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AMUSE-Virgo on the survival of super

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AMUSE-Virgo
AGN
Multi-wavelength
Survey
in Early types
HUNTING FOR QUIESCENT SUPER-MASSIVE BLACK
HOLES
Elena Gallo | Chandra Fellow | UCSB
Galaxies & super-massive black holes
Galaxies & super-massive black holes
Kormendy & Richstone 95, McLure & Dunlop 02, Tremaine et al
02, Marconi & Hunt 03, Ferrarese & Merritt 00; Gebhardt et al 00;
Galaxy evolution and black hole feedback
The quest for super-massive black holes:

prolonged periods of low-level SMBH activity needed in order to
reproduce the galaxies’ colors (`radio mode’, Croton et al. 06*).
*Millenium Run + semi-analytical recipes
Galaxy evolution and black hole feedback
Ciotti & Ostriker 2007
X-rays: AGN vs. `inactive’ galaxies
 ROSAT effectively
sensitive down to
1e40 erg/sec for
nearby galaxies
 Chandra allows to
bridge the gap
between active (1e-3
L_Edd) and (formally)
inactive galaxies
(<1e-6 L_Edd)
Pellegrini 2005; Soria et al
Scaling relations in faint/low-mass spheroids
Do super-massive black holes exist in faint / low-mass early types?
ACS Virgo Cluster Sample
(ACSVCS Cote’ et al 04)
Increasingly prominent
`compact stellar nuclei’
moving down the mass
function (<1e10 M_sun)
Ferrarese et al. 2006
Scaling relations in faint/low-mass spheroids
Do super-massive black holes exist in faint / low-mass early types?
SMBHs replaced by
`compact stellar nuclei’
moving down the mass
function. SMBHs:
- Dominate B mag < 20
- Disappear B mag > 18
- Coexist in between
Ferrarese et al. 2006
Scaling relations: SMBH occupation fraction
The active fraction is a lower limit
to the BH `occupation fraction’
Models where BHs formed in
metal-free proto-galaxies by direct
collapse of disks result in a
population of nearby low-mass
spheroids with no BHs
Volonteri et al 2007a,b
AMUSE: the survey

Targets 100 early type galaxies which compose the HST ACS Virgo Cluster Survey
(ACSVCS, Cote’ et al 04)
Chandra
ACIS-S
Hubble ACS
VLA
Spitzer MIPS

AMUSE, the team: E. Gallo, T. Treu, J.-H. Woo, J. Jacob, R. Antonucci, P. Marshall, L.
Bildsten, C. Liepski (UCSB)
http://tartufo.physics.ucsb.edu/~amuse/
AMUSE: the survey

Targets 100 early type galaxies which compose the HST ACS Virgo
Cluster Survey (ACSVCS, Cote’ et al 04)
- 84 new targets with Chandra ACIS-S (454 ksec) + 16 archival
- 57 new targets with Spitzer MIPS (9.5 hr) + 43 archival
- HST ACS archival data (100 orbits)
- VLA, in progress (with D. Axon)

AMUSE, the team: E. Gallo, T. Treu, J.-H. Woo, J. Jacob, R. Antonucci,
P. Marshall, L. Bildsten, C. Liepski (UCSB)
http://tartufo.physics.ucsb.edu/~amuse/
AMUSE: science goals

Census of super-massive black hole (SMBH) activity in the local
universe (Chandra+Spitzer+Hubble+VLA)

SMBH/active fraction/occupation fraction/mechanical heating
(Chandra+Spitzer+Hubble+VLA)

X-ray luminosity function of globular clusters + Ultra-luminous X-ray
sources in early type galaxies (Chandra+Hubble)

Testing SMBH mass scaling relations at the low mass end
(Hubble+Keck)
AMUSE: parameter space
100 early type Virgo galaxies, complete down to B = -18
Host stellar
Chandra sensitivity - BH
AMUSE: parameter space
`Fiducial’ BH mass
distribution:
54*/100 from velocity
dispersion
46/100 from B band
lum.
*out of 74 available in
the literature
AMUSE: first Chandra results

