Search

Start Over Capability Type Simple Cone Search
1271. Avg pitch angles & spiral amplitudes in S4G
ID:
ivo://CDS.VizieR/J/A+A/631/A94
Title:
Avg pitch angles & spiral amplitudes in S4G
Short Name:
J/A+A/631/A94
Date:
21 Oct 2021
Publisher:
CDS
Description:
Spiral galaxies are very common in the local Universe, but their formation, evolution, and interplay with bars remain poorly understood after more than a century of astronomical research on the topic. We use a sample of 391 nearby galaxies from the S4G survey to characterise the winding angle and amplitude of spiral arms as a function of disc properties, such as bar strength, in all kinds of spirals (grand-design, multi-armed, and flocculent). We derived global pitch angles in 3.6um de-projected images from i) average measurements of individual logarithmic spiral segments, and ii) for a subsample of 32 galaxies, from 2-D Fourier analyses. The strength of spirals was quantified from the tangential-to-radial force ratio and from the normalised m=2 Fourier density amplitudes. In galaxies with more than one measured logarithmic segment, the spiral pitch angle varies on average by ~10{deg} between segments, but by up to >=15-20{deg}. The distribution of the global pitch angle versus Hubble type (T) is very similar for barred and non-barred galaxies when 1<=T<=5. Most spiral galaxies (>90%) are barred for T>5. The pitch angle is not correlated with bar strength, and only weakly with spiral strength. The amplitude of spirals is correlated with bar strength (and less tightly, with bar length) for all types of spirals. The mean pitch angle is hardly correlated with the mass of the supermassive black hole (estimated from central stellar velocity dispersion), with central stellar mass concentration, or with shear, questioning previous results in the literature using smaller samples. We do not find observational evidence that spiral arms are driven by stellar bars or by invariant manifolds. Most likely, discs that are prone to the development of strong bars are also reactive to the formation of prominent spirals, explaining the observed coupling between bar and spiral amplitudes.
1272. A2163 VLA 20cm images
ID:
ivo://CDS.VizieR/J/A+A/619/A68
Title:
A2163 VLA 20cm images
Short Name:
J/A+A/619/A68
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this study, we investigate the X-ray properties of the intracluster gas and the radio morphology of the extraordinary cluster A2163. We analyze two Suzaku observations of A2163, one in the north-east (NE) and one in the south-west (SW) direction, and use archival XMM-Newton data to remove point sources in the field of view. To compare our findings in the X-ray regime with the radio emission, we obtain radio images of the cluster from an archival VLA observation at 20cm. We identify three shock fronts in A2163 in our spectral X-ray study. A clear shock front lies in the NE direction at a distance of 1.4Mpc from the center, with a Mach number of M=1.7^+0.3^_-0.2_, estimated from the temperature discontinuity. This shock coincides with the position of a known radio relic. We identify two additional shocks in the SW direction, one with M=1.5^+0.5^_-0.3_ at a distance of 0.7Mpc, which is likely related to a cool core remnant, and a strong shock with M=3.2^+0.6^_-0.7_ at a distance of 1.3Mpc, which also closely matches the radio contours. The complex structure of A2163 as well as the different Mach numbers and shock velocities suggest a merging scenario with two unequal merging constituents, where two shock fronts emerged in an early stage of the merger and traveled outwards while an additional shock front developed in front of the merging cluster cores.
1273. A VLA Search for Young Galactic Supernova Remnants
ID:
ivo://CDS.VizieR/J/AJ/104/704
Title:
A VLA Search for Young Galactic Supernova Remnants
Short Name:
J/AJ/104/704
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the attempt to identify very young galactic supernova remnants (SNRs), 290 known compact (<2') galactic plane radio sources were observed at 20cm using the VLA in its 36 km configuration. The VLA observations described could detect supernovae with diameters between 5 and 20"; these would have an age of between 25 and 100 yr. Compact structure was detected in 168 (58%) of the 290 different sources observed; 73 sources (25%) were unresolved or slightly resolved point sources, 21 (7%) were single-well resolved, 56 (19%) were double, 18 (6%) were triple or complex. The large scale structure was completely resolved out for 122 (42%) of sources. Additional observations at 6cm with the VLA in the 11 km configuration were made of 14 sources with apparent shell structures that might have been characteristic of young SNRs. Low resolution observations were made at 20cm of 62 fields where the source was completely resolved out in the high resolution images. Only one source, G25.5+0.2, is a possible very young SNR. New H66_alpha recombination line observations place severe constrains on any thermal interpretation for this object.
