Publication Date:
2014-03-25
Description:
We analysed data from the Cosmic Origins Spectrograph (COS) to characterize the spectral properties and outflows of the active galactic nucleus (AGN), Markarian 1513. Further investigation using previous data collected by the Space Telescope Imaging Spectrograph (STIS), Goddard High Resolution Spectrograph (GHRS), and International Ultraviolet Explorer ( IUE ) was used to examine variability in the outflows along with the AGN emission and continuum luminosity spanning 32 yr. The COS data contained two sets of intrinsic absorption systems. The first, which is associated with an outflow, was observed in Lyman α, N v , Si iv , and C iv , with an outflow velocity of –1521 ± 20 km s –1 . This absorption system prevailed through the historical Hubble Space Telescope observations spanning 15 yr, and COS data revealed a previously unobserved Si iv outflow absorption feature. A second absorption system was observed at –17 ± 20 km s –1 in Lyman α, N v , and the blue component of C iv (1548.2 Å), indicating the presence of an intervening cloud, but not necessarily an outflow. Variability was also observed in the continuum levels of the AGN spectrum, which dropped by nearly a factor of 2 in both the power-law index and flux level between the GHRS and COS data.
Print ISSN:
0035-8711
Electronic ISSN:
1365-2966
Topics:
Physics
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