- ID:
- ivo://CDS.VizieR/J/A+A/430/411
- Title:
- B-band photometry of ellipticals in Virgo
- Short Name:
- J/A+A/430/411
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a complete CCD imaging survey of 226 elliptical galaxies in the North-East quadrant of the Virgo cluster, representative of the properties of giant and dwarf elliptical galaxies in this cluster. We fit their radial light profiles with the Sersic r^1/n^ model of light distribution. We confirm the result of Graham & Guzman (2003AJ....125.2936G) that the apparent dichotomy between E and dE galaxies in the luminosity-<{mu}>_e_ plane no longer appears when other structural parameters are considered and can be entirely attributed to the onset of "core" galaxies at B_T_~-20.5mag. When "core" galaxies are not considered, E and dE form a unique family with n linearly increasing with the luminosity. For 90 galaxies we analyze the B-I color indices, both in the nuclear and in the outer regions. Both indices are bluer toward fainter luminosities. We find also that the outer color gradients do not show any significant correlation with the luminosity. The scatter in all color indicators increases significantly toward lower luminosities, e.g. galaxies fainter than B_T_~-15 have a B-I spread>0.5mag.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/148/75
- Title:
- Bent-tailed radio galaxies Chandra Deep Field South
- Short Name:
- J/AJ/148/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the 1.4GHz Australia Telescope Large Area Survey, supplemented by the 1.4GHz Very Large Array images, we undertook a search for bent-tailed (BT) radio galaxies in the Chandra Deep Field South. Here we present a catalog of 56 detections, which include 45 BT sources, 4 diffuse low-surface-brightness objects (1 relic, 2 halos, and 1 unclassified object), and a further 7 complex, multi-component sources. We report BT sources with rest-frame powers in the range 10^22^<=P_1.4 GHz_<=10^26^W/Hz, with redshifts up to 2 and linear extents from tens of kiloparsecs up to about 1Mpc. This is the first systematic study of such sources down to such low powers and high redshifts and demonstrates the complementary nature of searches in deep, limited area surveys as compared to shallower, large surveys. Of the sources presented here, one is the most distant BT source yet detected at a redshift of 2.1688. Two of the sources are found to be associated with known clusters: a wide-angle tail source in A3141 and a putative radio relic which appears at the infall region between the galaxy group MZ 00108 and the galaxy cluster AMPCC 40. Further observations are required to confirm the relic detection, which, if successful, would demonstrate this to be the least powerful relic yet seen with P_1.4GHz_=9x10^22^W/Hz. Using these data, we predict future 1.4GHz all-sky surveys with a resolution of ~10 arcsec and a sensitivity of 10{mu}Jy will detect of the order of 560,000 extended low-surface-brightness radio sources of which 440,000 will have a BT morphology.
- ID:
- ivo://CDS.VizieR/J/MNRAS/457/4160
- Title:
- BETA pilot multi-epoch continuum survey
- Short Name:
- J/MNRAS/457/4160
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Boolardy Engineering Test Array is a 6x12m dish interferometer and the prototype of the Australian Square Kilometre Array Pathfinder (ASKAP), equipped with the first generation of ASKAP's phased array feed (PAF) receivers. These facilitate rapid wide-area imaging via the deployment of simultaneous multiple beams within an ~30deg^2^ field of view. By cycling the array through 12 interleaved pointing positions and using nine digitally formed beams, we effectively mimic a traditional 1hx108 pointing survey, covering ~150deg^2^ over 711-1015MHz in 12h of observing time. Three such observations were executed over the course of a week. We verify the full bandwidth continuum imaging performance and stability of the system via self-consistency checks and comparisons to existing radio data. The combined three epoch image has arcminute resolution and a 1{sigma} thermal noise level of 375{mu}Jy/beam, although the effective noise is a factor of ~3 higher due to residual sidelobe confusion. From this we derive a catalogue of 3722 discrete radio components, using the 35 per cent fractional bandwidth to measure in-band spectral indices for 1037 of them. A search for transient events reveals one significantly variable source within the survey area. The survey covers approximately two-thirds of the Spitzer South Pole Telescope Deep Field. This pilot project demonstrates the viability and potential of using PAFs to rapidly and accurately survey the sky at radio wavelengths.
