Correction: Batković et al. Axion-like Particle Searches with IACTs. Universe 2021, 7, 185

The authors wish to make the following corrections to their paper [...

MAGIC and H.E.S.S. detect VHE gamma rays from the blazar OT081 for the first time: a deep multiwavelength study

https://pos.sissa.it/395/815/pdfPublished versio

Supernova SN1987A as a source of cosmic dust

Proučavanje kozmičke prašine bitan je dio astronomije. Kao takvo izvor je niza podataka o sastavu i izgledu Svemira. Glavne karakteristike prašine objasnit će nam pobliže njenu pojavu. Evolucija zrna prašine popraćena je brojnim procesima nukleacije, rasta i konačno destrukcije. Kako bismo saznali više o nukleaciji i stvaranju prašine, bitno je znati otkuda ona dolazi, odnosno gdje nastaje. Glavni izvori prašine u Svemiru su AGB zvijezde, nove i supernove. Glavni dio ovoga rada pripada potonjem izvoru. Supernova SN1987A u Velikom Magellanovom oblaku na udaljenosti od ⁓ 50 kpc pokazala se kao izvor velike količine prašine. Radi se o prašini s procijenjenih 0,5 s većinskim udjelom silikata i nešto manje ugljika te ostalih elemenata. Teorijskim modeliranjem prijenosa zračenja pomoću numeričkog koda DUSTY izračunali smo energijske spektralne raspodjele i usporedili ih s opažanjima. Tako dobivena svojstva prašine ukazuju na silikatni i ugljični sastav i ekspanziju ovojnice prašine pri čemu se njen radijus povećava, temperatura prašine opada, a veličina zrna prašine raste. Naposljetku su dani zaključci o tome kolika je važnost provedbe istraživanja kozmičke prašine kao krucijalnom izvoru podataka iz nama najvećeg poznatog laboratorija, Svemira

Supernova SN1987A as a source of cosmic dust

Proučavanje kozmičke prašine bitan je dio astronomije. Kao takvo izvor je niza podataka o sastavu i izgledu Svemira. Glavne karakteristike prašine objasnit će nam pobliže njenu pojavu. Evolucija zrna prašine popraćena je brojnim procesima nukleacije, rasta i konačno destrukcije. Kako bismo saznali više o nukleaciji i stvaranju prašine, bitno je znati otkuda ona dolazi, odnosno gdje nastaje. Glavni izvori prašine u Svemiru su AGB zvijezde, nove i supernove. Glavni dio ovoga rada pripada potonjem izvoru. Supernova SN1987A u Velikom Magellanovom oblaku na udaljenosti od ⁓ 50 kpc pokazala se kao izvor velike količine prašine. Radi se o prašini s procijenjenih 0,5 s većinskim udjelom silikata i nešto manje ugljika te ostalih elemenata. Teorijskim modeliranjem prijenosa zračenja pomoću numeričkog koda DUSTY izračunali smo energijske spektralne raspodjele i usporedili ih s opažanjima. Tako dobivena svojstva prašine ukazuju na silikatni i ugljični sastav i ekspanziju ovojnice prašine pri čemu se njen radijus povećava, temperatura prašine opada, a veličina zrna prašine raste. Naposljetku su dani zaključci o tome kolika je važnost provedbe istraživanja kozmičke prašine kao krucijalnom izvoru podataka iz nama najvećeg poznatog laboratorija, Svemira

Proučavanje potpisa aksionskih čestica u spektru aktivnih galaktičkih jezgri u području gama-zraka vrlo visokih energija

