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.

Terrestrial effects of possible astrophysical sources of an AD 774-775 increase in 14C production. (arXiv:1302.1501v2 [astro-ph.SR] UPDATED)

Terrestrial effects of possible astrophysical sources of an AD 774-775 increase in 14C production. (arXiv:1302.1501v2 [astro-ph.SR] UPDATED):
We examine possible sources of a substantial increase in tree ring 14C
measurements for the years AD 774-775. Contrary to claims regarding a coronal
mass ejection (CME), the required CME energy is not several orders of magnitude
greater than known solar events. We consider solar proton events (SPEs) with
three different fluences and two different spectra. The data may be explained
by an event with fluence about one order of magnitude beyond the October 1989
SPE. Two hard spectrum cases considered here result in moderate ozone
depletion, so no mass extinction is implied, though we do predict increases in
erythema and damage to plants from enhanced solar UV. We are able to rule out
an event with a very soft spectrum that causes severe ozone depletion and
subsequent biological impacts. Nitrate enhancements are consistent with their
apparent absence in ice core data. The modern technological implications of
such an event may be extreme, and considering recent confirmation of
superflares on solar-type stars, this issue merits attention.

The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission. (arXiv:1301.7307v1 [astro-ph.IM])

The Nuclear Spectroscopic Telescope Array (NuSTAR) Mission. (arXiv:1301.7307v1 [astro-ph.IM]):
The Nuclear Spectroscopic Telescope Array (NuSTAR) mission, launched on 13
June 2012, is the first focusing high-energy X-ray telescope in orbit. NuSTAR
operates in the band from 3 -- 79 keV, extending the sensitivity of focusing
far beyond the ~10 keV high-energy cutoff achieved by all previous X-ray
satellites. The inherently low-background associated with concentrating the
X-ray light enables NuSTAR to probe the hard X-ray sky with a more than
one-hundred-fold improvement in sensitivity over the collimated or coded-mask
instruments that have operated in this bandpass. Using its unprecedented
combination of sensitivity, spatial and spectral resolution, NuSTAR will pursue
five primary scientific objectives, and will also undertake a broad program of
targeted observations. The observatory consists of two co-aligned
grazing-incidence X-ray telescopes pointed at celestial targets by a three-axis
stabilized spacecraft. Deployed into a 600 km, near-circular, 6degree
inclination orbit, the Observatory has now completed commissioning, and is
performing consistent with pre-launch expectations. NuSTAR is now executing its
primary science mission, and with an expected orbit lifetime of ten years, we
anticipate proposing a guest investigator program, to begin in Fall 2014.

Relative velocity of dark matter and barions in clusters of galaxies and measurements of their peculiar velocities. (arXiv:1301.0024v1 [astro-ph.CO])

Relative velocity of dark matter and barions in clusters of galaxies and measurements of their peculiar velocities. (arXiv:1301.0024v1 [astro-ph.CO]):
The increasing sensitivity of current experiments, which nowadays routinely
measure the thermal SZ effect within galaxy clusters, provide the hope that
peculiar velocities of individual clusters of galaxies will be measured rather
soon using the kinematic SZ effect. Also next generation of X-ray telescopes
with microcalorimeters, promise first detections of the motion of the intra
cluster medium (ICM) within clusters. We used a large set of cosmological,
hydrodynamical simulations, which cover very large cosmological volume, hosting
a large number of rich clusters of galaxies, as well as moderate volumes where
the internal structures of individual galaxy clusters can be resolved with very
high resolution to investigate, how the presence of baryons and their
associated physical processes like cooling and star-formation are affecting the
systematic difference between mass averaged velocities of dark matter and the
ICM inside a cluster. We, for the first time, quantify the peculiar motion of
galaxy clusters as function of the large scale environment. We also demonstrate
that especially in very massive systems, the relative velocity of the ICM
compared to the cluster peculiar velocity add significant scatter onto the
inferred peculiar velocity, especially when measurements are limited to the
central regions of the cluster. Depending on the aperture used, this scatter
varies between 50% and 20%, when going from the core (e.g. ten percent of the
virial radius) to the full cluster (e.g. the virial radius).

