pinecone/core-2020-05-10-deduplication huggingface dataset:
Massive black hole recoil in high resolution hosts

The final inspiral and coalescence of a black hole binary can produce highly beamed gravitational wave radiation. To conserve linear momentum, the black hole remnant can recoil with kick velocity vkick 4000 km/s. We present two sets of full N-body simulations of recoiling massive black holes (MBH) in high-resolution, non-axisymmetric potentials. The host to the first set of simulations is the main halo of the Via Lactea I simulation (Diemand et al. 2007). The nature of the resulting orbits is investigated through a numerical model where orbits are integrated assuming an evolving, triaxial NFWpotential, and dynamical friction is calculated directly from the velocity dispersion along the major axes of the main halo of Via Lactea I. By comparing the triaxial case to a spherical model, we find that the wandering time spent by the MBH is significantly increased due to the asphericity of the halo. For kicks larger than 200 km/s, the remnant MBH does not return to the inner 200 pc within 1 Gyr, a timescale an order of magnitude larger than the upper limit of the estimated QSO lifetime. The second set of simulations is run using the outcome of a high-resolution gas-rich merger (Mayer et al. 2007) as host potential. In this case, a recoil velocity of 500 km/s cannot remove the MBH from the nuclear region. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Towards an accurate model for the Antennae Galaxies

In the framework of hierarchical structure formation ellipticals can form
from merging of smaller disk galaxies. The nearby interacting 'Antennae' galaxy
pair (NGC 4038/39) is one of the best-studied local systems of merging spirals,
thus presenting us with an ideal laboratory for the study of galaxy evolution
models. The Antennae are believed to be in a state prior to their final
encounter with rapid subsequent merging, which puts them in the first position
of the Toomre (1977) merger sequence. Here we present first numerical
high-resolution, self-consistent, smoothed particle hydrodynamics (SPH)
simulations of the Antennae system, including star formation and stellar
feedback, and compare our results to VLA HI observations by Hibbard et al.
(2001). We are able to obtain a close, but not yet perfect match to the
observed morphology and kinematics of the system.Comment: To be published in the proceedings of the "Galactic and Stellar
  Dynamics 2008" conference. 4 pages, 5 figures, 1 tabl
Pairing mechanisms for binary stars

Knowledge of the binary population in stellar groupings provides important
information about the outcome of the star forming process in different
environments. Binarity is also a key ingredient in stellar population studies
and is a prerequisite to calibrate the binary evolution channels. In these
proceedings we present an overview of several commonly used methods to pair
individual stars into binary systems, which we refer to as the pairing
function. Many pairing functions are frequently used by observers and
computational astronomers, either for the mathematical convenience, or because
they roughly describe the expected outcome of the star forming process. We
discuss the consequences of each pairing function for the interpretation of
observations and numerical simulations. The binary fraction and mass ratio
distribution generally depend strongly on the selection of the range in primary
spectral type in a sample. These quantities, when derived from a binary survey
with a mass-limited sample of target stars, are thus not representative for the
population as a whole.Comment: 4 pages, 2 figures, in: Galactic and stellar dynamics in the era of
  high-resolution surveys, Boily C., Combes F., Hensler G., eds., Strasbourg
  (France), March 2008, in press (Astron. Nachr.
Radial velocities, dynamics of stars and nebulosities with GAIA and
  VLT-GIRAFFE

This document is divided in two parts. The first part deals with the radial
velocities (RV) distributions for B-type stars and nebulosities observed with
the VLT-GIRAFFE in the Large and Small Magellanic Clouds towards the open
clusters NGC2004 and NGC330. Thanks to the resolution of GIRAFFE spectra, we
found that the RV distribution for the nebulosities in the LMC is bi-modal.
This bi-modality can be interpreted, in term of dynamics, by the expansion of
the LMC4 superbubble. The second part deals with the GAIA space mission and the
determination of the radial velocities by using Radial Velocity Spectrometer
(RVS) spectra. The methods to determine the radial velocities are presented as
well as preliminary results on simulated RVS spectra.Comment: Proceedings GSD2008 conference, submitted to A
Termination of star formation by BH feedback in equal- and unequal-mass
  mergers of disk and elliptical galaxies

