- ID:
- ivo://CDS.VizieR/J/MNRAS/464/666
- Title:
- Void Galaxy Survey, photometry and structure
- Short Name:
- J/MNRAS/464/666
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyse photometry from deep B-band images of 59 void galaxies in the Void Galaxy Survey (VGS), together with their near-infrared 3.6{mu}m and 4.5{mu}m Spitzer photometry. The VGS galaxies constitute a sample of void galaxies that were selected by a geometric-topological procedure from the Sloan Digital Sky Survey Data Release 7 data release, and which populate the deep interior of voids. Our void galaxies span a range of absolute B-magnitude from M_B_=-15.5 to -20, while at the 3.6{mu}m band their magnitudes range from M_3.6_=-18 to -24. Their B-[3.6] colour and structural parameters indicate these are star-forming galaxies. A good reflection of the old stellar population, the near-infrared band photometry also provide a robust estimate of the stellar mass, which for the VGS galaxies we confirm to be smaller than 3x10^10^M_{sun}_. In terms of the structural parameters and morphology, our findings align with other studies in that our VGS galaxy sample consists mostly of small late-type galaxies. Most of them are similar to Sd-Sm galaxies, although a few are irregularly shaped galaxies. The sample even includes two early-type galaxies, one of which is an AGN. Their Sersic indices are nearly all smaller than n=2 in both bands and they also have small half-light radii. In all, we conclude that the principal impact of the void environment on the galaxies populating them mostly concerns their low stellar mass and small size.
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Search Results
- ID:
- ivo://CDS.VizieR/J/other/NewA/11.293
- Title:
- Warped disks in spiral galaxies
- Short Name:
- J/other/NewA/11.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have analyzed the disk morphologies of 325 edge-on galaxies to derive the warp statistics in spiral galaxies using Digital Sky Survey. Galaxies were included in our study if their isophotal diameter (D25) satisfied logD25>1, and if their major-to-minor axis ratio was in the range a/b>9.5. We found that 236 out of the 325 sample galaxies (73%) had warps: 165 S-shaped (51%) and 71 U-shaped (22%). We additionally found that the warp properties (warp angles, warp radius, and warp asymmetry) as well as the warp frequency did not depend on galaxy morphology. A quite tight anticorrelation was observed between warp radius and warp amplitude, and a positive correlation was found between warp asymmetry and warp amplitude. A detailed analysis of the relations between warp parameters and galaxy properties revealed that strong warps are mostly caused by tidal interactions, whereas weak warps are formed by a variety of mechanisms including gas accretion. The present results indicate that the fractional warp radius coupled with warp angles representing the warp amplitude and warp curvature provide useful diagnostic indicators of the origin of warps.
- ID:
- ivo://CDS.VizieR/J/A+A/399/457
- Title:
- Warps in southern hemisphere galaxies
- Short Name:
- J/A+A/399/457
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalog of optical warps of galaxies is presented. This can be considered complementary to that reported by Sanchez-Saavedra et al. (1990MNRAS.246..458S), with 42 galaxies in the northern hemisphere, and to that by Reshetnikov & Combes (1999A&AS..138..101R), with 60 optical warps. The limits of the present catalog are: logr_25_>0.60, B_1_<14.5, DE(2000)<0{deg}, -2.5<t.7. Therefore, lenticular galaxies have also been considered. This catalog lists 150 warped galaxies out of a sample of 276 edge-on galaxies and covers the whole southern hemisphere, except the Avoidance Zone. It is therefore very suitable for statistical studies of warps. It also provides a source guide for detailed particular observations. We confirm the large frequency of warped spirals: nearly all galaxies are warped. The frequency and warp angle do not present important differences for the different types of spirals. However, no lenticular warped galaxy has been found within the specified limits. This finding constitutes an important restriction for theoretical models.
