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Title: X-RAY SPECTRAL CURVATURE OF HIGH-FREQUENCY-PEAKED BL LAC OBJECTS: A PREDICTOR FOR THE TeV FLUX

Abstract

Most of the extragalactic sources detected at TeV energies are BL Lac objects. They belong to the subclass of high-frequency-peaked BL Lac objects (HBLs) exhibiting spectral energy distributions with a lower energy peak in the X-ray band; this is widely interpreted as synchrotron emission from relativistic electrons. The X-ray spectra are generally curved and well described in terms of a log-parabolic shape. In a previous investigation of TeV HBLs (TBLs) we found two correlations between their spectral parameters. (1) The synchrotron peak luminosity L{sub p} increases with its peak energy E{sub p} and (2) the curvature parameter b decreases as E{sub p} increases. The first is consistent with the synchrotron scenario, while the second is expected from statistical/stochastic acceleration mechanisms for the emitting electrons. Here, we present an extensive X-ray analysis of a sample of HBLs observed with XMM-Newton and Swift but undetected at TeV energies (UBLs), to compare their spectral behavior with that of TBLs. Investigating the distributions of their spectral parameters and comparing the TBL X-ray spectra with that of UBLs, we develop a criterion to select the best HBL candidates for future TeV observations.

Authors:
; ;  [1];  [2]
  1. Harvard-Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States)
  2. Dipartimento di Fisica, Universita di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Roma (Italy)
Publication Date:
OSTI Identifier:
21587472
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 739; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/739/2/73; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; BL LACERTAE OBJECTS; ELECTRONS; X-RAY GALAXIES; X-RAY SPECTRA; COSMIC RADIO SOURCES; COSMIC RAY SOURCES; COSMIC X-RAY SOURCES; ELEMENTARY PARTICLES; FERMIONS; GALAXIES; LEPTONS; SPECTRA

Citation Formats

Massaro, F., Paggi, A., Elvis, M., and Cavaliere, A. X-RAY SPECTRAL CURVATURE OF HIGH-FREQUENCY-PEAKED BL LAC OBJECTS: A PREDICTOR FOR THE TeV FLUX. United States: N. p., 2011. Web. doi:10.1088/0004-637X/739/2/73; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Massaro, F., Paggi, A., Elvis, M., & Cavaliere, A. X-RAY SPECTRAL CURVATURE OF HIGH-FREQUENCY-PEAKED BL LAC OBJECTS: A PREDICTOR FOR THE TeV FLUX. United States. doi:10.1088/0004-637X/739/2/73; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
Massaro, F., Paggi, A., Elvis, M., and Cavaliere, A. Sat . "X-RAY SPECTRAL CURVATURE OF HIGH-FREQUENCY-PEAKED BL LAC OBJECTS: A PREDICTOR FOR THE TeV FLUX". United States. doi:10.1088/0004-637X/739/2/73; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA).
@article{osti_21587472,
title = {X-RAY SPECTRAL CURVATURE OF HIGH-FREQUENCY-PEAKED BL LAC OBJECTS: A PREDICTOR FOR THE TeV FLUX},
author = {Massaro, F. and Paggi, A. and Elvis, M. and Cavaliere, A.},
abstractNote = {Most of the extragalactic sources detected at TeV energies are BL Lac objects. They belong to the subclass of high-frequency-peaked BL Lac objects (HBLs) exhibiting spectral energy distributions with a lower energy peak in the X-ray band; this is widely interpreted as synchrotron emission from relativistic electrons. The X-ray spectra are generally curved and well described in terms of a log-parabolic shape. In a previous investigation of TeV HBLs (TBLs) we found two correlations between their spectral parameters. (1) The synchrotron peak luminosity L{sub p} increases with its peak energy E{sub p} and (2) the curvature parameter b decreases as E{sub p} increases. The first is consistent with the synchrotron scenario, while the second is expected from statistical/stochastic acceleration mechanisms for the emitting electrons. Here, we present an extensive X-ray analysis of a sample of HBLs observed with XMM-Newton and Swift but undetected at TeV energies (UBLs), to compare their spectral behavior with that of TBLs. Investigating the distributions of their spectral parameters and comparing the TBL X-ray spectra with that of UBLs, we develop a criterion to select the best HBL candidates for future TeV observations.},
doi = {10.1088/0004-637X/739/2/73; COUNTRY OF INPUT: INTERNATIONAL ATOMIC ENERGY AGENCY (IAEA)},
journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 739,
place = {United States},
year = {2011},
month = {10}
}