The Cluster and Field Galaxy AGN Fraction at z = 1 to 1.5: Evidence for a Reversal of the Local Anticorrelation Between Environment and AGN Fraction. (arXiv:1302.6253v1 [astro-ph.CO])

The Cluster and Field Galaxy AGN Fraction at z = 1 to 1.5: Evidence for a Reversal of the Local Anticorrelation Between Environment and AGN Fraction. (arXiv:1302.6253v1 [astro-ph.CO]):
The fraction of cluster galaxies that host luminous AGN is an important probe
of AGN fueling processes, the cold ISM at the centers of galaxies, and how
tightly black holes and galaxies co-evolve. We present a new measurement of the
AGN fraction in a sample of 13 clusters of galaxies (M >= 10^{14} Msun) at
1<z<1.5 selected from the Spitzer/IRAC Shallow Cluster Survey, as well as the
field fraction in the immediate vicinity of these clusters, and combine these
data with measurements from the literature to quantify the relative evolution
of cluster and field AGN from the present to z~3. We estimate that the cluster
AGN fraction at 1<z<1.5 is f_A = 3.0^{+2.4}_{-1.4}% for AGN with a rest-frame,
hard X-ray luminosity greater than L_{X,H} >= 10^{44} erg/s. This fraction is
measured relative to all cluster galaxies more luminous than M*_{3.6}(z)+1,
where M*_{3.6}(z) is the absolute magnitude of the break in the galaxy
luminosity function at the cluster redshift in the IRAC 3.6um bandpass. The
cluster AGN fraction is 30 times greater than the 3sigma upper limit on the
value for AGN of similar luminosity at z~0.25, as well as more than an order of
magnitude greater than the AGN fraction at z~0.75. AGN with L_{X,H} >= 10^{43}
erg/s exhibit similarly pronounced evolution with redshift. In contrast with
the local universe, where the luminous AGN fraction is higher in the field than
in clusters, the X-ray and MIR-selected AGN fractions in the field and clusters
are consistent at 1<z<1.5. This is evidence that the cluster AGN population has
evolved more rapidly than the field population from z~1.5 to the present. This
environment-dependent AGN evolution mimics the more rapid evolution of
star-forming galaxies in clusters relative to the field.

Can AGN feedback-driven star formation explain the size evolution of massive galaxies?. (arXiv:1302.4998v1 [astro-ph.GA])

Can AGN feedback-driven star formation explain the size evolution of massive galaxies?. (arXiv:1302.4998v1 [astro-ph.GA]):
Observations indicate that massive galaxies at z~2 are more compact than
galaxies of comparable mass at z~0, with effective radii evolving by a factor
of ~3-5. This implies that galaxies grow significantly in size but relatively
little in mass over the past ~10 Gyr. Two main physical models have been
proposed in order to explain the observed evolution of massive galaxies:
"mergers" and "puffing-up" scenarios. Here we introduce another possibility,
and discuss the potential role of the central active galactic nucleus (AGN)
feedback on the evolution of its host galaxy. We consider triggering of star
formation, due to AGN feedback, with radiation pressure on dusty gas as the
driving feedback mechanism. In this picture, stars are formed in the
feedback-driven outflow at increasingly larger radii and build up the outer
regions of the host galaxy. The resulting increase in size and stellar mass can
be compared with the observed growth of massive galaxies. Star formation in the
host galaxy is likely obscured due to dust extinction and reddening. We suggest
a number of observational predictions of our model, and discuss possible
implications for AGN feedback-driven star formation.

Quasar Absorption Lines in the Far Ultraviolet: An Untapped Gold Mine for Galaxy Evolution Studies. (arXiv:1303.0043v1 [astro-ph.CO])

Quasar Absorption Lines in the Far Ultraviolet: An Untapped Gold Mine for Galaxy Evolution Studies. (arXiv:1303.0043v1 [astro-ph.CO]):
This white paper emphasizes the potential of QSO absorption lines in the
rest-frame far/extreme UV at rest-frame wavelengths from ~500 to 2000 A. In
this wavelength range, species such as Ne VIII, Na IX, and Mg X can be
detected, providing diagnostics of gas with temperatures >> 10^{6} K, as well
as banks of adjacent ions such as O I, O II, O III, O IV, O V, and O VI (and
similarly N I - N V; S II - S VI; Ne II - Ne VIII, etc.), which constrain
physical conditions with unprecedented precision. A UV spectrograph with good
sensitivity down to observed wavelengths of 1000 A can detect these new probes
in absorption systems with redshift z(abs) > 0.3, and at these redshifts, the
detailed relationships between the absorbers and nearby galaxies and
large-scale environment can be studied from the ground. By observing QSOs at z
= 1.0 - 1.5, HST has started to exploit extreme-UV QSO absorption lines, but
HST can only reach a small number of these targets. A future, more sensitive UV
spectrograph could open up this new discovery space.

