- ID:
- ivo://CDS.VizieR/J/ApJ/812/34
- Title:
- Properties of UCD candidates in M87/M49/M60 regions
- Short Name:
- J/ApJ/812/34
- Date:
- 14 Jan 2022 08:28:26
- Publisher:
- CDS
- Description:
- We use imaging from the Next Generation Virgo cluster Survey (NGVS) to present a comparative study of ultra-compact dwarf (UCD) galaxies associated with three prominent Virgo sub-clusters: those centered on the massive red-sequence galaxies M87, M49, and M60. We show how UCDs can be selected with high completeness using a combination of half-light radius and location in color-color diagrams (u*iK_s_ or u*gz). Although the central galaxies in each of these sub-clusters have nearly identical luminosities and stellar masses, we find large differences in the sizes of their UCD populations, with M87 containing ~3.5 and 7.8 times more UCDs than M49 and M60, respectively. The relative abundance of UCDs in the three regions scales in proportion to sub-cluster mass, as traced by X-ray gas mass, total gravitating mass, number of globular clusters (GCs), and number of nearby galaxies. We find that the UCDs are predominantly blue in color, with ~85% of the UCDs having colors similar to blue GCs and stellar nuclei of dwarf galaxies. We present evidence that UCDs surrounding M87 and M49 may follow a morphological sequence ordered by the prominence of their outer, low surface brightness envelope, ultimately merging with the sequence of nucleated low-mass galaxies, and that envelope prominence correlates with distance from either galaxy. Our analysis provides evidence that tidal stripping of nucleated galaxies is an important process in the formation of UCDs.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/451/835
- Title:
- Properties of X-ray sources in M31/M33
- Short Name:
- J/A+A/451/835
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have obtained optical spectra for the 14 brightest optical counterparts of X-ray sources identified by XMM-Newton in the direction of M 31 and for 21 optical counterparts in the direction of M 33, using the 1.3m Skinakas telescope in Crete, Greece.
2883. PSCz catalog
- ID:
- ivo://CDS.VizieR/VII/221
- Title:
- PSCz catalog
- Short Name:
- VII/221
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The PSCz survey consists of redshifts, infra-red and optical photometry, and assorted other information for 18351 IRAS sources, mostly selected from the Point Source Catalog. The survey was designed to select almost all galaxies with flux brighter than 0.595Jy at 60 microns, over the 84% of the sky with extinction small enough that reliable and complete optical identification and spectroscopy was possible. Some of the sources are not galaxies and some are multiple entries for the same galaxy as described below. There are in total 15411 galaxies or possible galaxies, for which redshifts are available for 14677. The galaxies without redshift are mostly distant or at low latitude, as described below. Many of these galaxies have now been observed as part of the BTP project (Saunders et al 1999, astro-ph/9909174 "The Behind the Plane Survey"), and their redshifts will be included in future revisions of the catalogue. The main catalogue is "pscz.dat". There is also a short version of the catalogue, "psczvs.dat", containing sufficient information for most studies. They correspond to the version 2.2.
2884. PSF models fits maps
- ID:
- ivo://CDS.VizieR/J/A+A/601/A86
- Title:
- PSF models fits maps
- Short Name:
- J/A+A/601/A86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep imaging of the diffuse light that is emitted by stellar fine structures and outer halos around galaxies is often now used to probe their past mass assembly. Because the extended halos survive longer than the relatively fragile tidal features, they trace more ancient mergers. We use images that reach surface brightness limits as low as 28.5-29mag/arcsec^2^ (g-band) to obtain light and color profiles up to 5-10 effective radii of a sample of nearby early-type galaxies. These were acquired with MegaCam as part of the CFHT MATLAS large programme. These profiles may be compared to those produced using simulations of galaxy formation and evolution, once corrected for instrumental effects. Indeed they can be heavily contaminated by the scattered light caused by internal reflections within the instrument. In particular, the nucleus of galaxies generates artificial flux in the outer halo, which has to be precisely subtracted. We present a deconvolution technique to remove the artificial halos that makes use of very large kernels. The technique, which is based on PyOperators, is more time efficient than the model-convolution methods that are also used for that purpose. This is especially the case for galaxies with complex structures that are hard to model. Having a good knowledge of the point spread function (PSF), including its outer wings, is critical for the method. A database of MegaCam PSF models corresponding to different seeing conditions and bands was generated directly from the deep images. We show that the difference in the PSFs in different bands causes artificial changes in the color profiles, in particular a reddening of the outskirts of galaxies having a bright nucleus. The method is validated with a set of simulated images and applied to three representative test cases: NGC 3599, NGC 3489, and NGC 4274, which exhibits a prominent ghost halo for two of them. This method successfully removes this.
