Interpreting Sgr A*'s Most Luminous X-ray Flares Daryl Haggard - - PowerPoint PPT Presentation

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Interpreting Sgr A*'s Most Luminous X-ray Flares Daryl Haggard - - PowerPoint PPT Presentation

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Interpreting Sgr A*'s Most Luminous X-ray Flares Daryl Haggard McGill University What a wonderful day - and in our (my) lifetime. The wave revealed from a spectacular collision, spectacularly long gone. A new way to examine the universe!

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SLIDE 1

Interpreting Sgr A*'s Most Luminous X-ray Flares

Daryl Haggard McGill University

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SLIDE 2

Gravitational Waves!!!

What a wonderful day - and in our (my) lifetime. The wave revealed from a spectacular collision, spectacularly long gone. A new way to examine the universe! Exciting for your field and for you who dedicated yourself to it. Congratulations.

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SLIDE 3

Collaborators

Baganoff, Frederick Bower, Geoffrey Brinkerink, Christaan Bushouse, Howard Corales, Lia Coti-Zelati, Francesco Degenaar, Nathalie Dexter, Jason Falcke, Heino Fazzio, Giovanni Fragile, P. Chris Ghez, Andrea Gillessen, Stefan Heinke, Craig Hora, Joseph Kosack, Karl Law, Casey Markoff, Sera Marrone, Dan Morris, Mark Neilsen, Joey Nowak, Michael Ponti, Gabriele Rea, Nanda Roberts, Douglas Wang, Q. Daniel Willner, Steven Yusef-Zadeh, Farhad

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SLIDE 4

[Wang, et al., Science, 2013]

1” ~8000 AU

Sgr A* in the X-ray

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SLIDE 5

Time [s]

5

[Haggard et al, Atel #6242; Haggard, et al. in prep]

April 2013 Oct 2014

2013

Sgr A* Observing Gaps Removed

  • ~900 ks w/ Chandra
  • >70 hrs w/ VLA (+VLBA)
  • Daily obs w/ Swift
  • Fermi, NuSTAR, XMM,

Hubble, Spitzer 2014

Sgr A* X-ray Light Curve

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SLIDE 6

Time [s]

No Sign of G2

6

[Haggard et al, Atel #6242; Haggard, et al. in prep]

April 2013 Oct 2014

+ No VLA radio detection

2013

Sgr A* Observing Gaps Removed

  • ~900 ks w/ Chandra
  • >70 hrs w/ VLA (+VLBA)
  • Daily obs w/ Swift
  • Fermi, NuSTAR, XMM,

Hubble, Spitzer 2014

Sgr A* X-ray Light Curve

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SLIDE 7

X-rays from G2 Encounter?

[Morsony, et al. 2016]

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SLIDE 8
  • No shock front
  • G2 is clumpy and/or the

accretion flow is clumpy (G2 fell through a “void”)

  • G1 already cleared the path
  • Accretion flow is lower

density than expected

  • Non-detection may be

constraining

  • Uncertain viscosity and

accretion timescale

  • Years vs. months
  • Continued monitoring

may tell…

[Sadowski et al, 2013]

No X-ray or Radio Signature

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SLIDE 9

Time [s]

9

[Haggard et al, Atel #6242; Haggard, et al. in prep]

April 2013 Oct 2014

2013

Sgr A* Observing Gaps Removed

2014

Sgr A* X-ray Light Curve

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SLIDE 10

Time [s]

10

[Haggard et al, Atel #6242; Haggard, et al. in prep]

April 2013 Oct 2014

2013

Sgr A* Observing Gaps Removed

2014

Sgr A* X-ray Light Curve

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SLIDE 11

11

Sgr A* Bright (!) Flares

Time [s]

[Haggard et al, Atel #6242; Haggard, et al. in prep]

April 2013 Oct 2014 Sgr A* Observing Gaps Removed

~400x quiescent level! ~200x quiescent level!

Previous record-holder ~140x quiescent level (Nowak+12)

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SLIDE 12

1.25’’ ~ 10,000 AU ~ 1.25 x 105 Rs

Sgr A* magnetar

Magnetar “Contamination”

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SLIDE 13
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SLIDE 14

Sgr A* Two Brightest Flares

14

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SLIDE 15

2013 Bright Flare

15

[Haggard, et al. in prep]

  • Bright flares typically few 1000 s
  • Orbital Period w/in ~RISCO
  • Characteristic flyby time for asteroids

at 1 AU

  • Alfvén crossing time for magnetic

loops

  • G2’s pericenter: ~2200 RS (~150 AU)
  • Unrelated to G2 encounter
  • Double-peaked morphology
  • Duration: ~6.0 ks
  • Mean count rate: 0.41 cts/s
  • Fluence: ~2500 counts
  • Total emission (2-10 keV): ~2x1039 erg
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SLIDE 16

2013 Bright Flare

16

[Haggard, et al. in prep]

  • Bright flares typically few 1000 s
  • Orbital Period w/in ~RISCO
  • Characteristic flyby time for asteroids

at 1 AU

  • Alfvén crossing time for magnetic

loops

  • G2’s pericenter: ~2200 RS (~150 AU)
  • Unrelated to G2 encounter
  • Double-peaked morphology
  • Duration: ~6.0 ks
  • Mean count rate: 0.41 cts/s
  • Fluence: ~2500 counts
  • Total emission (2-10 keV): ~2x1039 erg