Star Formation and Gas Kinematics of Quasar Host Galaxies at z~6: New insights from ALMA. (arXiv:1302.4154v1 [astro-ph.CO])

Star Formation and Gas Kinematics of Quasar Host Galaxies at z~6: New insights from ALMA. (arXiv:1302.4154v1 [astro-ph.CO]):
We present ALMA observations of the [C II] 158 micron fine structure line and
dust continuum emission from the host galaxies of five redshift 6 quasars. We
also report complementary observations of 250 GHz dust continuum and CO (6-5)
line emission from the z=6.00 quasar SDSS J231038.88+185519.7. The ALMA
observations were carried out in the extended array at 0.7" resolution. We have
detected the line and dust continuum in all five objects. The derived [C II]
line luminosities are 1.6x10^{9} to 8.8x10^{9} Lsun and the [C II]-to-FIR
luminosity ratios are 3.0-5.6x10^{-4}, which is comparable to the values found
in other high-redshift quasar-starburst systems and local ultra-luminous
infrared galaxies. The sources are marginally resolved and the intrinsic source
sizes (major axis FWHM) are constrained to be 0.3" to 0.6" (i.e., 1.7 to 3.5
kpc) for the [C II] line emission and 0.2" to 0.4" (i.e., 1.2 to 2.3 kpc) for
the continuum. These measurements indicate that there is vigorous star
formation over the central few kpc in the quasar host galaxies. The ALMA
observations also constrain the dynamical properties of the atomic gas in the
starburst nuclei. The intensity-weighted velocity maps of three sources show
clear velocity gradients. Such velocity gradients are consistent with a
rotating, gravitationally bound gas component, although they are not uniquely
interpreted as such. Under the simplifying assumption of rotation, the implied
dynamical masses within the [C II]-emitting regions are of order 10^{10} to
10^{11} Msun. Given these estimates, the mass ratios between the SMBHs and the
spheroidal bulge are an order of magnitude higher than the mean value found in
local spheroidal galaxies, which is in agreement with results from previous CO
observations of high redshift quasars.

Galaxy Formation: Where Do We Stand?. (arXiv:1212.5641v1 [astro-ph.CO])

Galaxy Formation: Where Do We Stand?. (arXiv:1212.5641v1 [astro-ph.CO]):
This paper presents a review of the topic of galaxy formation and evolution,
focusing on basic features of galaxies, and how these observables reveal how
galaxies and their stars assemble over cosmic time. I give an overview of the
observed properties of galaxies in the nearby universe and for those at higher
redshifts up to z~10. This includes a discussion of the major processes in
which galaxies assemble and how we can now observe these - including the merger
history of galaxies, the gas accretion and star formation rates. I show that
for the most massive galaxies mergers and accretion are about equally important
in the galaxy formation process between z = 1-3, while this likely differs for
lower mass systems. I also discuss the mass differential evolution for
galaxies, as well as how environment can affect galaxy evolution, although mass
is the primary criteria for driving evolution. I also discuss how we are
beginning to measure the dark matter content of galaxies at different epochs as
measured through kinematics and clustering. Finally, I review how observables
of galaxies, and the observed galaxy formation process, compares with
predictions from simulations of galaxy formation, finding significant
discrepancies in the abundances of massive galaxies and the merger history. I
conclude by examining prospects for the future using JWST, Euclid, SKA, and the
ELTs in addressing outstanding issues.

