AGN proximity zone fossils and the delayed recombination of metal lines. (arXiv:1303.0019v1 [astro-ph.CO])

AGN proximity zone fossils and the delayed recombination of metal lines. (arXiv:1303.0019v1 [astro-ph.CO]):
We model the time-dependent evolution of metal-enriched intergalactic and
circumgalactic gas exposed to the fluctuating radiation field from an active
galactic nucleus (AGN). We consider diffuse gas densities (n_H=10^-5-10^-3
cm^-3) exposed to the extra-galactic background (EGB) and initially in thermal
equilibrium (T \sim 10^4-10^4.5 K). Once the proximate AGN field turns on,
additional photo-ionisation rapidly ionises the HI and metals. The enhanced AGN
radiation field turns off after a typical AGN lifetime (tau_AGN=1-20 Myr) and
the field returns to the EGB intensity, but the metals remain out of ionisation
equilibrium for timescales that can significantly exceed tau_AGN. We define
this phase as the AGN proximity zone "fossil" phase and show that high
ionisation stages (e.g. OVI, NeVIII, MgX) are in general enhanced, while the
abundances of low ions are reduced. In contrast, HI re-equilibrates rapidly
(<<tau_AGN) owing to its low neutral fraction at diffuse densities. We
demonstrate that metal column densities of intervening gas observed in
absorption in quasar sight lines are significantly affected by delayed
recombination for a wide range of densities, metallicities, and AGN strengths,
lifetimes, and duty cycles. We model the exceptionally strong z=0.9 NeVIII
absorbers observed by Tripp et al. (2011) as arising in a possible fossil zone
or near a recently turned-on AGN and we demonstrate that at low redshift even
moderate strength AGN could significantly enhance the high-ion metal columns in
the circumgalactic media of galaxies observed without active AGN. Fossil
proximity zones may be particularly important during the quasar era, z \sim
2-5. AGN proximity zone fossils allow a whole new class of non-equilibrium
solutions that may be applicable to a large fraction of observed metal
absorbers and which could potentially change the inferred physical conditions
and masses of diffuse gases.

Probing the Extended Gaseous Regions of M31 with Quasar Absorption Lines. (arXiv:1302.7026v1 [astro-ph.CO])

Probing the Extended Gaseous Regions of M31 with Quasar Absorption Lines. (arXiv:1302.7026v1 [astro-ph.CO]):
We present HST-COS spectra of ten quasars located behind M31, selected to
investigate the properties of gas associated with its extended disk and high
velocity clouds (HVCs). The sightlines have impact parameters ranging between
b= 13 kpc and 112 kpc. No absorption is detected in the four sightlines beyond
b=57 kpc. Of the six remaining sightlines, all of which lie at b<32 kpc and
within the N(HI)= 2E18 cm^{-2} boundary of the HI disk of M31, we detect
low-ionization absorption at M31 velocities along four of them (three of which
include MgII absorption). We also detect MgII absorption from an HVC. We find
that along sightlines where both are detected, the velocity location of the
low-ion gas tracks the peak in 21 cm emission. High-ionization absorption is
detected along the three inner sightlines, but not along the three outer
sightlines, for which CIV data exist. As inferred from 21 cm emission line
maps, only one sightline may have a damped Ly-alpha system. This sightline has
b= 17.5 kpc, and we detect both low- and high-ion absorption lines associated
with it. It is the strongest single MgII2796 absorption line that we detect,
with W_0(2796)=0.63 A.

The impact parameters through M31 are similar to the impact parameters of
galaxies identified with MgII absorbers at redshifts 0.1<z<1.0 in a 2011 study
by Rao et al. However, the M31 MgII2796 rest equivalent width values are
significantly smaller. In comparison, moderate-to-strong MgII absorption from
Milky Way gas is detected along all ten sightlines. Thus, this study indicates
that M31 does not present itself as an absorbing galaxy which is typical of
higher-redshift galaxies inferred to give rise to moderate-strength quasar
absorption lines. M31 also appears not to possess an extensive large gaseous
cross section, at least not along the direction of its major axis. (Abridged.)

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.

