Post on 30-Jan-2016
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Galactic Environment of Nearby Quiescent Supermassive Black
Holes
Q. Daniel Wang
University of Massachusetts
SMBH and galaxy formation are closely related
• Every 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
SMBH and bulge mass correlation
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)
IRAC 8 micro0.5-2 keV2-8 keV
Li & Wang 2007
GALEX far-UV excess vs. Hα
M31*: SMBH and its vicinity
• A 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).
P3 (M31*)
P2
P1
Chandra/ACIS 0.5-8 keV vs. HST/ACS (F330W)
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 keV• n ~ 0.1 cm-3
• Rb ~ 0.9”, Lb ~ 3x1040 erg/s
M31*P1
SSS
Chandra/ACIS source detection
With 1’ radius:
• Lx > 1036 erg/s: an enhanced number density dynamic formation
• 1036 > Lx > 1035: a deficit destruction of loosely bound LMXB?
Unresolved emission along the major-axis
Lx < 1035: : below the detection limit:
• CVs and active stars• hard (2-8 keV) emission
follows the near-IR light: a stellar origin
• soft (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 emission
•stellar contribution subtracted•characteristics 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
0.5-1(1-2) keV; along minor-axis
Diffuse emission along the minor axis
• X-ray shadows of spiral arms: extraplanar hot gas with a height > 2.5 kpc
Galactic bulge simulation• Parallel, adaptive mesh
refinement FLASH code• Finest refinement in one
octant down to 6 pc• Stellar mass injection
and SNe, following stellar light
• SN rate ~ 4x10-4 /yr• Mass injection rate ~0.1
Msun/yr)
10x10x10 kpc3 box
density distribution
Galactic Bulge Wind: Simulation
3x3x3 kpc3 box, density distribution
• Radiative cooling is not important in the bulge region, consistent with the observation
• Energy 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!
0.5-2 keV diffuse X-ray vs. Spitzer MIPS 24 μm
The Milky Way
~ 1055 erg, or > 104
SNe is needed over the past 2 x 107 years!
ROSAT Survey (1.5-keV Band)
Chandra survey of the Galactic center
Wang et al. (2002)
Massive star forming region: Composite Chandra map
Arches
Quintuplet GC
Chandra Intensity:
•1-4 keV
•4-6 keV
•4-9 keV
Wang, Hui, & Lang (2006)
X-ray Flare from Sgr A*
Baganoff et al. (2003)
•Peak L(2-10 keV) 1035 erg s-1
•Lasted for about 3 hrs•Variability ~ a few minutesBut the observed Lx is ~10-4 of the expected!
Diffuse X-ray Spectrum
Decomposed into three components:
• CVs with T ~ 108 K• Hot gas with T ~
107K• Nonthermal: inverse
Compton scattering, bremstrahlung, and reflection
Hui & Wang 2008
Imaging decomposition
CV Hot gas
nonthermal
absorption
Hot gas vs. radio continuum
Comparison with other extended X-ray-emitting features
Sgr A*
IRS 13
PWN
Diffuse
The 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).
Ongoing: 1) Deep Chandra Survey, 2) HST/NICMOS mapping of NIR continuum and Paschen- line emission (32’x13’, 144 orbits)
Great Observatory mapping of the GC
VLA 20cm Spitzer 8 m 1-9 keV
VLA 20cmSpitzer 8mSpitzer 3.6m
Conclusions• Cool 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 gas
• The heating may be due to steepening ofSN waves.
• The mass-loaded gas can produce subsonic outflows, consistent with X-ray observations:– moderate luminosity– low temperature– broad spatial distribution.
• Stellar energy feedback in galactic bulges may lead to the starvation of SMBHs!
T ≤107 K
Filling factor?
Composition?
Physical properties?
Heating and cooling?
Mass loading?
CMZ
Magnetic loopsCorona
Galactic disk