102 research outputs found
ATPMN: accurate positions and flux densities at 5 and 8 GHz for 8,385 sources from the PMN survey
We present a source catalogue of 9,040 radio sources resulting from
high-resolution observations of 8,385 PMN sources with the Australia Telescope
Compact Array. The catalogue lists flux density and structural measurements at
4.8 and 8.6 GHz, derived from observations of all PMN sources in the
declination range -87 deg < delta < -38.5 deg (exclusive of galactic latitudes
|b| 70 mJy (50 mJy south of delta = -73
deg). We assess the quality of the data, which was gathered in 1992-1994,
describe the population of catalogued sources, and compare it to samples from
complementary catalogues. In particular we find 127 radio sources with probable
association with gamma-ray sources observed by the orbiting Fermi Large Area
Telescope.Comment: 20 pages, 21 figure
Fe II Emission in 14 Low-Redshift Quasars: I - Observations
We present the spectra of 14 quasars with a wide coverage of rest wavelengths
from 1000 to 7300 A. The redshift ranges from z = 0.061 to 0.555 and the
luminosity from M_{B} = -22.69 to -26.32. We describe the procedure of
generating the template spectrum of Fe II line emission from the spectrum of a
narrow-line Seyfert 1 galaxy I Zw 1 that covers two wavelength regions of
2200-3500 A and 4200-5600 A. Our template Fe II spectrum is semi-empirical in
the sense that the synthetic spectrum calculated with the CLOUDY
photoionization code is used to separate the Fe II emission from the Mg II
line. The procedure of measuring the strengths of Fe II emission lines is
twofold; (1) subtracting the continuum components by fitting models of the
power-law and Balmer continua in the continuum windows which are relatively
free from line emissions, and (2) fitting models of the Fe II emission based on
the Fe II template to the continuum-subtracted spectra. From 14 quasars, we
obtained the Fe II fluxes in five wavelength bands, the total flux of Balmer
continuum, and the fluxes of Mg II, Halpha, and other emission lines, together
with the full width at half maxima (FWHMs) of these lines. Regression analysis
was performed by assuming a linear relation between any two of these
quantities. Eight correlations were found with a confidence level higher than
99%. The fact that six of these eight are related to FWHM or M_{BH} may imply
that M_{BH} is a fundamental quantity that controls Gamma or the spectral
energy distribution (SED) of the incident continuum, which in turn controls the
Fe II emission. Furthermore, it is worthy of noting that Fe II(O1)/Fe II(U1) is
found to tightly correlate with Fe II(O1)/Mg II, but not with Fe II(U1)/Mg II.Comment: 50 pages, 10 figures, accepted for publication in Ap
Contribution to the Diffuse Radio Background from Extragalactic Radio Sources
We examine the brightness of the Cosmic Radio Background (CRB) by comparing
the contribution from individual source counts to absolute measurements. We use
a compilation of radio counts to estimate the contribution of detected sources
to the CRB in several different frequency bands.We apply a Monte Carlo Markov
Chain technique to estimate the brightness values and uncertainties, paying
attention to various sources of systematic error. We compare our results to
absolute measurements from the ARCADE 2 experiment. At v = 150 MHz, 325 MHz,
408 MHz, 610 MHz, 1.4 GHz, 4.8 GHz, and 8.4 GHz our calculated contributions to
the background sky temperature are 18, 2.8, 1.6, 0.71, 0.11, 0.0032, 0.0059 K,
respectively. If the ARCADE 2 measurements are correct and come from sources,
then there must be an additional population of radio galaxies, fainter than
where current data are probing. More specifically, the Euclidean-normalized
counts at 1.4 GHz have to have an additional bump below about 10 {\mu}Jy.Comment: 9 pages, 7 figures, 3 tables, accepted MNRA
Fertility and gonadal function in female survivors after treatment of early unfavorable Hodgkin lymphoma (HL) within the German Hodgkin Study Group HD14 trial
Background In the HD14 trial, 2× BEACOPPescalated+2× ABVD (2+2) has improved the primary outcome. Compared with 4× ABVD, this benefit might be compromised by more infertility in women. Therefore, we analyzed gonadal function and fertility. Patients and methods Women ≤45 years in ongoing remission at least 1 year after therapy were included. Hormone parameters, menopausal symptoms, measures to preserve fertility, menstrual cycle, pregnancies, and offspring were evaluated. Results Three hundred and thirty one of 579 women addressed participated (57.2%) and 263 per-protocol treated patients qualified (A=ABVD: 137, B=2+2: 126, mean time after therapy 42 and 43 months, respectively). Regular menstrual cycle after treatment (A: 87%, B: 83%) and time to recovery (≤12 months) were not different. Follicle-stimulating hormone and anti-Muellerian hormone were significantly better in arm A. However, pregnancies after therapy favored arm B (A: 15%, B: 26%, P=0.043) and motherhood rates were equivalent to the German normal population. Multivariate analysis revealed prophylactic use of gonadotropin-releasing hormone (GnRH) analogues as highly significant prognostic factor for preservation of fertility (odds ratio=12.87, P=0.001). Severe menopausal symptoms were frequent in women ≥30 years (A: 21%, B: 25%). Conclusions Hormonal levels after 2+2 indicate a reduced ovarian reserve. However, 2+2 in combination with GnRH analogues does not compromise fertility within the evaluated observation tim
Wide-Field Imaging and Polarimetry for the Biggest and Brightest in the 20GHz Southern Sky
We present wide-field imaging and polarimetry at 20GHz of seven of the most
extended, bright (Stot >= 0.50 Jy), high-frequency selected radio sources in
the southern sky with declinations < -30 deg. Accompanying the data are brief
reviews of the literature for each source, The results presented here aid in
the statistical completeness of the Australia Telescope 20GHz Survey's bright
source sample. The data are of crucial interest for future cosmic microwave