- ID:
- ivo://CDS.VizieR/J/A+A/630/A135
- Title:
- Beyond the exoplanet mass-radius relation
- Short Name:
- J/A+A/630/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The mass and radius are two fundamental properties to characterize exoplanets but only for a relatively small fraction of exoplanets are they both available. The mass is often derived from radial velocity measurements while the radius is almost always measured with the transit method. For a large number of exoplanets, either the radius or the mass is unknown, while the host star has been characterized. Several mass-radius relations dependent on the planet's type have been published which often allow to predict the radius, as well as a bayesian code which forecasts the radius of an exoplanet given the mass or vice versa. Our goal is to derive the radius of exoplanets using only observables extracted from spectra used primarily to determine radial velocities and spectral parameters. Our objective is to obtain a mass-radius relation that is independent of the planet's type. We work with a database of confirmed exoplanets with known radii and masses as well as the planets from our Solar System. Using random forests, a machine learning algorithm, we compute the radius of exoplanets and compare the results to the published radii. Our code, BEM, is available online. On top of this, we also explore how the radius estimates compare to previously published mass-radius relations. The estimated radii reproduces the spread in radius found for high mass planets better than previous mass-radius relations. The average error on the radius is 1.8R_Earth_ across the whole range of radii from 1 to 22R_Earth_. We found that a random forest algorithm is able to derive reliable radii especially for planets between 4 and 20R_Earth_, for which the error is smaller than 25%. The algorithm has a low bias but still a high variance, which could be reduced by limiting the growth of the forest or adding more data. The random forest algorithm is a promising method to derive exoplanet properties. We show that the exoplanet's mass and equilibrium temperature are the relevant properties which constrain the radius, and do it with higher accuracy than the previous methods.
- ID:
- ivo://CDS.VizieR/J/MNRAS/435/1186
- Title:
- BI photometry of bulgeless galaxies
- Short Name:
- J/MNRAS/435/1186
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We examine the magnitude and size evolution of bulgeless (discs with no-bulge or pseudo-bulge) galaxies up to z~0.9 in rest-frame B band. Their evolution is compared to that of normal-discs (or discs with classical bulge). The study is done for luminous sources (M_B_<=-20) in two equal-volume redshift bins (0.4<=z<0.77 and 0.77<=z<1.0) and a local range (0.02<=z<0.05). The mean surface-brightness, mu_B_, from z_mean_=0.89 to z_mean_=0.04, shows a dimming of 0.79mag/arcsec2 for bulgeless galaxies and 1.16mag/arcsec2 for normal-discs. The characteristic magnitude, M_B_, shows an increase of 0.55mag for bulgeless galaxies and 0.95mag for normal-discs. Both dimming and faintness observed since z~0.9 is more pronounced for the normal-discs by ~0.4mag. The size distribution is log-normal and both bulgeless and normal-discs show a slight increase in the mean value, <{Delta}log(R_e_)>~0.11, from z_mean_=0.89 to z_mean_=0.04. The proportion of bulgeless galaxies in the full disc sample undergoes a considerable decline with decrease in redshift. This along with the larger dimming and faintness seen for normal-discs suggests that some fraction of the bulgeless sources switch to the normal-disc morphology with time. To ascertain the validity of studying morphology in the optical, the properties of the galaxies observed in both rest-frame B and I band are compared. The common sample is more luminous in the I band but the sizes are larger in the B band for more than 74 percent of the sources. The variation in the Sersic-index values of the galaxies in the two rest-bands is minor enough to have any effect on the morphological classification.
- ID:
- ivo://CDS.VizieR/J/other/RAA/19.81
- Title:
- Blue-core galaxies properties
- Short Name:
- J/other/RAA/19.8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We select 107 blue-core galaxies from the MaNGA survey, studying their morphology, kinematics as well as the gas-phase metallicity. Our results are as follows: (i) In our sample, 26% of blue-core galaxies have decoupled gas-star kinematics, indicating external gas accretion; 15% have bar-like structure and 8% show post-merger features, such as tidal tails and irregular gas/star velocity field. All these processes/features, such as accreting external misaligned gas, interaction and bar, can trigger gas inflow. Thus the central star-forming activities lead to bluer colors in their centers (blue-core galaxies). (ii) By comparing with the SDSS DR7 star-forming galaxy sample, we find that the blue-core galaxies have higher central gas-phase metallicity than what is predicted by the local mass-metallicity relation. We explore the origin of the higher metallicity, finding that not only the blue-core galaxies, but also the flat-gradient and red-core galaxies all have higher metallicity. This can be explained by the combined effect of redshift and galaxy color.
- ID:
- ivo://CDS.VizieR/J/MNRAS/418/1055
- Title:
- BOSS morphology of galaxies
- Short Name:
- J/MNRAS/418/1055
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the morphology and size of the luminous and massive galaxies at 0.3<z<0.7 targeted in the Baryon Oscillation Spectroscopic Survey (BOSS) using publicly available Hubble Space Telescope (HST) imaging, and catalogues, from the COSMic Origins Survey (COSMOS). Our sample (240 objects) provides a unique opportunity to check the visual morphology of these galaxies which were targeted based solely on stellar population modelling.