- ID:
- ivo://CDS.VizieR/J/MNRAS/308/897
- Title:
- QDOT all-sky IRAS redshift survey
- Short Name:
- J/MNRAS/308/897
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalogue from the QDOT survey consists of infrared properties and redshifts of an all-sky sample of 2387 IRAS galaxies brighter than the IRAS PSC 60{mu}m completeness limit (S_60_>0.6Jy), sparsely sampled at a rate of one-in-six. At |b|>10{deg}, after removing a small number of Galactic sources, the redshift completeness is better than 98% (2086/2127). New redshifts for 1401 IRAS sources were obtained in 1985-88 at several telescopes (see "Note (8)" below) to complete the catalogue; the measurement and reduction of these are described, and the new redshifts tabulated here. We also tabulate all sources at |b|>10{deg} with no redshift so far, and sources with conflicting alternative redshifts either from our own work, or from published velocities. A list of 95 ultraluminous galaxies (i.e. with L(60{mu}m)>10^12^L_{sun}_) is also provided.
- ID:
- ivo://CDS.VizieR/J/A+A/657/L15
- Title:
- Q1700-MD94 CI(1-0) datacube with NOEMA
- Short Name:
- J/A+A/657/L15
- Date:
- 21 Mar 2022 09:37:17
- Publisher:
- CDS
- Description:
- We use a combination of new NOrthern Extended Millimeter Array (NOEMA) observations of the pair of [CI] transitions, the CO(7-6) line, and the dust continuum, in addition to ancillary CO(1-0) and CO(3-2) data, to study the molecular gas properties of Q1700-MD94, a massive, main-sequence galaxy at z~2. We find that for a reasonable set of assumptions for a typical massive star-forming galaxy, the CO(1-0), the [CI](1-0) and the dust continuum yield molecular gas masses that are consistent within a factor of ~2. The global excitation properties of the molecular gas as traced by the [CI] and CO transitions are similar to those observed in other massive, star-forming galaxies at z~2. Our large velocity gradient (LVG) modeling using RADEX of the CO and [CI] spectral line energy distributions (SLEDs) suggests the presence of relatively warm (Tkin=41K), dense (n_H2_=8x10^3^cm^-3^) molecular gas, comparable to the high-excitation molecular gas component observed in main-sequence, star-forming galaxies at z~1. The galaxy size in the CO(1-0) and CO(7-6) line emission are comparable, which suggests that the highly-excited molecular gas is distributed throughout the disk powered by intense star formation activity. To confirm this scenario will require spatially resolved observations of the CO and [CI] lines which can now be obtained with NOEMA upgraded capabilities.
- ID:
- ivo://CDS.VizieR/J/MNRAS/253/485
- Title:
- QMW IRAS galaxy catalogue
- Short Name:
- J/MNRAS/253/485
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study presents a highly complete and reliable IRAS 60-micron galaxy catalog covering 82 percent of the sky. IRAS color conditions are used to exclude galactic sources, including the remaining cirrus sources. All sources flagged as extended, confused, or having a poor correlation coefficient with a point-source template are examined with the raw IRAS data and accurate fluxes determined using mapping routines. The completeness, reliability, and flux accuracy of the catalog are discussed. Identifications are made with existing optical galaxy catalogs and with galaxy redshift surveys in the literature. It is estimated that redshifts are available for 79 percent of the galaxies in the catalog with V less than 5000km/s, and the 3D distribution of such galaxies is displayed. The dipole component of the surface-brightness distribution of galaxies in the catalog is discussed.
