Cosmic gamma rays from galaxy clusters

Houston, B. P.; Wolfendale, A. W.; Young, E. C. M.

doi:10.1088/0305-4616/10/6/007

Cited by 20 publications

(10 citation statements)

References 6 publications

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“…Several emission mechanisms are believed to contribute to photon production inside the cluster such as inverse Compton scattering and neutral pion decay produced in several ways (see e.g. [106][107][108][109]). Concerning the case of emission at the blazar jet base, photons are likely produced via an inverse Compton process, where lower energy photons are boosted to energies in the HE and VHE bands [110][111][112][113].…”

Section: B High-energy Bandmentioning

confidence: 99%

Photon-ALP oscillations inducing modifications to photon polarization

Galanti¹

2022

Preprint

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Axion-like particles (ALPs) are very light, neutral, spin zero bosons predicted by many theories which try to extend and complete the standard model of elementary particles. ALPs interact primarily with two photons and can generate photon-ALP oscillations in the presence of an external magnetic field. They are attracting increasing interest since photon-ALP oscillations produce deep consequences in astrophysics particularly in the very-high-energy (VHE) band, where they increase the transparency of the Universe to VHE photons by partially preventing absorption caused by the extragalactic background light. Furthermore, ALPs explain why photons coming from flat spectrum radio quasars (a particular class of active galactic nuclei, AGN) have been observed for energies above 20 GeV -which represents a first hint for the existence of an ALP. In addition, ALPs solve an anomalous redshift dependence of blazar (an AGN class) spectra -which represents a second hint for the existence of an ALP. In this paper, we study another effect of the photon-ALP interaction: the change of the polarization state of photons. In particular, we study the propagation of the photon-ALP beam starting where photons are produced -we consider photons generated in a galaxy cluster or in the jet of a blazar -crossing several magnetized media (blazar jet, host galaxy, galaxy cluster, extragalactic space, Milky Way) up to their arrival at the Earth, where photons can be detected. In the presence of photon-ALP interaction, we analyze the photon survival probability Pγ→γ and the corresponding photon degree of linear polarization ΠL for observed energies in the range (1 − 10 15 ) eV dividing it into three energy bands: (i) X-ray band (10 −3 keV − 10 2 keV), (ii) high-energy (HE) band (10 −1 MeV − 10 4 MeV), (iii) VHE band (10 −2 TeV − 10 3 TeV). We observe that photons, which are expected as unpolarized in the absence of ALPs, are made partially polarized by photon-ALP interaction, which generally modifies the initial photon degree of linear polarization ΠL,0 in a sizable and measurable way. Our findings about the X-ray and HE bands can be tested by current and planned observatories like IXPE, Polstar, COSI, e-ASTROGAM and AMEGO. A possible detection of a departure of the photon polarization from the standard expectations would represent an additional hint for the existence of an ALP. We also discover a peculiar feature in the VHE band, where photons at energies above ∼ 1 TeV are fully polarized because of photon-ALP interaction. A possible detection of this feature would represent a proof for the existence of an ALP, but, unfortunately, current technologies do not allow yet to detect photon polarization up to so high energies.

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Section: B High-energy Bandmentioning

confidence: 99%

Photon-ALP oscillations inducing modifications to photon polarization

Galanti¹

2022

Preprint

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“…Clusters of galaxies have long been considered as possible candidates for the sources of TeV gamma rays emitted by protons and electrons accelerated at large-scale shocks or by a galactic wind or active galactic nuclei (AGNs) [1][2][3][4][5][6][7][8][9]. The cluster of galaxies in Perseus is one of the beststudied clusters owing to its relative proximity (its distance ∼ 100 Mpc or redshift z = 0.0179) and brightness.…”

Section: Introductionmentioning

confidence: 99%

Origin of very high energy emission in galaxy clusters

Sinitsyna

2017

EPJ Web Conf.

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Abstract. The Perseus cluster of galaxies with the central galaxy NGC 1275 is ideally suitable for studying both the physics of relativistic jets from Active Galactic Nuclei and for revealing the feedback role of the central galaxy. We present the results of fifteen-year-long observations of the AGN NGC 1275 at energies 800 GeV-40 TeV discovered by the SHALON telescope in 1996. The data obtained at very high energies by SHALON, namely the images of the galaxy and its surroundings, and the flux variability indicate that TeV γ -ray emission is produced by a number of processes: in particular, part of this emission is generated by relativistic jets in the nucleus of NGC 1275 itself. Unique data on GK Per(Nova 1901) and the IC 310 radio galaxy TeV γ -ray emission were obtained with the SHALON experiment for the first time.

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“…The cluster of galaxies in Perseus is one of the best-studied clusters owing to its relative proximity (its distance ∼ 100 Mpc or redshift z = 0.0179) and brightness. Clusters of galaxies have long been considered as possible candidates for the sources of TeV gamma rays emitted by protons and electrons accelerated at large-scale shocks or by a galactic wind or active galactic nuclei [1,2,3,4,5,6,7,8,9]. The dominant galaxy in the Perseus cluster is NGC 1275 (Figs.1,2,3).…”

Section: Pos(ffp14)062 Introductionmentioning

confidence: 99%

Very high energy gamma-emission of Perseus Cluster

Sinitsyna¹,

Sinitsyna²

2016

Proceedings of Frontiers of Fundamental Physics 14 — PoS(FFP14)

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The cluster of galaxies in Perseus have long been considered as possible candidates for the sources of high and very high energy γ-ray emission generated by various mechanisms. The Seyfert galaxy NGC 1275 is the central, dominant galaxy in the Perseus cluster of galaxies. NGC 1275 is known as a powerful source of radio and X-ray emission. The well-known extragalactic object NGC 1275 has been observed by the SHALON high-altitude mirror Cherenkov telescopes as a part of program of long-term studies of metagalactic gamma-ray sources. In 1996, the SHALON observations revealed a new metagalactic source of very high energy gamma-ray emission coincident in its coordinates with the galaxy NGC 1275. Having analyzed the SHALON data, we have determined such characteristics of NGC 1275 as the spectral energy distributions and images at energies > 800 GeV for the first time. The results obtained at very high energies by SHALON are indicate that a part of TeV γ-ray emission is generated by relativistic jets in the nucleus of NGC 1275 itself, but the presence of an extended structure around NGC 1275 is evidence of the interaction of cosmic rays and magnetic fields generated in the jets at the galactic center with the gas of the Perseus cluster. Also, we present the results of long-term observations of the Perseus Cluster which are revealed the γ-ray emission from the two of nearby object-GK Per of classical nova type, located at ∼ 3 • SW from NGC 1275 and the explosion of extragalactic supernova SN2006gy that is about 10 minutes away from NGC 1275. So, the explosion of extragalactic supernova was observed at TeV energies for the first time with SHALON Cherenkov telescope.

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Cosmic gamma rays from galaxy clusters

Cited by 20 publications

References 6 publications

Photon-ALP oscillations inducing modifications to photon polarization

Photon-ALP oscillations inducing modifications to photon polarization

Origin of very high energy emission in galaxy clusters

Very high energy gamma-emission of Perseus Cluster

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