Study of the gamma-Ray Radiation Properties of High-redshift Blazars at z>2.5

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Hauptverfasser: Wu, Fan, Dai, Benzhong
Format: Preprint
Veröffentlicht: 2025
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author Wu, Fan
Dai, Benzhong
author_facet Wu, Fan
Dai, Benzhong
contents We study a sample of 30 high-redshift blazars ($z>2.5$) by means of spectra and the radiation mechanism with Fermi Large Area Telescope $γ$-ray observations spanning 15 years. Three models -- the power law, power law with an exponential cutoff, and log-parabola -- are employed to analyze the spectral properties, and most sources exhibit significant curvature. The high-redshift blazars exhibit higher $γ$-ray luminosities and softer spectral indices compared with their low-redshift counterparts, where B3~1343+451 has the highest integrated flux, $\rm 1.13 \times 10^{-7} \mathrm{\ ph \ cm^{-2} s^{-1}}$. We use a standard one-zone leptonic emission model to reproduce the spectral energy distributions of 23 sources with multiwavelength observations. We find that modeling with infrared seed photons is systematically better than with broad-line region (BLR) photons based on a $χ^2$ test, which suggests that the $γ$-ray-emitting regions are most likely located outside the BLR. The fit results show that high-redshift blazars exhibit higher energy density, jet power, kinetic power, and accretion disk luminosities, along with lower synchrotron and inverse Compton (IC) peak frequencies, relative to their lower-redshift counterparts. We find that blazars with higher accretion disk luminosities tend to have lower IC peak frequencies, leading to more efficient cooling of high-energy electrons. The positive correlation between jet power and accretion disk luminosity further supports the possibility of an accretion-jet connection in these high-redshift sources.
format Preprint
id arxiv_https___arxiv_org_abs_2501_14137
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Study of the gamma-Ray Radiation Properties of High-redshift Blazars at z>2.5
Wu, Fan
Dai, Benzhong
High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
We study a sample of 30 high-redshift blazars ($z>2.5$) by means of spectra and the radiation mechanism with Fermi Large Area Telescope $γ$-ray observations spanning 15 years. Three models -- the power law, power law with an exponential cutoff, and log-parabola -- are employed to analyze the spectral properties, and most sources exhibit significant curvature. The high-redshift blazars exhibit higher $γ$-ray luminosities and softer spectral indices compared with their low-redshift counterparts, where B3~1343+451 has the highest integrated flux, $\rm 1.13 \times 10^{-7} \mathrm{\ ph \ cm^{-2} s^{-1}}$. We use a standard one-zone leptonic emission model to reproduce the spectral energy distributions of 23 sources with multiwavelength observations. We find that modeling with infrared seed photons is systematically better than with broad-line region (BLR) photons based on a $χ^2$ test, which suggests that the $γ$-ray-emitting regions are most likely located outside the BLR. The fit results show that high-redshift blazars exhibit higher energy density, jet power, kinetic power, and accretion disk luminosities, along with lower synchrotron and inverse Compton (IC) peak frequencies, relative to their lower-redshift counterparts. We find that blazars with higher accretion disk luminosities tend to have lower IC peak frequencies, leading to more efficient cooling of high-energy electrons. The positive correlation between jet power and accretion disk luminosity further supports the possibility of an accretion-jet connection in these high-redshift sources.
title Study of the gamma-Ray Radiation Properties of High-redshift Blazars at z>2.5
topic High Energy Astrophysical Phenomena
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2501.14137