The Fractional Ionization of the Warm Neutral Interstellar Medium. (arXiv:1301.3144v1 [astro-ph.GA])

The Fractional Ionization of the Warm Neutral Interstellar Medium. (arXiv:1301.3144v1 [astro-ph.GA]):
When the neutral interstellar medium is exposed to EUV and soft X ray
radiation, the argon atoms in it are far more susceptible to being ionized than
the hydrogen atoms. We make use of this fact to determine the level of
ionization in the nearby, warm, neutral medium (WNM). By analyzing FUSE
observations of ultraviolet spectra of 44 hot subdwarf stars a few hundred pc
away from the Sun, we can compare column densities of Ar I to those of O I,
where the relative ionization of oxygen can be used as a proxy for that of
hydrogen. The measured deficiency [ Ar I/O I]= 0.427+/- 0.11dex below the
expectation for a fully neutral medium implies that the electron density n(e)
\sim 0.04cm^- 3 if n(H)=0.5cm^- 3. This amount of ionization is considerably
larger than what we expect from primary photoionizations resulting from cosmic
rays, the diffuse X-ray background, and X-ray emitting sources within the
medium, along with the additional ionizations caused by energetic secondary
photoelectrons, Auger electrons, and photons from helium recombinations. We
favor an explanation that bursts of radiation created by previous, nearby
supernova remnants that have faded by now may have elevated the ionization, and
the gas has not yet recombined to a quiescent level. A different alternative is
that the low energy portion of the soft X ray background is poorly shielded by
the H I because it is frothy and has internal pockets of very hot, X-ray
emitting gases.

Long Term Variability of O VII Line Intensity toward the Lockman Hole Observed with Suzaku from 2006 to 2011. (arXiv:1301.5174v1 [astro-ph.HE])

Long Term Variability of O VII Line Intensity toward the Lockman Hole Observed with Suzaku from 2006 to 2011. (arXiv:1301.5174v1 [astro-ph.HE]):
Long-term time variabilities of the OVII (0.57 keV) emission in the soft
X-ray diffuse background were studied using six Suzaku annual observations of
blank sky towards the Lockman Hole made from 2006 to 2011. After time intervals
in which the emission was enhanced on time scales of a few tens of ks were
removed, the O VII intensity was found to be constant from 2006 to 2009 within
the 90% statistical errors. The intensity in 2010 and 2011 was higher by 2-3 LU
(photons/s/cm/sr) than the earlier values. The most plausible origin of the
fast variable component is Solar wind charge exchange (SWCX). The intensity
increase is not positively correlated with the proton flux at the L1 point.
Since all the observations were made in the same season of a year, the
variation cannot be explained by parallax of the SWCX induced X-ray emission
from the Heliosphere. We consider that it is related to the geometrical change
of slow and fast solar wind structures associated with the 11 year solar
activity. The observed variation was compared with that expected from the SWCX
induced X-ray emission model.

The Structure of the X-ray and Optical Emitting Regions of the Lensed Quasar Q 2237+0305. (arXiv:1301.5009v1 [astro-ph.CO])

The Structure of the X-ray and Optical Emitting Regions of the Lensed Quasar Q 2237+0305. (arXiv:1301.5009v1 [astro-ph.CO]):
We use gravitational microlensing to determine the size of the X-ray and
optical emission regions of the quadruple lens system Q 2237+0305. The optical
half-light radius, log(R_{1/2,V}/cm)=16.41\pm0.18 (at lambda_{rest}=2018 \AA),
is significantly larger than the observed soft,
log(R_{1/2,soft}/cm)=15.76^{+0.41}_{-0.34} (1.1-3.5 keV in the rest frame), and
hard, log(R_{1/2,hard}/cm)=15.46^{+0.34}_{-0.29} (3.5-21.5 keV in the rest
frame), band X-ray emission. There is a weak evidence that the hard component
is more compact than the soft, with log(R_{1/2,soft}/R_{1/2,hard}) \sim
0.30^{+0.53}_{-0.45}. This wavelength-dependent structure agrees with recent
results found in other lens systems using microlensing techniques, and favors
geometries in which the corona is concentrated near the inner edge of the
accretion disk. While the available measurements are limited, the size of the
X-ray emission region appears to be roughly proportional to the mass of the
central black hole.

