pinecone/core-2020-05-10-deduplication huggingface dataset:
On the angular distribution of IceCube high-energy events

The detection of high-energy astrophysical neutrinos of extraterrestrial
origin by the IceCube neutrino observatory in Antarctica has opened a unique
window to the cosmos that may help to probe both the distant Universe and our
cosmic backyard. The arrival directions of these high-energy events have been
interpreted as uniformly distributed on the celestial sphere. Here, we revisit
the topic of the putative isotropic angular distribution of these events
applying Monte Carlo techniques to investigate a possible anisotropy. A modest
evidence for anisotropy is found. An excess of events appears projected towards
a section of the Local Void, where the density of galaxies with radial
velocities below 3000 km/s is rather low, suggesting that this particular group
of somewhat clustered sources are located either very close to the Milky Way or
perhaps beyond 40 Mpc. The results of further analyses of the subsample of
southern hemisphere events favour an origin at cosmological distances with the
arrival directions of the events organized in a fractal-like structure.
Although a small fraction of closer sources is possible, remote hierarchical
structures appear to be the main source of these very energetic neutrinos. Some
of the events may have their origin at the IBEX ribbon.Comment: 8 pages, 6 figures, 1 table. Astronomische Nachrichten, 336, 657-664
  (September 2015). Minor correction
Dynamo saturation in direct simulations of the multi-phase turbulent
  interstellar medium

The ordered magnetic field observed via polarized synchrotron emission in
nearby disc galaxies can be explained by a mean-field dynamo operating in the
diffuse interstellar medium (ISM). Additionally, vertical-flux initial
conditions are potentially able to influence this dynamo via the occurrence of
the magneto-rotational instability (MRI). We aim to study the influence of
various initial field configurations on the saturated state of the mean-field
dynamo. This is motivated by the observation that different saturation behavior
was previously obtained for different supernova rates. We perform direct
numerical simulations (DNS) of three-dimensional local boxes of the vertically
stratified, turbulent interstellar medium, employing shearing-periodic boundary
conditions horizontally. Unlike in our previous work, we also impose a vertical
seed magnetic field. We run the simulations until the growth of the magnetic
energy becomes negligible. We furthermore perform simulations of equivalent 1D
dynamo models, with an algebraic quenching mechanism for the dynamo
coefficients. We compare the saturation of the magnetic field in the DNS with
the algebraic quenching of a mean-field dynamo. The final magnetic field
strength found in the direct simulation is in excellent agreement with a
quenched $\alpha\Omega$~dynamo. For supernova rates representative of the Milky
Way, field losses via a Galactic wind are likely responsible for saturation. We
conclude that the relative strength of the turbulent and regular magnetic
fields in spiral galaxies may depend on the galaxy's star formation rate. We
propose that a mean field approach with algebraic quenching may serve as a
simple sub-grid scale model for galaxy evolution simulations including a
prescribed feedback from magnetic fields
Effects of Turbulent Viscosity on A Rotating Gas Ring Around A Black
  Hole: Results in Numerical Simulation

In this paper, we present the time evolution of a rotationally axisymmetric
gas ring around a non rotating black hole using two dimensional grid-based
hydrodynamic simulation. We show the way in which angular momentum transport is
included in simulations of non-self-gravitating accretion of matter towards a
black hole. We use the Shakura-Sunyaev {\alpha} viscosity prescription to
estimate the turbulent viscosity for all major viscous stress tensors. We
investigate how a gas ring which is initially assumed to rotate with Keplerian
angular velocity is accreted on to a black hole and hence forms accretion disc
in the presence of turbulent viscosity. We show that the centrifugal pressure
supported sub-Keplerian flow with shocks forms when the ring starts to disperse
with inclusion of relatively small amount of viscosity. But, if the viscosity
is above the critical value, the shock disappears altogether and the whole disc
becomes Kepleiran which is subsonic everywhere except in a region close to the
horizon, where it supersonically enters to the black hole. We discovered a
multiple valued Mach number solution and the corresponding density
distributions that connects matter (a) from the initial Keplerian gas ring to a
sub-Keplerian disc with shocks in presence of small amount of viscosity and (b)
from the sub-Keplerian flow to a Keplerian disc in presence of huge amount of
viscosity. We calculate the temporal variations of the magnitude of various
time scales which ensure us about the stability of the flow.Comment: 8 pages, 7 figs, Accepted for Publication in AN. arXiv admin note:
  text overlap with arXiv:1307.3635, arXiv:1210.3515 by other author
Magnetic, chemically peculiar (CP2) stars in the SuperWASP survey