X-ray diagnostics of chemical composition of the accretion disk and donor star in ultra-compact X-ray binaries. (arXiv:1302.2070v1 [astro-ph.HE])

X-ray diagnostics of chemical composition of the accretion disk and donor star in ultra-compact X-ray binaries. (arXiv:1302.2070v1 [astro-ph.HE]):
Non-solar composition of the donor star in ultra-compact X-ray binaries may
have a pronounced effect on the fluorescent lines appearing in their spectra
due to reprocessing of primary radiation by the accretion disk and the white
dwarf surface. We show that the most dramatic and easily observable consequence
of the anomalous C/O abundance, is the significant, by more than an order of
magnitude, attenuation of the Ka line of iron. It is caused by screening of the
presence of iron by oxygen - in the C/O dominated material the main interaction
process for a E ~ 7keV photon is absorption by oxygen rather than by iron,
contrary to the solar composition case. Ionization of oxygen at high mass
accretion rates adds a luminosity dependence to this behavior - the iron line
is significantly suppressed only at low luminosity, log(LX) less than 37-37.5,
and should recover its nominal strength at higher luminosity. The increase of
the EW of the Ka lines of carbon and oxygen, on the other hand, saturates at
rather moderate values. Screening by He is less important, due to its low
ionization threshold and because in the accretion disk it is mostly ionized.
Consequently, in the case of the He-rich donor, the iron line strength remains
close to its nominal value, determined by the iron abundance in the accretion
disk. This opens the possibility of constraining the nature of donor stars in
UCXBs by means of X-ray spectroscopy with moderate energy resolution.

First results from a next-generation off-plane X-ray diffraction grating. (arXiv:1301.5531v1 [astro-ph.IM])

First results from a next-generation off-plane X-ray diffraction grating. (arXiv:1301.5531v1 [astro-ph.IM]):
Future NASA X-ray spectroscopy missions will require high throughput, high
resolution grating spectrometers. Off-plane reflection gratings are capable of
meeting the performance requirements needed to realize the scientific goals of
these missions. We have identified a novel grating fabrication method that
utilizes common lithographic and microfabrication techniques to produce the
high fidelity groove profile necessary to achieve this performance. Application
of this process has produced an initial pre-master that exhibits a radial
(variable line spacing along the groove dimension), high density (>6000
grooves/mm), laminar profile. This pre-master has been tested for diffraction
efficiency at the BESSY II synchrotron light facility and diffracts up to 55%
of incident light into usable spectral orders. Furthermore, tests of spectral
resolving power show that these gratings are capable of obtaining resolutions
well above 1300 ($\lambda/\Delta\lambda$) with limitations due to the test
apparatus, not the gratings. Obtaining these results has provided confidence
that this fabrication process is capable of producing off-plane reflection
gratings for the next generation of X-ray observatories.

Characterizing the Circumgalactic Medium of Nearby Galaxies with HST/COS and HST/STIS Absorption-Line Spectroscopy. (arXiv:1212.5658v1 [astro-ph.CO])

Characterizing the Circumgalactic Medium of Nearby Galaxies with HST/COS and HST/STIS Absorption-Line Spectroscopy. (arXiv:1212.5658v1 [astro-ph.CO]):
The Circumgalactic Medium (CGM) of late-type galaxies is characterized using
UV spectroscopy of 11 targeted QSO/galaxy pairs at z < 0.02 with the Hubble
Space Telescope Cosmic Origins Spectrograph and ~60 serendipitous
absorber/galaxy pairs at z < 0.2 with the Space Telescope Imaging Spectrograph.
CGM warm cloud properties are derived, including volume filling factors of
3-5%, cloud sizes of 0.1-30 kpc, masses of 10-1e8 solar masses and
metallicities of 0.1-1 times solar. Almost all warm CGM clouds within 0.5
virial radii are metal-bearing and many have velocities consistent with being
bound, "galactic fountain" clouds. For galaxies with L > 0.1 L*, the total mass
in these warm CGM clouds approaches 1e10 solar masses, ~10-15% of the total
baryons in massive spirals and comparable to the baryons in their parent galaxy
disks. This leaves >50% of massive spiral-galaxy baryons "missing". Dwarfs
(<0.1 L*) have smaller area covering factors and warm CGM masses (<5% baryon
fraction), suggesting that many of their warm clouds escape. Constant warm
cloud internal pressures as a function of impact parameter ($P/k ~ 10 cm^{-3}
K) support the inference that previous COS detections of broad, shallow O VI
and Ly-alpha absorptions are of an extensive (~400-600 kpc), hot (T ~ 1e6 K)
intra-cloud gas which is very massive (>1e11 solar masses). While the warm CGM
clouds cannot account for all the "missing baryons" in spirals, the hot
intra-group gas can, and could account for ~20% of the cosmic baryon census at
z ~ 0 if this hot gas is ubiquitous among spiral groups.

