Download Supermassive black hole activity in local field early

The AMUSE surveys: Down-sizing
in black hole accretion
Elena Gallo | University of Michigan
B. Miller & K. Gultekin (U. of Michigan), T. Treu & R. Antonucci
(UCSB), J.-H. Woo (Seoul U.)
12 Years of Science with Chandra, 218th AAS
Black holes and bulge relations
 Empirical correlation
between super-massive
black hole mass and bulge
properties (central stellar
velocity dispersion,
luminosity, Sersic index,
etc) suggest deep
evolutionary link
 However, poorly
constrained at the low
mass end
Gultekin+09
Evolution of quasar LF
 Quasar density peaked
near redshift z~2
 Lower-luminosity quasars
peak at lower redshifts
(“downsizing”)
 Quasars accrete/radiate
at 0.01-1 Eddington, but
only for relatively short
lifetimes (~108 yr)
Ciotti & Ostriker 07
Low-level SMBH activity
 Post-quasar phase: highly
sub-Eddington, radiatively
inefficient accretion (Sgr
A*: Lx/LEdd~1e-9)
 Simulations indicate “radio
mode” feedback at low
redshift is required to
quench cooling and inhibit
star formation (e.g., to
match observed galaxy
colors)
Croton+06
X-rays: AGN vs. ‘inactive’ galaxies
X-rays from inactive galaxies:
ROSAT effectively sensitive
down to 1e40 erg/sec for
nearby galaxies
Chandra bridges the gap
between active (>1E-2 L_Edd)
and (formally) inactive galaxies
Sub-arcsec angular resolution
is key
Pellegrini 05
The AMUSE surveys: science goals
 Two Large Chandra Programs (~1Msec) to bridge the gap
between AGN and formally inactive galaxies. Specifically, to:
 Investigate highly sub-Eddington (Lx/Ledd<1e-5) activity in
local super-massive BHs
 Quantify active fraction as a function of BH/host mass,
corrected for ‘Eddington incompleteness’
 Constrain the local BH occupation fraction
 Control for environmental effects on the nuclear activity
(cluster members vs. isolated galaxies)
AMUSE-Virgo: the survey
Targets 100 Virgo early type galaxies
which compose the HST ACS Virgo
Cluster Survey (VCS, Cote’ et al 2004):


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84 new targets with Chandra ACIS-S
(454 ksec Cycle 8, PI: Treu) + 16
archival (>1 Msec)
Complete down to Ledd for a 3 Msun
object
57 new targets with Spitzer MIPS (9.5
hr) + 43 archival
Archival HST ACS g- & z-band (100
orbits)
Nuclear black hole mass distribution
Black holes, star clusters & LMXBs
1. Diffuse gas emission
modeled and removed:
search for nuclear BH
limited to hard X-rays
(>2keV)
2. Astrometry matched to SDSS, positional accuracy: 0.2-0.5 arcsec
3. Contamination from Low-Mass X-ray Binaries (LMXBs)
addressed quantitatively based on X-ray luminosity function of
LMXBs:
• Gilfanov04) in the absence of nuclear star
• Sivakoff+ 2007 in the presence of a nuclear cluster
AMUSE-Virgo:Nuclear X-ray census
32/100 show a nuclear X-ray source
51/100 show a massive nuclear star cluster (HST)
6/100 show both a nuclear X-ray source and a star cluster
After accounting for LMXB contamination: 24-34% of the
galaxies host an active super- massive black hole (95% C.L.)
Next: ACTIVE FRACTION as a function of host stellar mass and
MBH
AMUSE-Virgo: Active fraction
Active fraction raises with
host stellar mass
(see Ho+97 Kaufmann+03,
Decarli+07, Seth+08,10)
Mostly due to ‘Eddington
incompleteness’: Dealing
with `Eddington-limited’
sub-samples results in
no evidence that the
fraction of active black
holes depends on host mass
(Gallo+10)
AMUSE-Virgo: Down-sizing
 Assume: Log( LX,38 )=A + B log( M BH,8)
 Bayesian code handles limits,
errors; Uncertainties: 0.44 dex on
MBH to be 0.44 dex, 30% on Lx ;
include intrinsic scatter
log LX
 Priors: MBH mass function powerlaw index -1, rotational invariance
for slope
‹LX / MBH ›MBH-0.62
 Most likely parameter value taken
to be median of 10000 random
draws from posterior distribution
 DOWN-SIZING: Lx/Ledd increases
with decreasing BH mass
log (MBH)
AMUSE-Virgo: Summary
32/100 nuclear X-ray sources ; 51/100 nuclear clusters ; 6/100 hybrids
Bona fide active black holes (after LMXB contamination assessment):
between 24-34% host an accreting black hole. Strong lower limit to
occupation fraction in the local universe.