Concurrent Supermassive Black Hole and Galaxy Growth: Linking Environment and Nuclear Activity in z = 2.23 H-alpha Emitters. (arXiv:1301.3922v1 [astro-ph.CO])

Concurrent Supermassive Black Hole and Galaxy Growth: Linking Environment and Nuclear Activity in z = 2.23 H-alpha Emitters. (arXiv:1301.3922v1 [astro-ph.CO]):
We present results from a ~100 ks Chandra observation of the 2QZ Cluster
1004+00 structure at z = 2.23 (hereafter, 2QZ Clus). 2QZ Clus was originally
identified as an overdensity of four optically-selected QSOs at z = 2.23 within
a 15x15 arcmin^2 region. Narrow-band imaging in the near-IR revealed that the
structure contains an additional overdensity of 22 z = 2.23 Halpha-emitting
galaxies (HAEs), resulting in 23 unique z = 2.23 HAEs/QSOs. Our Chandra
observations reveal that 3 HAEs in addition to the 4 QSOs harbor powerfully
accreting supermassive black holes (SMBHs), with 2-10 keV luminosities of
~(8-60) x 10^43 ergs/s and X-ray spectral slopes consistent with unobscured
AGN. Using a large comparison sample of 210 HAEs in Chandra-COSMOS (C-COSMOS),
we find suggestive evidence that the AGN fraction increases with local HAE
galaxy density. The 2QZ Clus HAEs reside in a moderately overdense environment
(a factor of ~2 times over the field), and after excluding optically-selected
QSOs, we find the AGN fraction is a factor of ~3.5^+3.8_-2.2 times higher than
C-COSMOS HAEs in similar environments. Using stacking analyses of the Chandra
data and Herschel SPIRE observations at 250 um, we respectively estimate mean
SMBH accretion rates (Mdot) and star-formation rates (SFRs) for the 2QZ Clus
and C-COSMOS samples. We find that the mean 2QZ Clus HAE stacked 2-10 keV
luminosity is QSO-like (~6-10 x 10^43 ergs/s), and the implied Mdot/SFR \sim
(1.6-3.2) x10^-3 is broadly consistent with the local MBH/M* relation and z ~ 2
X-ray selected AGN. The C-COSMOS HAEs are on average an order of magnitude less
X-ray luminous and have Mdot/SFR \sim (0.2-0.4) x10^-3, comparable to z ~ 1-2
star-forming galaxies with similar mean X-ray luminosities. We estimate that a
periodic QSO phase with duty cycle ~2-8% would be sufficient to bring the
star-forming galaxies onto the local MBH/M* relation.

PRIMUS: An observationally motivated model to connect the evolution of the AGN and galaxy populations out to z~1. (arXiv:1301.1689v1 [astro-ph.CO])

PRIMUS: An observationally motivated model to connect the evolution of the AGN and galaxy populations out to z~1. (arXiv:1301.1689v1 [astro-ph.CO]):
We present an observationally motivated model to connect the AGN and galaxy
populations at 0.2<z<1.0 and predict the AGN X-ray luminosity function (XLF).
We start with measurements of the stellar mass function of galaxies (from the
Prism Multi-object Survey) and populate galaxies with AGNs using models for the
probability of a galaxy hosting an AGN as a function of specific accretion rate
(the rate of supermassive black hole growth scaled relative to the host stellar
mass). Our model is based on measurements indicating that the specific
accretion rate distribution is a universal function across a wide range of host
stellar mass with slope gamma_1=0.65 and an overall normalization that evolves
strongly with redshift. We test several simple assumptions to extend this model
to high specific accretion rates (beyond the measurements) and compare the
predictions for the XLF with the observed data. We find good agreement with a
model that allows for a break in the specific accretion rate distribution at a
point corresponding to the Eddington limit, with a steep power-law tail to
super-Eddington ratios with slope gamma_2=-2.1 +0.3 -0.5. We convert between
specific accretion rate and Eddington ratio by assuming a scaling between black
hole mass and host stellar mass with an intrinsic scatter of +/-0.38 dex. Our
results show that samples of low luminosity AGNs are dominated by moderately
massive galaxies (M* ~ 10^{10-11} M_sun) growing with a wide range of accretion
rates -- a consequence of the shape of the galaxy stellar mass function rather
than a preference for AGN activity at a particular stellar mass. The observed
population of the most luminous AGN may be severely skewed to the most extreme
sources with elevated black hole masses relative to their host galaxies and in
rare phases of very rapid accretion.

