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Contributed talk at the international conference "Cosmology in Miramare" 2023
Tanja Petrushevska, 2023, published scientific conference contribution abstract

Abstract: The searches and observations of supernovae (SNe) have been motivated by the fact that they are exceptionally useful for various astrophysical and cosmological applications. Most prominently, Type Ia SNe (SNe Ia) have been used as distance indicators showing that the expansion rate of the Universe is accelerating. The strong gravitational lensing effect provides another powerful tool and occurs when a foreground mass distribution is located along the line of sight to a background source. It can happen so that galaxies and galaxy clusters can act as “gravitational telescopes”, boosting the faint signals from distant SNe and galaxies. Thanks to the magnification boost provided by the gravitational telescope, we are able to probe galaxies and SNe that otherwise would be undetectable. Therefore, the combination of the two tools, SNe and strong lensing, in the single phenomenon of strongly lensed SNe, provides a powerful simultaneous probe of several cosmological and astrophysical phenomena. By measuring the time delays of strongly lensed supernovae and having a high-quality strong lensing model of the galaxy cluster, it is possible to measure the Hubble constant with competitive precision. In this talk, I will present some of the past and recent results that have been possible due to the observations of strongly lensed supernovae and anticipate what we can expect in the future from the upcoming telescope surveys, such as the Vera C. Rubin Observatory and Nancy G. Roman Space Telescope.
Keywords: cosmology, supernovae, strong lensing
Published in RUNG: 07.09.2023; Views: 313; Downloads: 2
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Testing the predictions of axisymmetric distribution functions of galactic dark matter with hydrodynamical simulations
Mihael Petač, Julien Lavalle, Arturo Núñez-Castiñeyra, Emmanuel Nezri, 2021, original scientific article

Abstract: Signal predictions for galactic dark matter (DM) searches often rely on assumptions regarding the DM phase-space distribution function (DF) in halos. This applies to both particle (e.g. p-wave suppressed or Sommerfeld-enhanced annihilation, scattering off atoms, etc.) and macroscopic DM candidates (e.g. microlensing of primordial black holes). As experiments and observations improve in precision, better assessing theoretical uncertainties becomes pressing in the prospect of deriving reliable constraints on DM candidates or trustworthy hints for detection. Most reliable predictions of DFs in halos are based on solving the steady-state collisionless Boltzmann equation (e.g. Eddington-like inversions, action-angle methods, etc.) consistently with observational constraints. One can do so starting from maximal symmetries and a minimal set of degrees of freedom, and then increasing complexity. Key issues are then whether adding complexity, which is computationally costy, improves predictions, and if so where to stop. Clues can be obtained by making predictions for zoomed-in hydrodynamical cosmological simulations in which one can access the true (coarse-grained) phase-space information. Here, we test an axisymmetric extension of the Eddington inversion to predict the full DM DF from its density profile and the total gravitational potential of the system. This permits to go beyond spherical symmetry, and is a priori well suited for spiral galaxies. We show that axisymmetry does not necessarily improve over spherical symmetry because the (observationally unconstrained) angular momentum of the DM halo is not generically aligned with the baryonic one. Theoretical errors are similar to those of the Eddington inversion though, at the 10-20% level for velocity-dependent predictions related to particle DM searches in spiral galaxies. We extensively describe the approach and comment on the results.
Keywords: galaxy dynamics, dark matter experiments, dark matter simulations, dark matter theory, cosmology, nongalactic astrophysics, astrophysics of galaxies, high energy physics
Published in RUNG: 01.10.2021; Views: 1579; Downloads: 63
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Magnetic Fields and Afterglows of BdHNe: Inferences from GRB 130427A, GRB 160509A, GRB 160625B, GRB 180728A, and GRB 190114C
Jorge Armando Rueda, Remo Ruffini, Mile Karlica, Rahim Moradi, Yu Wang, 2020, original scientific article

