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First results from NuSTAR observations of Mkn 421

Show simple item record Balokovic, M. Ajello, M. Blandford, R. D. Boggs, S. E. Borracci, F. Chiang, J. Christensen, F. E. Craig, W. W. Forster, K. Furniss, A. Fürst, F. Ghisellini, G. Giebels, B. Giommi, P. Grefenstette, B. W. Hailey, C. J. Harrison, F. A. Hayashida, M. Humensky, B. Inoue, Y. Koglin, J. E. Krawczynski, H. Madejski, G. M. Madsen, K. K. Meier, D. L. Nelson, T. Ogle, P. Paneque, D. Perri, M. Puccetti, S. Reynolds, C. S. Sbarrato, T. Stern, D. Tagliaferri, G. Urry, C. M. Wehrle, A. E. Zhang, W. W. 2014-02-21T16:48:46Z 2014-02-21T16:48:46Z 2013-06-10
dc.identifier.citation The Innermost Regions of Relativistic Jets and Their Magnetic Fields, Granada, Spain, June 10-14, 2013 en_US
dc.identifier.clearanceno CL#13-4214
dc.description.abstract Mkn 421 is a nearby active galactic nucleus dominated at all wavelengths by a very broad nonthermal continuum thought to arise from a relativistic jet seen at a small angle to the line of sight. Its spectral energy distribution peaks in the X-ray and TeV -ray bands, where the energy output is dominated by cooling of highenergy electrons in the jet. In order to study the electron distribution and its evolution, we carried out a dedicated multi-wavelength campaign, including extensive observations by the recently launched highly sensitive hard Xray telescope NuSTAR, between December 2012 and May 2013. Here we present some intial results based on NuSTAR data from January through March 2013, as well as calibration observations conducted in 2012. Although the observations cover some of the faintest hard X-ray f ux states ever observed for Mkn 421, the sensitivity is high enough to resolve intra-day spectral variability. We f nd that in this low state the dominant f ux variations are smooth on timescales of hours, with typical intra-hour variations of . 5%. We do not f nd evidence for either a cutoff in the hard X-ray spectrum, or a rise towards a high-energy component, but rather that at low f ux the spectrum assumes a power law shape with a photon index of approximately 3. The spectrum is found to harden with increasing brightness. en_US
dc.description.sponsorship NASA/JPL en_US
dc.language.iso en_US en_US
dc.publisher Pasadena, CA : Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2013 en_US
dc.subject active galactic nuclei (AGN) en_US
dc.subject Synchrotron Self-Compton (SSC) model en_US
dc.title First results from NuSTAR observations of Mkn 421 en_US
dc.type Preprint en_US

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