The aim of this work of thesis is the investigation of axion-like particles (ALPs) signatures in the spectra of Active Galactic Nuclei (AGN), in the very-high-energy (VHE, E > 100GeV) -ray range. ALPs, which are candidates for Dark Matter, in the presence of strong magnetic fields could interact with the rays emitted by AGNs, and this effect could be observed in the VHE -ray spectra under the form of "wiggles" or oscillations. Here, the search for ALPs was performed on MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) data of the AGN NGC 1275, located in the Perseus cluster. 54:1 hours of MAGIC data have been analysed. The conversion probability of rays in ALPs (P) has been calculated for several values of the mass of ALPS (ma) and coupling (ga). A study of the parameter space for those two quantities has been performed. We found three different states of the source which correspond to flaring, active and low activity state, respectively. Data from the flaring state were used for the search of ALPs signatures. The spectrum is stable in the energy range 50 GeV - 700 GeV, with an integral flux of (8:53 0:24) 1010 cm2 s1 above the energy of 100 GeV. The spectrum can be described by a power-law with an exponential cut-off (EPWL) with index -2.4. In the study of ALPs parameters space, parameters combinations are narrowed down to 10 sets each with several possibilities of ma and coupling ga. Those sets are named S1 - S10 and the corresponding values of ma and ga are in the ranges 90 neV - 110 neV and 0:3 1011 GeV1 - 0:5 1011 GeV1, respectively. Using each set separately, the convolution of P with the EPWL fit was calculated and compared with the spectral energy distribution (SED) of the source. A quantitative preliminary comparison between the convolution and the intrinsic SED was performed by obtaining the sums of squared residuals for the dataset S1 - S10. We conclude that S10 (sum of squared residuals = 55:3), among the 10 sets studied, is the most promising set of parameters for the search of ALPs found in this preliminary study

Supernova SN1987A as a source of cosmic dust

Proučavanje kozmičke prašine bitan je dio astronomije. Kao takvo izvor je niza podataka o sastavu i izgledu Svemira. Glavne karakteristike prašine objasnit će nam pobliže njenu pojavu. Evolucija zrna prašine popraćena je brojnim procesima nukleacije, rasta i konačno destrukcije. Kako bismo saznali više o nukleaciji i stvaranju prašine, bitno je znati otkuda ona dolazi, odnosno gdje nastaje. Glavni izvori prašine u Svemiru su AGB zvijezde, nove i supernove. Glavni dio ovoga rada pripada potonjem izvoru. Supernova SN1987A u Velikom Magellanovom oblaku na udaljenosti od ⁓ 50 kpc pokazala se kao izvor velike količine prašine. Radi se o prašini s procijenjenih 0,5 s većinskim udjelom silikata i nešto manje ugljika te ostalih elemenata. Teorijskim modeliranjem prijenosa zračenja pomoću numeričkog koda DUSTY izračunali smo energijske spektralne raspodjele i usporedili ih s opažanjima. Tako dobivena svojstva prašine ukazuju na silikatni i ugljični sastav i ekspanziju ovojnice prašine pri čemu se njen radijus povećava, temperatura prašine opada, a veličina zrna prašine raste. Naposljetku su dani zaključci o tome kolika je važnost provedbe istraživanja kozmičke prašine kao krucijalnom izvoru podataka iz nama najvećeg poznatog laboratorija, Svemira

Proučavanje potpisa aksionskih čestica u spektru aktivnih galaktičkih jezgri u području gama-zraka vrlo visokih energija

The aim of this work of thesis is the investigation of axion-like particles (ALPs) signatures in the spectra of Active Galactic Nuclei (AGN), in the very-high-energy (VHE, E > 100GeV) -ray range. ALPs, which are candidates for Dark Matter, in the presence of strong magnetic fields could interact with the rays emitted by AGNs, and this effect could be observed in the VHE -ray spectra under the form of "wiggles" or oscillations. Here, the search for ALPs was performed on MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) data of the AGN NGC 1275, located in the Perseus cluster. 54:1 hours of MAGIC data have been analysed. The conversion probability of rays in ALPs (P) has been calculated for several values of the mass of ALPS (ma) and coupling (ga). A study of the parameter space for those two quantities has been performed. We found three different states of the source which correspond to flaring, active and low activity state, respectively. Data from the flaring state were used for the search of ALPs signatures. The spectrum is stable in the energy range 50 GeV - 700 GeV, with an integral flux of (8:53 0:24) 1010 cm2 s1 above the energy of 100 GeV. The spectrum can be described by a power-law with an exponential cut-off (EPWL) with index -2.4. In the study of ALPs parameters space, parameters combinations are narrowed down to 10 sets each with several possibilities of ma and coupling ga. Those sets are named S1 - S10 and the corresponding values of ma and ga are in the ranges 90 neV - 110 neV and 0:3 1011 GeV1 - 0:5 1011 GeV1, respectively. Using each set separately, the convolution of P with the EPWL fit was calculated and compared with the spectral energy distribution (SED) of the source. A quantitative preliminary comparison between the convolution and the intrinsic SED was performed by obtaining the sums of squared residuals for the dataset S1 - S10. We conclude that S10 (sum of squared residuals = 55:3), among the 10 sets studied, is the most promising set of parameters for the search of ALPs found in this preliminary study

