- ID:
- ivo://CDS.VizieR/J/A+A/585/A84
- Title:
- Shape parameters of lensing galaxies
- Short Name:
- J/A+A/585/A84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The luminosity profiles of galaxies acting as strong gravitational lenses can be tricky to study. Indeed, strong gravitational lensing images display several lensed components, both point-like and diffuse, around the lensing galaxy. Those objects limit the study of the galaxy luminosity to its inner parts. Therefore, the usual fitting methods perform rather badly on such images. Previous studies of strong lenses luminosity profiles using software such as like GALFIT or IMFITFITS and various PSF-determining methods have resulted in somewhat discrepant results. The present work aims at investigating the causes of those discrepancies, as well as at designing more robust techniques for studying the morphology of early-type lensing galaxies with the ability to subtract a lensed signal from their luminosity profiles. The morphology of early-type lensing galaxies with the ability to subtract a lensed signal from their luminosity profiles. Methods. We design a new method to independently measure each shape parameter, namely, the position angle, ellipticity, and half- light radius of the galaxy. Our half-light radius measurement method is based on an innovative scheme for computing isophotes that is well suited to measuring the morphological properties of gravitational lensing galaxies. Its robustness regarding various specific aspects of gravitational lensing image processing is analysed and tested against GALFIT. It is then applied to a sample of systems from the CASTLES database.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/404/1490
- Title:
- Shapes of BCGs in nearby clusters shapes
- Short Name:
- J/MNRAS/404/1490
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compare the apparent axial ratio distributions of the brightest cluster galaxies (BCGs) and normal ellipticals (Es) in our sample of 75 galaxy clusters from the WIde-field Nearby Galaxy-cluster Survey (WINGS). Most BCGs in our clusters (69 per cent) are classified as cD galaxies. The sample of cDs has been completed by 14 additional cDs (non-BCGs) we found in our clusters. We deproject the apparent axial ratio distributions of Es, BCGs and cDs using a bivariate version of the Lucy rectification algorithm, whose results are supported by an independent Monte Carlo technique. Finally, we compare the intrinsic shape distribution of BCGs to the corresponding shape distribution of the central part of cluster-sized dark matter haloes extracted from the GIF2 Lambda cold dark matter ({LAMBDA}CDM) N-body simulations (Gao et al., 2004MNRAS.355..819G).
- ID:
- ivo://CDS.VizieR/J/MNRAS/344/602
- Title:
- Shape statistics of SDSS superclusters
- Short Name:
- J/MNRAS/344/602
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the supercluster shape properties of the recently compiled Sloan Digital Sky Survey (SDSS) cluster catalogue using an approach based on differential geometry. We detect superclusters by applying the percolation algorithm to observed cluster populations, extended out to z_max_<=0.23 in order to avoid selection biases. We utilize a set of shapefinders in order to study the morphological features of superclusters with >=8 cluster members and find that filamentary morphology is the dominant supercluster shape feature, in agreement with previous studies.
- ID:
- ivo://CDS.VizieR/J/A+A/604/A119
- Title:
- SHARDS S0 and E/S0 with anti-truncated disc
- Short Name:
- J/A+A/604/A119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The controversy about the origin of the structure of early-type S0-E/S0 galaxies may be due to the difficulty of comparing surface brightness profiles with different depths, photometric corrections and point spread function (PSF) effects (which are almost always ignored). We aim to quantify the properties of Type-III (anti-truncated) discs in a sample of S0 galaxies at 0.2<z<0.6. In this paper, we present the sample selection and describe in detail the methods to robustly trace the structure in their outskirts and correct for PSF effects. We have selected and classified a sample of 150 quiescent galaxies at 0.2<z<0.6 in the GOODS-N field. We performed a quantitative structural analysis of 44 S0-E/S0 galaxies. We have corrected their surface brightness profiles for PSF distortions and analysed the biases in the structural and photometric parameters when the PSF correction is not applied. Additionally, we have developed Elbow, an automatic statistical method to determine whether a possible break is significant - or not - and its type. We have made this method publicly available. We find 14 anti-truncated S0-E/S0 galaxies in the range 0.2<z<0.6 (~30% of the final sample). This fraction is similar to the those reported in the local Universe. In our sample, ~25% of the Type-III breaks observed in PSF-uncorrected profiles are artifacts, and their profiles turn into a Type I after PSF correction. PSF effects also soften Type-II profiles. We find that the profiles of Type-I S0 and E/S0 galaxies of our sample are compatible with the inner profiles of the Type-III, in contrast with the outer profiles. We have obtained the first robust and reliable sample of 14 anti-truncated S0-E/S0 galaxies beyond the local Universe, in the range 0.2<z<0.6. PSF effects significantly affect the shape of the surface brightness profiles in galaxy discs even in the case of the narrow PSF of HST/ACS images, so future studies on the subject should make an effort to correct them.