Abstract: GRB 190114C is the first binary-driven hypernova (BdHN) fully observed from initial supernova (SN) appearance to the final emergence of the optical SN signal. It offers an unprecedented testing ground for the BdHN theory, which is here determined and further extended to additional gamma-ray bursts (GRBs). BdHNe comprise two subclasses of long GRBs, with progenitors a binary system composed of a carbon–oxygen star (COcore) and a neutron star (NS) companion. The COcore explodes as an SN, leaving at its center a newborn NS (νNS). The SN ejecta hypercritically accretes on both the νNS and the NS companion. BdHNe I are very tight binaries, where the accretion leads the companion NS to gravitationally collapse into a black hole (BH). In BdHN II, the accretion rate onto the NS is lower, so there is no BH formation. We observe the same afterglow structure for GRB 190114C and other selected examples of BdHNe I (GRB 130427A, GRB 160509A, GRB 160625B) and for BdHN II (GRB 180728A). In all cases, the afterglows are explained via the synchrotron emission powered by the νNS, and their magnetic field structures and their spin are determined. For BdHNe I, we discuss the properties of the magnetic field embedding the newborn BH, which was inherited from the collapsed NS and amplified during the gravitational collapse process, and surrounded by the SN ejecta.
Keywords: Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Cosmology and Nongalactic Astrophysics, General Relativity and Quantum Cosmology
Published in RUNG: 20.07.2020; Views: 2283; Downloads: 0
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The Dark Side of the Matter
Gabrijela Zaharijas, 2019, other component parts

Keywords: Dark matter, cosmology
Published in RUNG: 17.05.2020; Views: 2441; Downloads: 0
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Истражување на Вселената со супернови
Tanja Petrushevska, invited lecture at foreign university

Abstract: Lecture at the Physics department in Skopje, Macedonia.
Keywords: public lecture, supernovae, cosmology
Published in RUNG: 02.02.2018; Views: 2961; Downloads: 0
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Нобеловата награда за физика 2011
Tanja Petrushevska, 2012, popular article

Abstract: Оваа година Нобеловата награда за физика му припадна на важно откритие од областа на космологијата: забрзаното ширење на Универзумот. Ќе се обидам да го опишам ова откритие преку личното искуство, со тоа што присуствував на различните активности на Нобеловата недела, а и со тоа што мојата работа околу докторскиот труд е тесно поврзана со истата тема. Нобеловата награда е основана од пронаоѓачот на динамитот, шведскиот физичар Алфред Нобел (1833 - 1896) за најголеми достигања во областа на физиката, хемијата, медицината, книжевноста, мирот и економијата. Со исклучок на наградата за мир, Нобеловите награди се врачуваат во Стокхолм на годишната церемонија која се одржува на 10 декември, годишнина од смртта на Алфред Нобел. Оваа година го имав задоволството да присуствувам на церемонијата за доделување на Нобеловите награди. Да се присуствува на оваа церемонија е голема чест бидејќи сите гости се поканети лично од страна на Нобеловата фондација и нема билети на продажба за пошироката јавност. На 8-ми декември секоја година, на Универзитетот во Стокхолм, Нобеловците ги држат познатите Нобелови предавања кои се достапни за сите. Оваа година, половина од Нобеловата награда за физика ја доби Сол Перлмутер – основач на Supernova Cosmology project, додека пак другата половина од наградата им припадна на Брајан Шмит и Адам Рис од тимот на High-z Supernova Search. На 12 декември, добитниците на Нобеловата награда за физика и хемија го посетија Универзитетот на Стокхолм каде што имав прилика да ги сретнам. Мојот професор Ариел Губар од Стокхолм е дел од тимот којшто го издаде едниот од двата труда за кои беше доделена Нобеловата награда. Во почетокот на 1990-тите тој работел како пост-докторанд во лабораторија на "Беркли", САД, каде што се запознал со Сол Перлмутер. Заедно тие скицираат како да го спроведат истражувањето за суперновите. Соработката продолжува, и Сол Перлмутер во текот на следните години е чест посетител на Стокхолм. Тоа што јас го работам моментално во склоп на докторатот на некој начин претставува продолжение на откритието дека Универзумот се шири забрзано. Следниот чекор е да се истражува Вселената на сè поголеми растојанија, но иако суперновите се многу светли, сепак сме ограничени во тоа колку далечни супернови можеме да откриеме со сегашната генерација на телескопи. Но, оваа граница може да биде проширена со мала помош од гравитацијата. Тимот, од кој и јас сум дел, сега е составен од Ариел Губар и Раман Аманулах од универзитетот во Стокхолм, и моментално спроведуваме испитување со користење на податоците од Nordic Optic Telescope на Канарските острови, со други зборови, бараме далечни супернови со користење на различни масивни галактички јата како леќа.
Keywords: Нобелова награда, физика, 2011, космологија, ширење на вселената, Сол Перлмутер, Брајан Шмит, Адам Рис, Supernova Cosmology project, High-z Supernova Search
Published in RUNG: 29.01.2018; Views: 3221; Downloads: 0
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Search for Physics beyond the Standard Model with the CRESST Experiment
2017, master's thesis