Proučavanje potpisa aksionskih čestica u spektru aktivnih galaktičkih jezgri u području gama-zraka vrlo visokih energija

The aim of this work of thesis is the investigation of axion-like particles (ALPs) signatures in the spectra of Active Galactic Nuclei (AGN), in the very-high-energy (VHE, E > 100GeV) -ray range. ALPs, which are candidates for Dark Matter, in the presence of strong magnetic fields could interact with the rays emitted by AGNs, and this effect could be observed in the VHE -ray spectra under the form of "wiggles" or oscillations. Here, the search for ALPs was performed on MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) data of the AGN NGC 1275, located in the Perseus cluster. 54:1 hours of MAGIC data have been analysed. The conversion probability of rays in ALPs (P) has been calculated for several values of the mass of ALPS (ma) and coupling (ga). A study of the parameter space for those two quantities has been performed. We found three different states of the source which correspond to flaring, active and low activity state, respectively. Data from the flaring state were used for the search of ALPs signatures. The spectrum is stable in the energy range 50 GeV - 700 GeV, with an integral flux of (8:53 0:24) 1010 cm2 s1 above the energy of 100 GeV. The spectrum can be described by a power-law with an exponential cut-off (EPWL) with index -2.4. In the study of ALPs parameters space, parameters combinations are narrowed down to 10 sets each with several possibilities of ma and coupling ga. Those sets are named S1 - S10 and the corresponding values of ma and ga are in the ranges 90 neV - 110 neV and 0:3 1011 GeV1 - 0:5 1011 GeV1, respectively. Using each set separately, the convolution of P with the EPWL fit was calculated and compared with the spectral energy distribution (SED) of the source. A quantitative preliminary comparison between the convolution and the intrinsic SED was performed by obtaining the sums of squared residuals for the dataset S1 - S10. We conclude that S10 (sum of squared residuals = 55:3), among the 10 sets studied, is the most promising set of parameters for the search of ALPs found in this preliminary study

Axion-like Particle Searches with IACTs

The growing interest in axion-like particles (ALPs) stems from the fact that they provide successful theoretical explanations of physics phenomena, from the anomaly of the CP-symmetry conservation in strong interactions to the observation of an unexpectedly large TeV photon flux from astrophysical sources, at distances where the strong absorption by the intergalactic medium should make the signal very dim. In this latter condition, which is the focus of this review, a possible explanation is that TeV photons convert to ALPs in the presence of strong and/or extended magnetic fields, such as those in the core of galaxy clusters or around compact objects, or even those in the intergalactic space. This mixing affects the observed γ-ray spectrum of distant sources, either by signal recovery or the production of irregularities in the spectrum, called ‘wiggles’, according to the specific microscopic realization of the ALP and the ambient magnetic field at the source, and in the Milky Way, where ALPs may be converted back to γ rays. ALPs are also proposed as candidate particles for the Dark Matter. Imaging Atmospheric Cherenkov telescopes (IACTs) have the potential to detect the imprint of ALPs in the TeV spectrum from several classes of sources. In this contribution, we present the ALP case and review the past decade of searches for ALPs with this class of instruments