24 ± 1.74 km s−1 Mpc−1; [2, 3], these measurements thus being inconsistent at the ≈ 3.5σ level. Therefore, the results of additional independent and high- precision techniques, which rely on different physics, are of key importance. In this context, I will report our discovery of the first resolved multiply-imaged gra- vitationally lensed supernova Type Ia [4]. Moving forward, I will discuss some of the prospects of upcoming facilities such as the Large Synoptic Survey Telescope and James Webb Space Telescope [5, 6].
Najdeno v: ključnih besedah
Ključne besede: supernovae, strong lensing, neutron stars
Objavljeno: 29.11.2018; Ogledov: 2055; Prenosov: 0
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66.
Prospects for Strongly Lensed Supernovae Behind Hubble FrontierFields Galaxy Clusters with the James Webb Space Telescope
Tanja Petrushevska, 2018, izvirni znanstveni članek

Opis: Measuring time delays from strongly lensed supernovae (SNe) is emerging as a novel andindependent tool for estimating the Hubble constant (H0). This is very important given the recent discordin the value of H0) from two methods that probe different distance ranges. The success of this techniquewill rely of our ability to discover strongly lensed SNe with measurable time delays. Here, we present themagnifications and the time delay s for the multiply-imaged galaxies behind the Hubble Frontier Fields(HFF) galaxy clusters, by using recently published lensing models. Continuing on our previous work donefor Abell 1689 (A1689) and Abell 370, we also show the prospects of observing strongly lensed SNe behindthe HFF clusters with the upcoming James Webb Space Telescope (JWST). With four 1-hour visits inone year, the summed expectations of all six HFF clusters are ∼0 .5 core-collapse (CC) SNe and 0.06Type Ia SNe (SNe Ia) in F115W band, while with F150W the expectations are higher, ∼0.9 CC SNeand ∼0.06 SNe Ia. These estimates match those expected by only surveying A1689, proving that theperformance of A1689 as gravitational telescope is superior. In the five HFF clusters presented here, wefind that F150W will be able to detect SNe Ia (SNe IIP) exploding in 93 (80) pairs multiply-imaged galaxieswith time delays of less than 5 years.
Najdeno v: ključnih besedah
Ključne besede: supernovae, JWST, Hubble constant, strong lensing
Objavljeno: 03.01.2019; Ogledov: 1788; Prenosov: 0
.pdf Polno besedilo (278,75 KB)

67.
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, izvirni znanstveni članek

Opis: 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.
Najdeno v: ključnih besedah
Ključne besede: darn matter, axions, axion-like particles, core-collapse supernovae
Objavljeno: 15.06.2020; Ogledov: 1485; Prenosov: 55
.pdf Polno besedilo (30,47 MB)

68.
On the GeV Emission of the Type I BdHN GRB 130427A
Laura Beccera, She Sheng Xue, Yu Wang, Narek Sahakyan, Mile Karlica, Yen-Chen Chen, Simonetta Filippi, Christian Cherubini, Carlo Luciano Bianco, Jorge Armando Rueda, Rahim Moradi, Remo Ruffini, 2019, izvirni znanstveni članek

Opis: We propose that the inner engine of a type I binary-driven hypernova (BdHN) is composed of Kerr black hole (BH) in a non-stationary state, embedded in a uniform magnetic field B_0 aligned with the BH rotation axis and surrounded by an ionized plasma of extremely low density of 10^−14 g cm−3. Using GRB 130427A as a prototype, we show that this inner engine acts in a sequence of elementary impulses. Electrons accelerate to ultrarelativistic energy near the BH horizon, propagating along the polar axis, θ = 0, where they can reach energies of ~10^18 eV, partially contributing to ultrahigh-energy cosmic rays. When propagating with $\theta \ne 0$ through the magnetic field B_0, they produce GeV and TeV radiation through synchroton emission. The mass of BH, M = 2.31M ⊙, its spin, α = 0.47, and the value of magnetic field B_0 = 3.48 × 10^10 G, are determined self consistently to fulfill the energetic and the transparency requirement. The repetition time of each elementary impulse of energy ${ \mathcal E }\sim {10}^{37}$ erg is ~10^−14 s at the beginning of the process, then slowly increases with time evolution. In principle, this "inner engine" can operate in a gamma-ray burst (GRB) for thousands of years. By scaling the BH mass and the magnetic field, the same inner engine can describe active galactic nuclei.
Najdeno v: ključnih besedah
Povzetek najdenega: ...hole physics, binaries, gamma-ray burst, neutron stars, supernovae, Astrophysics - High Energy Astrophysical Phenomena...
Ključne besede: black hole physics, binaries, gamma-ray burst, neutron stars, supernovae, Astrophysics - High Energy Astrophysical Phenomena
Objavljeno: 20.07.2020; Ogledov: 1611; Prenosov: 0
.pdf Polno besedilo (1,09 MB)

69.
Extending the sample of core-collapse supernovae forsearches of axion-like-particle induced gamma-ray burstswith the Fermi LAT
Manuel Meyer, Tanja Petrushevska, 2021, objavljeni znanstveni prispevek na konferenci

Najdeno v: ključnih besedah
Ključne besede: dark matter, axions, supernovae
Objavljeno: 06.07.2021; Ogledov: 850; Prenosov: 0
.pdf Polno besedilo (2,32 MB)

70.
The Palomar Transient Factory core-collapse supernova host-galaxy sample
Amit Gal, Giorgos Leloudas, Jesper Sollerman, Avishay Gal-Yam, Angus H. Wright, Ragnhild Lunnan, Steve Schulze, Ofer Yaron, Eran O. Ofek, Tanja Petrushevska, 2021, izvirni znanstveni članek

Najdeno v: ključnih besedah
Povzetek najdenega: ... supernovae, galaxies, core-collapse supernovae, astronomy...
Ključne besede: supernovae, galaxies, core-collapse supernovae, astronomy
Objavljeno: 23.08.2021; Ogledov: 631; Prenosov: 28
.pdf Polno besedilo (9,93 MB)
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