ISM composition through X-ray spectroscopy of LMXBs. (arXiv:1301.1612v1 [astro-ph.GA])

ISM composition through X-ray spectroscopy of LMXBs. (arXiv:1301.1612v1 [astro-ph.GA]):
The diffuse interstellar medium (ISM) is an integral part of the evolution of
the entire Galaxy. Metals are produced by stars and their abundances are the
direct testimony of the history of stellar evolution. However, the interstellar
dust composition is not well known and the total abundances are yet to be
accurately determined. We probe ISM dust composition, total abundances, and
abundance gradients through the study of interstellar absorption features in
the high-resolution X-ray spectra of Galactic low-mass X-ray binaries (LMXBs).
We use high-quality grating spectra of nine LMXBs taken with XMM-Newton. We
measure the column densities of O, Ne, Mg, and Fe with an empirical model and
estimate the Galactic abundance gradients. The column densities of the neutral
gas species are in agreement with those found in the literature. Solids are a
significant reservoir of metals like oxygen and iron. Respectively, 15-25 % and
65-90 % of the total amount of O I and Fe I is found in dust. The dust amount
and mixture seem to be consistent along all the lines-of-sight (LOS). Our
estimates of abundance gradients and predictions of local interstellar
abundances are in agreement with those measured at longer wavelengths. Our work
shows that X-ray spectroscopy is a very powerful method to probe the ISM. For
instance, on a large scale the ISM appears to be chemically homogeneous showing
similar gas ionization ratios and dust mixtures. The agreement between the
abundances of the ISM and the stellar objects suggests that the local Galaxy is
also chemically homogeneous.

The Milky Way halo as a QSO absorption-line system. New results from an HST/STIS absorption-line catalogue of Galactic high-velocity clouds. (arXiv:1301.1345v1 [astro-ph.CO])

The Milky Way halo as a QSO absorption-line system. New results from an HST/STIS absorption-line catalogue of Galactic high-velocity clouds. (arXiv:1301.1345v1 [astro-ph.CO]):
We use archival UV absorption-line data from HST/STIS to statistically
analyse the absorption characteristics of the high-velocity clouds (HVCs) in
the Galactic halo towards more than 40 extragalactic background sources. We
determine absorption covering fractions of low- and intermediate ions (OI, CII,
SiIII, MgII, FeII, SiIII, CIV, and SiIV) in the range fc = 0.20 - 0.70. For
detailed analysis we concentrate on SiII absorption components in HVCs, for
which we investigate the distribution of column densities, b-values, and radial
velocities. Combining information for SiII and MgII, and using a geometrical
HVC model we investigate the contribution of HVCs to the absorption cross
section of strong MgII absorbers in the local Universe. We estimate that the
Galactic HVCs would contribute on average ~52 % to the total strong MgII cross
section of the Milky Way, if our Galaxy were to be observed from an exterior
vantage point. We further estimate that the mean projected covering fraction of
strong MgII absorption in the Milky Way halo and disc from an exterior vantage
point is fc(sMgII) = 0.31 for a halo radius of R = 61 kpc. These numbers,
together with the observed number density of strong MgII absorbers at low
redshift, indicate that the contribution of infalling gas clouds (i.e., HVC
analogues) in the halos of Milky Way-type galaxies to the cross section of
strong MgII absorbers is <34 %. These findings are in line with the idea that
outflowing gas (e.g., produced by galactic winds) in the halos of more actively
star-forming galaxies dominate the absorption-cross section of strong MgII
absorbers in the local Universe.

