pinecone/core-2020-05-10-deduplication huggingface dataset:
CHEERS: Future perspectives for abundance measurements in clusters with
  XMM-Newton

The CHEERS (CHEmical Enrichment RGS Sample) observations of clusters of
galaxies with XMM-Newton have shown to be valuable to constrain the chemical
evolution of the universe. The soft X-ray spectrum contains lines of the most
abundant metals from N to Ni, which provide relatively accurate abundances that
can be compared to supernova enrichment models. The accuracy of the abundances
is currently limited by systematic uncertainties introduced by the available
instruments and uncertainties in the modeling of the spectra, which are of the
order of 20-30%. We discuss the possible gain of extending the current samples
at low and high redshift. We conclude that expanding the samples would be
expensive in terms of exposure time, but will not yield significantly improved
results, because the current samples already reach the systematic limits. New
instrumentation, like Astro-H2 and ATHENA, and improvements to the atomic
databases are needed to make significant advances in this field.Comment: 7 pages, accepted for publication in Astronomische Nachrichten as
  part of the proceedings of the workshop 'XMM-Newton: The Next Decade', ESAC,
  Madrid, Spain, 9 - 11 May 201
X-ray selection of Compton Thick AGN at high redshift

Compton Thick (CT) AGN are a key ingredient of Cosmic X-ray Background (CXB)
synthesis models, but are still an elusive component of the AGN population
beyond the local Universe. Multi-wavelength surveys are the only way to find
them at z > 0.1, and a deep X-ray coverage is crucial in order to clearly
identify them among star forming galaxies. As an example, the deep and wide
COSMOS survey allowed us to select a total of 34 CT sources. This number is
computed from the 64 nominal CT candidates, each counted for its N H
probability distribution function. For each of these sources, rich
multi-wavelength information is available, and is used to confirm their
obscured nature, by comparing the expected AGN luminosity from spectral energy
distribution fitting, with the absorption-corrected X-ray luminosity. While
Chandra is more efficient, for a given exposure, in detecting CT candidates in
current surveys (by a factor ~2), deep XMM-Newton pointings of bright sources
are vital to fully characterize their properties: NH distribution above 10^25
cm^-2, reflection intensity etc., all crucial parameters of CXB models. Since
luminous CT AGN at high redshift are extremely rare, the future of CT studies
at high redshift will have to rely on the large area surveys currently
underway, such as XMM-XXL and Stripe82, and will then require dedicated
follow-up with XMM-Newton, while waiting for the advent of the ESA mission
Athena.Comment: 6 pages, 7 figures, to appear in Astronomische Nachrichten, presented
  at the XMM-Newton: The Next Decade conference, ESAC, Madrid, Spain, 9 - 11
  May 201
Cosmology with AGN: can we use quasars as standard candles?

The non-linear relation between X-ray and UV luminosity in quasars can be
used to estimate their distance. Recently, we have shown that despite the large
dispersion of the relation, a Hubble Diagram made of large samples of quasars
can provide unique constraints on cosmology at high redshift. Furthermore, the
dispersion of the relation is heavily affected by measurement errors: until now
we have used serendipitous X-ray observations, but dedicated observations would
significantly increase the precision of the distance estimates. We discuss the
future role of XMM in this new field, showing (1) the fundamental contribution
of the Serendipitous Source Catalogue and of large surveys, and (2) the
breakthrough advancements we may achieve with the observation of a large number
of SDSS quasars at high redshift: every ~10 quasars observed at z$\sim$3 would
be equivalent to discovering a supernova at that redshift.Comment: 5 pages, 6 figures, to appear in Astronomische Nachrichten, presented
  at the XMM-Newton: The Next Decade conference, ESAC, Madrid, Spain, 9 - 11
  May 201
Follow-up of eROSITA and Euclid Galaxy Clusters with XMM-Newton

A revolution in galaxy cluster science is only a few years away. The survey
machines eROSITA and Euclid will provide cluster samples of never-before-seen
statistical quality. XMM-Newton will be the key instrument to exploit these
rich datasets in terms of detailed follow-up of the cluster hot gas content,
systematically characterizing sub-samples as well as exotic new objects.Comment: 5 pages; to appear in Astronomische Nachrichten, presented at the
  "XMM-Newton: The Next Decade" conference, ESAC, Madrid, Spain, 9 - 11 May
  201
Simultaneous spectra and radio properties of BL Lac's