1274. A VLA survey of magnetic CVs. I. The data
ID:
ivo://CDS.VizieR/J/AJ/154/252
Title:
A VLA survey of magnetic CVs. I. The data
Short Name:
J/AJ/154/252
Date:
21 Oct 2021
Publisher:
CDS
Description:
The Jansky Very Large Array was used to observe 121 magnetic cataclysmic variables (MCVs). We report radio detections of 18 stars. Thirteen are new radio sources, increasing the number of MCVs that are radio sources by more than twofold, from 8 to 21. Most detections are at 8.7 GHz (X-band) with a lesser number at 5.4 and 21.1 GHz (C- and K-bands). With the exception of AE Aqr, whose flux density is typically >5 mJy, the flux densities are in the range of 24-780 {mu}Jy. Thirteen of the detections show highly circularly polarized emission, which is characteristic of electron-cyclotron maser emission. The data suggest that MCVs could possibly be divided into two classes of radio emitters: those dominated by weakly polarized gyrosynchrotron emission and those by highly polarized electron-cyclotron maser emission.
1275. A WISE view on extreme AGB stars
ID:
ivo://CDS.VizieR/J/A+A/659/A145
Title:
A WISE view on extreme AGB stars
Short Name:
J/A+A/659/A145
Date:
18 Mar 2022 08:25:03
Publisher:
CDS
Description:
Variability is a key property of stars on the asymptotic giant branch (AGB). Their pulsation period is related to the luminosity and mass-loss rate (MLR) of the star. Long-period variables (LPVs) and Mira variables are the most prominent of all types of variability of evolved stars. However, the reddest, most obscured AGB stars are too faint in the optical and have eluded large variability surveys. Our goal is to obtain a sample of LPVs with large MLRs by analysing WISE W1 and W2 light curves (LCs) for about 2000 sources, photometrically selected to include known C-stars with the 11.3 micron silicon carbide dust feature in absorption, and Galactic O-stars with periods longer than 1000 days. Epoch photometry was retrieved from the AllWISE and NEOWISE database and fitted with a sinus curve. Photometry from other variability surveys was also downloaded and fitted. For a subset of 316 of the reddest stars, spectral energy distributions (SEDs) were constructed, and, together with mid-infrared (MIR) spectra when available, fitted with a dust radiative transfer programme in order to derive MLRs. WISE based LCs and fits to the data are presented for all stars. Periods from the literature and periods from refitting other literature data are presented. The results of the spatial correlation with several (IR) databases is presented. About one-third of the sources are found to be not real, but it appears that these cannot be easily filtered out by using WISE flags. Some are clones of extremely bright sources, and in some cases the LCs show the known pulsation period. Inspired by a recent paper, a number of non-variable OH/IRs are identified. Based on a selection on amplitude, a sample of about 750 (candidate) LPVs is selected of which 145 have periods beyond 1000 days, many of them being new. For the subset of the stars with the colours of C-rich extremely red objects (EROs) the fitting of the SEDs (and available MIR spectra) separates them into C- and O-rich objects. Interestingly, the fitting of MIR spectra of mass-losing C-stars is shown to be a powerful tracer of interstellar reddening when AV larger than 2 mag. The number of Galactic EROs appears to be complete up to about 5 kpc and a total dust return rate in the solar neighbourhood for this class is determined. In the LMC 12 additional EROs are identified. Although this represents only about 0.15% of the total known LMC C-star population adding their MLRs increases the previously estimated dust return by 8%. Based on the EROs in the Magellanic Clouds, a bolometric period luminosity is derived. It is pointed out that due to their faintness, EROs and similar O-rich objects are ideal targets for a NIR version of Gaia to obtain distances, observing in the K-band or, even more efficiently, in the L-band.
1276. AWM 7 radial velocities
ID:
ivo://CDS.VizieR/J/AJ/116/2108
Title:
AWM 7 radial velocities
Short Name:
J/AJ/116/2108
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have measured redshifts and Kron-Cousins R-band magnitudes for a sample of galaxies in the poor cluster AWM 7. We have measured redshifts for 172 galaxies; 106 of these are cluster members. We determine the luminosity function (LF) from a photometric survey of the central 1.2x1.2h^-1^Mpc. The LF has a bump at the bright end and a faint-end slope of {alpha}=-1.37+/-0.16, populated almost exclusively by absorption-line galaxies. The cluster velocity dispersion is lower in the core (~530km/s) than at the outskirts (~680km/s), consistent with the cooling flow seen in the X-ray. The cold core extends ~150h^-1^kpc from the cluster center. The Kron-Cousins R-band mass-to-light ratio of the system is 650+/-170hM_{sun}_/L_{sun}_, substantially lower than previous optical determinations, but consistent with most previous X-ray determinations. We adopt H_0_=100hkm/s/Mpc throughout this paper; at the mean cluster redshift (5247+/-76km/s), 1h^-1^Mpc subtends 65.5'.
