Fast Infrared Flickering from GRS The Spirit of Stephen Eikenberry (University of Florida) As Channeled by David Rothstein (Cornell University) 19 October 2006

Collaborators Stephen Eikenberry (U. Florida) Shannon Patel (U. Florida & UC Santa Cruz) David Rothstein (Cornell) Ron Remillard (MIT) Guy Pooley (Cambridge) Ed Morgan (MIT)

GRS : Obligatory Jet Slide You know the chorus – sing along! Mirabel & Rodríguez (1994) ~ 6,000 AU Brightness ~ 600 mJy

3 Different Classes of Jets/Flares Class B (“large”) Class C (“medium”) Class A (“extra large”) Mirabel & Rodríguez (1994) ~ 6,000 AU Timescales ~ weeks Brightness ~ 600 mJy Eikenberry et al. (2000) Timescales ~ less than 30 minutes Brightness ~ 5-10 mJy (dereddened) Dhawan, Mirabel & Rodríguez (2000) Eikenberry et al. (1998a) Timescales ~ 30 minutes Brightness ~ mJy (dereddened)

Class A in the IR?? Sams, Eckart, & Sunyaev (1996) found IR elongation in GRS ; direction lies along radio jet axis Eikenberry & Fazio (1997) found that it was gone a few months later Transient resolved IR jet? Inspired HST/NICMOS ToO proposal Use plateau state + RXTE/ ASM hardness evolution to try and “catch” an outburst

ToO Observations with HST Feb-June 2003: GRS 1915 entered plateau and showed “trigger” signs Outburst “aborted” and returned to plateau Tried again at the “second end” No “major” relativistic outflow seen IR (1.9  m) variability & flux anti-correlated with X-ray RXTE/ASM Ryle Telescope HST/NICMOS

Broadband IR Photometry Points w/error bars are comparison star Diamonds show GRS flux

High-Speed Photometry NICMOS MultiAccum mode allows  t=8-sec photometry In 3 visits, find evidence of small (~10-30% = 1-3 mJy) IR “flickering” Comparison star is steady (w/in uncertainties) GRS1915 is variable at the 5  to 15  level These flares are much faster than previous IR variability in GRS1915

Fast Flickering Previous flares have: - total  t > s - e-fold rise/fall  ~300s 15 “Flickers” here have: - total  t fast as ~16-s - e-fold rise/fall  min ~30s This is an order of magnitude faster than seen before at long wavelengths (!) Flare #  (s) Flare #  (s) 1 58                9 Flicker e-fold Rise Times

Where Does It Come From – Disk? X-rays often fast enough Could this be IR reprocessing of X-ray flares in the inner disk on the outer disk? X-ray shows strong QPO at ~1-Hz during this time But … not much excess X-ray power at ~0.1 Hz Smooth X-ray lightcurve to 8-sec resolution  RMS deviations <2-3% RMS IR variation ~4-8%  IR flares not due to reprocessing of X-rays

Where Does It Come From – Jet? Previous IR variability definitely linked to jet IR flickering only during plateau state, when we “know” jet is present Perhaps the flickers are jet- driven Assume “standard” opening angle  1-degree If light-crossing time ~30-s here, then D  2.5 AU  IR flickers from base of jet Accretion Disk Jet (radio, infrared) Radio optically D ~50 AU R blob ~1 AU Artwork by D. Rothstein Klein-Wolt et al., 2002; Dhawan et al., 2000

Conclusions GRS has shown a range of IR variability related to jets, typically with  ~ s In 2003, GRS1915 showed higher and more variable IR flux in the plateau state than during X-ray/radio flares In the plateau state, IR variability included fast IR flickering on timescales with  ~30s This is ~x10 faster than previous types of IR flaring IR does not seem to be directly correlated with any particular X-ray variability (i.e. not reprocessed X-rays) If the IR flickering comes from the jet, then it seems likely that it arises near the base of the jet,  2.5 AU from the black hole