Abstract: In spite of the successes of observational astro- and particle physics and cosmology very much of the universe remains unknown. The Standard Model of particle physics is a theory describing the electromagnetic, weak, and strong nuclear interactions, as well as classifying all the subatomic particles known. But there is overwhelming evidence, that all the known particles, the ordinary (baryonic) matter, the building blocks of planets, stars and ourselves, only make up about 4.9% of the energy content of the universe. The standard model of cosmology (CDM) indicates that the total mass-energy of the universe contains beside the 4.9% ordinary matter two other components: 26.8% dark matter and 68.3% dark energy. The accelerating expansion of the Universe is the result of the effect of the dark energy with its most simple form given by a cosmological constant in Einstein's Equation. Dark matter is an unidentified type of matter that is not accounted for by dark energy and neutrinos and is generally believed to be a non-relativistic, charge neutral and non-baryonic new form of matter. Although dark matter has not been directly observed yet, its existence and properties are inferred from its gravitational effects such as the motions of visible matter, gravitational lensing, its influence on the universe's large-scale structure, and its effects in the cosmic microwave background. Thus the search for Dark Matter is the search for physics beyond the standard model. Although the nature of dark matter is yet unknown, its presence is crucial to understanding the future of the universe. The CRESST experiment is searching for direct evidence in the form of a nuclear recoil induced on a scintillating CaWO4 crystal by a dark matter particle, and is installed and taking data underground at Laboratory Nazionali del Gran Sasso (LNGS) in Italy. While both, dark energy and dark matter, have not been detected directly, a class of dark matter particles that interact only via gravity and the weak force, referred to asWeakly Interacting Massive Particles (WIMPs), has been established as the leading candidate among the dark matter community. For this thesis a special model of dark matter was studied, namely the dark photon. This thesis provides a detailed description of the calculation of the 90% upper limit on the dark photon kinetic mixing based on data from the second phase of the CRESST experiment. The analysis was carried out in a frequentist approach based on the (unbinned) maximum-likelihood method and likelihood ratios. To make a statement about the calculated result and its quality, the used algorithm had to be tested, what was done with Monte Carlo simulations (pseudo data).
Keywords: astro physics, particle physics, cosmology, universe, Standard Model of particle physics, standard model of cosmology, matter, ordinary matter, dark matter, dark energy, accelerating expansion of the Universe, non-baryonic, new form of matter, gravitational lensing, cosmic microwave background, search for physics beyond the standard model, CRESST experiment, direct detection, CaWO4 crystal, underground laboratory, Laboratory Nazionali del Gran Sasso, Weakly Interacting Massive Particles, WIMP, dark photon, 90% upper limit, upper limit, kinetic mixing, frequentist approach, unbinned, maximum likelihood
Published in RUNG: 13.10.2017; Views: 4182; Downloads: 0
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