The Atlas3D project - XIX. The hot-gas content of early-type galaxies: fast versus slow rotators. (arXiv:1301.2589v1 [astro-ph.GA])

The Atlas3D project - XIX. The hot-gas content of early-type galaxies: fast versus slow rotators. (arXiv:1301.2589v1 [astro-ph.GA]):
For early-type galaxies, the ability to sustain a corona of hot, X-ray
emitting gas could have played a key role in quenching their star-formation
history. Yet, it is still unclear what drives the precise amount of hot gas
around these galaxies. By combining photometric and spectroscopic measurements
for the early-type galaxies observed during the Atlas3D integral-field survey
with measurements of their X-ray luminosity based on X-ray data of both low and
high spatial resolution we conclude that the hot-gas content of early-type
galaxies can depend on their dynamical structure. Specifically, whereas slow
rotators generally have X-ray halos with luminosity L_X,gas and temperature T
values that are in line with what is expected if the hot-gas emission is
sustained by the thermalisaton of the kinetic energy carried by the
stellar-mass loss material, fast rotators tend to display L_X,gas values that
fall consistently below the prediction of this model, with similar T values
that do not scale with the stellar kinetic energy as observed in the case of
slow rotators. Considering that fast rotators are likely to be intrinsically
flatter than slow rotators, and that the few L_X,gas-deficient slow rotators
also happen to be relatively flat, the observed L_X,gas deficiency in these
objects would support the hypothesis whereby flatter galaxies have a harder
time in retaining their hot gas. We discuss the implications that a different
hot-gas content could have on the fate of both acquired and internally-produced
gaseous material, considering in particular how the L_X,gas deficiency of fast
rotators would make them more capable to recycle the stellar-mass loss material
into new stars than slow rotators. This is consistent with the finding that
molecular gas and young stars are detected only in fast rotators in the Atlas3D
sample, and that fast rotators tend to dustier than slow rotators. [Abridged]

The Escape Fraction of Ionizing Radiation from Primordial Galaxies. (arXiv:1212.4452v1 [astro-ph.CO])

The Escape Fraction of Ionizing Radiation from Primordial Galaxies. (arXiv:1212.4452v1 [astro-ph.CO]):
The escape of ionizing radiation from galaxies plays a critical role in the
evolution of gas in galaxies, and the heating and ionization history of the
intergalactic medium. Here, we present semi-analytic calculations of the escape
fraction of ionizing radiation for both hydrogen and helium from primordial
galaxies, as well as analytic derivations of these quantities. We consider
variations in the galaxy density profile, source type, location, and spectrum,
and gas clumping/distribution factors. For sufficiently hard first-light
sources, the helium ionization fronts closely track or even advance beyond that
of hydrogen. Key new results in this work include calculations of the escape
fractions for He I and He II ionizing radiation, and the impact of partial
ionization from X-rays from early AGN or stellar clusters on the escape
fractions from primordial halos. When factoring in frequency-dependent effects,
we find that X-rays play an important role in boosting the escape fractions for
both hydrogen and helium, but especially for He II. We briefly discuss the
implications of these results for recent observations of the He II reionization
epoch at low redshifts, as well as the UV data and emission-line signatures
from early galaxies anticipated from future satellite missions.

Hot X-ray coronae around massive spiral galaxies: a unique probe of structure formation models. (arXiv:1212.0541v1 [astro-ph.CO])

Hot X-ray coronae around massive spiral galaxies: a unique probe of structure formation models. (arXiv:1212.0541v1 [astro-ph.CO]):
Luminous X-ray gas coronae in the dark matter halos of massive spiral
galaxies are a fundamental prediction of structure formation models, yet such
coronae remained essentially unexplored. In this paper, for the very first
time, we detect and characterize extended hot X-ray coronae beyond the optical
disks of two normal massive spiral galaxies, NGC1961 and NGC6753. Based on
XMM-Newton X-ray observations, we detect hot gaseous emission extending out to
~60 kpc around both galaxies - well beyond their optical radii. The hot gas,
whose best-fit temperature is kT~0.6 keV and abundance is ~0.1 Solar, appears
to have a fairly uniform distribution, hinting that the quasi-static gas
resides in hydrostatic equilibrium in the potential well of the galaxies. The
bolometric luminosity of the hot gas in the (0.05-0.15)r_200 region, where
r_200 is the virial radius, is ~6e40 erg/s for both NGC1961 and NGC6753. We
derive the baryon mass fractions of NGC1961 and NGC6753 and obtain f_b~0.1,
which values fall short of the cosmic baryon fraction. The detected X-ray
coronae around NGC1961 and NGC6753 offer an excellent basis to probe structure
formation simulations. To this end, the observations are confronted with the
recently developed moving mesh code AREPO and the traditionally used smoothed
particle hydrodynamics code GADGET. The implemented subresolution physics and
the gravity solver are identical in the two codes, but they use different
methods to solve the hydrodynamical equations. We conclude that, while neither
model gives a perfect description, the observed luminosities, gas masses, and
abundances favor the AREPO code. Moreover, the shape of the observed density
profiles are also well reproduced by AREPO within ~0.4r_200. However, neither
model incorporates efficient feedback from supermassive black holes or
supernovae, which could alter the simulated properties of the X-ray coronae.
(abridged)