We present the results of nine years of the blazar observing programme at the
RATAN-600 radio telescope (2005-2014). The data were obtained at six frequency
bands (1.1, 2.3, 4.8, 7.7, 11.2, 21.7 GHz) for 290 blazars, mostly BL Lacs. In
addition, we used data at 37 GHz obtained quasi-simultaneously with the
Metsahovi radio observatory for some sources. The sample includes blazars of
three types: high-synchrotron peaked (HSP), low-synchrotron peaked (LSP), and
intermediate-synchrotron peaked (ISP). We present several epochs of flux
density measurements, simultaneous radio spectra, spectral indices and
properties of their variability. The analysis of the radio properties of
different classes of blazars showed that LSP and HSP BL Lac blazars are quite
different objects on average. LSPs have higher flux densities, flatter spectra
and their variability increases as higher frequencies are considered. On the
other hand, HSPs are very faint in radio domain, tend to have steep low
frequency spectra, and they are less variable than LSPs at all frequencies.
Another result is spectral flattening above 7.7 GHz detected in HSPs, while an
average LSP spectrum typically remains flat at both the low and high frequency
ranges we considered.Comment: 14 pages, 6 figures. Accepted for publication in Astronomische
  Nachrichte
Discovery of optical flickering from the symbiotic star EF Aquilae

We report optical CCD photometry of the recently identified symbiotic star EF
Aql. Our observations in Johnson V and B bands clearly show the presence of
stochastic light variations with an amplitude of about 0.2 mag on a time scale
of minutes. The observations point toward a white dwarf (WD) as the hot
component in the system. It is the 11-th object among more than 200 symbiotic
stars known with detected optical flickering. Estimates of the mass accretion
rate onto the WD and the mass loss rate in the wind of the Mira secondary star
lead to the conclusion that less than 1 per cent of the wind is captured by the
WD. Eight further candidates for the detection of flickering in similar systems
are suggested.Comment: 5 pages, submitted to A
Radial velocity measurements and orbit determination of eight
  single-lined spectroscopic binary systems

Since early 2015 a new radial velocity monitoring campaign is going on at the
University Observatory Jena. The aim of this project is to obtain current
radial velocity measurements of selected single-lined spectroscopic binary
systems, to redetermine and/or constrain their orbital solutions. In this paper
we characterize the properties of the target sample of the project, describe
the spectroscopic observations, the data-reduction and analysis and present the
first results of the project, taken with the fiber-linked astronomical
spectrograph FLECHAS. We present 391 radial velocity measurements of eight
spectroscopic binaries, which were taken within an epoch difference of 1.6
years. These radial velocities were used to determine the spectroscopic orbital
elements of the observed binary systems, which exhibit orbital periods in the
range between nearly one up to several dozens of days. We could constrain the
orbital solutions of seven of these binary systems, and redetermine the orbital
solution of phi Dra, whose orbit exhibits >4 times longer orbital period and is
more eccentric than given in the 9th Catalogue of Spectroscopic Binary Orbits.Comment: 10 pages, 1 figure, 13 tables, accepted for publication in A
Considerations on how to investigate planes of satellite galaxies

The existence of a spatially thin, kinematically coherent Disk of Satellites
(DoS) around the Milky Way (MW), is a problem that often garners vivacious
debate in the literature or at scientific meetings. One of the most recent
incarnations of this wrangle occurred with two papers by Maji et al, who argued
that these structures "maybe a misinterpretation of the data". These claims are
in stark contrast to previous works. Motivated by this and other recent
publications on this problem, we discuss necessary considerations to make,
observational effects to consider, and pitfalls to avoid when investigating
satellite galaxy planes such as the MW's DoS. In particular, we emphasize that
conclusions need to have a statistical basis including a determination of the
significance of satellite alignments, observational biases must not be ignored,
and measurement errors (e.g. for proper motions) need to be considered. We
discuss general problems faced by attempts to determine the dynamical stability
of the DoS via orbit integrations of MW satellite galaxies, and demonstrate
that to interpret simulations, it is helpful to compare them with a null case
of isotropically distributed satellite positions and velocities. Based on these
criteria, we find that the conclusions of Maji et al. do not hold up to
scrutiny, and that their hydrodynamic cosmological simulation of a single host
shows no evidence for a significant kinematic coherence among the simulated
satellite galaxies, in contrast to the observed MW system.Comment: 8 pages, 3 figures. Accepted for publication in Astronomische
  Nachrichten / Astronomical Note
The Pristine survey II: a sample of bright stars observed with FEROS

