- ID:
- ivo://CDS.VizieR/J/ApJS/182/216
- Title:
- Surface photometry of Virgo ellipticals
- Short Name:
- J/ApJS/182/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New surface photometry of all known elliptical galaxies in the Virgo cluster is combined with published data to derive composite profiles of brightness, ellipticity, position angle, isophote shape, and color over large radius ranges. These provide enough leverage to show that Sersic logI{prop.to}r^1/n^ functions fit the brightness profiles I(r) of nearly all ellipticals remarkably well over large dynamic ranges. Therefore, we can confidently identify departures from these profiles that are diagnostic of galaxy formation. Finally, we verify that there is a strong dichotomy between elliptical and spheroidal galaxies. Their properties are consistent with our understanding of their different formation processes: mergers for ellipticals and conversion of late-type galaxies into spheroidals by environmental effects and by energy feedback from supernovae.
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Search Results
- ID:
- ivo://CDS.VizieR/VII/184
- Title:
- Survey of 108 E-S0 galaxies
- Short Name:
- VII/184
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A survey has been performed of the morphological and photometric properties of 108 E-S0 galaxies out of a complete sample of 112: this sample is built from the Revised Shapley-Ames Catalogue (RSA) keeping objects with {delta}>-10deg and V_0_<3000km/s, rejecting SB0's and Local Group dwarfs. The data were mainly derived from our CCD observations at Observatoire de Haute-Provence: the camera allowed fields of 4x7arcmin (or 7x7 from the last run), the seeing being generally in the 2-3arcsec FWHM range. The measurements include the isophotal analysis according to Carter's (1978) principles, and the photometric profiles along the two main axis. Opposite semi-axis are measured separately to detect asymmetries.
- ID:
- ivo://CDS.VizieR/J/ApJ/639/724
- Title:
- Tadpole galaxies in the Hubble UDF
- Short Name:
- J/ApJ/639/724
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the Hubble Ultra Deep Field (HUDF, Cat. <II/258>) an abundance of galaxies is seen with a knot at one end plus an extended tail, resembling a tadpole. These "tadpole galaxies" appear dynamically unrelaxed - presumably in an early merging stage - where tidal interactions likely created the distorted knot-plus-tail morphology. Here we systematically select tadpole galaxies from the HUDF and study their properties as a function of their photometric redshifts.
- ID:
- ivo://CDS.VizieR/J/ApJS/199/27
- Title:
- The ATLBS Extended Source Sample
- Short Name:
- J/ApJS/199/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on the Australia Telescope Low Brightness Survey (ATLBS) we present a sample of extended radio sources and derive morphological properties of faint radio sources. One hundred nineteen radio galaxies form the ATLBS Extended Source Sample (ATLBS-ESS) consisting of all sources exceeding 30" in extent and integrated flux densities exceeding 1mJy. We give structural details along with information on galaxy identifications and source classifications. The ATLBS-ESS, unlike samples with higher flux-density limits, has almost equal fractions of FR-I and FR-II radio galaxies, with a large fraction of the FR-I population exhibiting 3C31-type structures. Significant asymmetry in lobe extents appears to be a common occurrence in the ATLBS-ESS FR-I sources compared with FR-II sources. We present a sample of 22 FR-Is at z>0.5 with good structural information. The detection of several giant radio sources, with size exceeding 0.7Mpc, at z>1 suggests that giant radio sources are not less common at high redshifts. The ESS also includes a sample of 28 restarted radio galaxies.
- ID:
- ivo://CDS.VizieR/J/ApJS/197/22
- Title:
- The Carnegie-Irvine Galaxy Survey (GGS). II.