A Deep X-ray View of the Hot Halo in the Edge-on Spiral Galaxy NGC 891. (arXiv:1211.1669v1 [astro-ph.CO])

A Deep X-ray View of the Hot Halo in the Edge-on Spiral Galaxy NGC 891. (arXiv:1211.1669v1 [astro-ph.CO]):
NGC 891 is a nearby edge-on galaxy that is similar to the Milky Way and has a
hot X-ray emitting halo that could arise from accretion, a galactic fountain,
or a combination of the two. The metallicity of the gas can help distinguish
between these models, and here we report on results that use 138 ks of archival
Chandra data and 92 ks of new XMM-Newton data to measure the temperature and
metallicity of the hot halo of the galaxy. We find good fits for a thermal
model with kT ~ 0.2 keV and Z ~ 0.1 solar, and rule out solar metallicity to
more than 99% confidence. This result suggests accretion from the intergalactic
medium as the origin for the hot halo. However, it is also possible to fit a
two-temperature thermal model with solar metallicity where kT_1 = 0.1 keV and
kT_2 = 0.25 keV. A consideration of the cooling rate and scale height prefers
the single-temperature model. We also find that the cooling rate in the hot gas
cannot explain the massive HI halo in the steady state. In addition, a galactic
fountain model cannot eject enough mass to account for the HI halo, and we
speculate that the neutral halo may be gas from a prior outflow that has since
cooled.

The X-ray Star Formation Story as Told by Lyman Break Galaxies in the 4 Ms CDF-S. (arXiv:1210.3357v1 [astro-ph.CO])

The X-ray Star Formation Story as Told by Lyman Break Galaxies in the 4 Ms CDF-S. (arXiv:1210.3357v1 [astro-ph.CO]):
We present results from deep X-ray stacking of >4000 high redshift galaxies
from z~1 to 8 using the 4 Ms Chandra Deep Field South (CDF-S) data, the deepest
X-ray survey of the extragalactic sky to date. The galaxy samples were selected
using the Lyman break technique based primarily on recent HST ACS and WFC3
observations. Based on such high specific star formation rates (sSFRs): log
SFR/M* > -8.7, we expect that the observed properties of these LBGs are
dominated by young stellar populations. The X-ray emission in LBGs, eliminating
individually detected X-ray sources (potential AGN), is expected to be powered
by X-ray binaries and hot gas. We find, for the first time, evidence of
evolution in the X-ray/SFR relation. Based on X-ray stacking analyses for z<4
LBGs (covering ~90% of the Universe's history), we find that the 2-10 keV X-ray
luminosity evolves weakly with redshift (z) and SFR as log LX = 0.93 log (1+z)
+ 0.65 log SFR + 39.80. By comparing our observations with sophisticated X-ray
binary population synthesis models, we interpret that the redshift evolution of
LX/SFR is driven by metallicity evolution in HMXBs, likely the dominant
population in these high sSFR galaxies. We also compare these models with our
observations of X-ray luminosity density (total 2-10 keV luminosity per Mpc^3)
and find excellent agreement. While there are no significant stacked detections
at z>5, we use our upper limits from 5<z<8 LBGs to constrain the SMBH accretion
history of the Universe around the epoch of reionization.

Galactic Outflows in Absorption and Emission: Near-UV Spectroscopy of Galaxies at 1 < z < 2. (arXiv:1209.4903v1 [astro-ph.CO])

Galactic Outflows in Absorption and Emission: Near-UV Spectroscopy of Galaxies at 1<z<2. (arXiv:1209.4903v1 [astro-ph.CO]):