- ID:
- ivo://CDS.VizieR/J/ApJ/872/91
- Title:
- SHELS galaxy sizes using Subaru/HSC imaging
- Short Name:
- J/ApJ/872/91
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the relationships between size, stellar mass, and average stellar population age (indicated by D_n_4000 indices) for a sample of ~11000 intermediate-redshift galaxies from the SHELS spectroscopic survey (Geller+ 2014, J/ApJS/213/35) augmented by high-resolution Subaru Telescope Hyper Suprime-Cam imaging. In the redshift interval 0.1<z<0.6, star-forming galaxies are on average larger than their quiescent counterparts. The mass-complete sample of ~3500M_*_>10^10^M_{sun}_ quiescent galaxies shows that the average size of a 10^11^M_{sun}_ quiescent galaxy increases by <~25% from z~0.6 to z~0.1. This growth rate is a function of stellar mass: the most massive (M_*_>10^10^M_{sun}_) galaxies grow significantly more slowly in size than quiescent systems an order of magnitude less massive that grow by 70% in the 0.1<~z<~0.3 redshift interval. For M_*_<10^11^M_{sun}_ galaxies, age and size are anticorrelated at fixed mass; more massive quiescent systems show no significant trend in size with average stellar population age. The evolution in absolute and fractional abundances of quiescent systems at intermediate redshift are also a function of galaxy stellar mass. The suite of evolutionary trends suggests that galaxies more massive than ~10^11^M_{sun}_ have mostly assembled their mass by z~0.6. Quiescent galaxies with lower stellar masses show more complex evolution that is characterized by a combination of individual quiescent galaxy size growth (through mergers) and an increase in the size of newly quenched galaxies joining the population at later times (progenitor bias). The low-mass population (M_*_~10^10^M_{sun}_) grows predominantly as a result of progenitor bias. For more massive (M_*_~5x10^10^M_{sun}_) quiescent galaxies, (predominantly minor) mergers and progenitor bias make more comparable contributions to the size growth. At intermediate redshift, quiescent size growth is mass-dependent; the most massive (M_*_>10^10^M_{sun}_) galaxies experience the least rapid increase in size from z~0.6 to z~0.1.
- ID:
- ivo://CDS.VizieR/J/MNRAS/440/843
- Title:
- SIM2D parameters of SDSS-DR7 galaxies
- Short Name:
- J/MNRAS/440/843
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using data from the Sloan Digital Sky Survey (SDSS)-DR7, including structural measurements from 2D surface brightness fits with gim2d, we show how the fraction of quiescent galaxies depends on galaxy stellar mass M*, effective radius Re, fraction of r-band light in the bulge, B/T, and their status as a central or satellite galaxy at 0.01<z<0.2. For central galaxies we confirm that the quiescent fraction depends not only on stellar mass, but also on Re. The dependence is particularly strong as a function of M*/Re^{alpha}^, with {alpha}~1.5. This appears to be driven by a simple dependence on B/T over the mass range 9<log(M*/M_{sun}_)<11.5, and is qualitatively similar even if galaxies with B/T>0.3 are excluded. For satellite galaxies, the quiescent fraction is always larger than that of central galaxies, for any combination of M*, Re and B/T. The quenching efficiency is not constant, but reaches a maximum of ~0.7 for galaxies with 9<log(M*/M_{sun}_)<9.5 and Re<1kpc. This is the same region of parameter space in which the satellite fraction itself reaches its maximum value, suggesting that the transformation from an active central galaxy to a quiescent satellite is associated with a reduction in Re due to an increase in dominance of a bulge component.