704. Warps of galaxies
- ID:
- ivo://CDS.VizieR/J/A+A/391/519
- Title:
- Warps of galaxies
- Short Name:
- J/A+A/391/519
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From a comparison of the different parameters of warped galaxies in the radio, and especially in the visible, we find that: a) No large galaxy (large mass or radius) has been found to have high amplitude in the warp, and there is no correlation of size/mass with the degree of asymmetry of the warp. b) The disc density and the ratio of dark to luminous mass show an opposing trend: smaller values give more asymmetric warps in the inner radii (optical warps) but show no correlation with the amplitude of the warp; however, in the external radii is there no correlation with asymmetry. c) A third anticorrelation appears in a comparison of the amplitude and degree of asymmetry in the warped galaxies. Hence, it seems that very massive dark matter haloes have nothing to do with the formation of warps but only with the degree of symmetry in the inner radii, and are unrelated to the warp shape for the outermost radii. Denser discs show the same dependence.
- ID:
- ivo://CDS.VizieR/J/MNRAS/416/927
- Title:
- Wide-field optical imaging of 4 fields
- Short Name:
- J/MNRAS/416/927
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present u-, g-, r-, i- and z-band optical images and associated catalogues taken primarily with the Isaac Newton Telescope Wide Field Camera on the European Large Area ISO Survey (ELAIS) N1 and N2, First Look Survey and Lockman Hole fields comprising a total of 1000h of integration time over 80deg^2^ and approximately 4.3 million objects. In this paper we outline the observations and data processing and characterize the completeness, reliability, photometric and astrometric accuracy of this data set. All images have been photometrically calibrated using the Sloan Digital Sky Survey and a uniform and homogeneous data set is composed over all the observed fields. Magnitude limits are u, g, r, i, z of 23.9, 24.5, 24.0, 23.3, 22.0 (AB, 5{sigma}). These data have been used for optical identification of past and ongoing projects including the surveys ELAIS, Spitzer Wide-Area Infrared Extragalactic Survey, Spitzer Extragalactic Representative Volume Survey and Herschel Multi-tiered Extragalactic Survey.
- ID:
- ivo://CDS.VizieR/J/A+A/633/A104
- Title:
- WINGS cluster galaxies structural parameters
- Short Name:
- J/A+A/633/A104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multi-wavelength analysis of the galaxies in nine clusters selected from the WINGS dataset, examining how galaxy structure varies as a function of wavelength and environment using the state of the art software galapagos-2. We simultaneously fit single-Sersic functions on three optical (u, B and V) and two near-infrared (J and K) bands thus creating a wavelength-dependent model of each galaxy. We measure the magnitudes, effective radius (Re), the Sersic index (n), axis ratio, and position angle in each band. The sample contains 790 cluster members (located close to the cluster centre <0.64xR200) and 254 non-member galaxies that we further separate based on their morphology into ellipticals, lenticulars, and spirals. We find that the Sersic index of all galaxies inside clusters remains nearly constant with wavelength while Re decreases as wavelength increases for all morphological types. We do not observe a significant variation on n and Re as a function of projected local density and distance from the clusters centre. Comparing the n and Re of bright cluster galaxies with a subsample of non-member galaxies we find that bright cluster galaxies are more concentrated (display high n values) and are more compact (low Re). Moreover, the light profile (N) and size (R) of bright cluster galaxies does not change as a function of wavelength in the same manner as non-member galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJS/247/43
- Title:
- WWFI g'-band obs. of bright cluster galaxies
- Short Name:
- J/ApJS/247/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of 170 local (z<~0.08) galaxy clusters in the northern hemisphere have been obtained with the Wendelstein Telescope Wide Field Imager (WWFI). We correct for systematic effects such as point-spread function broadening, foreground star contamination, relative bias offsets, and charge persistence. Background inhomogeneities induced by scattered light are reduced down to {Delta}SB>31 g' mag/arcsec^2^ by large dithering and subtraction of night-sky flats. Residual background inhomogeneities brighter than SB_{sigma}_<27.6 g' mag/arcsec^2^ caused by galactic cirrus are detected in front of 23% of the clusters. However, the large field of view allows discrimination between accretion signatures and galactic cirrus. We detect accretion signatures in the form of tidal streams in 22%, shells in 9.4%, and multiple nuclei in 47% of the brightest cluster galaxies (BCGs) and find two BCGs in 7% of the clusters. We measure semimajor-axis surface brightness profiles of the BCGs and their surrounding intracluster light (ICL) down to a limiting surface brightness of SB=30 g' mag/arcsec^2^. The spatial resolution in the inner regions is increased by combining the WWFI light profiles with those that we measured from archival Hubble Space Telescope images or deconvolved WWFI images. We find that 71% of the BCG+ICL systems have surface brightness (SB) profiles that are well described by a single Sersic function, whereas 29% require a double Sersic function to obtain a good fit. We find that BCGs have scaling relations that differ markedly from those of normal ellipticals, likely due to their indistinguishable embedding in the ICL.