Emission lines between 1 and 2 keV in Cometary X-ray Spectra. (arXiv:1212.0624v1 [astro-ph.EP])

Emission lines between 1 and 2 keV in Cometary X-ray Spectra. (arXiv:1212.0624v1 [astro-ph.EP]):
We present the detection of new cometary X-ray emission lines in the 1.0 to
2.0 keV range using a sample of comets observed with the Chandra X-ray
observatory and ACIS spectrometer. We have selected 5 comets from the Chandra
sample with good signal-to-noise spectra. The surveyed comets are: C/1999 S4
(LINEAR), C/1999 T1 (McNaught-Hartley), 153P/2002 (Ikeya-Zhang), 2P/2003
(Encke), and C/2008 8P (Tuttle). We modeled the spectra with an extended
version of our solar wind charge exchange (SWCX) emission model (Bodewits et
al. 2007). Above 1 keV, we find Ikeya-Zhang to have strong emission lines at
1340 and 1850 eV that we identify as being created by solar wind charge
exchange lines of Mg XI and Si XIII, respectively, and weaker emission lines at
1470, 1600, and 1950 eV formed by SWCX of Mg XII, Mg XI, and Si XIV,
respectively. The Mg XI and XII and Si XIII and XIV lines are detected at a
significant level for the other comets in our sample (LS4, MH, Encke, 8P), and
these lines promise additional diagnostics to be included in SWCX models. The
silicon lines in the 1700 to 2000 eV range are detected for all comets, but
with the rising background and decreasing cometary emission, we caution these
detections need further confirmation with higher resolution instruments.

Velocity width measurements of the coolest X-ray emitting material in the cores of clusters, groups and elliptical galaxies. (arXiv:1212.1259v1 [astro-ph.CO])

Velocity width measurements of the coolest X-ray emitting material in the cores of clusters, groups and elliptical galaxies. (arXiv:1212.1259v1 [astro-ph.CO]):
We examine the velocity width of cool X-ray emitting material using
XMM-Newton Reflection Grating Spectrometer (RGS) spectra of a sample of
clusters and group of galaxies and elliptical galaxies. Improving on our
previous analyses, we apply a spectral model which accounts for broadening due
to the spatial extent of the source. With both conventional and Markov Chain
Monte Carlo approaches we obtain limits, or in a few cases measurements, of the
velocity broadening of the coolest X-ray material. In our sample, we include
new observations targeting objects with compact, bright, line-rich cores. One
of these, MACSJ2229.7-2755, gives a velocity limit of 280 km/s at the 90 per
cent confidence level. Other systems with limits close to 300 km/s include
A1835, NGC4261 and NGC4472. For more than a third of the targets we find limits
better than 500 km/s. HCG62, NGC1399 and A3112 show evidence for ~400 km/s
velocity broadening. For a smaller sample of objects, we use
continuum-subtracted emission line surface brightness profiles to account for
the spatial broadening. Although there are significant systematic errors
associated with the technique (~150 km/s), we find broadening at the level of
280 to 500 km/s in A3112, NGC1399 and NGC4636.

High-Resolution X-Ray Spectroscopy of the Galactic Supernova Remnant Puppis A with the XMM-Newton RGS. (arXiv:1209.5496v2 [astro-ph.HE] UPDATED)

High-Resolution X-Ray Spectroscopy of the Galactic Supernova Remnant Puppis A with the XMM-Newton RGS. (arXiv:1209.5496v2 [astro-ph.HE] UPDATED):
We present high-resolution X-ray spectra of cloud-shock interaction regions
in the eastern and northern rims of the Galactic supernova remnant Puppis A,
using the Reflection Grating Spectrometer onboard the XMM-Newton satellite. A
number of emission lines including K alpha triplets of He-like N, O, and Ne are
clearly resolved for the first time. Intensity ratios of forbidden to resonance
lines in the triplets are found to be higher than predictions by thermal
emission models having plausible plasma parameters. The anomalous line ratios
cannot be reproduced by effects of resonance scattering, recombination, or
inner-shell ionization processes, but could be explained by charge-exchange
emission that should arise at interfaces between the cold/warm clouds and the
hot plasma. Our observations thus provide observational support for
charge-exchange X-ray emission in supernova remnants.