The magnetic chemically peculiar (CP2) stars of the upper main sequence are
well-suited for investigating the impact of magnetic fields on the surface
layers of stars, which leads to abundance inhomogeneities (spots) resulting in
photometric variability. The light changes are explained in terms of the
oblique rotator model; the derived photometric periods thus correlate with the
rotational periods of the stars. CP2 stars exhibiting this kind of variability
are classified as alpha2 Canum Venaticorum (ACV) variables. We have analysed
around 3 850 000 individual photometric WASP measurements of magnetic
chemically peculiar (CP2) stars and candidates selected from the Catalogue of
Ap, HgMn, and Am stars, with the ultimate goal of detecting new ACV variables.
In total, we found 80 variables, from which 74 are reported here for the first
time. The data allowed us to establish variability for 23 stars which had been
reported as probably constant in the literature before. Light curve parameters
were obtained for all stars by a least-squares fit with the fundamental sine
wave and its first harmonic. Because of the scarcity of Stroemgren uvbybeta
measurements and the lack of parallax measurements with an accuracy better than
20%, we are not able to give reliable astrophysical parameters for the
investigated objects.Comment: 10 pages, 1 figure, 1 tabl
Status of the Cherenkov Telescope Array Project

Gamma-ray astronomy holds a great potential for Astrophysics, Particle
Physics and Cosmology. The CTA is an inter- national initiative to build the
next generation of ground-based gamma-ray observatories, which will represent a
factor of 5-10 times improvement in the sensitivity of observations in the
range 100 GeV - 10 TeV, as well as an extension of the observational
capabilities down to energies below 100 GeV and beyond 100 TeV. The array will
consist of two telescope networks (one in the Northern Hemisphere and another
in the South) so to achieve a full-sky coverage, and will be com- posed by a
hybrid system of 4 different telescope types. It will operate as an
observatory, granting open access to the community through calls for submission
of proposals competing for observation time. The CTA will give us access to the
non-thermal and high-energy universe at an unprecedented level, and will be one
of the main instruments for high-energy astrophysics and astroparticle physics
of the next 30 years. CTA has now entered its prototyping phase with the first,
stand-alone instruments being built. Brazil is an active member of the CTA
consortium, and the project is represented in Latin America also by Argentina,
Mexico and Chile. In the next few months the consortium will define the site
for instal- lation of CTA South, which might come to be hosted in the Chilean
Andes, with important impact for the high-energy community in Latin America. In
this talk we will present the basic concepts of the CTA and the detailed
project of the observatory. Emphasis will be put on its scientific potential
and on the Latin-American involvement in the preparation and construction of
the observatory, whose first seed, the ASTRI mini-array, is currently being
constructed in Sicily, in a cooperation between Italy, Brazil and South Africa.Comment: 5 pages, 2 figures, Proceedings of Third Caribbean Symposium on
  Cosmology, Gravitation, Nuclear and Astroparticle Physics (STARS2015
  Conference), Havana, Cuba (10-16/May/2015
Chemical composition of a sample of bright solar-metallicity stars