1277. AXIS XMM-Newton Source Catalog
ID:
ivo://nasa.heasarc/axis
Title:
AXIS XMM-Newton Source Catalog
Short Name:
AXIS
Date:
01 Nov 2024
Publisher:
NASA/GSFC HEASARC
Description:
Recent results have revised upwards the total X-ray background (XRB) intensity below ~10 keV, therefore an accurate determination of the source counts is needed. There are also contradictory results on the clustering of X-ray selected sources. The authors have studied the X-ray source counts in four energy bands: soft (0.5 - 2 keV), hard (2 - 10 keV), XID (0.5 - 4.5 keV) and ultra-hard (4.5 - 7.5 keV) in order to evaluate the contribution of sources at different fluxes to the X-ray background. They have also studied the angular clustering of X-ray sources in those bands. AXIS (An XMM International Survey) is a survey of 36 high Galactic latitude XMM observations covering 4.8 square degrees in the Northern sky and containing 1433 serendipitous X-ray sources detected with 5-sigma significance. This survey has similar depth to the XMM catalogs and therefore serves as a pathfinder to explore their possibilities. The authors in their paper combined this survey with shallower and deeper surveys, and fitted the source counts with a Maximum Likelihood technique. Using only AXIS sources they studied the angular correlation using a novel robust technique. The AXIS source counts results are compatible with most previous samples in the soft, XID, ultra-hard and hard bands. This study has improved on previous results in the hard band. The fractions of the XRB resolved in the surveys used in this work are 87%, 85%, 60% and 25% in the soft, hard, XID and ultra-hard bands, respectively. Extrapolation of the source counts to zero flux is not sufficient to saturate the XRB intensity. Only galaxies and/or absorbed AGN could contribute the remaining unresolved XRB intensity. These results are compatible, within the errors, with recent revisions of the XRB intensity in the soft and hard bands. The maximum fractional contribution to the XRB comes from fluxes within about a decade of the break in the source counts (~10&lt;sup&gt;-14&lt;/sup&gt; cgs), reaching ~50% of the total in the soft and hard bands. Angular clustering (widely distributed over the sky and not confined to a few deep fields) is detected at 99-99.9% significance in the soft and XID bands, with no detection in the hard and ultra-hard band (probably due to the smaller number of sources). The authors cannot confirm the detection of significantly stronger clustering in the hard-spectrum hard sources. Medium-depth surveys such as AXIS are essential to determine the evolution of the X-ray emission in the Universe below 10 keV. Included here are the basic data for the 2560 X-ray sources in the reference paper which satified the selection criteria of having an emldetect detection likelihood &gt;= 10 (the default value) in at least one band, namely: (i) XMM-Newton pn count-rates in four XMM-Newton Science Analysis System (SAS) bands (band 2: 0.5 - 2 keV, band 3: 2 - 4.5 keV, band 4: 4.5 - 7.5 keV, band 5: 7.5 - 12 keV); (ii) spectral photon indices in the 0.5 - 4.5 keV band, the 2 - 10 keV band and the 0.5 - 10 keV band; (iii) fluxes in the soft (0.5 - 2 keV), hard (2 - 10 keV), XID (0.5 - 4.5 keV), ultra-hard (4.5 - 7.5 keV) and &quot;total&quot; (0.5 - 10 keV) bands; and (iv) flags describing to which of the samples discussed in the paper (soft, hard, XID or ultra-hard) each source belongs. There is no spectral or flux information given for the sources not belonging to any of the samples, but the count-rates of such sources are given for completeness. This table was created by the HEASARC in August 2007 based on &lt;a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/469/27"&gt;CDS catalog J/A+A/469/27&lt;/a&gt; file table23.dat. This is a service provided by NASA HEASARC .
1278. A XMM-Newton survey of the SXRB
ID:
ivo://CDS.VizieR/J/ApJS/187/388
Title:
A XMM-Newton survey of the SXRB
Short Name:
J/ApJS/187/388