Warm-hot gas in groups and galaxies toward H2356-309. (arXiv:1209.4080v1 [astro-ph.CO])

Warm-hot gas in groups and galaxies toward H2356-309. (arXiv:1209.4080v1 [astro-ph.CO]):
We present a detailed analysis of the galaxy and group distributions around
three reported X-ray absorption line systems in the spectrum of the quasar
H2356-309. Previous studies associated these absorbers with known large-scale
galaxy structures (i.e., walls and filaments) along the line of sight. Such
absorption lines typically trace 10^{5-7} K gas, and may be evidence of the
elusive warm-hot intergalactic medium (WHIM) thought to harbor the bulk of the
low-redshift "missing baryons;" alternatively, they may be linked to individual
galaxies or groups in the filaments. Here we combine existing galaxy survey
data with new, highly complete multi-object Magellan spectroscopy to
investigate the detailed galaxy distribution near each absorber. All of these
three absorption systems nominally lie within the virial radii of nearby
galaxies and/or groups, and could therefore arise in these virialized
structures rather than (or in addition to) the WHIM. However, we find no
additional galaxies near a fourth "void" absorber recently reported by
Zappacosta et al., suggesting that this system may indeed trace gas
unassociated with any individual halo. We therefore conclude that most X-ray
absorbers are coincident with galaxy and/or group environments, though some
could still trace the large-scale filamentary WHIM gas predicted by
simulations.

A Fast Flare and Direct Redshift Constraint in Far-UV Spectra of the Blazar S50716+714. (arXiv:1209.3325v1 [astro-ph.HE])

A Fast Flare and Direct Redshift Constraint in Far-UV Spectra of the Blazar S50716+714. (arXiv:1209.3325v1 [astro-ph.HE]):
The BL Lacertae object S50716+714 is one of the most studied blazars on the
sky due to its active variability and brightness in many bands, including VHE
gamma rays. We present here two serendipitous results from recent
far-ultraviolet spectroscopic observations by the Cosmic Origins Spectrograph
onboard the Hubble Space Telescope. First, the blazar increased in flux rapidly
by ~40% (-0.45 mag/h) followed by a slower decline (+0.36 mag/h) to previous
far-UV flux levels during the course of our 7.3 hour HST observations. We model
this flare using asymmetric flare templates and constrain the physical size,
and energetics of the emitting region. Furthermore, the spectral index of the
object softens considerably during the course of the flare from alpha_nu=-1.0
to alpha_nu=-1.4. Second, we constrain the source redshift directly using the
>30 intervening absorption systems. A system at z=0.2315 is detected in Lya,
Lyb, OVI, NV, and CIII and defines the lower bound on the source redshift. No
absorbers are seen in the remaining spectral coverage (0.2315<z_Lya<0.47) and
we set a statistical upper bound of z<0.304 (90% confidence) on the blazar.
This is the first direct redshift limit for this object and is consistent with
literature estimates of z=0.31+-0.08 based on the detection of a host galaxy.

Observed Limits on Charge Exchange Contributions to the Diffuse X-ray Background. (arXiv:1209.1657v1 [astro-ph.HE])

Observed Limits on Charge Exchange Contributions to the Diffuse X-ray Background. (arXiv:1209.1657v1 [astro-ph.HE]):
We present a high resolution spectrum of the diffuse X-ray background from
0.1 to 1 keV for a ~1 region of the sky centered at l=90, b=+60 using a
36-pixel array of microcalorimeters flown on a sounding rocket. With an energy
resolution of 11 eV FWHM below 1 keV, the spectrum's observed line ratios help
separate charge exchange contributions originating within the heliosphere from
thermal emission of hot gas in the interstellar medium. The X-ray sensitivity
below 1 keV was reduced by about a factor of four from contamination that
occurred early in the flight, limiting the significance of the results. The
observed centroid of helium-like O VII is 568+2-3 eV at 90% confidence. Since
the centroid expected for thermal emission is 568.4 eV while for charge
exchange is 564.2 eV, thermal emission appears to dominate for this line
complex, consistent with much of the high-latitude O VII emission originating
in 2-3 x 10^6 K gas in the Galactic halo. On the other hand, the observed ratio
of C VI Ly gamma to Ly alpha is 0.3+-0.2. The expected ratios are 0.04 for
thermal emission and 0.24 for charge exchange, indicating that charge exchange
must contribute strongly to this line and therefore potentially to the rest of
the ROSAT R12 band usually associated with 10^6 K emission from the Local Hot
Bubble. The limited statistics of this experiment and systematic uncertainties
due to the contamination require only >32% thermal emission for O VII and >20%
from charge exchange for C VI at the 90% confidence level. An experimental gold
coating on the silicon substrate of the array greatly reduced extraneous
signals induced on nearby pixels from cosmic rays passing through the
substrate, reducing the triggered event rate by a factor of 15 from a previous
flight of the instrument.

