Download AMUSE-Virgo on the survival of super

AMUSE-Virgo
AGN
MUlti-wavelength
Survey
in Early type
galaxies
Super-massive black holes in low-mass
early type galaxies
Elena Gallo | MIT
Galaxies & super-massive black holes
Kormendy & Richstone 95, McLure & Dunlop 02, Tremaine et
al 02, Marconi & Hunt 03, Ferrarese & Merritt 00; Gebhardt et
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)
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
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: 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: parameter space
100 early type Virgo galaxies, complete down to B = -18
Host stellar
Chandra sensitivity - BH
AMUSE: first Chandra results
Point-like nuclear X-ray source detected in 16/32 objects
Gallo et al 2008
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) = 0.06-0.12 =>
likely a SMBH
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
Gallo et al 2008
AMUSE-Virgo: latest results
Point-likenuclear
nuclearX-ray
X-raysource
sourcedetected
detectedinin32p/100
32/100 objects
Point-like
objects
AMUSE-Virgo: latest results
26/100 nuclear
super-massive
Point-like
nuclearX-ray
X-raysources
source likley
detected
in 32p/100 black
objectsholes
Gallo et al. in prep.
(Chandra+HST)
Summary

Nuclear X-ray source in 32/100 galaxies: –8.4 < log(L_X/L_Edd) < –
5.8

26/32 do not have a massive nuclear star cluster, hence have limited
contamination from low mass x-ray binaries

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

Low frequencies (radio, mid-IR) will be crucial for discriminating
SMBHs from LMXBs (in prep.)