high accretion rates, tidal disruption flares and recoils: recent results on supermassive black...

High accretion rates, tidal High accretion rates, tidal disruption flares and recoils: disruption flares and recoils: recent results on supermassive recent results on supermassive black holesblack holes

IntroductionIntroduction

Highly Highly accreting AGN accreting AGN on the M-sigma on the M-sigma relationrelation

Flares from Flares from tidally tidally disrupted starsdisrupted stars

Recoiling black Recoiling black holesholes

Peking University, 10. April 2008

Stefanie Stefanie KomossaKomossa

MPEMPE

BHs in astrophysical context:• how frequent are SMBHs, do they reside in all galaxies ?

• what is the distribution of their masses & spins ?

• when & how did most SMBHs form ? before, simultaneous with, after galaxies ? why are SMBH and

galaxy bulge properties so closely linked ? • how do SMBHs grow ? accretion, BH-BH merging, stellar disruptions; timescales ?• why are some SMBHs `dark´ ? how long do the phases of

accretion activity last, what is the relation between different types of „Active Galaxies“ (quasars – Seyfert galaxies), etc., ...

Supermassive Black Holes (SMBHs) Supermassive Black Holes (SMBHs) – key questions – key questions

the SMBH at our Galactic Centerthe SMBH at our Galactic Center

• stars in Keplerian orbits around central black hole high-precision measurement of BH mass: M = 42a3/GP2 = 3.6 Msun

• periastron of closest encounter: ~2000 RS (star S2, period: 15 yrs)

• constraints on mass/volume very tight

• only possible in our own G.C. ; in ~30 nearby galaxies we can

still resolve the „sphere of influence“ of the SMBH

[e.g., Schödel & 02, 03, Genzel & 03, Ghez & 03, 05, Eisenhauer & 05; Boganoff & 03, Aschenbach & 04, Eckart & 06, Krabbe & 06, Belanger & 06; Genzel &Karas 07]

the the MMBH BH - - relation relation

implies close link between BH and galaxy formation & evolution models: regulation of bulge- growth due to feedback from active BH and/or star formation

• correlation between black hole mass, MBH, and bulge stellar velocity dispersion,,

MBH/sun = 1.7 /0 (FF05)

[M-: Ferrarese & Merritt 00, Gebhardt & 00, MF01, Tremaine & 02, Ferrarese & Ford 05][models: e.g., Silk & Rees 98, Burkert & Silk 01, Haehnelt 03, Springel et al. 05, Li et al. 07, ...]

the the MMBH BH - - relation relation

• do all types of galaxies, at all times, follow the M- relation ?

• how do objects ‚move onto‘ the relation ?

check nearby AGN, accreting at high rates; i.e., rapidly growing their BHs

[M-: Ferrarese & Merritt 00, Gebhardt & 00, MF01, Tremaine & 02, Ferrarese & Ford 05][models: e.g., Silk & Rees 98, Burkert & Silk 01, Haehnelt 03, Springel et al. 05, Li et al. 07, ...]

seen at hi z ??

Active Galactic Nuclei (AGN)Active Galactic Nuclei (AGN)

• most luminous long-lived objects in the universe • powered by accretion onto supermassive black holes (SMBH)• strict „unified model“: key difference between AGN types (Sy1, Sy2, ....) due to viewing angle effects• emission lines provide a wealth of information on the physical conditions in the cores of AGN

MMBHBH and and measurements in AGN measurements in AGN

• in AGN, we have an independent way to measure BH masses from „reverberation mapping“ of the BLR, RBLR-L relation

[e.g., Kaspi et al. 2005, Peterson 2007]

• do we also have a way to measure ? Not really, AGN conti bright; stellar absorption features often superposed by bright conti & emission-complexes

[Nelson & Whittle 96, Nelson 2000]

use gaseous kinematics, traced by emission-lines, instead. Indeed, FWHM([OIII]) and * correlate - after removing

galaxies with strong kpc-scale radio sources.

AGNAGN on on the the MMBHBH – –relationrelation

• what about ‚extreme‘ AGN: Narrow-line Seyfert 1 galaxies - defined as AGN with narrow BLR Balmer lines (FWHMHb < 2000 km/s), weak [OIII]/H emission - at one extreme end of AGN correlation space (strongest FeII, steepest X-ray spectra, most rapid X-ray var., ...) NLS1s are AGN with low BH masses & high Eddington rates L/Ledd

objects rapidly growing their BHs, in the local universe do they follow the M- relation ?

method widely applied, up to high z [e.g., Shields & 03, Boroson 03, Greene & Ho 05, Salviander & 07, Netzer & 07, ... ]

• nearby ‚normal‘ AGN:

agree with MBH–relation if

is used as substitue for

• original claim: NLS1s are OFF MBH – relation

• few real measurements

(Botte 05: „on“; Zhou 06: „off“)

[Mathur et al. 01, Wang & Lu 01, Wandel 02, Grupe & Mathur 04, Bian & Zhao 04,06, Botte & 04, 05, Barth & 05, Mathur & Grupe 05a,b, Greene & Ho 05, Zhou & 06, Ryan & 07, Watson & 07, Komossa & Xu 07]

NLS1s on the NLS1s on the MMBHBH – – [OIII][OIII] planes planes

how reliable is [OIII] as substitute for stellar velocity dispersion ?

influence of outflows ?