- Short Name:
- J/ApJS/197/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Carnegie-Irvine Galaxy Survey (CGS) is a comprehensive investigation of the physical properties of a complete, representative sample of 605 bright (B_T_<=12.9mag) galaxies in the southern hemisphere. This contribution describes the isophotal analysis of the broadband (BVRI) optical imaging component of the project. We pay close attention to sky subtraction, which is particularly challenging for some of the large galaxies in our sample. Extensive crosschecks with internal and external data confirm that our calibration and sky subtraction techniques are robust with respect to the quoted measurement uncertainties. We present a uniform catalog of one-dimensional radial profiles of surface brightness and geometric parameters, as well as integrated colors and color gradients. We use the geometric parameters, in conjunction with the amplitude and phase of the m=2 Fourier mode, to identify bars and quantify their size and strength. Finally, we utilize the information encoded in the m=1 Fourier profiles to measure disk lopsidedness.
- ID:
- ivo://CDS.VizieR/J/ApJ/862/13
- Title:
- The Carnegie-Irvine Galaxy Survey. VI. Spirals
- Short Name:
- J/ApJ/862/13
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Carnegie-Irvine Galaxy Survey provides high-quality broadband optical images of a large sample of nearby galaxies for detailed study of their structure. To probe the physical nature and possible cosmological evolution of spiral arms, a common feature of many disk galaxies, it is important to quantify their main characteristics. We describe robust methods to measure the number of arms and their mean strength, length, and pitch angle. The arm strength depends only weakly on the adopted radii over which it is measured, and it is stronger in bluer bands than redder bands. The vast majority of clearly two-armed ("grand-design") spiral galaxies have a systematically higher relative amplitude of the m=2 Fourier mode in the main spiral region. We use both one-dimensional and two-dimensional Fourier decomposition to measure the pitch angle, finding reasonable agreement between these two techniques with a scatter of ~2{deg}. To understand the applicability and limitations of our methodology to imaging surveys of local and distant galaxies, we create mock images with properties resembling observations of local (z<~0.1) galaxies by the Sloan Digital Sky Survey and distant galaxies (0.1<~z<~1.1) observed with the Hubble Space Telescope. These simulations lay the foundation for forthcoming quantitative statistical studies of spiral structure to understand its formation mechanism, dependence on galaxy properties, and cosmological evolution.
- ID:
- ivo://CDS.VizieR/J/ApJ/821/114
- Title:
- The CGS. IV. Elliptical galaxies colors
- Short Name:
- J/ApJ/821/114
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Many recent observations and numerical simulations suggest that nearby massive, early-type galaxies (ETGs) were formed through a "two-phase" process. In the proposed second phase, the extended stellar envelope was accumulated through many dry mergers. However, details of the past merger history of present-day ellipticals, such as the typical merger mass ratio, are difficult to constrain observationally. Within the context and assumptions of the two-phase formation scenario, we propose a straightforward method, using photometric data alone, to estimate the average mass ratio of mergers that contributed to the build-up of massive elliptical galaxies. We study a sample of nearby massive elliptical galaxies selected from the Carnegie-Irvine Galaxy Survey, using two-dimensional analysis to decompose their light distribution into an inner, denser component plus an extended, outer envelope, each having a different optical color. The combination of these two substructures accurately recovers the negative color gradient exhibited by the galaxy as whole. The color difference between the two components (<{Delta}(B-V)>~0.10mag; <{Delta}(B-R)>~0.14mag), based on the slope of the M*-color relation for nearby ETGs, can be translated into an estimate of the average mass ratio of the mergers. The rough estimate, 1:5 to 1:10, is consistent with the expectation of the two-phase formation scenario, suggesting that minor mergers were largely responsible for building up the outer stellar envelopes of present-day massive ellipticals. With the help of accurate photometry, large sample sizes and more choices of colors promised by ongoing and future surveys, the approach proposed here can provide more insights into the growth of massive galaxies during the last few Gyr.
