Search

Start Over Capability Type Simple Cone Search
431. A 3D Voronoi+Gapper galaxy cluster finder. II.
ID:
ivo://CDS.VizieR/J/ApJ/869/145
Title:
A 3D Voronoi+Gapper galaxy cluster finder. II.
Short Name:
J/ApJ/869/145
Date:
21 Oct 2021
Publisher:
CDS
Description:
We identify 1901 galaxy clusters (N_g_>=2) with the gapping-filtering in radial velocity (VoML+G) algorithm (Paper I; Campusano+ 2017ApJ...838..109P) on the two-Degree Field Galaxy Redshift Survey (2dFGRS). We present the 341 clusters with at least 10 galaxies that are within 0.009<z<0.14 (the Catalog), of which 254 (~75%) have counterparts in the literature (NED), with the remainder (87) plausibly "new" because of incompleteness of previous searches or unusual galaxy contents. The 207 clusters within z=0.04--0.09 are used to study the properties of the galaxy systems in the nearby universe, including their galaxy contents parameterized by the late-type galaxy fractions (f_L_). For this nearly complete cluster subsample, we find the following: (i) 63% are dominated by early-type galaxies (i.e., the late-type-poor clusters, f_L_<0.5) with corresponding mean multiplicity and logarithmic virial mass (in units of M_{sun}_) of 22+/-1 and 12.91+/-0.04, respectively; and (ii) 37% are dominated by late-type galaxies (i.e., the late-type-rich clusters, f_L_>=0.5) with corresponding mean multiplicity and logarithmic virial mass (in units of M_{sun}_) of 15.7+/-0.9 and 12.66+/-0.07, respectively. The statistical analysis of the late-type fraction distribution supports, with a 3{sigma} confidence level, the presence of two population components. It is suggested that the late-type-poor galaxy systems reflect and extend the class of Abell-APM-EDCC clusters and that the late-type-rich systems (~one-third of the total) belong to a new, previously unappreciated class. The late-type-rich clusters, on average high mass-to-light ratio systems, appear to be more clustered on large scales than the late-type-poor clusters. A class of late-type-rich clusters is not predicted by current theory.
432. Ae/Be stars of Magellanic Bridge in JHKs
ID:
ivo://CDS.VizieR/J/ApJ/658/358
Title:
Ae/Be stars of Magellanic Bridge in JHKs
Short Name:
J/ApJ/658/358
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have found Herbig Ae/Be star candidates in the western region of the Magellanic Bridge. Using the near-infrared camera SIRIUS and the 1.4m telescope IRSF, we surveyed ~3.0{deg}x1.3{deg} (24{deg}<~RA<~36{deg}, -75.0{deg}<~DE<~-73.7{deg}) in the J, H, and Ks bands. On the basis of colors and magnitudes, about 200 Herbig Ae/Be star candidates are selected. Considering the contaminations by miscellaneous sources, such as foreground stars and early-type dwarfs in the Magellanic Bridge, we estimate that about 80 (#40%) of the candidates are likely to be Herbig Ae/Be stars. We also found one concentration of the candidates at the young star cluster NGC 796, strongly suggesting the existence of pre-main-sequence (PMS) stars in the Magellanic Bridge. This is the first detection of PMS star candidates in the Magellanic Bridge, and if they are genuine PMS stars, this could be direct evidence of recent star formation. However, the estimate of the number of Herbig Ae/Be stars depends on the fraction of classical Be stars, and thus a more precise determination of the Be star fraction or observations to differentiate between the Herbig Ae/Be stars and classical Be stars are required.
433. AEGIS: demographics of X-ray and optical AGN
ID:
ivo://CDS.VizieR/J/ApJ/728/38
Title:
AEGIS: demographics of X-ray and optical AGN
Short Name:
J/ApJ/728/38
Date:
21 Oct 2021
Publisher:
CDS
Description:
We develop a new diagnostic method to classify galaxies into active galactic nucleus (AGN) hosts, star-forming galaxies, and absorption-dominated galaxies by combining the [OIII]/H{beta} ratio with rest-frame U-B color. This can be used to robustly select AGNs in galaxy samples at intermediate redshifts (z<1). We compare the result of this optical AGN selection with X-ray selection using a sample of 3150 galaxies with 0.3<z<0.8 and I_AB_<22, selected from the DEEP2 Galaxy Redshift Survey and the All-wavelength Extended Groth Strip International Survey. Among the 146 X-ray sources in this sample, 58% are classified optically as emission-line AGNs, the rest as star-forming galaxies or absorption-dominated galaxies. The latter are also known as "X-ray bright, optically normal galaxies" (XBONGs).
434. AEGIS-X: Chandra deep survey
ID:
ivo://CDS.VizieR/J/ApJS/180/102
Title:
AEGIS-X: Chandra deep survey
Short Name:
J/ApJS/180/102