[Komossa & Xu 07]

NLS1s on the NLS1s on the MMBHBH – –relationrelation

• new analysis, based on sample of SDSS-NLS1s, plus BLS1 comparison sample; using several NLR emission lines (& decomposing complex [OIII] profile)

NLS1s onon MBH - SII]

NLS1s followfollow the MBH - [SII] relation

and they follow the MBH - [OIII] relation, if objects with outflows in [OIII] are removed

remaining scatter in the relation does not systematically depend on [OIII] strength, FeII, density, Mi, L/Ledd ?

• summary: NLS1 galaxies do follow M-, if objects dominated by outflows)* are removed

they evolve along the M- relation

• BH mass increases by fact. 10 within yr (L~Ledd), if BH keeps growing

• NLS1 hosts: no mergers, but perhaps excess of bars either acc. short-lived, or else secular processes at work to

adjust host properties, keeping them on the relation

NLS1s on the NLS1s on the MMBHBH – –relationrelation

)* also occur in BLS1s ( relevant for all studies which involve[OIII] lines as surrogate for *), but less often

extreme outflows in AGN: extreme outflows in AGN: on the nature of [OIII] „blue on the nature of [OIII] „blue

outliers“outliers“

• what causes the „blue outliers“, which have their whole [OIII] profile blueshifted, by up to several 100 km/s ?

[Komossa, Xu, Zhou, Storchi-Bergmann, Binette 08]

on the nature of [OIII] „blue on the nature of [OIII] „blue outliers“outliers“

• they show evidence for extreme outflows up to 1000 km/s affecting the (hi-ion BLR), CLR, and large parts of the NLR - while the outer NLR is quiescent• driving mechanism is still being investigated - radiation pressure, cloud-entrainment in jets, thermal winds • high L/Ledd, & pole-on view into an outflow ?

• is feedback due to outflows at work ? follow-up HST imaging: search for mergers a la Springel et al. / or bars

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Tidal disruption of stars by Tidal disruption of stars by SMBHsSMBHs

stellar distortion & disruption extreme squeezing of star ign. of nucl. burning

collision of unbound gas with ISM, shocks (?)

accretion phase(s): luminous flare of radiation

[artist‘s view; NASA/ CXC/ M. Weiss/ Komossa &

04]

giant-amplitude X-ray giant-amplitude X-ray outbursts from non-active outbursts from non-active galaxiesgalaxies

[e.g., Komossa & Bade 99, Halpern & 04, Komossa et al. 04, 08]

• initial flare of X-rays with Lx at least sev. 10 erg/s • from otherwise normal, non-active galaxies• still detected with Chandra ~10 yrs after the initial burst• fast rise, slow decline, consistent with predicted t law • amplitudes of variability: up to factor 6000 • disruption of solar-type star enough to power the flare

collective lightcurve, measured with ROSAT, XMM and Chandra

• NLS1 galaxies do follow the M–relation of BL-AGN and normal galaxies (large scatter, as usual), if [SII], [OIII]core are used to measure

• if BHs keep accreting for long time, host properties must adjust accordingly to keep them on M–

• location of galaxies on the M–plane does not systematically depend on emi-line strength, nNLR, L/Ledd, ... except:

• lines with systematic blueshifts in [OIII] have anomaleously broad profiles outflows dominate not suitable for measurements

(their non-removal was cause for previous claims that NLS1s deviate; all samples making use of [OIII] have to remove ‚blue outliers‘ )

• these [OIII] outliers are of independent interest because of their extreme large –scale outflows ( constraints on mechanisms to drive AGN winds on large scales, mechanisms of cloud entrainment ?)

Summary- part 1Summary- part 1

Summary – part 2Summary – part 2

• we have detected the emission-line light-echo & low-E tail (NUV, opt, NIR) of a high-E outburst (EUV, X) of huge amplitude

• likely caused by stellar tidal disruption

• such events are rare; provide rare chance & very efficient way to `map´ physical conditions in circum-nuclear gas (e.g., inner wall of dusty torus)

• large-scale spectroscopic surveys, like SDSS, well suited to find more `light-echos´, while future X-ray all-sky surveys will detect the actual X-ray flares