2009/01/22 by T. G. Wang, H. Y. Zhou, D. Grupe +5
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Balmer series #Emission spectrum #Extinction (optical mineralogy) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Optics #Physics #ROSAT #Spectral line #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.1088/0004-6256/137/4/4002
25 pages, 5 figures, accepted to AJ
arxiv created 2009/01/22 · openalex publication_date 2009/03/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present a detailed study of the X-ray and optical spectra of the luminous Seyfert galaxy Mrk 1393, which revealed variable partial obscuration of the active nucleus. The X-ray spectra obtained by XMM-Newton and Swift show moderate absorption with a column density around 3 × 10 21 cm −2 , consistent with a dust-reddening interpretation of the steep Balmer decrement seen in recent optical spectra. The X-ray flux in the 0.5–2 keV band during the XMM-Newton observation in 2005, and Swift observation in 2006 was a factor of 6 brighter than that of the ROSAT All Sky Survey in 1991. In the past four years, the broad-Hα line brightened by a factor of 4 accompanied by a decrease in the Balmer decrement. A comparison with literature spectra reveals variations in the dust extinction on timescales of several years, suggesting that the obscuring material are very close to the active nucleus. These observations indicate that a dust-to-gas ratio as high as the Galactic value can be present in moderately thick gas in the vicinity of the central engine within a few parsecs. We suggest that the obscuring material may be debris disrupted from the dusty torus.