The brightest ULIRG:watching the birth of a quasar. (arXiv:1301.3953v1 [astro-ph.CO])

The brightest ULIRG:watching the birth of a quasar. (arXiv:1301.3953v1 [astro-ph.CO]):
The extreme ULIRG F00183-7111 has recently been found to have a radio-loud
AGN with jets in its centre, representing an extreme example of the class of
radio-loud AGNs buried within dusty star-forming galaxies. This source appears
to be a rare example of a ULIRG glimpsed in the (presumably) brief period as it
changes from "quasar mode" to "radio mode" activity. Such transition stages
probably account for many of the high-redshift radio-galaxies and extreme
high-redshift ULIRGs, and so this object at the relatively low redshift of
0.328 offers a rare opportunity to study this class of objects in detail. We
have also detected the CO signal from this galaxy with the ATCA, and here
describe the implications of this detection for future ULIRG studies.

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.

A Chandra X-ray study of the interacting binaries in the old open cluster NGC6791. (arXiv:1301.2331v1 [astro-ph.HE])

A Chandra X-ray study of the interacting binaries in the old open cluster NGC6791. (arXiv:1301.2331v1 [astro-ph.HE]):
We present the first X-ray study of NGC6791, one of the oldest open clusters
known (8 Gyr). Our Chandra observation is aimed at uncovering the population of
close interacting binaries down to Lx ~ 1e30 erg/s (0.3-7 keV). We detect 86
sources within 8 arcmin of the cluster center, including 59 inside the
half-mass radius. We identify twenty sources with proper-motion cluster
members, which are a mix of cataclysmic variables (CVs), active binaries (ABs),
and binaries containing sub-subgiants. With follow-up optical spectroscopy we
confirm the nature of one CV. We discover one new, X-ray variable candidate CV
with Balmer and HeII emission lines in its optical spectrum; this is the first
X-ray--selected CV confirmed in an open cluster. The number of CVs per unit
mass is consistent with the field, suggesting that the 3-4 CVs observed in
NGC6791 are primordial. We compare the X-ray properties of NGC6791 with those
of a few old open (NGC6819, M67) and globular clusters (47Tuc, NGC6397). It is
puzzling that the number of ABs brighter than 1e30 erg/s normalized by cluster
mass is lower in NGC6791 than in M67 by a factor ~3 to 7. CVs, ABs, and
sub-subgiants brighter than 1e30 erg/s are under-represented per unit mass in
the globular clusters compared to the oldest open clusters, and this accounts
for the lower total X-ray luminosity per unit mass of the former. This
indicates that the net effect of dynamical encounters may be the destruction of
even some of the hardest (i.e. X-ray--emitting) binaries.

Clusters of galaxies and variation of the fine structure constant. (arXiv:1212.1075v1 [astro-ph.CO])

Clusters of galaxies and variation of the fine structure constant. (arXiv:1212.1075v1 [astro-ph.CO]):
We propose a new method to probe for variations in the fine structure
constant alpha using clusters of galaxies, opening up a window on a new
redshift range for such constraints. Hot clusters shine in the X-ray mainly due
to bremsstrahlung, while they leave an imprint on the CMB frequency spectrum
through the Sunyaev-Zel'dovich effect. These two physical processes can be
characterized by the integrated Comptonization parameter Y_SZ DA^2 and its
X-ray counterpart, the Y_X parameter. The ratio of these two quantities is
expected to be constant from numerical simulations and current observations. We
show that this fact can be exploited to constrain alpha, as the ratio of the
two parameters depends on the fine structure constant as alpha^{3.5}. We
determine current constraints from a combination of Planck SZ and XMM-Newton
data, testing different models of variation of alpha. When fitting for a
constant value of alpha, we find that current constraints are at the 1% level,
comparable with current CMB constraints. We discuss strategies for further
improving these constraints by almost an order of magnitude.