We present binary galaxy merger simulations of gas-rich disks (Sp-Sp), of
early-type galaxies and disks (E-Sp, mixed mergers), and mergers of early-type
galaxies (E-E, dry mergers) with varying mass ratios and different progenitor
morphologies. The simulations include radiative cooling, star formation and
black hole (BH) accretion and the associated feedback processes. We find for
Sp-Sp mergers, that the peak star formation rate and BH accretion rate decrease
and the growth timescales of the central black holes and newly formed stars
increase with higher progenitor mass ratios. The termination of star formation
by BH feedback in disk mergers is significantly less important for higher
progenitor mass ratios (e.g. 3:1 and higher). In addition, the inclusion of BH
feedback suppresses efficiently star formation in dry E-E mergers and mixed
E-Sp mergers.Comment: To be published in the proceedings of the "Galactic and Stellar
  Dynamics 2008" conference. 4 pages, 4 figure
Sigma-drop in galaxies and the sigma-metallicity degeneracy

In some galaxies, the central velocity dispersion, sigma, is depressed with
respect to the surroundings. This sigma-drop phenomenon may have different
physical origins, bearing information about the internal dynamics of the host
galaxy. In this article, we stress the importance also of observational
artifacts due to the sigma-metallicity degeneracy: when a spectrum of a
population is compared with a template of miss-matched metallicity, the
velocity dispersion may be wrongly estimated. A sigma-drop may appear in place
of a metallicity peak. The discussion is illustrated using VLT/FORS spectra of
diffuse elliptical galaxies. Some of the sigma-drop galaxies reported in the
literature may be analysis artifacts.Comment: (1) Observatoire de Lyon, France (2) University of Sofia, Bulgaria
  (3) Ghent University, Belgium 4 pages, 3 figures. Proceeding at Galactic &
  Stellar Dynamics conference, Strasbourg 2008, To appear in Astronomische
  Nachrichte
APOGEE: The Apache Point Observatory Galactic Evolution Experiment

APOGEE is a large-scale, NIR, high-resolution (R~20,000) spectroscopic survey
of Galactic stars. It is one of the four experiments in SDSS-III. Because
APOGEE will observe in the H band, it will be the first survey to pierce
through Galactic dust and provide a vast, uniform database of chemical
abundances and radial velocities for stars across all Galactic populations
(bulge, disk, and halo). The survey will be conducted with a dedicated,
300-fiber, cryogenic, spectrograph that is being built at the University of
Virginia, coupled to the ARC 2.5m telescope at Apache Point Observatory. APOGEE
will use a significant fraction of the SDSS-III bright time during a three-year
period to observe, at high signal-to-noise ratio (S/N>100), about 100,000 giant
stars selected directly from 2MASS down to a typical flux limit of H<13. The
main scientific objectives of APOGEE are: (1) measuring unbiased metallicity
distributions and abundance patterns for the different Galactic stellar
populations, (2) studying the processes of star formation, feedback, and
chemical mixing in the Milky Way, (3) surveying the dynamics of the bulge and
disk, placing constraints on the nature and influence of the Galactic bar and
spiral arms, and (4) using extensive chemodynamical data, particularly in the
inner Galaxy, to unravel its formation and evolution.Comment: 4 pages, 2 figures; proceedings of the conference on Galactic &
  Stellar Dynamics in Strasbourg 16-20 March 200
Peculiarities in the stellar velocity distribution of galaxies with a
  two-armed spiral structure

We expand our pervious numerical study of the properties of the stellar
velocity distribution within the disk of a two-armed spiral galaxy by
considering spiral stellar density waves with different global Fourier
amplitudes, C_2. We confirm our previous conclusion that the ratio
\sigma_1:\sigma_2 of smallest versus largest principal axes of the stellar
velocity ellipsoid becomes abnormally small near the outer edges of the stellar
spiral arms. The extent to which the stellar velocity ellipsoid is elongated
(as compared to the unperturbed value typical for the axisymmetric disk)
increases with the strength of the spiral density wave. In particular, the
C_2=0.06 spiral can decrease the unperturbed value of \sigma_1:\sigma_2 by 20%,
while the C_2=0.13 spiral can decrease the unperturbed \sigma_1:\sigma_2 by a
factor of 3. The abnormally small values of the \sigma_1:\sigma_2 ratio can
potentially be used to track the position of {\it stellar} spiral density
waves. The \sigma_{\phi\phi}:\sigma_{rr} ratio is characterized by a more
complex behaviour and exhibits less definite minima near the outer edges of the
spiral arms. We find that the epicycle approximation is violated near the
spiral arms and cannot be used in spiral galaxies with C_2 >= 0.05-0.06 or in
galaxies with the amplitude of the spiral stellar density wave (relative to the
unperturbed background) of order 0.1 or greater.Comment: 4 pages, 3 figures, conference presentation at "Galactic and Stellar
  Dynamics in the Era of High-resolution Surveys", Strasbourg 16-20 March 200
The chromospherically active binary star EI Eridani II. Long-term
  Doppler imaging