On the diversity and complexity of absorption line profiles produced by outflows in Active Galactic Nuclei. (arXiv:1208.6044v1 [astro-ph.CO])

On the diversity and complexity of absorption line profiles produced by outflows in Active Galactic Nuclei. (arXiv:1208.6044v1 [astro-ph.CO]):
Understanding the origin of AGN absorption line profiles and their diversity
could help to explain the physical structure of the accretion flow, and also to
assess the impact of accretion on the evolution of the AGN host galaxies. Here
we present our first attempt to systematically address the issue of the origin
of the complexities observed in absorption profiles. Using a simple method, we
compute absorption line profiles against a continuum point source for several
simulations of accretion disk winds. We investigate the geometrical,
ionization, and dynamical effects on the absorption line shapes. We find that
significant complexity and diversity of the absorption line profile shapes can
be produced by the non-monotonic distribution of the wind velocity, density,
and ionization state. Non-monotonic distributions of such quantities are
present even in steady-state, smooth disk winds, and naturally lead to the
formation of multiple and detached absorption troughs. These results
demonstrate that the part of a wind where an absorption line is formed is not
representative of the entire wind. Thus, the information contained in the
absorption line is incomplete if not even insufficient to well estimate gross
properties of the wind such as the total mass and energy fluxes. In addition,
the highly dynamical nature of certain portions of disk winds can have
important effects on the estimates of the wind properties. For example, the
mass outflow rates can be off up to two orders of magnitude with respect to
estimates based on a spherically symmetric, homogeneous, constant velocity
wind.

Absorption Features in the X-ray Spectrum of an Ordinary Radio Pulsar. (arXiv:1208.5400v1 [astro-ph.HE])

Absorption Features in the X-ray Spectrum of an Ordinary Radio Pulsar. (arXiv:1208.5400v1 [astro-ph.HE]):
The vast majority of known non-accreting neutron stars (NSs) are
rotation-powered radio and/or gamma-ray pulsars. So far, their multiwavelength
spectra have all been described satisfactorily by thermal and non-thermal
continuum models, with no spectral lines. Spectral features have, however, been
found in a handful of exotic NSs and thought to be a manifestation of their
unique traits. Here we report the detection of absorption features in the X-ray
spectrum of an ordinary rotation-powered radio pulsar, J1740+1000. Our findings
bridge the gap between the spectra of pulsars and other, more exotic, NSs,
suggesting that the features are more common in the NS spectra than they have
been thought so far.

The Disk-Wind-Jet Connection in the Black Hole H 1743-322. (arXiv:1208.4514v1 [astro-ph.HE])

The Disk-Wind-Jet Connection in the Black Hole H 1743-322. (arXiv:1208.4514v1 [astro-ph.HE]):
X-ray disk winds are detected in spectrally soft, disk-dominated phases of
stellar-mass black hole outbursts. In contrast, compact, steady, relativistic
jets are detected in spectrally hard states that are dominated by non-thermal
X-ray emission. Although these distinctive outflows appear to be almost
mutually exclusive, it is possible that a disk wind persists in hard states but
cannot be detected via X-ray absorption lines owing to very high ionization.
Here, we present an analysis of a deep, 60 ksec Chandra/HETGS observation of
the black hole candidate H 1743-322 in the low/hard state. The spectrum shows
no evidence of a disk wind, with tight limits, and within the range of ionizing
flux levels that were measured in prior Chandra observations wherein a wind was
clearly detected. In H 1743-322, at least, disk winds are actually diminished
in the low/hard state, and disk winds and jets are likely state-dependent and
anti-correlated. These results suggest that although the launching radii of
winds and jets may differ by orders of magnitude, they may both be tied to a
fundamental property of the inner accretion flow, such as the mass accretion
rate and/or the magnetic field topology of the disk. We discuss these results
in the context of disk winds and jets in other stellar-mass black holes, and
possible launching mechanisms for black hole outflows.

