Fast Infrared Flickering from GRS 1915+105

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 1915+105: 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 ~ weeksBrightness ~ 600 mJy

Eik

enb

erry

et a

l. (2

00

0)

Timescales ~ less than 30 minutesBrightness ~ 5-10 mJy (dereddened)

Dhaw

an, M

irabel &

Rodríg

uez

(20

00

)Eikenberry et al. (1998a)

Timescales ~ 30 minutesBrightness ~ 50-200 mJy (dereddened)

Class A in the IR??• Sams, Eckart, & Sunyaev

(1996) found IR elongation in GRS 1915+105; 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 (1.9m) 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 1915+105 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 >200-2000s - 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 8 9 45 5

2 31 4 10 55 6

3 43 7 11 51 9

4 27 9 12 48 9

5 49 7 13 30 4

6 64 13

14 28 3

7 52 9 15 37 5

8 28 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 thin @ D ~50 AU

Rblob ~1 AU

Artwork by D. Rothstein

Klein-Wolt et al., 2002; Dhawan et al., 2000

Conclusions• GRS 1915+105 has shown a range of IR variability

related to jets, typically with ~200-300s• 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