Extremely metal-poor (EMP) stars are old objects formed in the first Gyr of
the Universe. They are rare and, to select them, the most successful strategy
has been to build on large and low-resolution spectroscopic surveys. The
combination of narrow- and broad band photometry provides a powerful and
cheaper alternative to select metal-poor stars. The on-going Pristine Survey is
adopting this strategy, conducting photometry with the CFHT MegaCam wide field
imager and a narrow-band filter centred at 395.2 nm on the CaII-H and -K lines.
In this paper we present the results of the spectroscopic follow-up conducted
on a sample of 26 stars at the bright end of the magnitude range of the Survey
(g<=15), using FEROS at the MPG/ESO 2.2 m telescope. From our chemical
investigation on the sample, we conclude that this magnitude range is too
bright to use the SDSS gri bands, which are typically saturated. Instead the
Pristine photometry can be usefully combined with the APASS gri photometry to
provide reliable metallicity estimates.Comment: AN accepte
Stringent limits on the masses of the supermassive black holes in seven
  nearby galaxies

We present new stringent limits on the mass $M_{bh}$ of the central
supermassive black hole for a sample of 7 nearby galaxies. Our $M_{bh}$
estimates are based on the dynamical modeling of the central width of the
nebular emission lines measured over subarcsecond apertures with the Hubble
Space Telescope. The central stellar velocity dispersion $\sigma_c$ of the
sample galaxies is derived from new long-slit spectra from ground-based
observations and the bulge effective radius is obtained from a two-dimensional
photometric decomposition of the i-band images from the Sloan Digital Sky
Survey. The derived stringent $M_{bh}$ limits run parallel and above the
$M_{bh}-\sigma_c$ relation with no systematic trend depending on the galaxy
distance or morphology. This gives further support to previous findings
suggesting that the nuclear gravitational potential is remarkably well traced
by the width of the nebular lines when the gas is centrally peaked. With our
investigation, the number of galaxies with stringent $M_{bh}$ limits obtained
from nebular-line width increases to 114 and can be used for studying the
scaling relations between $M_{bh}$ and properties of their host galaxies.Comment: 13 pages, 8 figures, AN in pres
Supernova Ejecta in Ocean Cores Used as Time Constraints for Nearby
  Stellar Groups

Evidence of a supernova event, discussed in Wallner et al., was discovered in
the deep-sea crusts with two signals dating back to 2-3 and 7-9 Myr ago. In
this contribution, we place constraints on the birth-site of the supernova
progenitors from the ejecta timeline, the initial mass function, and the ages
of nearby stellar groups. We investigated the Scorpius-Centaurus OB
Association, the nearest site of recent massive star formation, and the moving
group Tucana-Horologium. Using the known stellar mass of the remaining massive
stars within these subgroups and factoring in travel time for the ejecta, we
have constrained the ages and masses of the supernova progenitors by using the
initial mass function and then compared the results to the canonical ages of
each subgroup. Our results identify the Upper Scorpius and Lower Centaurus-Crux
subgroups as unlikely birth-sites for these supernovae. We find that
Tucana-Horologium is the likely birth-site of the supernova 7-9 Myr ago and
Upper Centaurus-Lupus is the likely birth-site for the supernova 2-3 Myr ago.Comment: 9 Pages, 3 figures, 8 table
Near-UV transit photometry of HAT-P-32 b with the LBT: Silicate aerosols
  in the planetary atmosphere