Benchmarking atomic data for astrophysics: a first look at the soft X-ray lines. (arXiv:1208.2142v1 [astro-ph.SR])

Benchmarking atomic data for astrophysics: a first look at the soft X-ray lines. (arXiv:1208.2142v1 [astro-ph.SR]):
A collection of the best solar and laboratory spectra in the soft X-rays is
used here to perform a preliminary benchmark in this wavelength region, by
comparing observed vs. predicted wavelengths and calibrated solar irradiances.
The benchmark focuses on the Fe IX - Fe XIV ions,for which we have recently
calculated the relevant atomic data, however a few other ions have also been
benchmarked. The iron ions are dominating the soft X-rays, however a large
fraction of the strongest soft X-ray lines due to n=4 -> n=3 transitions were
previously unidentified. The strongest transitions are all identified here, in
particular the decays from the core-excited levels (3s 3p^l 4s, l=$ 5,4,3,2,1
for Fe X, Fe XI, Fe XII, Fe XIII, and Fe XIV respectively) which are the
strongest soft X-ray transitions from these ions. Many new identifications are
proposed, some only tentatively. Good agreement in terms of solar irradiances
between the soft X-ray and EUV (n=3 -> n=3) transitions is found, confirming
the reliability of the new large-scale calculations. Some of the new atomic
data and identifications are particularly important for the Solar Dynamic
Observatory (SDO) Atmospheric Imaging Assembly (AIA) 94 A band.

X-ray photoionized bubble in the wind of Vela X-1 pulsar supergiant companion. (arXiv:1208.1827v1 [astro-ph.SR])

X-ray photoionized bubble in the wind of Vela X-1 pulsar supergiant companion. (arXiv:1208.1827v1 [astro-ph.SR]):
Vela X-1 is the archetype of high-mass X-ray binaries, composed of a neutron
star and a massive B supergiant. The supergiant is a source of a strong
radiatively-driven stellar wind. The neutron star sweeps up this wind, and
creates a huge amount of X-rays as a result of energy release during the
process of wind accretion. Here we provide detailed NLTE models of the Vela X-1
envelope. We study how the X-rays photoionize the wind and destroy the ions
responsible for the wind acceleration. The resulting decrease of the radiative
force explains the observed reduction of the wind terminal velocity in a
direction to the neutron star. The X-rays create a distinct photoionized region
around the neutron star filled with a stagnating flow. The existence of such
photoionized bubbles is a general property of high-mass X-ray binaries. We
unveiled a new principle governing these complex objects, according to which
there is an upper limit to the X-ray luminosity the compact star can have
without suspending the wind due to inefficient line driving

On the Weak-Wind Problem in Massive Stars: X-ray Spectra Reveal a Massive Hot Wind in \mu\ Columbae. (arXiv:1208.0820v1 [astro-ph.SR])

On the Weak-Wind Problem in Massive Stars: X-ray Spectra Reveal a Massive Hot Wind in \mu\ Columbae. (arXiv:1208.0820v1 [astro-ph.SR]):
\mu\ Columbae is a prototypical weak-wind O-star for which we have obtained a
high-resolution X-ray spectrum with the Chandra LETG/ACIS-S instrument and a
low resolution spectrum with Suzaku. This allows us, for the first time, to
investigate the role of X-rays on the wind structure in a bona fide weak-wind
system and to determine whether there actually is a massive, hot wind. The
X-ray emission measure indicates that the outflow is an order of magnitude
greater than that derived from UV lines and is commensurate with the nominal
wind-luminosity relationship for O-stars. Therefore, the ``weak-wind
problem''---identified from cool wind UV/optical spectra---is largely resolved
by accounting for the hot wind seen in X-rays. From X-ray line profiles,
Doppler shifts, and relative strengths, we find that this weak-wind star is
typical of other late O dwarfs. The X-ray spectra do not suggest a magnetically
confined plasma---the spectrum is soft and lines are broadened; Suzaku spectra
confirm the lack of emission above 2 keV. Nor do the relative line shifts and
widths suggest any wind decoupling by ions. The He-like triplets indicate that
the bulk of the X-ray emission is formed rather close to the star, within 5
stellar radii. Our results challenge the idea that some OB stars are
``weak-wind'' stars that deviate from the standard wind-luminosity
relationship. The wind is not weak, but it is hot and its bulk is only
detectable in X-rays.