We study large-scale outflows in a sample of 96 star-forming galaxies at
1<z<2, using near-UV spectroscopy of FeII and MgII absorption and emission. The
average blueshift of the FeII interstellar absorption lines with respect to the
systemic velocity is -85+/-10 km/s at z~1.5, with standard deviation 87 km/s;
this is a decrease of a factor of two from the average blueshift measured for
far-UV interstellar absorption lines in similarly selected galaxies at z~2. The
profiles of the MgII 2796, 2803 lines show much more variety than the FeII
profiles, which are always seen in absorption; MgII ranges from strong emission
to pure absorption, with emission more common in galaxies with blue UV slopes
and at lower stellar masses. Outflow velocities, as traced by the centroids and
maximum extent of the absorption lines, increase with increasing stellar mass
with 2-3sigma significance, in agreement with previous results. We study fine
structure emission from FeII*, finding several lines of evidence in support of
the model in which this emission is generated by the re-emission of continuum
photons absorbed in the FeII resonance transitions in outflowing gas. In
contrast, photoionization models indicate that MgII emission arises from the
resonant scattering of photons produced in HII regions, accounting for the
differing profiles of the MgII and FeII lines. A comparison of the strengths of
the FeII absorption and FeII* emission lines indicates that massive galaxies
have more extended outflows and/or greater extinction, while two-dimensional
composite spectra indicate that emission from the outflow is stronger at a
radius of ~10 kpc in high mass galaxies than in low mass galaxies.

Clustering, Bias and the Accretion Mode of X-ray selected AGN. (arXiv:1209.6460v1 [astro-ph.CO])

Clustering, Bias and the Accretion Mode of X-ray selected AGN. (arXiv:1209.6460v1 [astro-ph.CO]):
We present the spatial clustering properties of 1466 X-ray selected AGN
compiled from the Chandra CDF-N, CDF-S, eCDF-S, COSMOS and AEGIS fields in the
0.5-8 keV band. The X-ray sources span the redshift interval 0<z<3 and have a
median value of Med{z}=0.976.We employ the projected two-point correlation
function to infer the spatial clustering and find a clustering length of r0=
7.2+-0.6 h^{-1} Mpc and a slope of \gamma=1.48+-0.12, which corresponds to a
bias of b=2.26+-0.16. Using two different halo bias models, we consistently
estimate an average dark-matter host halo mass of Mh\sim 1.3 (+-0.3) x 10^{13}
h^{-1} M_sun. The X-ray AGN bias and the corresponding dark-matter host halo
mass, are significantly higher than the corresponding values of optically
selected AGN (at the same redshifts). %indicating different populations of AGN.
The redshift evolution of the X-ray selected AGN bias indicates, in agreement
with other recent studies, that a unique dark-matter halo mass does not fit
well the bias at all the different redshifts probed.

Furthermore, we investigate if there is a dependence of the clustering
strength on X-ray luminosity. To this end we consider only 650 sources around
z~1 and we apply a procedure to disentangle the dependence of clustering on
redshift. We find indications for a positive dependence of the clustering
length on X-ray luminosity, in the sense that the more luminous sources have a
larger clustering length and hence a higher dark-matter halo mass. In detail we
find for an average luminosity difference of \delta\log_{10} L_x ~ 1 a halo
mass difference of a factor of ~3.

These findings appear to be consistent with a galaxy-formation model where
the gas accreted onto the supermassive black hole in intermediate luminosity
AGN comes mostly from the hot-halo atmosphere around the host galaxy.

Two stellar-mass black holes in the globular cluster M22. (arXiv:1210.0901v1 [astro-ph.HE])

Two stellar-mass black holes in the globular cluster M22. (arXiv:1210.0901v1 [astro-ph.HE]):
Hundreds of stellar-mass black holes likely form in a typical globular star
cluster, with all but one predicted to be ejected through dynamical
interactions. Some observational support for this idea is provided by the lack
of X-ray-emitting binary stars comprising one black hole and one other star
("black-hole/X-ray binaries") in Milky Way globular clusters, even though many
neutron-star/X-ray binaries are known. Although a few black holes have been
seen in globular clusters around other galaxies, the masses of these cannot be
determined, and some may be intermediate-mass black holes that form through
exotic mechanisms. Here we report the presence of two flat-spectrum radio
sources in the Milky Way globular cluster M22, and we argue that these objects
are black holes of stellar mass (each ~ 10-20 times more massive than the Sun)
that are accreting matter. We find a high ratio of radio-to-X-ray flux for
these black holes, consistent with the larger predicted masses of black holes
in globular clusters compared to those outside. The identification of two black
holes in one cluster shows that the ejection of black holes is not as efficient
as predicted by most models, and we argue that M22 may contain a total
population of ~ 5-100 black holes. The large core radius of M22 could arise
from heating produced by the black holes.