We present a detailed analysis of seven young stars observed with the
spectrograph SOPHIE at the Observatoire de Haute-Provence for which the
chemical composition was incomplete or absent in the literature. For five
stars, we derived the stellar parameters and chemical compositions using our
automatic pipeline optimized for F, G, and K stars, while for the other two
stars with high rotational velocity, we derived the stellar parameters by using
other information (parallax), and performed a line-by-line analysis.
Chromospheric emission-line fluxes from CaII are obtained for all targets. The
stellar parameters we derive are generally in good agreement with what is
available in the literature. We provide a chemical analysis of two of the stars
for the first time. The star HIP 80124 shows a strong Li feature at 670.8 nm
implying a high lithium abundance. Its chemical pattern is not consistent with
it being a solar sibling, as has been suggested.Comment: To be published on A
Peranso - Light Curve and Period Analysis Software

A time series is a sample of observations of well-defined data points
obtained through repeated measurements over a certain time range. The analysis
of such data samples has become increasingly important not only in natural
science but also in many other fields of research. Peranso offers a complete
set of powerful light curve and period analysis functions to work with large,
astronomical data sets. Substantial attention has been given to ease-of-use and
data accuracy, making it one of the most productive time series analysis
software available. In this paper, we give an introduction to Peranso and its
functionality.Comment: 8 pages, 1 figur
Radio properties of Compact Steep Spectrum and GHz-Peaked Spectrum radio
  sources

Compact steep spectrum (CSS) and GHz-peaked spectrum (GPS) radio sources
represent a large fraction of the extragalactic objects in flux density-limited
samples. They are compact, powerful radio sources whose synchrotron peak
frequency ranges between a few hundred MHz to several GHz. CSS and GPS radio
sources are currently interpreted as objects in which the radio emission is in
an early evolutionary stage. In this contribution I review the radio properties
and the physical characteristics of this class of radio sources, and the
interplay between their radio emission and the ambient medium of the host
galaxy.Comment: 9 pages, 4 figures. Accepted for publication in Astronomische
  Nachrichten. Review presented at the 5th Workshop on CSS and GPS radio
  sources, held in Rimini (Italy) in May 201
Radio source evolution

Baldwin (1982) wrote that \emph{the distribution of sources in the radio
luminosity, $P$, overall physical size, $D$, diagram} could be considered as
\emph{the radio astronomer's $H-R$ diagram}. However, unlike the case of stars,
not only the intrinsic properties of the jets, but also those of the host
galaxy and the intergalactic medium are relevant to explain the evolutionary
tracks of radio radio sources. In this contribution I review the current status
of our understanding of the evolution of radio sources from a theoretical and
numerical perspective, using the $P-D$ diagram as a framework. An excess of
compact (linear size $\leq 10$~kpc) sources could be explained by low-power
jets being decelerated within the host galaxy, as shown by recent numerical
simulations. Finally, I discuss the possible tracks that radio sources may
follow within this diagram, and the physical processes that can explain the
different tracks.Comment: Submitted for publication in Astronomische Nachrichten. Review
  contribution to the proceedings of the 5th Workshop on CSS and GPS radio
  sources, held in Rimini (Italy) in May 2015. Applied some minor corrections
  as suggested by the referee and updated the bibliograph
Dichotomy in the population of young AGN: optical, radio and X-ray
  properties

There are numerous examples of radio sources with various sizes which
surprisingly exhibit very similar morphology. This observational fact helped to
create a standard evolutionary model in which young and small radio-loud active
galactic nuclei (AGN) called gigahertz-peaked spectrum (GPS) sources and
compact steep spectrum (CSS) sources, become large-scale radio objects.
However, many details of this evolutionary process are still unclear. We
explored evolution scenarios of radio-loud AGN using new radio, optical and
X-ray data of so far unstudied low luminosity compact (LLC) sources and we
summarize the results in this paper. Our studies show that the evolutionary
track is very 'personalized' although we can mention common factors affecting
it. These are interaction with the ambient medium and AGN power. The second
feature affects the production of the radio jets which if they are weak are
more vulnerable for instabilities and disruption. Thus not all GPS and CSS
sources will be able to develop large scale morphologies. Many will fade away
being middle-aged (10^5 years). It seems that only radio strong, high
excitation compact AGN can be progenitors of large-scale FRII radio sources.Comment: 4 pages, 3 figures, Accepted for publication in Astronomische
  Nachrichten. Contribution to the proceedings of the 5th Workshop on CSS and
  GPS radio sources, held in Rimini (Italy) in May 201
A LOFAR view on the duty cycle of young radio sources