Data from 11 years of continuous spectroscopic observations of the active RS
CVn-type binary star EI Eridani - gained at NSO/McMath-Pierce, KPNO/Coude Feed
and during the MUSICOS 98 campaign - were used to obtain 34 Doppler maps in
three spectroscopic lines for 32 epochs, 28 of which are independent of each
other. Various parameters are extracted from our Doppler maps: average
temperature, fractional spottedness, and longitudinal and latitudinal
spot-occurrence functions. We find that none of these parameters show a
distinct variation nor a correlation with the proposed activity cycle as seen
from photometric long-term observations. This suggests that the photometric
brightness cycle may not necessarily be due to just a cool spot cycle. The
general morphology of the spot pattern remains persistent over the whole period
of 11 years. A large cap-like polar spot was recovered from all our images. A
high degree of variable activity was noticed near latitudes of approx. 60-70
degrees where the appendages of the polar spot emerged and dissolved
Structure, spectra and variability of some GPS radio sources

We report the results of multifrequency-VLBI observations of
GHz-Peaked-Spectrum (GPS) radio sources. The VLBI structure and component
spectra of some GPS sources are presented. Our VLBI results show that about 80%
of the GPS galaxies exhibit a compact double or CSO-like structure, while the
GPS quasars tend to show a core-jet. The component spectra of the GPS galaxies
are often steep/convex, and the core has a flat spectrum but it is usually
hidden or weak. In addition, we studied the variability of GPS sources by
comparing new flux density measures, acquired with the Urumqi 25m telescope at
4.85 GHz, with previous 87GB data. The results show that 44% of the GPS quasars
varied higher than 10% in passed 20 years, while the fraction is only 12% for
the GPS galaxies meaning that the GPS quasars are much more variable than GPS
galaxies. In total, 25% of GPS sources show >10% variability at 4.85 GHz in our
sample.Comment: 4 pages, 7 figure
Modelling the broad-band spectra of X-ray emitting GPS galaxies

The study of the broad-band emission of GHz-Peaked-Spectrum (GPS) radio
galaxies is a powerful tool to investigate the physical processes taking place
in the central, kpc-sized region of their active hosts, where the jets
propagate and the lobes expand, interacting with the surrounding interstellar
medium (ISM). We recently developed a new dynamical-radiative model to describe
the evolution of the GPS phenomenon (Stawarz et al. 2008): as the relativistic
jets propagate through the ISM, gradually engulfing narrow-line emitting gas
clouds along their way, the electron population of the expanding lobes evolves,
emitting synchrotron light, as well as inverse-Compton radiation via
up-scattering of the photon fields from the host galaxy and its active nucleus.
The model, which successfully reproduces the key features of the GPS radio
sources as a class, provides a description of the evolution of their spectral
energy distribution (SED) with the lobes' expansion, predicting significant and
complex X-ray to gamma-ray emission. We apply here the model to the broad-band
SED's of a sample of known, X-ray emitting GPS galaxies, and show that: (i) the
free-free absorption mechanism enables us to reproduce the radio continuum at
frequencies below the turnover; (ii) the lobes' non-thermal, inverse-Compton
emission can account for the observed X-ray spectra, providing a viable
alternative to the thermal, accretion-dominated scenario. We also show that, in
our sample, the relationship between the X-ray and radio hydrogen column
densitities, N_H and N_HI, is suggestive of a positive correlation, which, if
confirmed, would support the scenario of high-energy emitting lobes.Comment: 4 pages, 2 figures, accepted for publication in Astronomische
  Nachrichten (issue dedicated to the Proceedings of "The Fourth Workshop on
  Compact Steep Spectrum and GHz-Peaked Spectrum Radio Sources"
Radio Bimodality: Spin, Accretion Mode, or Both?