Broad-band exoplanet transit photometry can characterize the planetary
atmosphere when observed at multiple selected filters. This observing technique
can reveal gradients in the spectra of extrasolar planets, for example the
slope of decreasing opacity from short to long optical wavelengths caused by
aerosol scattering. In this work we observed a transit of the hot Jupiter
HAT-P-32 b in the shortest wavelength possible from the ground using the Large
Binocular Telescope (LBT). The data comprise the best-quality ground-based
U-band taken so far of an exoplanet transit. Compared to broad-band
observations of intermediate and long optical wavelength published previously,
a clear scattering slope in the planetary transmission spectrum is revealed.
Most likely, the scattering particles are magnesium silicate aerosols larger
than 0.1 micrometer. We define a spectral index to compare this scattering
feature of HAT-P-32 b to published results of other exoplanets. It turns out to
be very typical in amplitude within the comparison sample. Furthermore, we
searched for correlation in this sample of the spectral index with planetary
equilibrium temperature, surface acceleration and stellar activity indicator,
but could not reveal any.Comment: accepted for publication in Astronomical Notes (AN). Version2,
  several typos correcte
Discovery of a New Quasar: SDSS J022155.26-064916.6

We report the discovery of a new quasar: SDSS J022155.26-064916.6. This
object was discovered while reducing spectra of a sample of stars being
considered as spectrophotometric standards for the Dark Energy Survey. The flux
and wavelength calibrated spectrum is presented with four spectral lines
identified. From these lines, the redshift is determined to be z is
approximately equal to 0.806. In addition, the rest-frame u-, g-, and r-band
luminosity, determined using a k-correction obtained with synthetic photometry
of a proxy QSO, are reported as 7.496 $\times 10^{13}$ solar luminosities,
2.049 $\times 10^{13}$ solar luminosities, and $1.896 \times 10^{13}$ solar
luminosities, respectively
A new approach for short-spacing correction of radio interferometric
  data sets

The short-spacing problem describes the inherent inability of
radio-interferometric arrays to measure the integrated flux and structure of
diffuse emission associated with extended sources. New interferometric arrays,
such as SKA, require solutions to efficiently combine interferometer and
single-dish data.
  We present a new and open source approach for merging single-dish and cleaned
interferometric data sets requiring a minimum of data manipulation while
offering a rigid flux determination and full high angular resolution. Our
approach combines single-dish and cleaned interferometric data in the image
domain. This approach is tested for both Galactic and extragalactic HI data
sets. Furthermore, a quantitative comparison of our results to commonly used
methods is provided. Additionally, for the interferometric data sets of NGC4214
and NGC5055, we study the impact of different imaging parameters as well as
their influence on the combination for NGC4214.
  The approach does not require the raw data (visibilities) or any additional
special information such as antenna patterns. This is advantageous especially
in the light of upcoming radio surveys with heterogeneous antenna designs.Comment: 15 pages, accepted for publication by Astronomical Note
The contribution of kinetic helicity to turbulent magnetic diffusivity

Using numerical simulations of forced turbulence, it is shown that for
magnetic Reynolds numbers larger than unity, i.e., beyond the regime of
quasilinear theory, the turbulent magnetic diffusivity attains an additional
negative contribution that is quadratic in the kinetic helicity. In particular,
for large magnetic Reynolds numbers, the turbulent magnetic diffusivity without
helicity is about twice the value with helicity. Such a contribution was not
previously anticipated, but, as we discuss, it turns out to be important when
accurate estimates of the turbulent magnetic diffusivity are needed.Comment: 4 pages, 4 figures, Astron. Nachr., in pres
PLATO as it is: a legacy mission for Galactic archaeology

Deciphering the assembly history of the Milky Way is a formidable task, which
becomes possible only if one can produce high-resolution
chrono-chemo-kinematical maps of the Galaxy. Data from large-scale astrometric
and spectroscopic surveys will soon provide us with a well-defined view of the
current chemo-kinematical structure of the Milky Way, but will only enable a
blurred view on the temporal sequence that led to the present-day Galaxy. As
demonstrated by the (ongoing) exploitation of data from the pioneering
photometric missions CoRoT, Kepler, and K2, asteroseismology provides the way
forward: solar-like oscillating giants are excellent evolutionary clocks thanks
to the availability of seismic constraints on their mass and to the tight
age-initial-mass relation they adhere to. In this paper we identify five key
outstanding questions relating to the formation and evolution of the Milky Way
that will need precise and accurate ages for large samples of stars to be
addressed, and we identify the requirements in terms of number of targets and
the precision on the stellar properties that are needed to tackle such
questions. By quantifying the asteroseismic yields expected from PLATO for
red-giant stars, we demonstrate that these requirements are within the
capabilities of the current instrument design, provided that observations are
sufficiently long to identify the evolutionary state and allow robust and
precise determination of acoustic-mode frequencies. This will allow us to
harvest data of sufficient quality to reach a 10% precision in age. This is a
fundamental pre-requisite to then reach the more ambitious goal of a similar
level of accuracy, which will only be possible if we have to hand a careful
appraisal of systematic uncertainties on age deriving from our limited
understanding of stellar physics, a goal which conveniently falls within the
main aims of PLATO's core science.Comment: 17 pages, 9 figures, accepted for publication in Astronomical Note
Galaxy overdensities around 3C radio galaxies and quasars at $1<z<2.5$
  revealed by Spitzer $3.6/4.5\mu$m and Pan-STARRS

