2013/08/01 by Avery E. Broderick, Christoph Pfrommer, Ewald Puchwein +1 · 29 citations
Physics and Astronomy · #Accretion (finance) #Astrophysics and Cosmic Phenomena #Blazar #Dark Matter and Cosmic Phenomena #Extragalactic background light #Fermi Gamma-ray Space Telescope #Luminosity #Neutrino Physics Research #Population #Quasar #Redshift #astro-ph.CO #astro-ph.HE
paper · pdf · doi:10.1088/0004-637x/790/2/137
published in The Astrophysical Journal 790(2), 137 (IOP Publishing) · 14 pages, 13 figures, submitted to ApJ
arxiv created 2013/08/01 · openalex publication_date 2014/07/15 · arxiv updated 2015/06/16 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Fermi has been instrumental in constraining the luminosity function and redshift evolution of gamma-ray bright BL Lac objects, a subpopulation of blazars with almost featureless optical spectra. This includes limits on the spectrum and anisotropy of the extragalactic gamma-ray background (EGRB), redshift distribution of nearby Fermi active galactic nuclei (AGNs), and the construction of a –log S relation. Based on these, it has been argued that the evolution of the gamma-ray bright BL Lac population must be much less dramatic than that of other AGNs. However, critical to such claims is the assumption that inverse Compton cascades reprocess emission above a TeV into the Fermi energy range, substantially enhancing the strength of the observed limits. Here we demonstrate that in the absence of such a process, due, e.g., to the presence of virulent plasma beam instabilities that preempt the cascade, a population of TeV-bright BL Lac objects that evolve similarly to quasars is consistent with the population of hard gamma-ray BL Lac objects observed by Fermi . Specifically, we show that a simple model for the properties and luminosity function is simultaneously able to reproduce their –log S relation, local redshift distribution, and contribution to the EGRB and its anisotropy without any free parameters . Insofar as the naturalness of a picture in which the hard gamma-ray BL Lac population exhibits the strong redshift evolution observed in other tracers of the cosmological history of accretion onto halos is desirable, this lends support for the absence of the inverse Compton cascades and the existence of the beam plasma instabilities.