32 OBJECTS: 16 ARCHIVAL + 16 NEW (5.4 ksec each: sensitive to 4e38
erg/sec, or L_Edd for a 3 M_Sun object)

Search for accretion-powered activity from SMBH:
- improve astrometry (match to SDSS-DR5)
- separate hot gas from low mass X-ray binaries (LMXBs)
- search for point like nuclear X-ray source
AMUSE: first Chandra results
1. Search for point-like sources (wavdetect) & fit their
cumulative spectrum.
2. Fit diffuse emission with a 2 component model: thermal
(APEC) plus absorbed power law (unresolved LMXBs),
estimate kT_gas
3. Search for nuclear X-ray source above kT_gas
AMUSE: first Chandra results

Point-like nuclear X-ray source detected in 16/32 objects:
- 4/16 belong to the new 5.4 ksec obs. Of the remaining 12 (archival data):
- 9/12 already reported in the literature

Contamination:
- CXB: negligible (<1e-6 sources, Chandra DF South, Rosati et al 02 )
- Low-mass X-ray binaries (LMXBs):
FIELD LMXBs (Gilfanov 04)
STAR CLUSTERs (Sivakoff et al 07)
Nuclear SMBHs
Point-like nuclear X-ray source detected in 16/32 objects
Chandra ACIS-S
SMBHs in low-mass spheroids

2 of the detected nuclei in
galaxies with B mag > -18,
where nuclear star clusters
become increasingly common
(Ferrarese et al 2006)
vcc1178: M*=9e9 M_Sun
vcc1297: M*=11e9 M_Sun

Increased LMXB chance
contamination
SMBHs vs compact stellar nuclei

2 of the detected nuclei in
galaxies with B mag > -18:
vcc1178 also hosts a compact
stellar nucleus
M_nucleus = 3.6-4.7e7 M_Sun
r_h = 25-30 pc

LMXB contamination:
n_x (>6e38) = 0.06
HST ACS - g band
(X-ray) Active fraction

STATISTICALLY SIGNIFICANT
INCREASE IN THE ACTIVE HST ACS - g band
FRACTION TOWARDS HIGH
HOSTS’ STELLAR MASSES

3-44 % active in hosts with
M*<1e10 M_sun

49-87 % active in hosts with
M*>1e10 M_Sun
(95% confidence level)
Eddington ratio distribution

For the 16 detected nuclei
– 8.4< log(L_X/L_Edd)< – 5.8

Bolometric correction ?
f_bol =8-60 (Marconi et al. 04)
Non detections: stacking

12 snapshot observations, 62.3
ksec net exposure

L_X<3.8e37 erg/sec
(average distance 16.5
Mpc)

L_X/L_Edd < 3e-8
(average M_BH=9.3e6
M_Sun)
SMBH mechanical feedback
For 15 nearby galaxies with
measured: L_X , L_Radio,
M_BH,
L_kin:
log (L_kin / L_Edd) = 0.49 (_X) – 0.78
AMUSE (16 X-ray active nuclei):
– 5 < log(L_kin / L_Edd) < – 3
In agreement with `radio-mode’
expectations (Croton et al 06)
Merloni & Heinz
AMUSE-Virgo: first Chandra results

Nuclear SMBHs in 16/32 galaxies: –8.4 < log(L_X/L_Edd) < –5.8

L_kin in agreement with models for cosmic structure formation with
SMBH feedback (`radio mode’)

Two of the detected nuclei hosted in galaxies with B mag > –18.
SMBHs and compact stellar nuclei are NOT mutually exclusive.

The fraction of X-ray active nuclei rises as a function of the host stellar
mass: 3-44% below M*=1e10 M_Sun, 49-87% above.
Gallo et al., ApJ, 2008
AMUSE-Virgo: next

Chandra & Spitzer survey completed; VLA in progress; Keck
approved; VLBA-follow-up on radio cores planned

Low frequencies (radio, mid-IR) crucial for discriminating SMBHs from
LMXBs for galaxies with prominent nuclear star clusters

Search for ULXs in dwarf galaxies, possibly associated with globular
clusters (Jacob et al, in prep.)
Black hole mass distribution
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