- ID:
- ivo://CDS.VizieR/J/ApJS/247/20
- Title:
- The CGS. IX. R-band single-Sersic fits to ellipticals
- Short Name:
- J/ApJS/247/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the statistical properties of 320 bulges of disk galaxies in the Carnegie-Irvine Galaxy Survey, using robust structural parameters of galaxies derived from image fitting. We apply the Kormendy relation to classify classical and pseudo bulges and characterize the bulge dichotomy with respect to the structural properties of the bulges and the physical properties of the host galaxies. We confirm previous findings that pseudo bulges on average have smaller Sersic indices, lower bulge-to-total ratios, and fainter surface brightnesses than classical bulges. Our sizable sample statistically shows that pseudo bulges are more intrinsically flattened than classical bulges. Pseudo bulges are most frequent (incidence >~80%) in late-type spirals (later than Sc). Our measurements support the picture in which pseudo bulges arose from star formation induced by inflowing gas, while classical bulges were born out of violent processes such as mergers and coalescence of clumps. We reveal differences with the literature that warrant attention: (1) the bimodal distribution of Sersic indices presented by previous studies is not reproduced in our study; (2) classical and pseudo bulges have similar relative bulge sizes; and (3) the pseudo bulge fraction is considerably smaller in early-type disks than reported in previous studies based on one-dimensional surface brightness profile fitting. We attribute these differences to our improved image quality, more robust bulge-to-disk decomposition technique, and to the different classification criteria that we applied. Moreover, we find that barred galaxies do not host more pseudo bulges or more prominent pseudo bulges than unbarred galaxies. Various implications of these findings are discussed.
- ID:
- ivo://CDS.VizieR/J/ApJS/244/34
- Title:
- The CGS. VIII. R-band images of disk galaxies
- Short Name:
- J/ApJS/244/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multicomponent decomposition of high-quality R-band images of 320 disk galaxies from the Carnegie-Irvine Galaxy Survey. In addition to bulges and disks, we successfully model nuclei, bars, disk breaks, nuclear/inner lenses, and inner rings. Our modeling strategy treats nuclear rings and nuclear bars as part of the bulge component, while other features such as spiral arms, outer lenses, and outer rings are omitted from the fits because they are not crucial for accurate bulge measurements. The error budget of bulge parameters includes the uncertainties from sky-level measurements and model assumptions. Comparison with multicomponent decomposition from the Spitzer Survey of Stellar Structure in Galaxies reveals broad agreement for the majority of the overlapping galaxies, but for a considerable fraction of galaxies there are significant differences in bulge parameters caused by different strategies in model construction. We confirm that on average bulge prominence decreases from early- to late-type disk galaxies, although the large scatter of bulge-to-total ratios in each morphological bin limits the application of Hubble type as an accurate predictor of bulge-to-total ratio. In contrast with previous studies claiming that barred galaxies host weaker bulges, we find that barred and unbarred spiral galaxies have similar bulge prominence.
- ID:
- ivo://CDS.VizieR/J/ApJS/215/22
- Title:
- The Extended Virgo Cluster Catalog (EVCC)
- Short Name:
- J/ApJS/215/22
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new catalog of galaxies in the wider region of the Virgo cluster, based on the Sloan Digital Sky Survey (SDSS) Data Release 7. The Extended Virgo Cluster Catalog (EVCC) covers an area of 725deg^2^ or 60.1Mpc^2^. It is 5.2 times larger than the footprint of the classical Virgo Cluster Catalog (VCC) and reaches out to 3.5 times the virial radius of the Virgo cluster. We selected 1324 spectroscopically targeted galaxies with radial velocities less than 3000km/s. In addition, 265 galaxies that have been overlooked in the SDSS spectroscopic survey but have available redshifts in the NASA Extragalactic Database are also included. Our selection process secured a total of 1589 galaxies, 676 of which are not included in the VCC. The certain and possible cluster members are defined by means of redshift comparison with a cluster infall model. We employed two independent and complementary galaxy classification schemes: the traditional morphological classification based on the visual inspection of optical images and a characterization of galaxies from their spectroscopic features. SDSS u, g, r, i, and z passband photometry of all EVCC galaxies was performed using Source Extractor. We compare the EVCC galaxies with the VCC in terms of morphology, spatial distribution, and luminosity function. The EVCC defines a comprehensive galaxy sample covering a wider range in galaxy density that is significantly different from the inner region of the Virgo cluster. It will be the foundation for forthcoming galaxy evolution studies in the extended Virgo cluster region, complementing ongoing and planned Virgo cluster surveys at various wavelengths.
