2016/06/15 by M. L. Parker, S. Komossa, W. Kollatschny +12 · 63 citations
Physics and Astronomy · #Accretion (finance) #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Balmer series #Emission spectrum #Flare #Flux (metallurgy) #Galaxy #Gamma-ray bursts and supernovae #Light curve #Physics #ROSAT #Sky #Spectral line #astro-ph.HE
paper · pdf · doi:10.1093/mnras/stw1449
published in Monthly Notices of the Royal Astronomical Society 461(2), 1927-1936 (Oxford University Press) · 10 pages, 10 figures. Accepted for publication in MNRAS
arxiv created 2016/06/15 · openalex publication_date 2016/06/20 · arxiv updated 2016/07/27 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We report the detection of high-amplitude X-ray flaring of the AGN HE 1136-2304, which is accompanied by a strong increase in the flux of the broad Balmer lines, changing its Seyfert type from almost type 2 in 1993 down to 1.5 in 2014. HE 1136-2304 was detected by the XMM–Newton slew survey at >10 times the flux it had in the ROSAT all-sky survey, and confirmed with Swift follow-up after increasing in X-ray flux by a factor of ∼30. Optical spectroscopy with SALT shows that the AGN has changed from a Seyfert 1.95 to a Seyfert 1.5 galaxy, with greatly increased broad line emission and an increase in blue continuum AGN flux by a factor of >4. The X-ray spectra from XMM–Newton and NuSTAR reveal moderate intrinsic absorption and a high energy cutoff at ∼100 keV. We consider several different physical scenarios for a flare, such as changes in obscuring material, tidal disruption events, and an increase in the accretion rate. We find that the most likely cause of the increased flux is an increase in the accretion rate, although it could also be due to a change in obscuration.