background missions as a collection of information about candidate calibrator
sources. We are able to obtain data for seven of the nine sources identified by
our selection criteria. We report that Pictor A is thus far the best
extragalactic calibrator candidate for the Low Frequency Instrument of the
Planck European Space Agency mission due to its high level of integrated
polarized flux density (0.50+/-0.06 Jy) on a scale of 10 arcmin. Six of the
seven sources have a clearly detected compact radio core, with either a null or
less than two percent detection of polarized emission from the nucleus. Most
sources with detected jets have magnetic field alignments running in a
longitudinal configuration, however PKS1333-33 exhibits transverse fields and
an orthogonal change in field geometry from nucleus to jets.Comment: 17 pages, 9 figures, 2 table
Multifrequency VLBA study of the blazar S5 0716+714 during the active state in 2004 II. Large-scale jet kinematics and the comparison of the different methods of VLBI data imaging as applied to kinematic studies of AGN
We study the jet kinematics of the blazar S5 0716+714 during its active state
in 2003-2004 with multi-epoch VLBI observations. Aims. We present a kinematic
analysis of the large-scale (0-12 mas) jet of 0716+714, based on the results of
six epochs of VLBA monitoring at 5 GHz. Additionally, we compare kinematic
results obtained with two imaging methods based on different deconvolution
algorithms. The blazar 0716+714 has a diffuse large-scale jet and a very faint
bright compact core. Experiments with simulated data showed that the
conventional data reduction procedure based on the CLEAN deconvolution
algorithm does not perform well in restoring this type of structure. This might
be the reason why previous kinematic studies of this source yielded ambiguous
results. In order to obtain accurate kinematics of this source, we
independently applied two imaging techniques to the raw data: the conventional
method, based on difference mapping, which uses CLEAN deconvolution, and the
generalized maximum entropy method (GMEM) realized in the VLBImager package
developed at the Pulkovo Observatory in Russia. The results of both methods
give us a consistent kinematic scenario: the large-scale jet of 0716+714 is
diffuse and stationary. Differences between the inner (0-1 mas) and outer (1-12
mas) regions of the jet in brightness and velocity of the components could be
explained by the bending of the jet, which causes the angle between the jet
direction and the line of sight to change from ~5 deg to ~11 deg. For the
source 0716+714 both methods worked at the limit of their capability.Comment: 13 pages, 7 figures. Accepted for publication in A&A, 201
Radio Frequency Spectra of 388 Bright 74 MHz Sources
As a service to the community, we have compiled radio frequency spectra from
the literature for all sources within the VLA Low Frequency Sky Survey (VLSS)
that are brighter than 15 Jy at 74 MHz. Over 160 references were used to
maximize the amount of spectral data used in the compilation of the spectra,
while also taking care to determine the corrections needed to put the flux
densities from all reference on the same absolute flux density scale. With the
new VLSS data, we are able to vastly improve upon previous efforts to compile
spectra of bright radio sources to frequencies below 100 MHz because (1) the
VLSS flux densities are more reliable than those from some previous low
frequency surveys and (2) the VLSS covers a much larger area of the sky
(declination >-30 deg.) than many other low frequency surveys (e.g., the 8C
survey). In this paper, we discuss how the spectra were constructed and how
parameters quantifying the shapes of the spectra were derived. Both the spectra
and the shape parameters are made available here to assist in the calibration
of observations made with current and future low frequency radio facilities.Comment: Accepted to ApJ
Fertility and gonadal function in female survivors after treatment of early unfavorable Hodgkin lymphoma (HL) within the German Hodgkin Study Group HD14 trial
In the HD14 trial, 2×BEACOPPescalated+2×ABVD (2+2) has improved the primary outcome. Compared with 4×ABVD, this benefit might be compromised by more infertility in women. Therefore, we analyzed gonadal function and fertility
Spectral energy distribution and radio halo of NGC253 at low radio frequencies
A. D. Kapinska, 'Spectral Energy Distribution and Radio Halo of NGC 253 at Low Radio Frequencies', The Astrophysical Journal, Vol. 838(68), 15 pp, March 2017. The version of record is available online at doi: https://doi.org/10.3847/1538-4357/aa5f5d. © 2017. The American Astronomical Society. All rights reserved.We present new radio continuum observations of NGC253 from the Murchison Widefield Array at frequencies between 76 and 227 MHz. We model the broadband radio spectral energy distribution for the total flux density of NGC253 between 76 MHz and 11 GHz. The spectrum is best described as a sum of central starburst and extended emission. The central component, corresponding to the inner 500pc of the starburst region of the galaxy, is best modelled as an internally free-free absorbed synchrotron plasma, with a turnover frequency around 230 MHz. The extended emission component of the NGC253 spectrum is best described as a synchrotron emission flattening at low radio frequencies. We find that 34% of the extended emission (outside the central starburst region) at 1 GHz becomes partially absorbed at low radio frequencies. Most of this flattening occurs in the western region of the SE halo, and may be indicative of synchrotron self-absorption of shock re-accelerated electrons or an intrinsic low-energy cut off of the electron distribution. Furthermore, we detect the large-scale synchrotron radio halo of NGC253 in our radio images. At 154 - 231 MHz the halo displays the well known X-shaped/horn-like structure, and extends out to ~8kpc in z-direction (from major axis).Peer reviewedFinal Published versio
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