- ID:
- ivo://CDS.VizieR/J/A+AS/145/405
- Title:
- Box- and peanut-shaped bulges. I.
- Short Name:
- J/A+AS/145/405
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- NIR observations reveal that dust extinction does almost not influence the shape of bulges. There is no substantial difference between the shape of bulges in the optical and in the NIR. Our analysis reveals that 45% of all bulges are box- and peanut-shaped (b/p). The frequency of b/p bulges for all morphological types from S0 to Sd is >40%. In particular, this is for the first time that such a large frequency of b/p bulges is reported for galaxies as late as Sd. The fraction of the observed b/p bulges is large enough to explain the origin of b/p bulges by a barred potential (Luetticke et al., 2000, A&A, accepted).
- ID:
- ivo://CDS.VizieR/J/MNRAS/468/2058
- Title:
- Boxy/peanut-shaped bulges in barred galaxies
- Short Name:
- J/MNRAS/468/2058
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From a sample of 84 local barred, moderately inclined disc galaxies, we determine the fraction that hosts boxy or peanut-shaped (B/P) bulges (the vertically thickened inner parts of bars). We find that the frequency of B/P bulges in barred galaxies is a very strong function of stellar mass: 79 per cent of the bars in galaxies with log (M*/M_{sun}_)w>=10.4 have B/P bulges, while only 12 per cent of those in lower mass galaxies do. (We find a similar dependence in data published by Yoshino & Yamauchi for edge-on galaxies.) There are also strong trends with other galaxy parameters - e.g. Hubble type: 77 per cent of S0-Sbc bars, but only 15 per cent of Sc-Sd bars, have B/P bulges - but these appear to be side effects of the correlations of these parameters with stellar mass. In particular, despite indications from models that a high gas content can suppress bar buckling, we find no evidence that the (atomic) gas mass ratio M_HI+He_/M* affects the presence of B/P bulges, once the stellar-mass dependence is controlled for. The semimajor axes of B/P bulges range from one-quarter to three-quarters of the full bar size, with a mean of R_box_/L_bar_=0.42+/-0.09 and R_box_/a_{epsilon}_=0.53+/-0.12 (where R_box_ is the size of the B/P bulge and a_{epsilon}_ and L_bar_ are lower and upper limits on the size of the bar).
- ID:
- ivo://CDS.VizieR/J/A+A/625/A36
- Title:
- Breaks in surf. brightness prof. of galaxy disks
- Short Name:
- J/A+A/625/A36
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using a sample of 175 low-inclination galaxies from the S^4^G, we investigate the origins of up-bending (Type III) breaks in the 3.6{mu}m surface brightness profiles of disk galaxies. We reanalyzed a sample of previously identified Type III disk break-hosting galaxies using a new, unbiased break-finding algorithm, which uncovered many new, sometimes subtle disk breaks across the whole sample. We classified each break by its likely origin through close examination of the galaxy images across wavelengths, and compare samples of galaxies separated by their outermost identified break types in terms of their stellar populations and local environments. We find that more than half of the confirmed Type III breaks in our sample can be attributed to morphological asymmetry in the host galaxies. As these breaks are mostly an artifact of the azimuthal averaging process, their status as physical breaks is questionable. Such galaxies occupy some of the highest density environments in our sample, implying that much of this asymmetry is the result of tidal disturbance. We also find that Type III breaks related to extended spiral arms or star formation often host down-bending (Type II) breaks at larger radius which were previously unidentified. Such galaxies reside in the lowest density environments in our sample, in line with previous studies that found a lack of Type II breaks in clusters. Galaxies occupying the highest density environments most often show Type III breaks associated with outer spheroidal components. We find that Type III breaks in the outer disks of galaxies arise most often through environmental influence: either tidal disturbance (resulting in disk asymmetry) or heating through, for example, galaxy harrassment (leading to spheroidal components). Galaxies hosting the latter break types also show bimodal distributions in central g-r color and morphological type, with more than half of such galaxies classified as Sa or earlier; this suggests these galaxies may be evolving into early-type galaxies. By contrast, we find that Type III breaks related to apparently secular features (e.g., spiral arms) may not truly define their hosts' outer disks, as often in such galaxies additional significant breaks can be found at larger radius. Given this variety in Type III break origins, we recommend in future break studies making a more detailed distinction between break subtypes when seeking out, for example, correlations between disk breaks and environment, to avoid mixing unlike physical phenomena.
