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Title: Multiwavelength Study of Quiescent States of Mrk 421 with Unprecedented Hard X-Ray Coverage Provided by NuSTAR in 2013

Authors:
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Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC); National Aeronautics and Space Administration (NASA)
OSTI Identifier:
1313954
Report Number(s):
SLAC-PUB-16788
Journal ID: ISSN 1538-4357; arXiv:1512.02235
DOE Contract Number:
AC02-76SF00515
Resource Type:
Journal Article
Resource Relation:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 819; Journal Issue: 2
Country of Publication:
United States
Language:
English
Subject:
Astrophysics,ASTRO, GRQC

Citation Formats

Balokovic, M., Paneque, D., Madejski, G., Furniss, A., Chiang, J., Ajello, M., Alexander, D.M., Barret, D., Blandford, R., Boggs, S.E., Christensen, F.E., Craig, W.W., Forster, K., Giommi, P., Grefenstette, B.W., Hailey, C.J., Harrison, F.A., Hornstrup, A., Kitaguchi, T., Koglin, J.E., and Madsen, K.K. Multiwavelength Study of Quiescent States of Mrk 421 with Unprecedented Hard X-Ray Coverage Provided by NuSTAR in 2013. United States: N. p., 2016. Web. doi:10.3847/0004-637X/819/2/156.
Balokovic, M., Paneque, D., Madejski, G., Furniss, A., Chiang, J., Ajello, M., Alexander, D.M., Barret, D., Blandford, R., Boggs, S.E., Christensen, F.E., Craig, W.W., Forster, K., Giommi, P., Grefenstette, B.W., Hailey, C.J., Harrison, F.A., Hornstrup, A., Kitaguchi, T., Koglin, J.E., & Madsen, K.K. Multiwavelength Study of Quiescent States of Mrk 421 with Unprecedented Hard X-Ray Coverage Provided by NuSTAR in 2013. United States. doi:10.3847/0004-637X/819/2/156.
Balokovic, M., Paneque, D., Madejski, G., Furniss, A., Chiang, J., Ajello, M., Alexander, D.M., Barret, D., Blandford, R., Boggs, S.E., Christensen, F.E., Craig, W.W., Forster, K., Giommi, P., Grefenstette, B.W., Hailey, C.J., Harrison, F.A., Hornstrup, A., Kitaguchi, T., Koglin, J.E., and Madsen, K.K. 2016. "Multiwavelength Study of Quiescent States of Mrk 421 with Unprecedented Hard X-Ray Coverage Provided by NuSTAR in 2013". United States. doi:10.3847/0004-637X/819/2/156. https://www.osti.gov/servlets/purl/1313954.
@article{osti_1313954,
title = {Multiwavelength Study of Quiescent States of Mrk 421 with Unprecedented Hard X-Ray Coverage Provided by NuSTAR in 2013},
author = {Balokovic, M. and Paneque, D. and Madejski, G. and Furniss, A. and Chiang, J. and Ajello, M. and Alexander, D.M. and Barret, D. and Blandford, R. and Boggs, S.E. and Christensen, F.E. and Craig, W.W. and Forster, K. and Giommi, P. and Grefenstette, B.W. and Hailey, C.J. and Harrison, F.A. and Hornstrup, A. and Kitaguchi, T. and Koglin, J.E. and Madsen, K.K.},
abstractNote = {},
doi = {10.3847/0004-637X/819/2/156},
journal = {The Astrophysical Journal (Online)},
number = 2,
volume = 819,
place = {United States},
year = 2016,
month = 8
}
  • Here we report the results of a multiband observing campaign on the famous blazar 3C 279 conducted during a phase of increased activity from 2013 December to 2014 April, including first observations of it with NuSTAR. The γ-ray emission of the source measured by Fermi-LAT showed multiple distinct flares reaching the highest flux level measured in this object since the beginning of the Fermi mission, with F(E>100 MeV) of 10 -5 photons cm -2 s -1, and with a flux-doubling time scale as short as 2 hr. The γ-ray spectrum during one of the flares was very hard, with an index of Γ γ =1.7±0.1, which is rarely seen in flat-spectrum radio quasars. The lack of concurrent optical variability implies a very high Compton dominance parameter L γ/L syn > 300. Two 1 day NuSTAR observations with accompanying Swift pointings were separated by 2 weeks, probing different levels of source activity. While the 0.5-70 keV X-ray spectrum obtained during the first pointing, and fitted jointly with Swift-XRT is well-described by a simple power law, the second joint observation showed an unusual spectral structure: the spectrum softens by ΔΓ xmore » $$\simeq$$ 0.4 at ~ keV. Modeling the broadband spectral energy distribution during this flare with the standard synchrotron plus inverse-Compton model requires: (1) the location of the γ-ray emitting region is comparable with the broad-line region radius, (2) a very hard electron energy distribution index p $$\simeq$$ 1, (3) total jet power significantly exceeding the accretion-disk luminosity L j/L d ≳ 10, and (4) extremely low jet magnetization with L B/L j ≲ 10 -4. In conclusion, we also find that single-zone models that match the observed γ-ray and optical spectra cannot satisfactorily explain the production of X-ray emission.« less
  • We present NuSTAR high-energy X-ray observations of the pulsar wind nebula (PWN)/supernova remnant G21.5–0.9. We detect integrated emission from the nebula up to ∼40 keV, and resolve individual spatial features over a broad X-ray band for the first time. The morphology seen by NuSTAR agrees well with that seen by XMM-Newton and Chandra below 10 keV. At high energies, NuSTAR clearly detects non-thermal emission up to ∼20 keV that extends along the eastern and northern rim of the supernova shell. The broadband images clearly demonstrate that X-ray emission from the North Spur and Eastern Limb results predominantly from non-thermal processes.more » We detect a break in the spatially integrated X-ray spectrum at ∼9 keV that cannot be reproduced by current spectral energy distribution models, implying either a more complex electron injection spectrum or an additional process such as diffusion compared to what has been considered in previous work. We use spatially resolved maps to derive an energy-dependent cooling length scale, L(E)∝E{sup m} with m = –0.21 ± 0.01. We find this to be inconsistent with the model for the morphological evolution with energy described by Kennel and Coroniti. This value, along with the observed steepening in power-law index between radio and X-ray, can be quantitatively explained as an energy-loss spectral break in the simple scaling model of Reynolds, assuming particle advection dominates over diffusion. This interpretation requires a substantial departure from spherical magnetohydrodynamic, magnetic-flux-conserving outflow, most plausibly in the form of turbulent magnetic-field amplification.« less
  • No abstract prepared.
  • The dynamical center of our galaxy hosts a supermassive black hole, Sgr A*, which has been the target of an extensive multiwavelength campaign for a week in April 2007. We report here the detection of a bright flare from the vicinity of the horizon, observed simultaneously in X-rays (XMM-Newton) and NIR (VLT/NACO) on April 4{sup th}. For the first time, such an event also benefitted from a soft {gamma}-rays (INTEGRAL/ISGRI) and MIR (VLT/VISIR) coverage, which enabled us to derive upper limits at both ends of Sgr A* spectral energy distribution (SED). We discuss the physical implications of the contemporaneous lightmore » curves as well as the SED, in terms of synchrotron, synchrotron self-Compton and external Compton emission processes.« less
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