galactic environment of nearby quiescent supermassive black holes
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DESCRIPTIONGalactic Environment of Nearby Quiescent Supermassive Black Holes. Q. Daniel Wang University of Massachusetts. SMBH and bulge mass correlation. SMBH and galaxy formation are closely related. Every galaxy probably contains a SMBH. Their masses are correlated. - PowerPoint PPT Presentation
Galactic Environment of Nearby Quiescent Supermassive Black HolesQ. Daniel Wang University of Massachusetts
SMBH and galaxy formation are closely relatedEvery galaxy probably contains a SMBH.Their masses are correlated.Physically, how this correlation is achieved is not clear.The SMBH growth is largely from gas accretion AGNs
But most of SMBHs are not active in nearby galaxies. They are starved. Why?Little gas falls into the galaxy center?Or the infalling gas is being removed, due to episodic AGN feedback or some continuous processes?Answering these questions will help to understand the formation of SMBHs and galaxies in general.
M31 (d=780 kpc)
GALEX far-UV excess vs. H
M31*: SMBH and its vicinityA red star cluster forming an elongated disk (Tremaine 1995)Mbh ~ 2 x 108 Msun (Bender et al. 2005)Apparent young (A-type) stars (t ~ 200 Myr) around the SMBH Alternatively, they may be post-HB stars formed from stripped redgiants and/or stellar mergers (e.g., Demargue & Virani 2007).
Chandra/ACIS limit on the X-ray luminosity of M31*Lx ~ 1(+-0.3)x1036 erg/s, consistent with the previous 3 upper limit from a Chandra/HRC (Garcia et al. 2005)kT ~ 0.3 keVn ~ 0.1 cm-3Rb ~ 0.9, Lb ~ 3x1040 erg/sChandra/ACIS 0.5-8 keV vs. HST/ACS (F330W)M31*P1SSS
Chandra/ACIS source detectionWith 1 radius:Lx > 1036 erg/s: an enhanced number density dynamic formation1036 > Lx > 1035: a deficit destruction of loosely bound LMXB?
Voss & Gilfanov 2007
Unresolved emission along the major-axisLx < 1035: : below the detection limit:CVs and active starshard (2-8 keV) emission follows the near-IR light: a stellar originsoft (0.5-2 keV) emission only follows the near-IR light at large radii; excess in the inner bulge diffuse gas
0.5-1(2-8) keV; along major-axis
Diffuse soft X-ray emissionstellar contribution subtractedcharacteristics of hot gas in the bulge: z0 ~ 600 pc; T~ 0.3 keV; L0.5-2 keV ~ 31038 erg/s IRAC 8 micro, K-band, 0.5-2 keV
Diffuse emission along the minor axisX-ray shadows of spiral arms: extraplanar hot gas with a height > 2.5 kpc0.5-1(1-2) keV; along minor-axis
Galactic bulge simulationParallel, adaptive mesh refinement FLASH codeFinest refinement in one octant down to 6 pcStellar mass injection and SNe, following stellar light SN rate ~ 4x10-4 /yrMass injection rate ~0.1 Msun/yr)
10x10x10 kpc3 boxdensity distribution
Galactic Bulge Wind: SimulationRadiative cooling is not important in the bulge region, consistent with the observationEnergy not dissipated locally Most of the energy is in the bulk motion and in waves The wind solution does depend on the outer boundary condition!
3x3x3 kpc3 box, density distribution
0.5-2 keV diffuse X-ray vs. Spitzer MIPS 24 m
The Milky Way
~ 1055 erg, or > 104 SNe is needed over the past 2 x 107 years!
ROSAT Survey (1.5-keV Band)
2MASS Image of the GC regionRed: K band Green: H band Blue: J band
MSX 25m ImagePrice et al. (2000)
Radio Continuum (90cm)LaRosa et al. 2000
Galactic Center: EnvironmentStrong absorption from NIR to soft X-ray Strong scattering and dispersion of low frequency radio wave Large amounts of molecular gas (~ 107 Msun)But small filling factor (< 10%)Very active in star formationClose to 10% of the SF in the GalaxySN rate ~ 1 per 103 yrs 1041 ergs/sShort orbital period (~ a few x 106 yr)Large tidal and shear forcesVery high B field (up to ~ 1 mG)Toroidal B field in dense cloudsPoloidal B field in intercloud gasVery hard diffuse X-ray emissionMuch harder than spectra of SNRs
Questions to be answeredWhat are in the Galactic center?Has a giant starburst recently occurred in the Galactic center?Massive stars end as supernovae black holes and neutron stars as well as hot gasNo known pulsars within r ~ 1oWhat is the nature of this hard X-ray emission (> 2 keV), and the Galactic ridge emission in general?Is there a substantial outflow from the Galactic center?Was the central black hole substantially more active in the recent past?
Chandra survey of the Galactic center Wang et al. (2002)
Massive star forming region: Composite Chandra mapChandra Intensity:1-4 keV4-6 keV4-9 keVWang, Hui, & Lang (2006)
X-ray Flare from Sgr A*Baganoff et al. (2003)Peak L(2-10 keV) 1035ergs-1Lasted for about 3 hrsVariability ~ a few minutesBut the observed Lx is ~10-4 of the expected!
Diffuse X-ray SpectrumDecomposed into three components:CVs with T ~ 108 KHot gas with T ~ 107KNonthermal: inverse Compton scattering, bremstrahlung, and reflectionHui & Wang 2008
Imaging decompositionCVHot gasnonthermalabsorption
Hot gas vs. radio continuum
Galactic Center: inner pc regionVLT SINFONI near-IR (Eisenharer et al. 05)ACIS-I 1-9 keV (Wang, Lu, Gotthelf 06; see also Baganoff et al. 03)Sgr A*IRS 13PWN?
Comparison with other extended X-ray-emitting featuresSgr A*IRS 13PWNDiffuseThe spectra of Sgr A*, IRS 13, and diffuse X-ray emission all show the Fe K line at ~6.6 keV NEI emission from gas heated recently (net~103 cm-3 yr).
Great Observatory mapping of the GCOngoing: 1) Deep Chandra Survey, 2) HST/NICMOS mapping of NIR continuum and Paschen- line emission (32x13, 144 orbits) VLA 20cm Spitzer 8 m 1-9 keV
ConclusionsCool gas is expected to fall into nuclear regions of disk galaxies.The gas can be heated, however, responsible for excess of far-UV and Halpha emission as well as mass-loading to hot gasThe heating may be due to steepening ofSN waves.The mass-loaded gas can produce subsonic outflows, consistent with X-ray observations:moderate luminositylow temperaturebroad spatial distribution.Stellar energy feedback in galactic bulges may lead to the starvation of SMBHs!
T 107 KFilling factor?Composition?Physical properties?Heating and cooling?Mass loading?CMZ
P1: apocenter, P2 disk density concentration toward the center.All extendedThe GC provides a unique lab for high-energy phenomena and processes in a galactic nuclear environment