31. Search for Axionlike-Particle-Induced Prompt γ -Ray Emission from Extragalactic Core-Collapse Supernovae with the Fermi Large Area TelescopeManuel 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.
Ključne besede: darn matter, axions, axion-like particles, core-collapse supernovae
Objavljeno v RUNG: 15.06.2020; Ogledov: 2663; Prenosov: 78
 Celotno besedilo (30,47 MB) |
32. Black holes, gravitational waves and fundamental physics: a roadmapLeor Barack, Tanja Petrushevska, Andreja Gomboc, Katja Bricman, Aurora Clerici, Christopher Eckner, Nada Ihanec, Gabrijela Zaharijas, 2019, pregledni znanstveni članek Opis: 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.
Ključne besede: black holes, gwverse
Objavljeno v RUNG: 24.06.2019; Ogledov: 3674; Prenosov: 0
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35. Prospects for Strongly Lensed Supernovae Behind Hubble FrontierFields Galaxy Clusters with the James Webb Space TelescopeTanja 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.
Ključne besede: supernovae, JWST, Hubble constant, strong lensing
Objavljeno v RUNG: 03.01.2019; Ogledov: 3042; Prenosov: 0
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36. Exploring the Universe with supernovaeTanja 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].
Ključne besede: supernovae, strong lensing, neutron stars
Objavljeno v RUNG: 29.11.2018; Ogledov: 3138; Prenosov: 0
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38. A hot and fast ultra-stripped supernova that likely formed a compact neutron star binaryTanja Petrushevska, 2018, izvirni znanstveni članek Opis: Compact neutron star binary systems are produced from binary massive stars through stellar evolution involving up to two supernova explosions. The final stages in the formation of these systems have not been directly observed. We report the discovery of iPTF 14gqr (SN 2014ft), a type Ic supernova with a fast-evolving light curve indicating an extremely low ejecta mass (≈0.2 solar masses) and low kinetic energy (≈2 × 1050 ergs). Early photometry and spectroscopy reveal evidence of shock cooling of an extended helium-rich envelope, likely ejected in an intense pre-explosion mass-loss episode of the progenitor. Taken together, we interpret iPTF 14gqr as evidence for ultra-stripped supernovae that form neutron stars in compact binary systems.
Ključne besede: supernova, neutron stars, gravitational waves
Objavljeno v RUNG: 12.10.2018; Ogledov: 3452; Prenosov: 0
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