summary probing strong gravity in agn kirpal nandra imperial college london
TRANSCRIPT
SUMMARY
PROBING STRONG GRAVITY IN AGN
Kirpal NandraImperial College London
PROBING STRONG GRAVITY
• The Promise• The Probes• The Progress• The Problems• The Prospects• Probably…
PaulReviewsObservations (and Theory)
THE PROMISE
• What are the processes close to the event horizon?• Are black holes in AGN spinning?• How does BH spin evolve on the Cosmic Scale?• How does matter behave in the strong field?• Does it obey the predictions of GR?
THE PROBES
• Broad emission lines • Narrow emission lines• Narrow absorption lines• Variability/reverb. • Broadband/disk/reflection spectra• Polarimetry• Binary Black Holes• Microlensing
(Zoghbi, de Marco, Ponti, Goosmann)
(Iwasawa, Ballantyne, Guainazzi, de la Calle, Svoboda, Miniutti)
(Cappi, Reeves,)
(Dovciak)
(Laor, Walton)
(Cappi)
(Komossa, Liu)
NOBODY!
+ Nikolajuk: TBC
PROBES: MICROLENSING
RX J1131-123116
Chartas et al. 2009Dai et al. 2009
MICROLENSING!
Direct measurement of size of emission region: X-rays from 10 Rg (Optical 70 Rg)
THE PROGRESS
Risaliti et al. 2005NGC1365
Mrk 509 (long-look, 200ks)
MC et al., 2009Dadina et al. ‘05
Obs1
Obs2
Obs3
Variability allows to place limits on location, mass, etc.
(See also Krongold et al. 2007 on NGC4051)
Cappi
PROGRESS: INFLOWS/OUTFLOWS
PROGRESS: HOTSPOTS
Turner et al. 2005Iwasawa et al. 2004
Cappi, Iwasawa, Reeves, De Marco
PROGRESS: THE INNER FLOW
IwasawaNikolajuk
PROGRESS: BROAD LINES
45% of XMM-Newton Seyfert sample with >30,000 counts
Nandra et al. (2007)De La Calle, Guainazzi
PROGRESS: BROAD LINES
Zoghbi
If η implies a*
Fanidakis et al.arXiv:0911.1128
PROGRESS: SPIN MEASUREMENT
Laor: disk continuum fitting
PROGREES: SPIN MEASUREMENT
Miniutti: broad emission lines
SWIFT J1247Fairall-9
Implications for black hole accretion/merger history through cosmic time (also Ballantyne)
PROGRESS: STRONG GRAVITY
IwasawaWalton
Svoboda
THE PROBLEMS
• Broad lines• Predicted to be universal, but not always observed• Degenerate with complex absorption• Lines are much weaker than we might have hoped• Sometimes variable, sometimes now
• Narrow lines• NOT predicted unless extreme anisotropic effects. • Limited statistical significance (Vaughan & Uttley)• “Spallation” of Fe • Non-repeatable observations -> cannot test models• Should be transient (Kepler timescale) – is this too convenient?
• QPOs• Finally one decent AGN example (RE 1034; Middleton)• Ooops it went away (Middleton)• Which QPO to associate with GBHC?• Interpretation in GBHC not clear despite vastly better data
Overall, two major problems:1)Repeatability of observations 2)Prediction and testing of models
PROBLEMS: BROAD LINES
Zoghbi
Absorption highly unlikely to be sole explanation, but details (e.g. spin) very hard to disentangle
K. Nandra: broad lines in AGN
PROBLEMS: BROAD LINES
Disk line upper limits typically 50-100 eV
Criteria: <99% significance for blurred reflection12 total: IC4329A (1) NGC 5506(1), NGC 5548(1) NGC 7469(1)
30% of Sample
Why are broad lines absent? (Almost) unavoidable prediction of accreting
systems…Ionization, Fe abundance, Extreme blurring?
Ignacio de la Calle16 February 2010
6.7
PROBLEMS: S/N RATIO
De la Calle
PROBLEMS: NARROW FEATURES Lines statistical significance? (transient
features, number of trials in time and energy, etc…)
Identifications of edges/lines energies? (Kallman et al. 2005, Kaspi et al. for
PG1211)
Local “contamination”? (PDS456 at risk? McKernan et al. ’04, ‘05)
Publication bias? Only positive detection, low signif., Vaughan & Uttley ‘08)
cz (km/s)
Out
flow
v (
km/s
)
Solutions: Large Samples, Systematic analysis:Cappi, de Marco, de la Calle, Ponti
Strong narrow K line at 6.4 keV. Constant flux over 3 years.
However redshifted but relatively narrow line emission is observed at 5.4 keV and 5.9 keV in 2005 low state.
Obs 1 vs Obs2
PROBLEMS: NARROW LINES
Reeves
PROBLEMS: NARROW LINES
Suzaku All XMM co-add
Mostly S. Vaughan
5.4 keV
If 5.4 keV is real, it is variable (thus not spallation)
Reeves
PROBLEMS: LINE VARIABILITYBhayani & Nandra (2010)
Variability key to break degeneracies: Iwasawa, Zoghbi, Reeves, de Marco, Ponti, Goosmann
BUT… source behaviour not predictable with current models
PROSPECTS: REVERBERATION
Zoghbi Reeves
PROSPECTS: POLARIZATION
Dovciak
X-ray polarimetry: a new window to be opened by GEMS, NHXM, IXO
PROSPECTS: BH SPINASTRO-H: First high resolution, high throughput spectroscopy at 6 keV
IXO XMSNGC 3783 300ks
MCG-6-30-15 100ks
IXO
IXO: ULTRA-HIGH THROUGHPUT
IXO
ASTRO-H
PROSPECTS: TRACING HOTSPOTS
IXO: high throughput
Flux constraint ~20%
400s exposure:1/10 tKeplerian at 6 rg
C. Reynolds
PROSPECTS: TESTING GR?
GR correct
=0.5
0.2=0.0 (GR)
Johanssen & Psaltis (2009)
Testing the no-hair theorem=0
C. Reynolds
PROGNOSIS
• Strong gravity effects in AGN can be probed• For example, lensing shows X-rays arise within ~10 Rg
• Major issues:• Model degeneracies• Unrepeatable observations• Lack of testable model framework
• Major progress• Large samples, systematic analysis• Variability studies, reverberation
• Huge future potential • High resolution spectroscopy• High throughput spectroscopy• Polarimetry
See you in Progue 2020!
Promising Prospects for Proactive Promotion of Proposed Projects
IXO