X-ray Echo from the Sagittarius C Complex and 500-year Activity History of Sagittarius A*. (arXiv:1211.4529v1 [astro-ph.GA])

X-ray Echo from the Sagittarius C Complex and 500-year Activity History of Sagittarius A*. (arXiv:1211.4529v1 [astro-ph.GA]):
This paper presents the Suzaku results obtained for the Sagittarius (Sgr) C
region using the concept of X-ray reflection nebulae (XRNe) as the echo of past
flares from the super massive black hole, Sgr A*. The Sgr C complex is composed
of several molecular clouds proximately located in projected distance. The
X-ray spectra of Sgr C were analyzed on the basis of a view that XRNe are
located inside the Galactic center plasma X-ray emission with an oval
distribution around Sgr A*. We found that the XRNe are largely separated in the
line-of-sight position, and are associated with molecular clouds in different
velocity ranges detected by radio observations. We also applied the same
analysis to the Sgr B XRNe and completed a long-term light curve for Sgr A*
occurring in the past. As a new finding, we determined that Sgr A* was
experiencing periods of high luminosity already 500 years ago, which is longer
than the previously reported value. Our results are consistent with a scenario
that Sgr A* was continuously active with sporadic flux variabilities of Lx =
1-3 x 10^39 erg s^-1 in the past 50 to 500 years. The average past luminosity
was approximately 4-6 orders of magnitude higher than that presently observed.
In addition, two short-term flares of 5-10 years are found. Thus, the past
X-ray flare should not be a single short-term flare, but can be interpreted as
multiple flares superposed on a long-term high state.

Search for serendipitous TNO occultation in X-rays. (arXiv:1211.4650v1 [astro-ph.EP])

Search for serendipitous TNO occultation in X-rays. (arXiv:1211.4650v1 [astro-ph.EP]):
To study the population properties of small, remote objects beyond Neptune's
orbit in the outer solar system, of kilometer size or smaller, serendipitous
occultation search is so far the only way. For hectometer-sized Trans-Neptunian
Objects (TNOs), optical shadows actually disappear because of diffraction.
Observations at shorter wave lengths are needed. Here we report the effort of
TNO occultation search in X-rays using RXTE/PCA data of Sco X-1 taken from June
2007 to October 2011. No definite TNO occultation events were found in the 334
ks data. We investigate the detection efficiency dependence on the TNO size to
better define the sensible size range of our approach and suggest upper limits
to the TNO size distribution in the size range from 30 m to 300 m. A list of
X-ray sources suitable for future larger facilities to observe is proposed.

Plerionic Supernova Remnants. (arXiv:1210.5406v1 [astro-ph.GA])

Plerionic Supernova Remnants. (arXiv:1210.5406v1 [astro-ph.GA]):
Plerions represent ideal laboratories for the search for neutron stars, the
study of their relativistic winds, and their interaction with their surrounding
supernova ejecta and/or the interstellar medium. As well, they are widely
believed to represent efficient engines for particle acceleration up to the
knee of the cosmic ray spectrum (at about 1E15 eV). Multi-wavelength
observations from the radio to the highest TeV energies, combined with
modelling, have opened a new window to study these objects, and particularly
shed light on their intrinsic properties, diversity, and evolution.
High-resolution X-ray observations are further revealing the structure and
sites for shock acceleration. The missing shells in the majority of these
objects remain puzzling, and the presence of plerions around highly magnetized
neutron stars is still questionable. I review the current status and statistics
of observations of plerionic supernova remnants (SNRs), highlighting combined
radio and X-ray observations of a growing class of atypical, non Crab-like,
plerionic SNRs in our Galaxy. I will also briefly describe the latest
developments to our high-energy SNRs catalogue recently released to the
community, and finally highlight the key questions to be addressed in this
field with future high-energy missions, including Astro-H in the very near
future.

