THE EVOLUTION OF SWIFT/BAT BLAZARS AND THE ORIGIN OF THE MeV BACKGROUND

By M. Ajello, L. Costamante, R. Sambruna, N. Gehrels, J. Chiang, A. Rau, A. Escala, J. Greiner, J. Tueller, J. Wall and 1 more. 2009

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We use three years of data from the Swift/Burst Alert Telescope (BAT) survey to select a complete sample of X-ray blazars above 15 keV. This sample comprises 26 flat-spectrum radio quasars (FSRQs) and 12 BL Lacertae (BL Lac) objects detected over a redshift range of 0.03 < z < 4.0. We use this sample to determine, for the first time in the 15–55 keV band, the evolution of blazars. We find that, contrary to the Seyfert-like active galactic nuclei (AGNs) detected by BAT, the population of blazars shows strong positive evolution. This evolution is comparable to the evolution of luminous optical quasi-stellar objects (QSOs) and luminous X-ray-selected AGNs. We also find evidence for an epoch dependence of the evolution as determined previously for radio-quiet AGNs. We interpret both these findings as a strong link between accretion and jet activity. In our sample, the FSRQs evolve strongly, while our best fit shows that BL Lac objects might not evolve at all. The blazar population accounts for 10%–20% (depending on the evolution of the BL Lac objects) of the cosmic X-ray background (CXB) in the 15–55 keV band. We find that FSRQs can explain the entire CXB emission for energies above 500 keV solving the mystery of the generation of the MeV background. The evolution of luminous FSRQs shows a peak in redshift (zc = 4.3 ± 0.5) which is larger than the one observed in QSOs and X-ray-selected AGNs. We argue that FSRQs can be used as tracers of massive elliptical galaxies in the early universe.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/a396aedc5c47d37c44775f1d03e49e5dbb430eb8

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Citations in the corpus

BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift/BAT 70-month AGN Catalog (2017, methodology): “We flagged all blazars in our sample according to the latest release (5.0.0, Massaro et al. 2015) of the Roma BZCAT28 catalog (Massaro et al. 2009), and using the results of recent works on BAT detected blazars (Ajello et al. 2009; Maselli et al. 2013).”
FERMI LARGE AREA TELESCOPE GAMMA-RAY DETECTION OF THE RADIO GALAXY M87 (2009, methodology): “…between the X-ray and LAT measurements, we determined integrated 3σ upper limits in three hard X-ray bands (following, Ajello et al. 2008) based on theSwi f t/BAT dataset in Ajello et al. (2009), including about another additional year of exposure (i.e.,∼4 years total from Mar. 2005 - Jan. 2009).”
THREE-YEAR SWIFT–BAT SURVEY OF ACTIVE GALACTIC NUCLEI: RECONCILING THEORY AND OBSERVATIONS? (2010, methodology): “As already reported in Ajello et al. (2009a), this stacking technique allows us to determine the average properties of a source population.”
FERMI LARGE AREA TELESCOPE VIEW OF THE CORE OF THE RADIO GALAXY CENTAURUS A (2010, methodology): “This spectrum is constructed325 by calculating weighted averages of the source spectra extracted over short exposures (e.g. 300 s).326 These spectra are accurate to the mCrab level and the reader is referred to Ajello et al. (2009a) for327 more details.328 5.”
THE 22 MONTH SWIFT-BAT ALL-SKY HARD X-RAY SURVEY (2009, methodology): “More details are described in the papers by Ajello et al. (2009) and Okajima et al. (ApJ, submitted).”
Formation of supermassive black holes (2010, background): “Ajello et al (2009) recently published the list of blazars detected in the all sky survey by the Burst Alert Telescope (BAT) onboard the Swift satellite.”
THE COSMIC EVOLUTION OF FERMI BL LACERTAE OBJECTS (2013, methodology): “The absence of any drop-out provides an upper limit to the source redshift limited by the bluest available pass band (e.g., z ≤ 1.3 based on Swift/UVOT in the study of Rau et al. 2012).”
THE FIRST CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE (2010, background): “This source is associated with ESO 323-G77, a nearby (z = 0.015) Seyfert 1.2 galaxy detected also by Swift-BAT (see, e.g., Ajello et al. 2009 and Section 6.3).”
THE FERMI-LAT HIGH-LATITUDE SURVEY: SOURCE COUNT DISTRIBUTIONS AND THE ORIGIN OF THE EXTRAGALACTIC DIFFUSE BACKGROUND (2010, unknown): “3.2 of Ajello et al. (2009).”
THE LUMINOSITY FUNCTION OF FERMI-DETECTED FLAT-SPECTRUM RADIO QUASARS (2011, methodology): “Because the rising part of the IC peak is in the hard ( (cid:2) 10 keV) X-ray band, high-redshift objects are more easily selected in this band (see, e.g., the Swift / BAT results in Ajello et al. 2009a).”
A simplified view of blazars: clearing the fog around long‐standing selection effects (2011, methodology): “This was first suggested by Wall, Pope & Scott (2008) and applied by Ajello et al. (2009) to a sample of Swift/BAT blazars.”
INSIGHTS INTO THE HIGH-ENERGY γ-RAY EMISSION OF MARKARIAN 501 FROM EXTENSIVE MULTIFREQUENCY OBSERVATIONS IN THE FERMI ERA (2011, methodology): “The spectrum was extracted following the recipes presented in Ajello et al. (2008, 2009b).”
CONTRIBUTION OF GAMMA-RAY-LOUD RADIO GALAXIES’ CORE EMISSIONS TO THE COSMIC MeV AND GeV GAMMA-RAY BACKGROUND RADIATION (2011, background): “Blazars, which are one type of AGN with the direction of a relativistic jet coinciding with our line of sight, are also proposed (Ajello et al. 2009).”