A new scenario is suggested to explain a large diversity of the AGN radio
properties and their dependence on the galaxy morphology. The scenario is based
on the assumption that the growth of supermassive BHs is dominated by the
accretion only during the quasar (high accretion rate) phase, otherwise - by
mergers with less massive black holes. Following that, BHs are expected to spin
much faster in giant ellipticals than in disk galaxies. Within the frame of the
spin paradigm this explains the observed relation of the radio-dichotomy with
the galaxy morphology. Various theoretical and observational aspects of such a
dichotomy are discussed. In particular, the issue of the intermittency and
suppression of a jet production at high accretion rates is addressed and a
scenario for production of powerful, extended radio sources is drafted.Comment: 4 pages, accepted for publication in Astronomische Nachrichten (issue
  dedicated to the Proceedings of "The 4th Workshop on Compact Steep Spectrum
  and GHz-Peaked Spectrum Radio Sources" held at Riccione, Italy, 26-29 May
  2008
EURONEAR - Data Mining of Asteroids and Near Earth Asteroids

Besides new observations, mining old photographic plates and CCD image
archives represents an opportunity to recover and secure newly discovered
asteroids, also to improve the orbits of Near Earth Asteroids (NEAs),
Potentially Hazardous Asteroids (PHAs) and Virtual Impactors (VIs). These are
the main research aims of the EURONEAR network. As stated by the IAU, the vast
collection of image archives stored worldwide is still insufficiently explored,
and could be mined for known NEAs and other asteroids appearing occasionally in
their fields. This data mining could be eased using a server to search and
classify findings based on the asteroid class and the discovery date as
"precoveries" or "recoveries". We built PRECOVERY, a public facility which uses
the Virtual Observatory SkyBoT webservice of IMCCE to search for all known
Solar System objects in a given observation. To datamine an entire archive,
PRECOVERY requires the observing log in a standard format and outputs a
database listing the sorted encounters of NEAs, PHAs, numbered and un-numbered
asteroids classified as precoveries or recoveries based on the daily updated
IAUMPC database. As a first application, we considered an archive including
about 13,000 photographic plates exposed between 1930 and 2005 at the
Astronomical Observatory in Bucharest, Romania. PRECOVERY can be applied to
other archives, being intended as a public facility offered to the community by
the EURONEAR project. This is the first of a series of papers aimed to improve
orbits of PHAs and NEAs using precovered data derived from archives of images
to be data mined in collaboration with students and amateurs. In the next paper
we will search the CFHT Legacy Survey, while data mining of other archives is
planned for the near future.Comment: Accepted in Astronomische Nachrichten (Feb 2009
The FIRST radio survey: The K-z diagram of FIRST radio sources
  identified in the Bo\"{o}tes and Cetus fields

This paper presents the Hubble diagram (K-z relation) for FIRST (Faint Images
of the Radio Sky at 20 cm) radio sources identified in the Bootes and Cetus
fields. The correlation between the K magnitude of the FIRST-NDWFS sample and
the photometric redshifts found to be linear. The dispersion about the best fit
line is given by 1.53 for the whole sample and 0.75 at z>1. The paper also
presents a composite K-z diagram of FIRST radio sources and low-frequency
selected radio samples with progressively fainter flux-density limits (3CRR,
6C, 7CRS and the EIS-NVSS sample). The majority of FIRST radio sources lie
fainter than the no evolution curve (3L* galaxies) probably highlighting the
fact that the galaxy luminosity is correlated with the radio power.Comment: 7 pages, 4 figures and 1 table. Accepted for publiation in
  Astronomische Nachrichte
The Cygnus X region XXIII. Is 18P87 galactic or extragalactic?

The radio source 18P87, previously thought to be a point source, has been
serendipitously found to be resolved into a core-jet geometry in VLA maps. HI
absorption of continuum emission (in data from the Canadian Galactic Plane
Survey) appears in gas with radial velocities > +2 km/s but not in brightly
emitting gas at lower radial velocity. Examination of further archival
observations at radio, infrared and optical wavelengths suggests that the
"obvious" interpretation as a radio galaxy requires a rather unusual object of
this kind and a highly unusual local line of sight. We argue that 18P87 may be
a Galactic object, a local astrophysical jet. If this is correct it could have
arisen from outbursts of a microquasar.Comment: Accepted for publication in Astronomische Nachrichte
Magnetic survey of emission line B-type stars with FORS1 at the VLT