A High-Energy Catalogue of Galactic Supernova Remnants and Pulsar Wind Nebulae. (arXiv:1210.5264v1 [astro-ph.GA])

A High-Energy Catalogue of Galactic Supernova Remnants and Pulsar Wind Nebulae. (arXiv:1210.5264v1 [astro-ph.GA]):
Motivated by the wealth of past, existing, and upcoming X-ray and gamma-ray
missions, we have developed the first public database of high-energy
observations of all known Galactic Supernova Remnants (SNRs):
this http URL The catalogue links to, and
complements, other existing related catalogues, including Dave Green's radio
SNRs catalogue. We here highlight the features of the high-energy catalogue,
including allowing users to filter or sort data for various purposes. The
catalogue is currently targeted to Galactic SNR observations with X-ray and
gamma-ray missions, and is timely with the upcoming launch of X-ray missions
(including Astro-H). We are currently developing the existing database to
include an up-to-date Pulsar Wind Nebulae (PWNe)-dedicated webpage, with the
goal to provide a global view of PWNe and their associated neutron
stars/pulsars. This extensive database will be useful to both theorists to
apply their models or design numerical simulations, and to observers to plan
future observations or design new instruments. We welcome input and feedback
from the SNR/PWN/neutron stars community.

EITHER keV sterile neutrinos OR quasi-degenerate active neutrinos. (arXiv:1210.6036v1 [hep-ph])

EITHER keV sterile neutrinos OR quasi-degenerate active neutrinos. (arXiv:1210.6036v1 [hep-ph]):
We present a No-Go theorem for keV sterile neutrino Dark Matter: if sterile
neutrinos at the keV scale play the role of Dark Matter, they are typically
unstable and their decay produces an astrophysical monoenergetic X-ray line. It
turns out that the observational bound on this line is so strong that it
contradicts the existence of a quasi-degenerate spectrum of active neutrinos in
a seesaw type I framework where the Casas-Ibarra matrix R is real. This is the
case in particular for models without CP violation. We give a general proof of
this theorem. While the theorem (like every No-Go theorem) relies on certain
assumptions, the situation under which it applies is still sufficiently general
to lead to interesting consequences for keV neutrino model building. In fact,
depending on the outcome of the next generation experiments, one might be able
to rule out whole classes of models for keV sterile neutrinos.

The ASTRO-H X-ray Observatory. (arXiv:1210.4378v1 [astro-ph.IM])

The ASTRO-H X-ray Observatory. (arXiv:1210.4378v1 [astro-ph.IM]):
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly
successful X-ray missions initiated by the Institute of Space and Astronautical
Science (ISAS). ASTRO-H will investigate the physics of the high-energy
universe via a suite of four instruments, covering a very wide energy range,
from 0.3 keV to 600 keV. These instruments include a high-resolution,
high-throughput spectrometer sensitive over 0.3-2 keV with high spectral
resolution of Delta E < 7 eV, enabled by a micro-calorimeter array located in
the focal plane of thin-foil X-ray optics; hard X-ray imaging spectrometers
covering 5-80 keV, located in the focal plane of multilayer-coated, focusing
hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4-12
keV, with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and
a non-focusing Compton-camera type soft gamma-ray detector, sensitive in the
40-600 keV band. The simultaneous broad bandpass, coupled with high spectral
resolution, will enable the pursuit of a wide variety of important science
themes.

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.

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.

Black hole bombs and photon mass bounds. (arXiv:1209.0465v1 [gr-qc] CROSS LISTED)

Black hole bombs and photon mass bounds. (arXiv:1209.0465v1 [gr-qc] CROSS LISTED):
Generic extensions of the standard model predict the existence of ultralight
bosonic degrees of freedom. Several ongoing experiments are aimed at detecting
these particles or constraining their mass range. Here we show that massive
vector fields around rotating black holes can give rise to a strong
superradiant instability which extracts angular momentum from the hole. The
observation of supermassive spinning black holes imposes limits on this
mechanism. We show that current supermassive black hole spin estimates provide
the tightest upper limits on the mass of the photon (mv<4x10^{-20} eV according
to our most conservative estimate), and that spin measurements for the largest
known supermassive black holes could further lower this bound to mv<10^{-22}
eV. Our analysis relies on a novel framework to study perturbations of rotating
Kerr black holes in the slow-rotation regime, that we developed up to second
order in rotation, and that can be extended to other spacetime metrics and
other theories.