- ID:
- ivo://CDS.VizieR/J/AJ/147/93
- Title:
- Simulation of massive early type galaxies
- Short Name:
- J/AJ/147/93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The next generation of giant-segmented mirror telescopes (>20m) will enable us to observe galactic nuclei at much higher angular resolution and sensitivity than ever before. These capabilities will introduce a revolutionary shift in our understanding of the origin and evolution of supermassive black holes by enabling more precise black hole mass measurements in a mass range that is unreachable today. We present simulations and predictions of the observations of nuclei that will be made with the Thirty Meter Telescope (TMT) and the adaptive optics assisted integral-field spectrograph IRIS, which is capable of diffraction-limited spectroscopy from Z band (0.9{mu}m) to K band (2.2{mu}m). These simulations, for the first time, use realistic values for the sky, telescope, adaptive optics system, and instrument to determine the expected signal-to-noise ratio of a range of possible targets spanning intermediate mass black holes of ~10^4^M_{sun}_ to the most massive black holes known today of >10^10^M_{sun}_. We find that IRIS will be able to observe Milky Way mass black holes out the distance of the Virgo Cluster, and will allow us to observe many more of the brightest cluster galaxies where the most massive black holes are thought to reside. We also evaluate how well the kinematic moments of the velocity distributions can be constrained at the different spectral resolutions and plate scales designed for IRIS. We find that a spectral resolution of ~8000 will be necessary to measure the masses of intermediate mass black holes. By simulating the observations of galaxies found in Sloan Digital Sky Survey DR7, we find that over 10^5^ massive black holes will be observable at distances between 0.005<z<0.18 with the estimated sensitivity and angular resolution provided by access to Z-band (0.9{mu}m) spectroscopy from IRIS and the TMT adaptive optics system. These observations will provide the most accurate dynamical measurements of black hole masses to enable the study of the demography of massive black holes, address the origin of the M_BH_-{sigma} and M_BH_-L relationships, and evolution of black holes through cosmic time.
- ID:
- ivo://CDS.VizieR/J/AJ/142/199
- Title:
- Sizes and luminosities of stellar systems
- Short Name:
- J/AJ/142/199
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use a combined imaging and spectroscopic survey of the nearby central cluster galaxy, M87, to assemble a sample of 34 confirmed UltraCompact Dwarfs (UCDs) with half-light radii of >=10pc measured from Hubble Space Telescope (HST) images. This doubles the existing sample in M87, making it the largest such sample for any galaxy, while extending the detection of UCDs to unprecedentedly low luminosities (MV=-9). With this expanded sample, we find no correlation between size and luminosity, in contrast to previous suggestions, and no general correlation between size and galactocentric distance. We explore the relationships between UCDs, less luminous extended clusters (including faint fuzzies), Globular Clusters (GCs), as well as early-type galaxies and their nuclei, assembling an extensive new catalog of sizes and luminosities for stellar systems. Most of the M87 UCDs follow a tight color-magnitude relation, offset from the metal-poor GCs. This, along with kinematical differences, demonstrates that most UCDs are a distinct population from normal GCs, and not simply a continuation to larger sizes and higher luminosities. The UCD color-magnitude trend couples closely with that for Virgo dwarf elliptical nuclei. We conclude that the M87 UCDs are predominantly stripped nuclei. The brightest and reddest UCDs may be the remnant nuclei of more massive galaxies while a subset of the faintest UCDs may be tidally limited and related to more compact star clusters. In the broader context of galaxy assembly, blue UCDs may trace halo build-up by accretion of low-mass satellites, while red UCDs may be markers of metal-rich bulge formation in larger galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/622/A83
- Title:
- Sizes of infinity regions
- Short Name:
- J/A+A/622/A83
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Backreactions from large-scale inhomogeneities may provide an elegant explanation for the observed accelerated expansion of the universe without the need to introduce dark energy. We propose a cosmological test for a specific model of inhomogeneous cosmology, called timescape cosmology. Using large-scale galaxy surveys such as SDSS and 2MRS, we test the variation of expansion expected in the {Lambda}-CDM model versus a more generic differential expansion using our own calibrations of bounds suggested by timescape cosmology. Our test measures the systematic variations of the Hubble flow towards distant galaxies groups as a function of the matter distribution in the lines of sight to those galaxy groups. We compare the observed systematic variation of the Hubble flow to mock catalogues from the Millennium Simulation in the case of the {Lambda}-CDM model, and a deformed version of the same simulation that exhibits more pronounced differential expansion. We perform a series of statistical tests, ranging from linear regressions to Kolmogorov-Smirnov tests, on the obtained data. They consistently yield results preferring {Lambda}-CDM cosmology over our approximated model of timescape cosmology. Our analysis of observational data shows no evidence that the variation of expansion differs from that of the standard {Lambda}-CDM model.
- ID:
- ivo://CDS.VizieR/J/A+A/229/362
- Title:
- Small-scale structures in HI hole of M33
- Short Name:
- J/A+A/229/362
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent high-resolution HI observations of M33 reveal a large number of regions that are devoid of emission. We interpret these regions as holes formed by interstellar winds; a catalogue containing 148 of these HI holes has been compiled. Their diameters range from the survey resolution limit (>40pc) to 1kpc. The swept-up mass, estimated from surrounding HI densities, ranges from 10^3^M_{sun}_ to 10^7^M_{sun}_. Energies needed to excavate such holes are between 10^49^ to 10^54^erg. Indicative ages, based on derived expansion velocities and diameters, show a cutoff near 7x10^6^yr. Three statistical analysis techniques are applied to determine positional correlation of the H I holes with H II regions, OB associations, and supernova remnants.
