- ID:
- ivo://CDS.VizieR/J/ApJ/857/144
- Title:
- Tidal features from RESOLVE survey & DECaLS images
- Short Name:
- J/ApJ/857/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study tidal features around galaxies in the REsolved Spectroscopy Of a Local VolumE (RESOLVE) survey. Our sample consists of 1048 RESOLVE galaxies that overlap with the DECam Legacy Survey, which reaches an r-band 3{sigma} depth of ~27.9mag/arcsec^2^ for a 100arcsec^2^ feature. Images were masked, smoothed, and inspected for tidal features such as streams, shells, or tails/arms. We find tidal features in 17+/-2% of our galaxies, setting a lower limit on the true frequency. The frequency of tidal features in the gas-poor (gas-to-stellar mass ratio <0.1) subsample is lower than in the gas-rich subsample (13+/-3% versus 19+/-2%). Within the gas-poor subsample, galaxies with tidal features have higher stellar and halo masses, ~3x closer distances to nearest neighbors (in the same group), and possibly fewer group members at fixed halo mass than galaxies without tidal features, but similar specific star formation rates. These results suggest tidal features in gas-poor galaxies are typically streams/shells from dry mergers or satellite disruption. In contrast, the presence of tidal features around gas-rich galaxies does not correlate with stellar or halo mass, suggesting these tidal features are often tails/arms from resonant interactions. Similar to tidal features in gas-poor galaxies, tidal features in gas-rich galaxies imply 1.7x closer nearest neighbors in the same group; however, they are associated with diskier morphologies, higher star formation rates, and higher gas content. In addition to interactions with known neighbors, we suggest that tidal features in gas-rich galaxies may arise from accretion of cosmic gas and/or gas-rich satellites below the survey limit.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/130/2647
- Title:
- Tidal features of 126 nearby red galaxies
- Short Name:
- J/AJ/130/2647
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of tidal debris associated with 126 nearby red galaxies, selected from the 1.2{deg}^2^ Multiwavelength Survey by Yale-Chile (MUSYC, Cat. <J/ApJS/162/1>) and the 9.3{deg}^2^ NOAO Deep Wide-Field Survey (Jannuzi & Dey, 1999ASPC..191..111J). In the full sample, 67 galaxies (53%) show morphological signatures of tidal interactions consisting of broad fans of stars, tails, and other asymmetries at very faint surface brightness levels. When restricting the sample to the 86 bulge-dominated early-type galaxies, the fraction of tidally disturbed galaxies rises to 71%, which implies that for every "normal" undisturbed elliptical there are two that show clear signs of interactions. The tidal features are red and smooth and often extend over >50kpc.
- ID:
- ivo://CDS.VizieR/J/ApJ/869/6
- Title:
- Tidal interactions and mergers in EDisCS clusters
- Short Name:
- J/ApJ/869/6
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the fraction of tidal interactions and mergers (TIMs) with well-identified observability timescales (f_TIM_) in group, cluster, and accompanying field galaxies and its dependence on redshift (z), cluster velocity dispersion ({sigma}), and environment analyzing Hubble Space Telescope/ACS images and catalogs from the ESO Distant Cluster Survey. Our sample consists of 11 clusters, seven groups, and accompanying field galaxies at 0.4<=z<=0.8. We derive f_TIM_ using both a visual classification of galaxy morphologies and an automated method, the G-M_20_ method. We calibrate this method using the visual classifications that were performed on a subset of our sample. We find marginal evidence for a trend between f_TIM_ and z, in that higher z values correspond to higher f_TIM_. However, we also cannot rule out the null hypothesis of no correlation at higher than 68% confidence. No trend is present between f_TIM_ and {sigma}. We find that f_TIM_ shows suggestive peaks in groups, and tentatively in clusters at R>0.5xR_200_, implying that f_TIM_ gets boosted in these intermediate-density environments. However, our analysis of the local densities of our cluster sample does not reveal a trend between f_TIM_ and density, except for a potential enhancement at the very highest densities. We also perform an analysis of projected radius-velocity phase space for our cluster members. Our results reveal that TIM and undisturbed galaxies only have a 6% probability of having been drawn from the same parent population in their velocity distribution and 37% in radii, in agreement with the modest differences obtained in f_TIM_ at the clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/320/776
- Title:
- Tidal radii of 7 globular clusters
- Short Name:
- J/A+A/320/776
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new tidal radii for seven Galactic globular clusters using the method of automated star counts on Schmidt plates of the Tautenburg, Palomar and UK telescopes. The plates were fully scanned with the APM system in Cambridge (UK). Special account was given to a reliable background subtraction and the correction of crowding effects in the central cluster region. For the latter we used a new kind of crowding correction based on a statistical approach to the distribution of stellar images and the luminosity function of the cluster stars in the uncrowded area. The star counts were correlated with surface brightness profiles of different authors to obtain complete projected density profiles of the globular clusters. Fitting an empirical density law (King 1962AJ.....67..471K) we derived the following structural parameters: tidal radius rt, core radius rc and concentration parameter c. In the cases of NGC 5466, M 5, M 12, M 13 and M 15 we found an indication for a tidal tail around these objects (cf. Grillmair et al., 1995AJ....109.2553G).
