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THE COSMOLOGICAL IMPACT OF LUMINOUS TeV BLAZARS. I. IMPLICATIONS OF PLASMA INSTABILITIES FOR THE INTERGALACTIC MAGNETIC FIELD AND EXTRAGALACTIC GAMMA-RAY BACKGROUND

Abstract

Inverse Compton cascades (ICCs) initiated by energetic gamma rays (E {approx}> 100 GeV) enhance the GeV emission from bright, extragalactic TeV sources. The absence of this emission from bright TeV blazars has been used to constrain the intergalactic magnetic field (IGMF), and the stringent limits placed on the unresolved extragalactic gamma-ray background (EGRB) by Fermi have been used to argue against a large number of such objects at high redshifts. However, these are predicated on the assumption that inverse Compton scattering is the primary energy-loss mechanism for the ultrarelativistic pairs produced by the annihilation of the energetic gamma rays on extragalactic background light photons. Here, we show that for sufficiently bright TeV sources (isotropic-equivalent luminosities {approx}> 10{sup 42} erg s{sup -1}) plasma beam instabilities, specifically the 'oblique' instability, present a plausible mechanism by which the energy of these pairs can be dissipated locally, heating the intergalactic medium. Since these instabilities typically grow on timescales short in comparison to the inverse Compton cooling rate, they necessarily suppress the ICCs. As a consequence, this places a severe constraint on efforts to limit the IGMF from the lack of a discernible GeV bump in TeV sources. Similarly, it considerably weakens the Fermi limits  More>>
Authors:
Broderick, Avery E; Chang, Philip; Pfrommer, Christoph [1] 
  1. Canadian Institute for Theoretical Astrophysics, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)
Publication Date:
Jun 10, 2012
Product Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 752; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANNIHILATION; ASTRONOMY; ASTROPHYSICS; BL LACERTAE OBJECTS; COMPARATIVE EVALUATIONS; COMPTON EFFECT; COSMIC PHOTONS; DENSITY; ENERGY LOSSES; GAMMA RADIATION; GEV RANGE; LUMINOSITY; MAGNETIC FIELDS; PAIR PRODUCTION; PHOTON EMISSION; PLASMA INSTABILITY; QUASARS; RED SHIFT; RELATIVISTIC RANGE; TEV RANGE
OSTI ID:
22037115
Country of Origin:
United States
Language:
English
Other Identifying Numbers:
Journal ID: ISSN 0004-637X; CODEN: ASJOAB; TRN: US12Q1613126851
Availability:
Available from http://dx.doi.org/10.1088/0004-637X/752/1/22
Submitting Site:
USN
Size:
[23 page(s)]
Announcement Date:
Feb 02, 2013

Citation Formats

Broderick, Avery E, Chang, Philip, and Pfrommer, Christoph. THE COSMOLOGICAL IMPACT OF LUMINOUS TeV BLAZARS. I. IMPLICATIONS OF PLASMA INSTABILITIES FOR THE INTERGALACTIC MAGNETIC FIELD AND EXTRAGALACTIC GAMMA-RAY BACKGROUND. United States: N. p., 2012. Web. doi:10.1088/0004-637X/752/1/22.
Broderick, Avery E, Chang, Philip, & Pfrommer, Christoph. THE COSMOLOGICAL IMPACT OF LUMINOUS TeV BLAZARS. I. IMPLICATIONS OF PLASMA INSTABILITIES FOR THE INTERGALACTIC MAGNETIC FIELD AND EXTRAGALACTIC GAMMA-RAY BACKGROUND. United States. doi:10.1088/0004-637X/752/1/22.
Broderick, Avery E, Chang, Philip, and Pfrommer, Christoph. 2012. "THE COSMOLOGICAL IMPACT OF LUMINOUS TeV BLAZARS. I. IMPLICATIONS OF PLASMA INSTABILITIES FOR THE INTERGALACTIC MAGNETIC FIELD AND EXTRAGALACTIC GAMMA-RAY BACKGROUND." United States. doi:10.1088/0004-637X/752/1/22. https://www.osti.gov/servlets/purl/10.1088/0004-637X/752/1/22.
@misc{etde_22037115,
title = {THE COSMOLOGICAL IMPACT OF LUMINOUS TeV BLAZARS. I. IMPLICATIONS OF PLASMA INSTABILITIES FOR THE INTERGALACTIC MAGNETIC FIELD AND EXTRAGALACTIC GAMMA-RAY BACKGROUND}
author = {Broderick, Avery E, Chang, Philip, and Pfrommer, Christoph}
abstractNote = {Inverse Compton cascades (ICCs) initiated by energetic gamma rays (E {approx}> 100 GeV) enhance the GeV emission from bright, extragalactic TeV sources. The absence of this emission from bright TeV blazars has been used to constrain the intergalactic magnetic field (IGMF), and the stringent limits placed on the unresolved extragalactic gamma-ray background (EGRB) by Fermi have been used to argue against a large number of such objects at high redshifts. However, these are predicated on the assumption that inverse Compton scattering is the primary energy-loss mechanism for the ultrarelativistic pairs produced by the annihilation of the energetic gamma rays on extragalactic background light photons. Here, we show that for sufficiently bright TeV sources (isotropic-equivalent luminosities {approx}> 10{sup 42} erg s{sup -1}) plasma beam instabilities, specifically the 'oblique' instability, present a plausible mechanism by which the energy of these pairs can be dissipated locally, heating the intergalactic medium. Since these instabilities typically grow on timescales short in comparison to the inverse Compton cooling rate, they necessarily suppress the ICCs. As a consequence, this places a severe constraint on efforts to limit the IGMF from the lack of a discernible GeV bump in TeV sources. Similarly, it considerably weakens the Fermi limits on the evolution of blazar populations. Specifically, we construct a TeV-blazar luminosity function from those objects currently observed and find that it is very well described by the quasar luminosity function at z {approx} 0.1, shifted to lower luminosities and number densities, suggesting that both classes of sources are regulated by similar processes. Extending this relationship to higher redshifts, we show that the magnitude and shape of the EGRB above {approx}10 GeV are naturally reproduced with this particular example of a rapidly evolving TeV-blazar luminosity function.}
doi = {10.1088/0004-637X/752/1/22}
journal = {Astrophysical Journal}
issue = {1}
volume = {752}
journal type = {AC}
place = {United States}
year = {2012}
month = {Jun}
}