Ionized Gas in the First 10 Kiloparsecs of the Interstellar Galactic Halo: Metal Ion Fractions. (arXiv:1209.4640v1 [astro-ph.GA])

Ionized Gas in the First 10 Kiloparsecs of the Interstellar Galactic Halo: Metal Ion Fractions. (arXiv:1209.4640v1 [astro-ph.GA]):
We present direct measures of the ionization fractions of several sulfur ions
in the Galactic warm ionized medium (WIM). We obtained high resolution
ultraviolet absorption line spectroscopy of post-asymptotic giant branch stars
in the the globular clusters Messier 3 [(l,b)=(42.2, +78.7); d=10.2 kpc, z=10.0
kpc] and Messier 5 [(l,b)=(3.9, +46.8); d=7.5 kpc, z = +5.3 kpc] with the
Hubble Space Telescope and Far Ultraviolet Spectroscopic Explorer to measure,
or place limits on, the column densities of S I, S II, S III, S IV, S VI, and H
I. These clusters also house millisecond pulsars, whose dispersion measures
give an electron column density from which we infer the H II column in these
directions. We find fractions of S+2 in the WIM for the M 3 and M 5 sight lines
x(S+2) = N(S+2)/N(S) = 0.33+/-0.07 and 0.47+/-0.09, respectively, with
variations perhaps related to location. With negligible quantities of the
higher ionization states, we conclude S+ and S+2 account for all of the S in
the WIM. We extend the methodology to study the ion fractions in the warm and
hot ionized gas of the Milky Way, including the high ions Si+3, C+3, N+4, and
O+5. The vast majority of the Galactic ionized gas is warm (T ~ 10^4 K) and
photoionized (the WIM) or very hot (T > 4x10^5 K) and collisionally ionized.
The common tracer of ionized gas beyond the Milky Way, O+5, traces <1% of the
total ionized gas mass of the Milky Way.

Accreting SMBHs in the COSMOS field and the connection to their host galaxies. (arXiv:1209.1640v1 [astro-ph.CO])

Accreting SMBHs in the COSMOS field and the connection to their host galaxies. (arXiv:1209.1640v1 [astro-ph.CO]):
Using the wide multi-band photometry available in the COSMOS field we explore
the host galaxy properties of a large sample of Active Galactic Nuclei (AGN)
obtained by combining X-ray and optical spectroscopic selections. Based on a
careful study of their Spectral Energy Distribution (SED), which has been
parametrized using a 2-component (AGN+galaxy) model fit, we derived
dust-corrected rest-frame magnitudes, colors, stellar masses and star formation
rates (SFRs). We find that AGN hosts span a large range of stellar masses and
SFRs. No color-bimodality is seen at any redshift in the AGN hosts, which are
found to be mainly massive, red galaxies. Once accounting for the color-mass
degeneracy in well defined mass-matched samples, we find a residual marginal
enhancement of AGN incidence in redder galaxies with lower specific star
formation rates, and we argue that this result might emerge because of our
ability to properly account for AGN light contamination and dust extinction.
Interestingly, we find that the probability for a galaxy to host a black hole
growing at any given "specific accretion rate" (i.e. the ratio of X-ray
luminosity to the host stellar mass) is almost independent of the host galaxy
mass, while it decreases as a power-law with Lx/M. By analyzing the
normalization of such probability distribution, we show how the incidence of
AGN increases with redshift as rapidly as (1+z)^4, in close resemblance with
the overall evolution of the specific star formation rate of the entire galaxy
population. Although AGN activity and star formation in galaxies do appear to
have a common triggering mechanism, at least in a statistical sense, within the
COSMOS sample we do not find strong evidence of any 'smoking gun' signaling
powerful AGN influence on the star-forming properties of their hosts galaxies.

Discovery of an active supermassive black hole in the bulge-less galaxy NGC 4561. (arXiv:1209.1354v1 [astro-ph.CO])