- ID:
- ivo://CDS.VizieR/J/MNRAS/404/1321
- Title:
- TiII in Milky way and Magellanic clouds
- Short Name:
- J/MNRAS/404/1321
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We discuss several sets of TiII absorption-line data, which probe a variety of interstellar environments in our Galaxy and in the Magellanic Clouds. Comparisons of high-resolution [full width at half-maximum (FWHM)~1.3-1.5km/s] TiII spectra of Galactic targets with corresponding high-resolution spectra of NaI, KI and CaII reveal both similarities and differences in the detailed structure of the absorption-line profiles - reflecting component-to-component differences in the ionization and depletion behaviour of those species. Moderate-resolution (FWHM~3.4-4.5km/s) spectra of more heavily reddened Galactic stars provide more extensive information on the titanium depletion in colder, denser clouds - where more than 99.9 per cent of the Ti may be in the dust phase. Moderate-resolution (FWHM~4.5-8.7km/s) spectra of stars in the Magellanic Clouds suggest that the titanium depletion is generally much less severe in the Large and Small Magellanic Clouds than in our Galaxy [for a given N(Htot), E(B-V), or molecular fraction f(H2)]- providing additional evidence for differences in depletion patterns in those two lower-metallicity galaxies. We briefly discuss possible implications of these results for the interpretation of gas-phase abundances in quasi-stellar object absorption-line systems and of variations in the D/H ratio in the local Galactic interstellar medium.
- ID:
- ivo://CDS.VizieR/J/AJ/146/97
- Title:
- Ti line list for the Lick hallow-cathode lamp
- Short Name:
- J/AJ/146/97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the wavelength calibration of the Hamilton echelle spectrograph (the Lick observatory). The main problem of the calibration arises from the fact that thorium lines are absent in the spectrum of ThAr hollow-cathode lamp now under the operation. On the other hand, numerous unknown strong lines are present in the spectrum. These lines was identified with titanium. We estimate the temperature of the lamp gas which permits us to calculate the intensities of the lines, and to select a large number of relevant TiI and TiII lines. The titanium line list for the Lick hallow-cathode lamp is presented. The wavelength calibration using this line list was made with accuracy about 0.006{AA}.
22247. TIMASSS. I.
- ID:
- ivo://CDS.VizieR/J/A+A/532/A23
- Title:
- TIMASSS. I.