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the EGIS-X survey, a series of deep Chandra ACIS-I observations of the Extended Groth Strip. The survey comprises pointings at eight separate positions, each with nominal exposure of 200ks, covering a total area of approximately 0.67deg^2^ in a strip of length 2 degrees. We describe in detail an updated version of our data reduction and point-source-detection algorithms used to analyze these data. A total of 1325 band-merged sources have been found to a Poisson probability limit of 4x10^-6^, with limiting fluxes of 5.3x10^-21^W/m2 in the soft (0.5-2keV) band and 3.8x10^-19^W/m2 in the hard (2-10keV) band. We present simulations verifying the validity of our source-detection procedure and showing a very small, <1.5%, contamination rate from spurious sources. Optical/NIR counterparts have been identified from the DEEP2, CFHTLS, and Spitzer/Infrared Array Camera (IRAC) surveys of the same region. Using a likelihood ratio method, we find optical counterparts for 76% of our sources, complete to R_AB_=24.1, and, of the 66% of the sources that have IRAC coverage, 94% have a counterpart to a limit of 0.9uJy at 3.6um (m_AB_=23.8). After accounting for (small) positional offsets in the eight Chandra fields, the astrometric accuracy of Chandra positions is found to be 0"8rms; however, this number depends both on the off-axis angle and the number of detected counts for a given source. All data products described in this paper are made available via a public Web site.
435. AEGIS-X Chandra Extended Groth Strip X-Ray Point Source Catalog
ID:
ivo://nasa.heasarc/aegisx
Title:
AEGIS-X Chandra Extended Groth Strip X-Ray Point Source Catalog
Short Name:
AEGISX
Date:
14 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the X-ray sources detected in the AEGIS-X survey, a series of deep Chandra ACIS-I observations of the Extended Groth Strip (EGS). The survey comprises pointings at eight separate positions, each with nominal exposure of 200 ks, covering a total area of approximately 0.67 deg&lt;sup&gt;2&lt;/sup&gt; in a strip of length 2 degrees. In their paper, the authors describe in detail an updated version of the data reduction and point-source-detection algorithms used to analyze these data. A total of 1325 band-merged sources have been found to a Poisson probability limit of 4 x 10&lt;sup&gt;-6&lt;/sup&gt;, with limiting fluxes of 5.3 x 10&lt;sup&gt;-17&lt;/sup&gt; erg cm&lt;sup&gt;-2&lt;/sup&gt; s&lt;sup&gt;-1&lt;/sup&gt; in the soft (0.5 - 2 keV) band and 3.8 x 10&lt;sup&gt;-16&lt;/sup&gt; erg cm&lt;sup&gt;-2&lt;/sup&gt; s&lt;sup&gt;-1&lt;/sup&gt; in the hard (2 - 10 keV) band. They present simulations verifying the validity of their source-detection procedure and showing a very small, &lt;1.5%, contamination rate from spurious sources. Optical/NIR counterparts have been identified from the DEEP2, CFHTLS, and Spitzer/Infrared Array Camera (IRAC) surveys of the same region. Using a likelihood ratio method, they find optical counterparts for 76% of their sources, complete to R&lt;sub&gt;AB&lt;/sub&gt; = 24.1, and, of the 66% of the sources that have IRAC coverage, 94% have a counterpart to a limit of 0.9 uJy at 3.6 um (m&lt;sub&gt;AB&lt;/sub&gt; = 23.8). After accounting for (small) positional offsets in the eight Chandra fields, the astrometric accuracy of Chandra positions is found to be 0.8 arcseconds rms; however, this number depends both on the off-axis angle and the number of detected counts for a given source. This table was created by the HEASARC in February 2009 based on the electronic versions of Tables 9, 10 and 11 from the paper which were obtained from the Astrophysical Journal web site. It is also available from the CDS at &lt;a href="https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/180/102"&gt;https://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/180/102&lt;/a&gt;. This is a service provided by NASA HEASARC .
436. AEGIS-X Deep Survey Chandra X-Ray Point Source Catalog
ID:
ivo://nasa.heasarc/aegisxdcxo
Title:
AEGIS-X Deep Survey Chandra X-Ray Point Source Catalog
Short Name:
AEGISXDCXO
Date:
14 Feb 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table is based on the results of deep Chandra imaging of the central region of the Extended Groth Strip, the AEGIS-X Deep (AEGIS-XD) survey. When combined with previous Chandra observations of a wider area of the strip, AEGIS-X Wide (AEGIS-XW), these provide data to a nominal exposure depth of 800ks in the three central ACIS-I fields, a region of approximately 0.29 deg&lt;sup&gt;2&lt;/sup&gt;. This is currently the third deepest X-ray survey in existence; a factor ~2-3 shallower than the Chandra Deep Fields (CDFs), but over an area ~3 times greater than each CDF. This table contains a catalog of 937 point sources detected in the deep Chandra observations, along with identifications of the X-ray sources from deep ground-based, Spitzer, GALEX, and Hubble Space Telescope imaging. Using a likelihood ratio analysis, the authors associate multiband counterparts for 929/937 of their X-ray sources, with an estimated 95% reliability,making the identification completeness approximately 94% in a statistical sense. Reliable spectroscopic redshifts for 353 of the X-ray sources are available predominantly from Keck (DEEP2/3) and MMT Hectospec, so the current spectroscopic completeness is ~38%. For the remainder of the X-ray sources, the authors compute photometric redshifts based on multiband photometry in up to 35 bands from the UV to mid-IR. Particular attention is given to the fact that the vast majority of the X-ray sources are active galactic nuclei and require hybrid templates. The photometric redshifts have a mean accuracy sigma = 0.04 and an outlier fraction of approximately 5%, reaching sigma = 0.03 with less than 4% outliers in the area covered by CANDELS. The new AEGIS-XD Chandra data were taken at three nominal pointing positions, which the authors have designated AEGIS-1, AEGIS-2, and AEGIS-3. These observations were all taken in the time period 2007 December 11 to 2009 June 26 using the ACIS-I instrument. The centers of the 3 AEGIS fields correspond fairly closely to those of the EGS-3, EGS-4, and EGS-5 fields of Laird et al. (2009, ApJS, 180, 102). The Rainbow Cosmological Surveys Database (&lt;a href="http://rainbowx.fis.ucm.es/Rainbow_Database/Home.html"&gt;http://rainbowx.fis.ucm.es/Rainbow_Database/Home.html&lt;/a&gt;; see Section 4 of the reference paper for more details) contains many multiwavelength photometric datasets giving information on optical and infrared sources in these fields. The characteristics of these datasets are given in Table 7 of the reference paper. This table was created by the HEASARC in February 2016 based on the &lt;a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/220/10"&gt;CDS catalog J/ApJS/220/10&lt;/a&gt; files table11.dat, table12.dat, table13.dat, table14.dat and table15.dat. This is a service provided by NASA HEASARC .
437. AEGIS-X Deep survey of EGS (AEGIS-XD)
ID:
ivo://CDS.VizieR/J/ApJS/220/10
Title:
AEGIS-X Deep survey of EGS (AEGIS-XD)
Short Name:
J/ApJS/220/10
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results of deep Chandra imaging of the central region of the Extended Groth Strip, the AEGIS-X Deep (AEGIS-XD) survey. When combined with previous Chandra observations of a wider area of the strip, AEGIS-X Wide (AEGIS-XW), these provide data to a nominal exposure depth of 800ks in the three central ACIS-I fields, a region of approximately 0.29deg^2^. This is currently the third deepest X-ray survey in existence; a factor ~2-3 shallower than the Chandra Deep Fields (CDFs), but over an area ~3 times greater than each CDF. We present a catalog of 937 point sources detected in the deep Chandra observations, along with identifications of our X-ray sources from deep ground-based, Spitzer, GALEX, and Hubble Space Telescope imaging. Using a likelihood ratio analysis, we associate multiband counterparts for 929/937 of our X-ray sources, with an estimated 95% reliability, making the identification completeness approximately 94% in a statistical sense. Reliable spectroscopic redshifts for 353 of our X-ray sources are available predominantly from Keck (DEEP2/3) and MMT Hectospec, so the current spectroscopic completeness is ~38%. For the remainder of the X-ray sources, we compute photometric redshifts based on multiband photometry in up to 35 bands from the UV to mid-IR. Particular attention is given to the fact that the vast majority the X-ray sources are active galactic nuclei and require hybrid templates. Our photometric redshifts have mean accuracy of {sigma}=0.04 and an outlier fraction of approximately 5%, reaching {sigma}=0.03 with less than 4% outliers in the area covered by CANDELS.
438. A faint companion around CrA-9
ID:
ivo://CDS.VizieR/J/MNRAS/502/6117
Title:
A faint companion around CrA-9
Short Name:
J/MNRAS/502/6117
Date:
21 Oct 2021
Publisher:
CDS
Description:
Understanding how giant planets form requires observational input from directly imaged protoplanets. We used VLT/NACO and VLT/SPHERE to search for companions in the transition disc of 2MASS J19005804-3645048 (hereafter CrA-9), an accreting M0.75 dwarf with an estimated age of 1-2Myr. We found a faint point source at ~0.7-arcsec separation from CrA-9 (~108au projected separation). Our 3-epoch astrometry rejects a fixed background star with a 5{sigma} significance. The near-IR absolute magnitudes of the object point towards a planetary-mass companion. However, our analysis of the 1.0-3.8um spectrum extracted for the companion suggests it is a young M5.5 dwarf, based on both the 1.13um Na index and comparison with templates of the Montreal Spectral Library. The observed spectrum is best reproduced with high effective temperature (3057^+119^_-36_K) BT-DUSTY and BT-SETTL models, but the corresponding photometric radius required to match the measured flux is only 0.60^+0.01^_-0.04_ Jovian radius. We discuss possible explanations to reconcile our measurements, including an M-dwarf companion obscured by an edge-on circum-secondary disc or the shock-heated part of the photosphere of an accreting protoplanet. Follow-up observations covering a larger wavelength range and/or at finer spectral resolution are required to discriminate these two scenarios.
439. A faint galaxy survey to B = 24.
ID:
ivo://CDS.VizieR/J/MNRAS/273/157
Title:
A faint galaxy survey to B = 24.
Short Name:
J/MNRAS/273/157
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using the multi-slit LDSS-2 spectrograph on the William Herschel Telescope we have completed a redshift survey in the magnitude range 22.5<B<24 which produced 73 redshifts representing a 73% complete sample uniformly selected from four deep fields at high galactic latitude. The survey extends to z>1 and includes the highest redshift galaxy (z=1.108) yet discovered in a field sample.
440. AFGL 2591 multi-wavelength maps
ID:
ivo://CDS.VizieR/J/A+A/551/A43
Title:
AFGL 2591 multi-wavelength maps
Short Name:
J/A+A/551/A43
Date:
21 Oct 2021
Publisher:
CDS
Description:
While it is currently unclear from a theoretical standpoint which forces and processes dominate the formation of high-mass stars, and hence determine the mode in which they form, much of the recent observational evidence suggests that massive stars are born in a similar manner to their low-mass counterparts. This paper aims to investigate the hypothesis that the embedded luminous star AFGL 2591-VLA 3 (2.3E+5L_{sun}_ at 3.33kpc) is forming according to a scaled-up version of a low-mass star formation scenario. We present multi-configuration Very Large Array 3.6cm and 7mm, as well as Combined Array for Research in Millimeter Astronomy C^18^O and 3mm continuum observations to investigate the morphology and kinematics of the ionized gas, dust, and molecular gas around AFGL 2591. We also compare our results to ancillary Gemini North near-IR images, and model the near-IR to sub-mm Spectral Energy distribution (SED) and Two Micron All Sky Survey (2MASS) image profiles of AFGL 2591 using a Monte-Carlo dust continuum radiative transfer code. The observed 3.6 cm images uncover for the first time that the central powering source AFGL 2591-VLA 3 has a compact core plus collimated jet morphology, extending 4000AU eastward from the central source with an opening angle of <10{deg} at this radius. However, at 7mm VLA 3 does not show a jet morphology, but instead compact (< 500AU) emission, some of which (<0.57mJy of 2.9mJy) is estimated to be from dust emission. The spectral index of AFGL 2591-VLA 3 between 3.6cm and 7mm was found to be between 0.4 and 0.5, similar to that of an ionized wind. If the 3.6cm emission is modelled as an ionized jet, the jet has almost enough momentum to drive the larger-scale flow. However, assuming a shock efficiency of 10%, the momentum rate of the jet is not sufficient to ionize itself via only shocks, and thus a significant portion of the emission is instead likely created in a photoionized wind. The C18O emission uncovers dense entrained material in the outflow(s) from these young stars. The main features of the SED and 2MASS images of AFGL 2591-VLA 3 are also reproduced by our model dust geometry of a rotationally flattened envelope with and without a disk. The above results are consistent with a picture of massive star formation similar to that seen for low-mass protostars. However, within its envelope, AFGL 2591-VLA 3 contains at least four other young stars, constituting a small cluster. Therefore it appears that AFGL 2591-VLA 3 may be able to source its accreting material from a shared gas reservoir while still exhibiting the phenomena expected during the formation of low-mass stars.

Limit your search

more »

more »

more »

more »

more »

more »