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For High frequency BL Lac objects (HBLs) like H1426+428, a significant fraction of their TeV gamma-rays emitted are likely to be absorbed in interactions with the diffuse IR background, yielding $e^\pm$ pairs. The resulting $e^\pm$ pairs…

Astrophysics · Physics 2009-11-10 Y. Z. Fan , Z. G. Dai , D. M. Wei

Ultrahigh energy cosmic ray (UHECR) protons interacting with the cosmic microwave background (CMB) produce UHE electrons and gamma-rays that in turn initiate electromagnetic cascades on CMB and infrared photons. As a result, a background of…

High Energy Astrophysical Phenomena · Physics 2015-05-18 V. Berezinsky , A. Gazizov , M. Kachelriess , S. Ostapchenko

Very high energy (VHE: >100 GeV) gamma rays coming from AGN can pair-produce on the intergalactic background light generating an electromagnetic cascade. If the Intergalactic Magnetic Field (IGMF) is sufficiently strong, this cascade may…

High Energy Astrophysical Phenomena · Physics 2014-06-19 Mateo Fernandez Alonso

The presence of non-zero helicity in intergalactic magnetic fields (IGMF) has been suggested as a clear signature for their primordial origin. We extend a previous analysis of diffuse Fermi-LAT gamma-ray data from 2.5 to more than 11 years…

High Energy Astrophysical Phenomena · Physics 2020-11-06 M. Kachelriess , B. C. Martinez

The recent observation of the 21-cm global absorption signal by EDGES suggests that the intergalactic medium (IGM) gas has been cooler than the cosmic microwave background during $15 \lesssim z \lesssim 20$. This result can provide a strong…

Cosmology and Nongalactic Astrophysics · Physics 2019-07-23 Teppei Minoda , Hiroyuki Tashiro , Tomo Takahashi

The measurement of magnetic fields in cosmic web filaments can be used to reveal the magnetogenesis of the Universe. In previous work, we produced first estimates of the field strength and its redshift evolution using the Faraday Rotation…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-22 E. Carretti , F. Vazza , S. P. O'Sullivan , V. Vacca , A. Bonafede , G. Heald , C. Horellou , S. Mtchedlidze , T. Vernstrom

We discuss the magnetic field influence on diffuse gamma-ray emission from extragalactic electromagnetic cascades initiated by ultra-high energy cosmic rays. Regions in space vary considerably in field strength: it is possibly of 10^(-12) G…

High Energy Astrophysical Phenomena · Physics 2023-10-16 A. Uryson

$\gamma$-ray emission of blazars infer the presence of large-scale magnetic fields in the intergalactic medium, but their origin remains a mystery. Using recent data from MAGIC, H.E.S.S. and $\textit{Fermi}$-LAT, we investigate whether the…

High Energy Physics - Phenomenology · Physics 2024-05-07 María Olalla Olea-Romacho

The attenuation of high-energy gamma-ray spectrum due to the electron-positron pair production against the extragalactic background light (EBL) provides an indirect method to measure the EBL of the universe. We use the measurements of the…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Yan Gong , Asantha Cooray

The extragalactic magnetic field could be detected by searching for signatures of the electromagnetic cascade initiated by high-energy photons on the intergalactic radiation and deflected by the field. This process produces a time delay and…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-04 Boris Stern , Igor Tkachev

We estimate the contribution to the extragalactic gamma-ray background (EGRB) from both intrinsic and cascade emissions produced by blazars using a simple semi- analysis method for two models of the blazar gamma-ray luminosity function…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Dahai Yan , Houdun Zeng , Li Zhang

Primordial magnetic fields (PMFs) may explain observations of magnetic fields on extragalactic scales. They are most cleanly constrained by measurements of cosmic microwave background radiation (CMB) anisotropies. Their effects on cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2024-11-18 Karsten Jedamzik , Tom Abel , Yacine Ali-Haimoud

Strong accretion shocks are expected to illuminate the warm-hot inter-galactic medium encompassed by the filaments of the cosmic web, through synchrotron radio emission. Given their high sensitivity, low-frequency large radio facilities may…

Cosmology and Nongalactic Astrophysics · Physics 2021-08-18 Nicola Locatelli , Franco Vazza , Annalisa Bonafede , Serena Banfi , Gianni Bernardi , Claudio Gheller , Andrea Botteon , Timothy Shimwell

Primordial magnetic fields (PMFs) may significantly influence 21-cm physics via two mechanisms: (i) magnetic heating of the intergalactic medium (IGM) through ambipolar diffusion (AD) and decaying magnetohydrodynamic turbulence (DT), (ii)…

Cosmology and Nongalactic Astrophysics · Physics 2025-01-27 Arko Bhaumik , Debarun Paul , Supratik Pal

High-energy gamma-rays propagating in the intergalactic medium can interact with background infrared photons to produce e+e- pairs, resulting in the absorption of the intrinsic gamma-ray spectrum. TeV observations of the distant blazar 1ES…

Astrophysics · Physics 2009-06-23 P. d'Avezac , G. Dubus , B. Giebels

If ultra-high-energy cosmic rays (UHECRs) originate from extragalactic sources, understanding the propagation of charged particles through the magnetized large scale structure (LSS) of the universe is crucial in the search for the…

Astrophysics · Physics 2009-11-13 Santabrata Das , Hyesung Kang , Dongsu Ryu , Jungyeon Cho

One of the most promising ways to probe intergalactic magnetic fields (IGMFs) is through gamma rays produced in electromagnetic cascades initiated by high-energy gamma rays or cosmic rays in the intergalactic space. Because the charged…

High Energy Astrophysical Phenomena · Physics 2021-07-07 Rafael Alves Batista , Andrey Saveliev

Any attempt to understand the ubiquitous nature of the magnetic field in the present universe seems to lead us towards its primordial origin. For large-scale magnetic fields, however, their strength and length scale may not necessarily…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-01 Subhasis Maiti , Debaprasad Maity , Rohan Srikanth

Very high energy gamma-rays from blazars traversing cosmological distances through the metagalactic radiation field can convert into electron-positron pairs in photon-photon collisions. The converted gamma-rays initiate electromagnetic…

Astrophysics · Physics 2009-11-13 Tanja M. Kneiske , Karl Mannheim

The origin of magnetic fields in the universe is an open problem. Seed magnetic fields possibly produced in early times may have survived up to the present day close to their original form, providing an untapped window to the primeval…

High Energy Astrophysical Phenomena · Physics 2020-10-09 Rafael Alves Batista , Andrey Saveliev