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Introduction Highly accreting AGN on the M-sigma relation Flares from tidally disrupted stars

High accretion rates, tidal disruption flares and recoils: recent results on supermassive black holes. Stefanie Komossa MPE. Introduction Highly accreting AGN on the M-sigma relation Flares from tidally disrupted stars Recoiling black holes.

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Introduction Highly accreting AGN on the M-sigma relation Flares from tidally disrupted stars

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  1. High accretion rates, tidal disruption flares and recoils: recent results on supermassive black holes Stefanie Komossa MPE Introduction Highly accreting AGN on the M-sigma relation Flares from tidally disrupted stars Recoiling black holes Peking University, 10. April 2008

  2. 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) – key questions

  3. stars in Keplerian orbits around central black hole  high-precision measurement of BH mass: M = 4p2a3/GP2 = 3.6 106 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 the SMBH at our Galactic Center [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]

  4. the MBH - s relation • correlation between black hole mass, MBH, and bulge stellar velocity dispersion,s*, • MBH/(108 Msun)= 1.7 (s*/s0)4.9(FF05) • implies close link between BH and galaxy formation & evolution • models: regulation of bulge- • growth due to feedback • from active BH and/or star • formation [M-s: 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, ...]

  5. the MBH - s relation • do all types of galaxies, at • all times, follow the M-s* • relation ? • how do objects ‚move • onto‘ the relation ? • check nearby AGN, accreting at high rates; i.e., rapidly growing their BHs seen at hi z ?? [M-s: 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, ...]

  6. 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

  7. MBH and s 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 measures* ? Not really, AGN conti bright; stellar absorption features often superposed by bright conti & emission-complexes • use gaseous kinematics, traced by emission-lines, instead. Indeed, FWHM([OIII]) and s* correlate - after removing galaxies with strong kpc-scale radio sources. [Nelson & Whittle 96, Nelson 2000]

  8. AGN on the MBH –s relation • whatabout ‚extreme‘ AGN: • Narrow-line Seyfert 1 galaxies • - defined as AGN with narrow • BLR Balmer lines (FWHMHb < 2000 • km/s), weak [OIII]/Hb 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 dothey follow the M-s relation ? • nearby‚normal‘ AGN: • agree with MBH–s*relation if s[OIII] • is used as substitue for s* method widely applied, up to high z [e.g., Shields & 03, Boroson 03, Greene & Ho 05, Salviander & 07, Netzer & 07, ... ]

  9. NLS1s on the MBH – s[OIII] planes • original claim: NLS1s are OFFMBH – s[OIII] relation • few real s* measurements (Botte 05: „on“; Zhou 06: „off“) • how reliable is [OIII] as substitute for stellar velocity dispersion ? • influence of outflows ? [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]

  10. NLS1s on the MBH –s*relation • new analysis, based on sample of SDSS-NLS1s, plus BLS1 comparison sample; using several NLR emission lines (& decomposing complex [OIII] profile) [Komossa & Xu 07] • NLS1s follow the MBH - s[SII] relation • and they follow the MBH - s[OIII] relation, if objects with outflows in [OIII] are removed NLS1s on MBH - s[SII] • remaining scatter in the relation does not systematically depend on [OIII] strength, FeII, density, Mi, L/Ledd ?

  11. NLS1s on the MBH –s*relation • summary: NLS1 galaxies do follow M-s, if objects dominated by outflows)* are removed •  they evolve along the M-s relation • BH mass increases by fact. 10 within 108 yr (L~Ledd), if BH keeps growing • NLS1 hosts: no mergers, but perhaps excess of bars  either acc. short-lived, or else secularprocesses at work to adjust host properties, keeping them on the relation )* also occur in BLS1s ( relevant for all studies which involve [OIII] lines as surrogate for s*), but less often

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

  13. on the nature of [OIII] „blue outliers“ [Komossa, Xu, Zhou, Storchi-Bergmann, Binette 08] • 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 ? • isfeedback due to outflows at work ?follow-up HST imaging:search for • mergers a la Springel et al. / or bars

  14. Tidal disruption of stars by SMBHs accretion phase(s): luminous flare of radiation stellar distortion & disruption extreme squeezing of star  ign. of nucl. burning collision of unbound gas with ISM, shocks (?) [artist‘s view; NASA/ CXC/ M. Weiss/ Komossa & 04]

  15. giant-amplitude X-ray outbursts from non-active galaxies • initial flare of X-rays with • Lx at least sev. 1044 erg/s • from otherwise normal, • non-activegalaxies • still detected with • Chandra ~10 yrs after • the initial burst • fast rise, slow decline, • consistent with predicted • t-5/3 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 [e.g., Komossa & Bade 99, Halpern & 04, Komossa et al. 04, 08]

  16. Summary- part 1 • NLS1 galaxies do follow the M–s relation of BL-AGN and normal galaxies (large scatter, as usual), if [SII], [OIII]core are used to measure s • if BHs keep accreting for long time, host properties must adjust accordingly to keep them on M–s • location of galaxies on the M–s 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 s* 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 ?)

  17. Summary – 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

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