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Contemporaneous broadband observations of three high-redshift BL Lac Objects

Ackermann, M. (2016) Contemporaneous broadband observations of three high-redshift BL Lac Objects. Astrophysical Journal, 820 (1). Art. No. 72. ISSN 0004-637X. doi:10.3847/0004-637X/820/1/72.

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We have collected broadband spectral energy distributions (SEDs) of three BL Lac objects 3FGL J0022.1−1855 (z = 0.689), 3FGL J0630.9−2406 (z ≳ 1.239), and 3FGL J0811.2−7529 (z = 0.774), detected by Fermi with relatively flat gigaelectronvolt spectra. By observing simultaneously in the near-infrared to hard X-ray band, we can well characterize the high end of the synchrotron component of the SED. Thus, fitting the SEDs to synchro-Compton models of the dominant emission from the relativistic jet, we can constrain the underlying particle properties and predict the shape of the gigaelectronvolt Compton component. Standard extragalactic background light (EBL) models explain the high-energy absorption well, with poorer fits for high-ultraviolet models. The fits show clear evidence for EBL absorption in the Fermi spectrum of our highest-redshift source 3FGL J0630.9−2406. While synchrotron self-Compton models adequately describe the SEDs, the situation may be complicated by possible external Compton components. For 3FGL J0811.2−7529, we also discover a nearby serendipitous source in the X-ray data, which is almost certainly another lower synchrotron peak frequency (ν^(sy)_(pk)) BL Lac, that may contribute flux in the Fermi band. Since our sources are unusual high-luminosity, moderate ν^(sy)_(pk) BL Lacs, we compare these quantities and the Compton dominance, the ratio of peak inverse Compton to peak synchrotron luminosities (L^(IC)_(pk)/L^(sy)_(pk)), with those of the full Fermi BL Lac population.

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Additional Information:© 2016 The American Astronomical Society. Received 2015 November 30; accepted 2016 February 14; published 2016 March 21. This work was supported under NASA Contract No. NNG08FD60C and made use of data from the NuSTAR mission, a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Operations, Software, and Calibration teams for support with the execution and analysis of these observations. This research has made use of the NuSTAR Data Analysis Software (NuSTARDAS), jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l'Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), the High Energy Accelerator Research Organization (KEK), and the Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council, and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d'Études Spatiales in France. H.A. acknowledges support provided by the NASA-sponsored Fermi Contract NAS5-00147 and by the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC). Part of the funding for GROND (both hardware and personnel) was generously granted from the Leibniz Prize to Prof. G. Hasinger (DFG grant HA 1850/28-1).
Subject Keywords:BL Lacertae objects: general – BL Lacertae objects: individual (3FGL J0022.1−1855, 3FGL J0630.9 −2406, 3FGL J0811.2−7529) – galaxies: active – radiation mechanisms: non-thermal
Issue or Number:1
Record Number:CaltechAUTHORS:20170614-160827182
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Official Citation:M. Ackermann et al 2016 ApJ 820 72
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:78221
Deposited By: Joy Painter
Deposited On:14 Jun 2017 23:16
Last Modified:15 Nov 2021 17:37

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