Gamma-Ray Bursts: Death of a Star and the Birth of a Black Hole AGN with Extreme X-ray amplitude variations, or how they might fool you! Gamma-Ray Bursts: Death of a Star and the Birth of a Black Hole Dirk Grupe Swift Mission Operating Center Department of Astrophysics and Astronomy Pennsylvania State University

The way the discover typically TDEs is by a few X-ray 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 Blank slide for drafting title slide.

The typical TDE candidate has two observations, one in an extremely high state and one in a low state – often discovered archival data RX J1624.9+7554: RASS: 0.54 counts s-1 pointed: gone 15 month later! Blank slide for drafting title slide. XMM J1847-6317 (Lin et al. 2011, ApJ 738, 52; see also Dacheng Lin's talk) Optical spectrum of RX J1624+74 (Grupe et al. 1999, A&A 350)

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. Log CR ROSAT pointed RX J2217-59 IC 3599 Blank slide for drafting title slide. RX J1624+75 WPVS 007 Log CR RASS ROSAT RASS vs pointed obs. (Grupe et al. 2001, A&A367, 470) Swift observations of two epochs (Grupe et al. 2010, ApJS 187, 64

WPVS 007 is a normal Narrow-Line Seyfert 1 galaxy which has shown extreme X-ray bahavior. Blank slide for drafting title slide. Grupe et al. 2007, AJ, 133, 1988

Making things worse the decay slope of the long term light curve is close to 5/3 ROSAT PSPC Count rate Blank slide for drafting title slide. Time [years]

WPVS 007's high state X-ray spectrum is also extremely soft, exactly what is expected from a TDE Blank slide for drafting title slide. Grupe et al. 1995, A&A 300

So, is WPVS 007 a TDE? No, because we detect it in X-rays again with Swift Blank slide for drafting title slide. 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 Blank slide for drafting title slide. 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 Blank slide for drafting title slide. BAL QSO Leighly et al. 2009, ApJ, 701, 176 FUSE observation in November 2003

RX J2217.9-5941: Narrow-Line Seyfert 1 galaxy with strong X-ray decay Blank slide for drafting title slide. Factor of ~30 between RASS and HRI Typical spectrum of an AGN with A partial covering absorber Grupe et al., 2001, A&A 369 Grupe et al., 2004, AJ, 128 Chandra data from 2003 Shown is the lower flux spectrum from August 2003 Recent Swift observations how it still in a low state

The next example is Mkn 335 – a typically X-ray Bright Narrow-Line Seyfert 1 galaxy Blank slide for drafting title slide. Swift XRT X-ray low state a factor of 35 fainter than compared with XMM a year earlier Grupe et al. 2007, ApJ, 668, L111 Again partial covering absorber Grupe et al. 2008, ApJ, 681, 982

Mkn 335 becomes even more dramatic when looking at the spectral energy distribution XMM 2000 Swift 2007 Blank slide for drafting title slide. Grupe et al. 2007, ApJ, 668, L111

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 Blank slide for drafting title slide. Grupe et al. 2012, ApJS, 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 W2 Blank slide for drafting title slide.

The UV however does not help you here either 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 Blank slide for drafting title slide.

The UV however does not help you here either. Some Seyfert 1 The UV however does not help you here either. Some Seyfert 1.5s show even variability by 1.5 mag in the UV within less than a year Swift UVOT W2 mag epoch 2 Swift UVOT W2 mag difference Blank slide for drafting title slide. Swift UVW2 mag epoch 1 Swift XRT CR ratio Grupe et al. 2010, ApJS, 187, 64

XMM program to observe AGN in deep minimum states: PG 0844+349 and 1H 0707-495 Blank slide for drafting title slide. 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 How can we distinguish between a TDE in an AGN and e.g. accretion disk instability or just absorption? Blank slide for drafting title slide. 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 Blank slide for drafting title slide. 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 1s 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 (NLS1s) can fool you! Blank slide for drafting title slide.