- ID:
- ivo://CDS.VizieR/J/ApJ/591/640
- Title:
- XMM-LSS low-frequency radio counterparts
- Short Name:
- J/ApJ/591/640
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The XMM Large-Scale Structure Survey (XMM-LSS) is a major project to map the large-scale structure of the universe out to cosmological distances. An 8x8 region will be surveyed by XMM with planned optical follow-up to produce a three-dimensional map of many hundreds of clusters out to a redshift of z=1. To explore the relation of the large-scale structure to the location and properties of extragalactic radio sources, the XMM-LSS project also includes a low-frequency radio survey of this region. This combination will provide unprecedented insight into how the radio source formation and evolution are affected by the local environment. Here we present preliminary results from our 325 and 74MHz surveys in this region. At 325MHz, we have a flux limit of 4mJy/beam, a resolution of 6.3", and a total of 256 source detections over 5.6deg^2^. At 74MHz, we have a flux limit of 275mJy/beam, a resolution of 30", and a total of 211 source detections over 110deg^2^. We describe these results and explore what they tell us about the population of extragalactic low-frequency radio sources. The 74MHz survey represents the first presentation of a deep, subarcminute resolution survey at such a low frequency. This was made possible by recent advances in both hardware and data reduction algorithms, which we describe in detail.
- ID:
- ivo://CDS.VizieR/J/A+A/639/A5
- Title:
- X-ray absorption in INTEGRAL AGN
- Short Name:
- J/A+A/639/A5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this work the INTEGRAL hard X-ray selected sample of AGN has been used to investigate the possible contribution of absorbing material distributed within the host galaxies to the total amount of NH measured in the X-ray band. We collected all the available axial ratio measurements of the galaxies hosting our AGN together with their morphological information and find that also for our hard X-ray selected sample a deficit of edge-on galaxies hosting type 1 AGN is present. We estimate that in our hard X-ray selected sample there is a deficit of 24% (+/-5%) of type 1 AGN. Possible bias in redshift has been excluded, as we found the same effect in a well determined range of z where the number and the distributions of the two classes are statistically the same. Our findings clearly indicate that material located in the host galaxy on scales of hundreds of parsecs and not aligned with the putative absorbing torus of the AGN can contribute to the total amount of column density. This galactic absorber can be large enough to hide the broad line region of some type 1 AGN causing their classification as type 2 objects and giving rise to the deficiency of type 1 in edge-on galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/446/2709
- Title:
- X-ray bright AGN in massive galaxy clusters
- Short Name:
- J/MNRAS/446/2709
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a new analysis of the X-ray selected active galactic nuclei (AGN) population residing in and behind 135 of the most massive galaxy clusters in the redshift range of 0.2<z<0.9 observed with Chandra. With a sample of more than 11000 X-ray point sources, we are able to measure, for the first time, evidence for evolution in the cluster AGN population beyond the expected evolution of field AGN. Our analysis shows that overall number density of cluster AGN scales with the cluster mass as ~M_500_-1.2. There is no evidence for the overall number density of cluster member X-ray AGN depending on the cluster redshift in a manner different than field AGN, nor is there any evidence that the spatial distribution of cluster AGN (given in units of the cluster overdensity radius r_500_) strongly depends on the cluster mass or redshift. The M^-1.2+/-0.7^ scaling relation we measure is consistent with theoretical predictions of the galaxy merger rate in clusters, which is expected to scale with the cluster velocity dispersion, {sigma}, as ~{sigma}^-3^ or ~M^-1^. This consistency suggests that galaxy mergers may be an important contributor to the cluster AGN population, a result that is further corroborated by visual inspection of Hubble images for 23 spectroscopically confirmed cluster member AGN in our sample. A merger-driven scenario for the triggering of X-ray AGN is not strongly favoured by studies of field galaxies, however, suggesting that different mechanisms may be primarily responsible for the triggering of cluster and field X-ray AGN.