[Neilsen+13]

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SLIDE 17

Spectroscopy

Flare NH [1023 cm-2] Γ fx (2-8 keV, abs) [erg/cm2/s] Duration [ks] Fluence [erg/cm-2] Energy (2-10keV) [erg] Haggard+ 1.43-1.5

+0.69

2.1-0.3

+0.1

2.1-0.3

+0.4 x 10-11

6.6 1.4±0.3 x 10-7 1.7 x 10-39 Nowak+12 1.43-3.6

+4.4

2.0-0.6

+0.7 8.5±0.9 x 10-12

5.6 4.7±0.5 x 10-8 1.0 x 10-39 Porquet+08 (Nowak+12) 1.63-2.6

+3.0

2.4-0.3

+0.4

4.8-0.3

+0.2 x 10-12

2.9 1.4±0.1 x 10-8 3.5 x 10-38 Porquet+03 (Nowak+12) 1.61-2.2

+1.9

2.3±0.3 7.7±0.3 x 10-12 2.8 2.2±0.1 x 10-8 5.3 x 10-38

17

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SLIDE 18

Morphology & Timing

Time [s]

  • Bins: 50 sec
  • Timing: 0.4 sec

18

[Haggard, et al. in prep]

Sgr A* Bright Flare Magnetar

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SLIDE 19

Power Spectral Distribution

Poisson noise

[Haggard, et al. in prep]

2 ks 6 ks 600 s 300 s 150 s

PISCO = 247 s (max spin) PISCO = 1819 s (no spin)

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SLIDE 20

Radio View

X-ray (Chandra) Radio 3.6 cm (VLA)

Time (hours) Counts (sec) Flux (Jy)

[Yusef-Zadeh, Haggard, et al. in prep]

  • Continuous

coverage

  • Radio (3.6 cm) flux

increase of 25%

  • Cross correlation

peak >130 min

  • Consistent with

previous time delay estimates

  • Anti-correlation

radio-X-ray peak

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SLIDE 21

Increased Flare Rate?

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SLIDE 22

[Pon4, et al. 2015]

Flare Rates: Chandra, XMM, Swift

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SLIDE 23

[Pon4, et al. 2015]

Flare Rates: Chandra, XMM, Swift

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SLIDE 24

[Pon4, et al. 2015]

Increase in Bright Flares?

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Increase in Bright Flares?

  • Observed increase may be connected to G2, but may

instead arise from flare clustering

  • Faint flares cluster on timescales of ~20-70 ks in

Chandra data from 1999-2012 (Yuan & Wang 2015)

  • Analysis of the faint flares in the 2013-2015 data is
  • ngoing (Swift and XMM Newton cannot weigh in

due to magnetar contamination)

  • Could indicate that the flare clustering has a

luminosity dependence; correlation between flare fluence and duration already estabilshed

  • No increase in the rate connected to S2’s last

passage in ~2002; next close passage in 2018!

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SLIDE 26

G1/G2 Modeled Orbits

[Madigan, et al. 2016]

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SLIDE 27

G1/G2 Modeled Orbits

Keplerian No Inflow With Inflow

[Madigan, et al. 2016]

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SLIDE 28

[Pon4, et al. 2015]

Increase in Bright Flares?

  • Last Chandra Obs:

Oct 21, 2015

  • Next Chandra Obs:

Feb 13 & 14, 2016

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SLIDE 29

Asteroid Disruption Magnetic Reconnection

What’s Causing the Flares?

Markoff et al. 2001; Liu & Melia 2002; Liu et al. 2004; Yuan et al. 2003, 2004; Eckart et al. 2004, 2006; Marrone et al. 2008; Cadez et al. 2008; Kostic et al. 2009; Dodds- Eden et al. 2009; Yuan et al. 2009a; Zubovas et al. 2012; Witzel et al. 2012; Yusef- Zadeh et al. 2012; Nowak et al. 2012; Neilsen et al. 2013; Chan et al. 2015

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SLIDE 30

GRMHD Modeling

[Chan, et al. 2015]

  • General relativistic magnetohydrodynamic simulations
  • Variability and time lags from short-lived B-flux tubes

and strong-field gravitational lensing near the horizon

  • No X-ray flares … yet?
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SLIDE 31

[Marrone, et al. 2008, Yusef-Zadeh et al. 2009]

We need more simultaneous radio/submm/IR/X-ray flares!!!

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SLIDE 32

Coordinated Spitzer Obs

32

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SLIDE 33

Everyone interested in monitoring Sgr A* is encouraged to

  • bserve at the same times as Chandra and Spitzer if possible.

https://www.cfa.harvard.edu/irac/gc/

Joint Spitzer/Chandra Monitoring for bright flares in 2016

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SLIDE 34

Summary

  • No X-ray or radio G2 sighting; continued

monitoring may distinguish G2’s origin and fate

  • Sgr A* flares detected by Chandra
  • Faint and two very bright flares
  • Bright flares: spectrum comparable to other bright flares,

asymmetric morphologies, detailed timing, radio lag

  • Flare rate: Perhaps some increase or clustering for brightest

flares?

  • Flare mechanism still highly debated
  • Other Excellent X-ray + Multiwavelength Science
  • XMM & Swift: lightcurves, spectroscopy
  • VLA/VLBA: lightcurves, astrometry, polarization
  • Absorption measure along Sgr A* line of sight