Discovery of an active supermassive black hole in the bulge-less galaxy NGC 4561. (arXiv:1209.1354v1 [astro-ph.CO]):
We present XMM-Newton observations of the Chandra-detected nuclear X-ray
source in NGC 4561. The hard X-ray spectrum can be described by a model
composed of an absorbed power-law with Gamma= 2.5^{+0.4}_{-0.3}, and column
density N_H=1.9^{+0.1}_{-0.2} times 10^{22} atoms cm^{-2}. The absorption
corrected luminosity of the source is L(0.2 - 10.0 keV) = 2.5 times 10^{41}
ergs s^{-1}, with bolometric luminosity over 3 \times 10^{42} ergs s^{-1}.
Based on the spectrum and the luminosity, we identify the nuclear X-ray source
in NGC 4561 to be an AGN, with a black hole of mass M_BH > 20,000 solar masses.
The presence of a supermassive black hole at the center of this bulge-less
galaxy shows that black hole masses are not necessarily related to bulge
properties, contrary to the general belief. Observations such as these call
into question several theoretical models of BH--galaxy co-evolution that are
based on merger-driven BH growth; secular processes clearly play an important
role. Several emission lines are detected in the soft X-ray spectrum of the
source which can be well parametrized by an absorbed diffuse thermal plasma
with non-solar abundances of some heavy elements. Similar soft X-ray emission
is observed in spectra of Seyfert 2 galaxies and low luminosity AGNs,
suggesting an origin in the circumnuclear plasma.

Precise Identifications of Submillimeter Galaxies: Measuring the History of Massive Star-Forming Galaxies to z>5. (arXiv:1209.1626v1 [astro-ph.CO])

Precise Identifications of Submillimeter Galaxies: Measuring the History of Massive Star-Forming Galaxies to z>5. (arXiv:1209.1626v1 [astro-ph.CO]):
We carried out extremely sensitive Submillimeter Array (SMA) 340 GHz (860
micron) continuum imaging of a complete sample of SCUBA 850 micron sources (>4
sigma) with fluxes >3 mJy in the GOODS-N. Using these data and new SCUBA-2
data, we find that 4 of the 16 SCUBA sources are spurious. A further 3 resolve
into multiple fainter SMA galaxies, suggesting that our understanding of the
most luminous high-redshift dusty galaxies may not be as reliable as we
thought. Ten of the 16 independent SMA sources have spectroscopic redshifts
(optical/infrared or CO) to z=5.18. Using a new, ultradeep 20 cm image obtained
with the Karl G. Jansky Very Large Array (rms of 2.5 microJy), we find that all
16 of the SMA sources are detected at >5 sigma. Using Herschel far-infrared
(FIR) data, we show that the 5 isolated SMA sources with Herschel detections
are well described by an Arp 220 spectral energy distribution template in the
FIR. They also closely obey the local FIR-radio correlation, a result that does
not suffer from a radio bias. We compute the contribution from the 16 SMA
sources to the universal star formation rate per comoving volume. With
individual star formation rates in the range 700-5000 solar masses per year,
they contribute ~30% of the extinction-corrected ultraviolet selected star
formation rate density from z=1 to at least z=5. Star formation histories
determined from extinction-corrected ultraviolet populations and from
submillimeter galaxy populations only partially overlap, due to the extreme
ultraviolet faintness of some submillimeter galaxies.

Galaxy Gas Fractions at High-Redshift: The Tension between Observations and Cosmological Simulations. (arXiv:1209.0771v1 [astro-ph.CO])

Galaxy Gas Fractions at High-Redshift: The Tension between Observations and Cosmological Simulations. (arXiv:1209.0771v1 [astro-ph.CO]):
CO measurements of z~1-4 galaxies have found that their baryonic gas
fractions are significantly higher than galaxies at z=0, with values ranging
from 20-80 %. Here, we suggest that the gas fractions inferred from
observations of star-forming galaxies at high-z are overestimated, owing to the
adoption of locally-calibrated CO-H2 conversion factors (Xco). Evidence from
both observations and numerical models suggest that Xco varies smoothly with
the physical properties of galaxies, and that Xco can be parameterised simply
as a function of both gas phase metallicity and observed CO surface brightness.
When applying this functional form, we find fgas ~10-40 % in galaxies with
M*=10^10-10^12 Msun at high-z. Moreover, the scatter in the observed fgas-M*
relation is lowered by a factor of two. The lower inferred gas fractions arise
physically because the interstellar media of high-z galaxies have higher
velocity dispersions and gas temperatures than their local counterparts, which
results in an Xco that is lower than the z=0 value for both quiescent discs and
starbursts. We further compare these gas fractions to those predicted by
cosmological galaxy formation models. We show that while the canonically
inferred gas fractions from observations are a factor of 2-3 larger at a given
stellar mass than predicted by models, our rederived Xco values for z=1-4
galaxies results in revised gas fractions that agree significantly better with
the simulations.