We report the results of our search for magnetic fields in a sample of 16
field Be stars, the binary emission-line B-type star upsilon Sgr, and in a
sample of fourteen members of the open young cluster NGC3766 in the Carina
spiral arm. The sample of cluster members includes Be stars, normal B-type
stars and He-strong/He-weak stars. Nine Be stars have been studied with
magnetic field time series obtained over ~1 hour to get an insight into the
temporal behaviour and the correlation of magnetic field properties with
dynamical phenomena taking place in Be star atmospheres. The
spectropolarimetric data were obtained at the European Southern Observatory
with the multi-mode instrument FORS1 installed at the 8m Kueyen telescope. We
detect weak photospheric magnetic fields in four field Be stars, HD62367, mu
Cen, o Aqr, and epsilon Tuc. The strongest longitudinal magnetic field,
<B_z>=117+-38G, was detected in the Be star HD62367. Among the Be stars studied
with time series, one Be star, lambda Eri, displays cyclic variability of the
magnetic field with a period of 21.12min. The binary star upsilon Sgr, in the
initial rapid phase of mass exchange between the two components with strong
emission lines in the visible spectrum, is a magnetic variable star, probably
on a timescale of a few months. The maximum longitudinal magnetic field
<B_z>=-102+-10G at MJD54333.018 was measured using hydrogen lines. The cluster
NGC3766 seems to be extremely interesting, where we find evidence for the
presence of a magnetic field in seven early B-type stars out of the observed
fourteen cluster members.Comment: 9 pages, 8 figures, 3 tables, accepted for publication in
  Astronomische Nachrichte
Signals From the Epoch of Cosmological Recombination

The physical ingredients to describe the epoch of cosmological recombination
are amazingly simple and well-understood. This fact allows us to take into
account a very large variety of physical processes, still finding potentially
measurable consequences for the energy spectrum and temperature anisotropies of
the Cosmic Microwave Background (CMB). In this contribution we provide a short
historical overview in connection with the cosmological recombination epoch and
its connection to the CMB. Also we highlight some of the detailed physics that
were studied over the past few years in the context of the cosmological
recombination of hydrogen and helium. (abrigded)Comment: 39 pages, 22 figures, Proceedings of JENAM 2008 Vienn
The Cepheid Impostor HD 18391 and its Anonymous Parent Cluster

New and existing photometry for the G0 Ia supergiant HD 18391 is analyzed in
order to confirm the nature of the variablity previously detected in the star,
which lies off the hot edge of the Cepheid instability strip. Small-amplitude
variability at a level of \Delta V = 0.016+-0.002 is indicated, with a period
of P=123.04+-0.06 d. A weaker second signal may be present at P=177.84+-0.18
with \Delta V = 0.007+-0.002, likely corresponding to fundamental mode
pulsation if the primary signal represents overtone pulsation (123.04/177.84 =
0.69). The star, with a spectroscopic reddening of E(B-V) = 1.02, is associated
with heavily-reddened B-type stars in its immediate vicinity that appear to be
outlying members of an anonymous young cluster centered ~10 arcmin to the west
and 1661+-73 pc distant. The cluster has nuclear and coronal radii of r_n=3.5
arcmin and R_c=14 arcmin, respectively, while the parameters for HD 18391
derived from membership in the cluster with its outlying B stars are consistent
with those implied by its Cepheid-like pulsation, provided that it follows the
semi-period-luminosity relation expected of such objects. Its inferred
luminosity as a cluster member is M_V=-7.76+-0.10, its age (9+-1)x10^6 years,
and its evolutionary mass ~19 M_{\sun}. HD 18391 is not a classical Cepheid,
yet it follows the Cepheid period-luminosity relation closely, much like
another Cepheid impostor, V810 Cen.Comment: Accepted for Publication (Astronomische Nachrichten
Galactic Sun's motion in the Cold Dark Matter, MOdified Newtonian
  Dynamics and MOdified Gravity scenarios

We numerically integrate the equations of motion of the Sun in Galactocentric
Cartesian rectangular coordinates for -4.5 Gyr <= t <= 0 in Newtonian mechanics
with two different models for the Cold Dark Matter (CDM) halo, in MOdified
Newtonian Dynamics (MOND) and in MOdified Gravity (MOG) without resorting to
CDM. The initial conditions used come from the latest kinematical determination
of the 3D Sun's motion in the Milky Way (MW) by assuming for the rotation speed
of the Local Standard of Rest (LSR) the recent value \Theta_0=268 km s^-1 and
the IAU recommended value \Theta_0=220 km s^-1; the Sun is assumed located at
8.5 kpc from the Galactic Center (GC).
  For \Theta_0=268 km s^-1 the birth of the Sun, 4.5 Gyr ago, would have
occurred at large Galactocentric distances (12-27 kpc depending on the model
used), while for \Theta_0=220 km s^-1 it would have occurred at about 8.8-9.3
kpc for almost all the models used. The integrated trajectories are far from
being circular, especially for \Theta_0=268 km s^-1, and differ each other with
the CDM models yielding the widest spatial extensions for the Sun's orbital
path.Comment: LaTex2e, 6 pages, 3 figures, 7 table