Compact Steep Spectrum, Gigahertz Peaked Spectrum and High Frequency Peak
(CSS, GPS, HFP) sources are considered to be young radio sources but the
details of their duty cycle are not well understood. In some cases they are
thought to develop in large radio galaxies, while in other cases their jets may
experience intermittent activity or die prematurely and remain confined within
the host galaxy. By studying in a systematic way the presence and the
properties of any extended emission surrounding these compact sources we can
provide firmer constraints on their evolutionary history and on the timescales
of activity of the radio source. Remnant emission from previous outbursts is
supposed to have very low surface brightness and to be brighter at low
frequency. Taking advantage of the unprecedented sensitivity and resolution
provided by the Low Frequency Array (LOFAR) we have started a systematic search
of new CSS, GPS and HFP sources with extended emission, as well as a more
detailed study of some well-known of these sources. Here we present the key
points of our search in the LOFAR fields and a more in-depth analysis on the
source B2 0258+35, a CSS source surrounded by a pair of large, diffuse radio
lobes.Comment: 5 pages, 2 figures, in press for Astronomische Nachrichten.
  Contribution to the Proceedings of the "Fifth Workshop on Compact Steep
  Spectrum and GHz-Peaked Spectrum Radio Sources", held in Rimini (Italy) in
  May 201
An Evolutionary Sequence of Young Radio Galaxies

We have observed the faintest sample of Gigahertz Peaked Spectrum (GPS) and
Compact Steep Spectrum (CSS) sources to date, using the Australia Telescope
Compact Array. We test the hypothesis that GPS and CSS sources are the youngest
radio galaxies, place them into an evolutionary sequence along with a number of
other young Active Galactic Nuclei (AGN) candidates, and search for evidence of
the evolving accretion mode and its relationship to star formation. GPS/CSS
sources have very small radio jets that have been recently launched from the
central Supermassive Black Hole and grow in linear size as they evolve, which
means that the linear size of the jets is an excellent indicator of the
evolutionary stage of the AGN. We use high-resolution radio observations to
determine the linear size of GPS/CSS sources, resolve their jets and observe
their small-scale morphologies. We combine this with other multi-wavelength age
indicators, including the spectral age, colours, optical spectra and Spectral
Energy Distribution of the host galaxy, in an attempt to assemble all age
indicators into a self-consistent model. We observe the most compact sources
with Very Large Baseline Interferometry, which reveals their parsec-scale
structures, giving us a range of source sizes and allowing us to test what
fraction of GPS/CSS sources are young and evolving.Comment: 6 pages, 3 figures, accepted in Astronomische Nachrichten as part of
  proceedings for the 5th workshop on Compact Steep Spectrum and GHz-Peaked
  Spectrum Radio Source
Fossil shell emission in dying radio loud AGNs

We investigate shell emission associated with dying radio loud AGNs. First,
based on our recent work by Ito et al. (2015), we describe the dynamical and
spectral evolutions of shells after stopping the jet energy injection. We find
that the shell emission overwhelms that of the radio lobes soon after stopping
the jet energy injection because fresh electrons are continuously supplied into
the shell via the forward shock while the radio lobes rapidly fade out without
jet energy injection. We find that such fossil shells can be a new class of
target sources for SKA telescope. Next, we apply the model to the nearby radio
source 3C84. Then, we find that the fossil shell emission in 3C84 is less
luminous in radio band while it is bright in TeV gamma-ray band and it can be
detectable by CTA.Comment: 5 pages, 5 figures, 1 table, in press for Astronomische Nachrichten.
  Contribution to the Proceedings of the "Fifth Workshop on Compact Steep
  Spectrum and GHz-Peaked Spectrum Radio Sources", held in Rimini (Italy) in
  May 201
The Fermi-LAT view of young radio sources