AVERAGE Lx/Ledd DECREASES WITH INCREASING BLACK HOLE
MASS (Gallo+08,10)
PLUS :
Spizter MIPS results: absorption, dust reprocessing etc. (Leipski+ Paper
III, submitted)
Off-nuclear X-ray source population (Katolik+ Paper IV, in prep.)
Influence of environment
 Relative to their cluster
counterparts, local field earlytype galaxies tend to:
 Have a lower incidence of
past major mergers
 Face reduced ram pressure
stripping, but outflows less
confined
 Generally have more cold gas
(e.g., higher HI content)
along with younger stellar
populations
AMUSE-Field
 Chandra snapshots of 75 field spheroids (PI Gallo, Cycle 11, 479
ks), plus 25 archival within 30 Mpc
 Sensitive down to the Eddington limit for a 6 Msun BH
 Sample drawn from HyperLeda catalog, with following
criteria:
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
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Spheroidal, MB<-13
v<1800 km/s and d<30 Mpc
o
o
b>294 or b<230 (no Virgo or Fornax)
o
o
l>30 or l<-30 (avoids absorption from Galactic plane)
AMUSE-Field: Active Fraction
 34/75 X-ray nuclei
 Detection fraction
increases with Mstar
 Assuming LMXB
contamination as for
Virgo (red), ~40% X-ray
active fraction (filled
histogram, upper)
 Comparable to Virgo;
(dashed lines, lower)
B.Miller+ in prep.
AMUSE-Field: Stacking
 Stacked 0.3-7 keV images of
snapshot observations
lacking nuclear X-ray
detection (after removing
off-nuclear X-ray sources) 291
ks of net exposure
 31 net counts within 5’’
aperture (2.8 sigma)
 log(Lx) = 37.7, consistent with
LMXB origin
B.Miller+ in prep.
Virgo vs Field: Eddington ratios
 Lx/LEdd versus MBH and Mstar for field (blue, purple) and Virgo (red)
 Lx/LEdd declines with increasing MBH, Mstar
 Field sample includes relatively more low MBH, Mstar objects: all
comparisons based on weighted subsamples consistent with Virgo
Virgo vs Field: Down-sizing
 Assume: Log( LX,38 )=A + B log( M BH,8)
 Bayesian code handles limits, errors;
Uncertainties: 0.44 dex on MBH to be
0.44 dex, 30% on Lx ; include intrinsic
scatter
 Priors: MBH mass function power-law
index -1, rotational invariance
 Most likely parameter value taken to
be median of 10000 random draws
from posterior distribution
 DOWN-SIZING IN BOTH SAMPLES:
Lx/Ledd increases with decreasing
BH/host mass
B.Miller+ in prep.
Virgo vs Field: Down-sizing
 Slopes consistent between the field
and Virgo samples; also holds for
detections only, as well as for the
weighted subsamples
 Intercept slightly higher for the field
sample
B.Miller+ in prep.
The AMUSE-surveys
 Two Large Chandra Programs (Cycle 8 & 11) to investigate the
rate of highly sub-Eddington accretion onto nuclear supermassive BHs in nearby early type galaxies: 200 objects (100 in
Virgo, 100 field, D<30 Mpc)
 Overall active fraction: 30% (Virgo), 40% (Field); does NOT
increase with host mass
 Evidence for DOWN-SIZING: ‘smaller’ BHs shine closer to their
Eddington limit
 The large-scale environment does not appear to influence
strongly activity in local spheroids; Field galaxies show
modestly enhanced nuclear X-ray emission, perhaps due to
greater access to fuel supply