- Short Name:
- J/A+A/532/A23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/587/A29
- Title:
- Time and positions of coronal bright points
- Short Name:
- J/A+A/587/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is possible to detect and track coronal bright points (CBPs) in Solar Dynamics Observatory / Atmospheric Imaging Assembly (SDO/AIA) images. A combination of high resolution and high cadence provides a wealth of data that can be used to determine velocity flows on the solar surface with very high accuracy. We derived a very accurate solar rotation profile and investigated meridional flows, torsional oscillations, and horizontal Reynolds stress based on ~6 months of SDO/AIA data. We used a segmentation algorithm to detect CBPs in SDO/AIA images. We also used invariance of the solar rotation profile with central meridian distance (CMD) to determine the height of CBPs in the 19.3nm channel. The best fit solar rotation profile is given by {omega}(b)=(14.4060+/-0.0051+(-1.662+/-0.050)sin^2^b+ (-2.742+/-0.081)sin^4^b){deg}/day. The height of CBPs in the SDO/AIA 19.3nm channel was found to be ~6500km. Meridional motion is predominantly poleward for all latitudes, while solar velocity residuals show signs of torsional oscillations. Horizontal Reynolds stress was found to be smaller than in similar works, but still showed transfer of angular momentum towards the solar equator. Most of the results are consistent with Doppler measurements rather than tracer measurements. The fairly small calculated value of horizontal Reynolds stress might be due to the particular phase of the solar cycle. Accuracy of the calculated rotation profile indicates that it is possible to measure changes in the profile as the solar cycle evolves. Analysis of further SDO/AIA CBP data will also provide a better understanding of the temporal behaviour of the rotation velocity residuals, meridional motions, and Reynolds stress.
- ID:
- ivo://CDS.VizieR/J/A+A/488/481
- Title:
- Time delays and H0 from WFI J2033-4723
- Short Name:
- J/A+A/488/481
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Gravitationally lensed quasars can be used to map the mass distribution in lensing galaxies and to estimate the Hubble constant H0 by measuring the time delays between the quasar images. Here we report the measurement of two independent time delays in the quadruply imaged quasar WFI J2033-4723 (z=1.66). Our data consist of R-band images obtained with the Swiss 1.2m EULER telescope located at La Silla and with the 1.3m SMARTS telescope located at Cerro Tololo. The light curves have 218 independent epochs spanning 3 full years of monitoring between March 2004 and May 2007, with a mean temporal sampling of one observation every 4th day. We measure the time delays using three different techniques, and we obtain Dt(B-A)=35.5+/-1.4days (3.8%) and Dt(B-C)=62.6^+4.1^_-2.3_days (^+6.5%^_-3.7%_), where A is a composite of the close, merging image pair. After correcting for the time delays, we find R-band flux ratios of FA/FB=2.88+/-0.04, FA/FC=3.38+/-0.06, and FA1/FA2=1.37+/-0.05 with no evidence for microlensing variability over a time scale of three years. However, these flux ratios do not agree with those measured in the quasar emission lines, suggesting that longer term microlensing is present. Our estimate of H0 agrees with the concordance value: non-parametric modeling of the lensing galaxy predicts H0=67^+13^_-10_km/s/Mpc, while the Single Isothermal Sphere model yields H0=63^+7^_-3_km/s/Mpc (68% confidence level). More complex lens models using a composite de Vaucouleurs plus NFW galaxy mass profile show twisting of the mass isocontours in the lensing galaxy, as do the non-parametric models. As all models also require a significant external shear, this suggests that the lens is a member of the group of galaxies seen in field of view of WFI J2033-4723.
- ID:
- ivo://CDS.VizieR/J/ApJS/228/11
- Title:
- Time-dependent cooling in photoionized plasma
- Short Name:
- J/ApJS/228/11
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- I explore the thermal evolution and ionization states in gas cooling from an initially hot state in the presence of external photoionizing radiation. I compute the equilibrium and nonequilibrium cooling efficiencies, heating rates, and ion fractions for low-density gas cooling while exposed to the ionizing metagalactic background radiation at various redshifts (z=0-3), for a range of temperatures (10^8^-10^4^K), densities (10^-7^-10^3^cm^-3^), and metallicities (10^-3^-2 times solar). The results indicate the existence of a threshold ionization parameter, above which the cooling efficiencies are very close to those in photoionization equilibrium (so that departures from equilibrium may be neglected), and below which the cooling efficiencies resemble those in collisional time-dependent gas cooling with no external radiation (and are thus independent of density).