Compact Symmetric Objects (CSO) are considered to be the young version of
Fanaroff-Riley type I and type II radio galaxies, with typical sizes smaller
than 1 kpc and ages of the order of a few thousand years. Before the launch of
the Fermi satellite, young radio sources were predicted to emerge as a possible
new gamma-ray emitting population detectable by the Large Area Telescope (LAT).
After more than 6 years of Fermi operation the question of young radio sources
as gamma-ray emitting objects still remains open. In this contribution we
discuss candidate gamma-ray emitting CSO and future perspective for detecting
young radio sources with Fermi-LAT.Comment: 6 pages, 4 figures. Proceedings of the 5th Workshop on CSS and GPS
  radio sources, held in Rimini (Italy) in 2015 May 27-29. To be published in
  Astronomische Nachrichte
Radio Properties of the $\gamma$-ray Emitting CSO Candidate 2234+282

Most of the gamma-ray emitting active galactic nuclei (AGN) are blazars,
although there is still a small fraction of non-blazar AGN in the Fermi/LAT
catalog. Among these misaligned gamma-ray-emitting AGN, a few can be classified
as Compact Symmetric Objects (CSOs). In contrast to blazars in which gamma-ray
emission is generally thought to originate from highly beamed relativistic
jets, the source of gamma-ray emission in unbeamed CSOs remains an open
question. The rarity of the gamma-ray emitting CSOs is a mystery as well. Here
we present the radio properties of the gamma-ray CSO candidate 2234+282.Comment: 4 pages, accepted for publication in Astronomische Nachrichte
Accretion in active galactic nuclei and disk-jet coupling

We review the current state of understanding how accretion onto a black hole
proceeds and what are they key elements needed to form relativistic jets. Since
the theoretical progress is severely halted by the lack of deep understanding
of the microphysics involved, particularly in the presence of strong magnetic
fields, all proposed solutions have a status of models, and their selection has
to be based directly on observational constraints.Comment: Review presented at the conference 5th Workshop on Compact Steep
  Spectrum and GHz-Peaked Spectrum Radio Sources, Rimini, comments welcom
Search for Extreme Rotation Measures in CSS Sources

Magnetized plasmas traversed by linearly polarized light will reveal their
presence by the frequency dependent Faraday rotation of the angle of
polarization. The regions surrounding the black holes powering the jets in AGNs
are expected to have dense magnetized plasmas, possibly giving rise to very
large Faraday rotations. Compact steep spectrum (CSS) sources are good
candidates to search for very large Faraday rotated components as they contain
compact emission from close to the black hole and many are strongly depolarized
at centimeter wavelengths as expected from strong Faraday effects. We present
data on several CSS sources (3C48, 3C138 and 3C147) observed with the VLA at
frequencies between 20 and 48 GHz in the most extended configuration. Large,
but not excessive rotation measures are reported
A possible link between high rotation measure and CSS-GPS sources

We report here the study, in the radio band, of a sample of candidates of
high Rotation Measure (RM). The point-like objects (at kpc scale) were selected
by choosing unpolarised sources from the NVSS which show significant linear
polarisation at 10.45 GHz. Assuming in-band depolarisation, this feature
suggests the presence of a very dense medium surrounding them in a combination
of a strong magnetic field. Further single-dish observations were performed
with the 100-m Effelsberg telescope to characterise the SEDs of the sample and
to well determine their RM in the 11 to 2 cm wavelength range. Besides, a
wideband (L, S, C and X band ) full polarisation observational campaign was
performed at the JVLA facility. It allows us to analyse the in-band RM for the
most extreme objects. Some Effelsberg results and analysis, and preliminary
JVLA results are presented. The observations reveal that sources with young,
newly growing, radio components at high frequency (i.e. GPS and HFP sources)
are characterised by a really dense and/or a magnetised medium that strongly
rotates the polarisation angle at the different frequencies, leading to a
high-RM.Comment: Paper accepted to by published on Astronomische Nachrichten Journal.
  arXiv admin note: text overlap with arXiv:1510.0113