- ID:
- ivo://CDS.VizieR/J/MNRAS/447/3856
- Title:
- QSO-galaxy pairs from SDSS
- Short Name:
- J/MNRAS/447/3856
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometric and spectroscopic measurements of 53 QSO-galaxy pairs from the Sloan Digital Sky Survey (SDSS), where nebular emission lines from a 0<z<0.84 foreground galaxy are detected in the fibre spectra of a background QSO, bringing the overall sample to 103 QSO-galaxy pairs detected in the SDSS. We here study the nature of these systems. Detected foreground galaxies appear at impact parameters between 0.37 and 12.68 kpc. The presence of oxygen and Balmer emission lines allows us to determine the emission line metallicities for our sample, which are on average supersolar in value. Star formation rates for our sample are in the range 0.01-12M_{sun}_/yr. We utilize photometric redshift fitting techniques to estimate the M* values of our galaxies (logM*=7.34-11.54), and extrapolate this relationship to those galaxies with no imaging detections. Where available, we measure the absorption features present in the QSO spectrum due to the foreground galaxy and the relationships between their rest equivalent widths. We report an anticorrelation between impact parameter and E(B-V)(g-i), as well as a correlation between galaxy colour (u- r) and E(B-V)(g-i). We find that our sample is one of late-type, star-forming galaxies comparable to field galaxies in a similar redshift range, providing important clues to better understand absorption systems. These galaxies represent a sample of typical galaxies in the local Universe for which abundances, extinction, morphology, and absorption properties may be measured using background QSOs with great potential for follow-up observations.
2889. QSO J1721+8842 spectra
- ID:
- ivo://CDS.VizieR/J/A+A/657/A113
- Title:
- QSO J1721+8842 spectra
- Short Name:
- J/A+A/657/A113
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- High-redshift binary quasars provide key insights into mergers and quasar activity, and are useful tools for probing the spatial kinematics and chemistry of galaxies along the line-of-sight. However, only three sub-10-kpc binaries have been confirmed above z=1. Gravitational lensing would provide a way to easily resolve such binaries, study them in higher resolution, and provide more sightlines, though the required alignment with a massive foreground galaxy is rare. Through image deconvolution of StanCam Nordic Optical Telescope (NOT) monitoring data, we reveal two further point sources in the known, z~2.38, quadruply lensed quasar (quad), J1721+8842. An ALFOSC/NOT long-slit spectrum shows that the brighter of these two sources is a quasar with z=2.369+/-0.007 based on the CIII] line, while the CIII] redshift of the quad is z=2.364+/-0.003. Lens modelling using point source positions rules out a single source model, favouring an isothermal lens mass profile with two quasar sources separated by ~6.0kpc (0.73") in projection. Given the resolving ability from lensing and current lensed quasar statistics, this discovery suggests a large population of undiscovered, unlensed sub-10-kpc binaries. We also analyse spectra of two images of the quad, showing narrow Ly{alpha} emission within the trough of a proximate damped Lyman-{alpha} absorber (PDLA). An apparent mismatch between the continuum and narrow line flux ratios provides a new potential tool for simultaneously studying microlensing and the quasar host galaxy. Signs of the PDLA are also seen in the second source, however a deeper spectrum is still required to confirm this. Thanks to the multiple lines-of-sight from lensing and two quasar sources, this system offers simultaneous sub-parsec and kpc-scale probes of a PDLA.
2890. QSOs in the M3 field
- ID:
- ivo://CDS.VizieR/J/A+A/392/851
- Title:
- QSOs in the M3 field
- Short Name:
- J/A+A/392/851
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from a variability and proper motion (VPM) search for QSOs in the field around M3. The VPM search is demonstrated to be powerful technique for efficiently finding QSOs without major selection effects with regard to the spectral energy distribution. Remarkably, the properties of the VPM QSOs do not significantly differ from those of samples from more conventional optical search techniques. The lightcurves of the QSOs from the resulting sample provide an interesting data set for the statistical investigation of QSO long-term variability.
