AGN with Extreme Xray amplitude variations GammaRay Bursts
AGN with Extreme X-ray amplitude variations, Gamma-Ray Bursts: Death of a Star and the or how they Birth ofmight a Black fool Hole you! Dirk Grupe Swift Mission Operating Center Department of Astrophysics and Astronomy Pennsylvania State University
The way the discover typically TDEs is by a few Xray observations that indicate a rapidly decaying source IC 3599 by Grupe et al. (1995) Brandt et al. (1995) But IC 3599 is a Seyfert 2 galaxy It is however an example where we have more than 2 data points
The typical TDE candidate has two observations, one in an extremely high state and one in a low state – often discovered archival data RX J 1624. 9+7554: RASS: 0. 54 counts s-1 pointed: gone 15 month later! XMM J 1847 -6317 Optical spectrum of RX J 1624+74 (Grupe et al. 1999, A&A 350) (Lin et al. 2011, Ap. J 738, 52; see also Dacheng Lin's talk)
Log CR ROSAT pointed What can also happen in a survey is that we see an AGN as a bright source and then in a later observation as an extremely faint X-ray emitter. RX J 2217 -59 IC 3599 RX J 1624+75 WPVS 007 Log CR RASS ROSAT RASS vs pointed obs. (Grupe et al. 2001, A&A 367, 470) Swift observations of two epochs (Grupe et al. 2010, Ap. JS 187, 64
WPVS 007 is a normal Narrow-Line Seyfert 1 galaxy which has shown extreme X-ray bahavior. Grupe et al. 2007, AJ, 133, 1988
ROSAT PSPC Count rate Making things worse the decay slope of the long term light curve is close to 5/3 Time [years]
WPVS 007's high state X-ray spectrum is also extremely soft, exactly what is expected from a TDE Grupe et al. 1995, A&A 300
So, is WPVS 007 a TDE? No, because we detect it in X-rays again with Swift Grupe et al. 2007, AJ 133; 2008, AJ 136; 2012 in prep
The low-state X-ray spectrum of WPVS 007 can be modeled by a partial covering absorber Absorption not a flare or TDE Grupe et al. 1995, A&A 300 Grupe et al. 2008, AJ, 136 partial covering absorber WPVS 007 is not a TDE, but an highly absorbed AGN!
The real answer, however, came from UV observations: WPVS 007 shows extremely deep UV absorption troughs, just like a BAL QSO! WPVS 007 BAL QSO Leighly et al. 2009, Ap. J, 701, 176 FUSE observation in November 2003
RX J 2217. 9 -5941: Narrow-Line Seyfert 1 galaxy with strong X-ray decay Factor of ~30 between RASS and HRI Grupe et al. , 2001, A&A 369 Grupe et al. , 2004, AJ, 128 Recent Swift observations how it still in a low state Typical spectrum of an AGN with A partial covering absorber Chandra data from 2003 Shown is the lower flux spectrum from August 2003
The next example is Mkn 335 – a typically X-ray Bright Narrow-Line Seyfert 1 galaxy Swift XRT X-ray low state a factor of 35 fainter than compared with XMM a year earlier Grupe et al. 2008, Ap. J, 681, 982 Grupe et al. 2007, Ap. J, 668, L 111 Again partial covering absorber
Mkn 335 becomes even more dramatic when looking at the spectral energy distribution XMM 2000 Swift 2007 Grupe et al. 2007, Ap. J, 668, L 111
Mkn 335 has show bright and extreme low states several times in the last 5 years! Swift monitoring since May 2007 X-ray as well as UV Mkn 335 shows variability by factors of more than 30 in X-rays and by about 1 mag in the UV Grupe et al. 2012, Ap. JS, 199, 28
Mkn 335 switches back and forth between high and low states during the last few years. Swift monitoring in 2010 to 2012 XRT count rate and Hardness ratio And UVOT in W 2
The UV however does not help you here either. Mkn 355 and WPVS 007 vary strongly in the UV as well WPVS 007 Swift UVOT
Swift UVW 2 mag epoch 1 Grupe et al. 2010, Ap. JS, 187, 64 Swift UVOT W 2 mag difference Swift UVOT W 2 mag epoch 2 The UV however does not help you here either. Some Seyfert 1. 5 s show even variability by 1. 5 mag in the UV within less than a year Swift XRT CR ratio
XMM program to observe AGN in deep minimum states: PG 0844+349 and 1 H 0707 -495 Gallo et al. , 2011, MNRAS 412, 161 Fabian et al. , 2012, MNRAS 419, 116
How can we distinguish between a TDE in an AGN and e. g. accretion disk instability or just absorption? Method 1: Look at the X-ray spectrum!
Besides X-rays the answer may come from Optical spectra as well, again the example here is IC 3599 Brandt et al. , 1995, MNRAS Grupe et al. , 1995, A&A 299 Strong H and He lines material of a main sequence star! See also Drew Clausen's talk (Monday), Komossa & Bade (1999)
Some AGN may fool you and look like TDEs - Some AGN vary by factors of several 100 in X-rays And by > 1 mag in the UV Best example is WPVS 007 Variability NOT caused by tidal disruption Caused by absorption All these source have one thing in common: They are Narrow Line Seyfert 1 s TDEs can occur in Seyferts (e. g. IC 3599) If discovered on time, keep monitoring Look at the X-ray spectrum and get optical spectra and look for strong H and He line Be Aware, These sources (NLS 1 s) can fool you!
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