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present measurements of the soft X-ray background (SXRB) OVII and OVIII intensity between l=120{deg} and l=240{deg}, the first results of a survey of the SXRB using archival XMM-Newton observations. We do not restrict ourselves to blank-sky observations, but instead use as many observations as possible, removing bright or extended sources by hand if necessary. In an attempt to minimize contamination from near-Earth solar wind charge exchange (SWCX) emission, we remove times of high solar wind proton flux from the data. Without this filtering we are able to extract measurements from 586 XMM-Newton observations. With this filtering, ~1/2 of the observations are rendered unusable, and we are able to extract measurements from 303 observations. The oxygen intensities are typically ~0.5-10 photons/cm^2^/s/sr (line units, L.U.) for OVII and ~0-5L.U. for OVIII. The proton flux filtering does not systematically reduce the oxygen intensities measured from a given observation. However, the filtering does preferentially remove the observations with higher oxygen intensities. Our data set includes 69 directions with multiple observations, whose oxygen intensity variations can be used to constrain SWCX models. After removing observations likely to be contaminated by heliospheric SWCX emission, we use our results to examine the Galactic halo.
1279. Azimuthal anistropy of stellar galactic disks
ID:
ivo://CDS.VizieR/J/A+A/618/A121
Title:
Azimuthal anistropy of stellar galactic disks
Short Name:
J/A+A/618/A121
Date:
21 Oct 2021
Publisher:
CDS
Description:
The ellipsoid of stellar random motions is a fundamental ingredient of galaxy dynamics. Yet it has long been difficult to constrain this component in disks others than the Milky Way. This article presents the modeling of the azimuthal-to-radial axis ratio of the velocity ellipsoid of galactic disks from stellar dispersion maps using integral field spectroscopy data of the CALIFA survey. The measured azimuthal anisotropy is shown to be not strongly dependent on the assumed vertical-to-radial dispersion ratio of the ellipsoid. The anisotropy distribution shows a large diversity in the orbital structure of disk galaxies from tangential to radial stellar orbits. Globally, the orbits are isotropic in inner disk regions and become more radial as a function of radius, although this picture tends to depend on galaxy morphology and luminosity. The Milky Way orbital anisotropy profile measured from the Second Gaia Data Release is consistent with those of CALIFA galaxies. A new correlation is evidenced, linking the absolute magnitude or stellar mass of the disks to the azimuthal anisotropy. More luminous disks have more radial orbits and less luminous disks have isotropic and somewhat tangential orbits. This correlation is consistent with the picture in galaxy evolution in which orbits become more radial as the mass grows and is redistributed as a function of time. With the help of circular velocity curves, it is also shown that the epicycle theory fails to reproduce the diversity of the azimuthal anisotropy of stellar random motions, as it predicts only nearly radial orbits in the presence of flat curves. The origin of this conflict is yet to be identified. It also questions the validity of the vertical-to-radial axis ratio of the velocity ellipsoid derived by many studies in the framework of the epicyclic approximation.
1280. A z=0 Multiwavelength Galaxy Synthesis (z0MGS). I.
ID:
ivo://CDS.VizieR/J/ApJS/244/24
Title:
A z=0 Multiwavelength Galaxy Synthesis (z0MGS). I.
Short Name:
J/ApJS/244/24
Date:
14 Mar 2022 07:45:54
Publisher:
CDS
Description:
We present an atlas of ultraviolet and infrared images of ~15750 local (d<~50Mpc) galaxies, as observed by NASA's Wide-field Infrared Survey Explorer (WISE) and Galaxy Evolution Explorer (GALEX) missions. These maps have matched resolution (FWHM 7.5" and 15"), matched astrometry, and a common procedure for background removal. We demonstrate that they agree well with resolved intensity measurements and integrated photometry from previous surveys. This atlas represents the first part of a program (the z=0 Multiwavelength Galaxy Synthesis) to create a large, uniform database of resolved measurements of gas and dust in nearby galaxies. This atlas allows us estimate local and integrated star formation rates (SFRs) and stellar masses (M_*_) across the local galaxy population in a uniform way. In the appendix, we use the population synthesis fits of Salim+ (2016ApJS..227....2S and 2018ApJ...859...11S) to calibrate integrated M_*_ and SFR estimators based on GALEX and WISE. Because they leverage a Sloan Digital Sky Survey (SDSS)-based training set of >100000 galaxies, these calibrations have high precision and allow us to rigorously compare local galaxies to SDSS results. We provide these SFR and M_*_ estimates for all galaxies in our sample and show that our results yield a "main sequence" of star-forming galaxies comparable to previous work. We also show the distribution of intensities from resolved galaxies in NUV-to-WISE1 versus WISE1-to-WISE3 space, which captures much of the key physics accessed by these bands.

Limit your search

more »

more »

more »

more »

more »

more »