Luminous radio sources are thought to lie in galaxy clusters or
proto-clusters. The complete sample of 64 high-redshift 3C sources at $1<z<2.5$
has been mapped with the Spitzer Space Telescope. The IRAC $3.6\mu$m and
$4.5\mu$m 5-$\sigma$ detection limit of $4\mu$Jy (22.4 AB mag) allows us to
search for the brightest candidate cluster member galaxies associated with the
3C sources. To remove the contamination of foreground stars and galaxies along
the lines of sight toward the 3C sources we apply color cuts: removed sources
satisfy either the IRAC1/2 cut $[3.6] - [4.5] < -0.3$ or the Pan-STARRS/IRAC
cut $i - [4.5] < 0.5$ if detected by Pan-STARRS. For both selection methods,
about half of the 3C radio sources show significant overdensities ($>3\sigma$)
within 30" ($\sim$250 kpc) projected distance from the radio source compared to
the surrounding galaxy densities measured in the $50''-120''$ annulus. The
Pan-STARRS/IRAC cut reveals higher average overdensities than the IRAC1/2 cut
and also a decline of overdensities at $z>1.4$. To infer the nature of the
cluster members, we rerun the analysis using a stronger IRAC1/2 cut $[3.6] -
[4.5] < -0.1$ which removes $1<z<1.4$ passive ellipticals but not star-forming
galaxies. For the strong cut, the overdensities, on average, completely
disappear at $1<z<1.4$. We therefore suggest that the 4.5$\mu$m detected
cluster member galaxies are mainly passive ellipticals
Interacting Fields and Flows: Magnetic Hot Jupiters

We present Magnetohydrodynamic (MHD) simulations of the magnetic interactions
between a solar type star and short period hot Jupiter exoplanets, using the
publicly available MHD code PLUTO. It has been predicted that emission due to
magnetic interactions such as the electron cyclotron maser instability (ECMI)
will be observable. In our simulations, a planetary outflow, due to UV
evaporation of the exoplanets atmosphere, results in the build-up of
circumplanetary material. We predict the ECMI emission and determine that the
emission is prevented from escaping from the system. This is due to the
evaporated material leading to a high plasma frequency in the vicinity of the
planet, which inhibits the ECMI process.Comment: Conference proceedings: "14th Potsdam Thinkshop: Stellar Magnetism:
  Challenges, Connections, and Prospects", Potsdam 201
Long-term variations of turbulent transport coefficients in a solar-like
  convective dynamo simulation

The Sun, aside from its eleven year sunspot cycle is additionally subject to
long term variation in its activity. In this work we analyse a solar-like
convective dynamo simulation, containing approximately 60 magnetic cycles,
exhibiting equatorward propagation of the magnetic field, multiple frequencies,
and irregular variability, including a missed cycle and complex parity
transitions between dipolar and quadrupolar modes. We compute the turbulent
transport coefficients, describing the effects of the turbulent velocity field
on the mean magnetic field, using the test-field method. The test-field
analysis provides a plausible explanation of the missing cycle in terms of the
reduction of $\alpha_{\phi\phi}$ in advance of the reduced surface activity,
and enhanced downward turbulent pumping during the event to confine some of the
magnetic field at the bottom of the convection zone, where local maximum of
magnetic energy is observed during the event. At the same time, however, a
quenching of the turbulent magnetic diffusivities is observed, albeit
differently distributed in depth compared to the other transport coefficients.
Therefore, dedicated mean-field modelling is required for verification.Comment: 11 pages, 12 figures, accepted by AN for 14th Potsdam Thinksho