- ID:
- ivo://CDS.VizieR/J/ApJ/754/67
- Title:
- Longslit spectroscopy of local bulges
- Short Name:
- J/ApJ/754/67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the Marcario Low Resolution Spectrograph (LRS) at the Hobby-Eberly- Telescope (HET) to study the kinematics of pseudobulges and classical bulges in the nearby universe. We present major-axis rotational velocities, velocity dispersions, and h3 and h4 moments derived from high-resolution (39km/s) spectra for 45 S0 to Sc galaxies; for 27 of the galaxies we also present minor axis data. We combine our kinematics with bulge-to-disk decompositions. We demonstrate for the first time that purely kinematic diagnostics of the bulge dichotomy agree systematically with those based on Sersic index. Low Sersic index bulges have both increased rotational support (higher v/sigma values) and on average lower central velocity dispersions. Further- more, we confirm that the same correlation also holds when visual morphologies are used to diagnose bulge type. The previously noted trend of photometrically flattened bulges to have shallower velocity dispersion profiles turns to be significant and systematic if the Sersic index is used to distinguish between pseudobulges and classical bulges. The anti-correlation between h3 and v/sigma observed in elliptical galaxies is also observed in intermediate type galaxies, irrespective of bulge type. Finally, we present evidence for formerly undetected counter rotation in the two systems NGC 3945 and NGC 4736.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/635/A5
- Title:
- LoTSS giant radio galaxies. I.
- Short Name:
- J/A+A/635/A5
- Date:
- 02 Mar 2022 11:49:28
- Publisher:
- CDS
- Description:
- Giant radio galaxies (GRGs) are a subclass of radio galaxies, which have grown to megaparsec scales. GRGs are much rarer than normal-sized radio galaxies (<0.7Mpc) and the reason for their gigantic sizes is still debated. Here, we report on the biggest sample of GRGs identified to date. These objects were found in the LOFAR Two-metre Sky Survey (LoTSS) first data release images, which cover a 424 deg^2^ region. Of the 239 GRGs found, 225 are new discoveries. The GRGs in our sample have sizes ranging from 0.7Mpc to 3.5Mpc and have redshifts (z) between 0.1 and 2.3. Seven GRGs have sizes above 2Mpc and one has a size of ~3.5Mpc. The sample contains 40 GRGs hosted by spectroscopically confirmed quasars. Here, we present the search techniques employed and the resulting catalogue of the newly discovered large sample of GRGs along with their radio properties. In this paper, we also show for the first time that the spectral index of GRGs is similar to that of normal-sized radio galaxies, indicating that most of the GRG population is not dead or is not similar to a remnant-type radio galaxy. We find that 20 out of 239 GRGs in our sample are located at the centres of clusters and we present our analysis on their cluster environment and radio morphology.
- ID:
- ivo://CDS.VizieR/J/MNRAS/466/2570
- Title:
- Low ionization emission-line regions galaxies
- Short Name:
- J/MNRAS/466/2570
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using spatially resolved spectroscopy from SDSS-IV MaNGA we have demonstrated that low ionization emission-line regions (LIERs) in local galaxies result from photoionization by hot evolved stars, not active galactic nuclei, hence tracing galactic region hosting old stellar population where, despite the presence of ionized gas, star formation is no longer occurring. LIERs are ubiquitous in both quiescent galaxies and in the central regions of galaxies where star formation takes place at larger radii. We refer to these two classes of galaxies as extended LIER (eLIER) and central LIER (cLIER) galaxies, respectively. cLIERs are late-type galaxies primarily spread across the green valley, in the transition region between the star formation main sequence and quiescent galaxies. These galaxies display regular disc rotation in both stars and gas, although featuring a higher central stellar velocity dispersion than star-forming galaxies of the same mass. cLIERs are consistent with being slowly quenched inside-out; the transformation is associated with massive bulges, pointing towards the importance of bulge growth via secular evolution. eLIERs are morphologically early types and are indistinguishable from passive galaxies devoid of line emission in terms of their stellar populations, morphology and central stellar velocity dispersion. Ionized gas in eLIERs shows both disturbed and disc-like kinematics. When a large-scale flow/rotation is observed in the gas, it is often misaligned relative to the stellar component. These features indicate that eLIERs are passive galaxies harbouring a residual cold gas component, acquired mostly via external accretion. Importantly, quiescent galaxies devoid of line emission reside in denser environments and have significantly higher satellite fraction than eLIERs. Environmental effects thus represent the likely cause for the existence of line-less galaxies on the red sequence.
- ID:
- ivo://CDS.VizieR/J/ApJ/653/240
- Title:
- Low-mass SDSS dwarf galaxy properties
- Short Name:
- J/ApJ/653/240
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the gas content and baryonic Tully-Fisher relationship for extremely low luminosity dwarf galaxies in the absolute magnitude range -13.5>M_r_-5logh_70_>-16. The sample is selected from the Sloan Digital Sky Survey and consists of 101 galaxies for which we have obtained follow-up HI observations using the Arecibo Observatory and Green Bank Telescope. This represents the largest homogeneous sample of dwarf galaxies at low luminosities with well-measured HI and optical properties. The sample spans a range of environments, from dense groups to truly isolated galaxies.
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/2723
- Title:
- Low-redshift clusters in the SAMI Pilot Survey
- Short Name:
- J/MNRAS/451/2723
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using new integral field observations of 106 galaxies in three nearby clusters, we investigate how the intrinsic scatter of the Fundamental Plane depends on the way in which the velocity dispersion and effective radius are measured. Our spatially resolved spectroscopy, combined with a cluster sample with negligible relative distance errors, allows us to derive a Fundamental Plane with minimal systematic uncertainties. From the apertures we tested, we find that velocity dispersions measured within a circular aperture with radius equal to one effective radius minimizes the intrinsic scatter of the Fundamental Plane. Using simple yet powerful Jeans dynamical models, we determine dynamical masses for our galaxies. Replacing luminosity in the Fundamental Plane with dynamical mass, we demonstrate that the resulting Mass Plane has further reduced scatter, consistent with zero intrinsic scatter. Using these dynamical models, we also find evidence for a possibly non-linear relationship between dynamical mass-to-light ratio and velocity dispersion.
- ID:
- ivo://CDS.VizieR/J/ApJ/857/104
- Title:
- Low surface brightness galaxies from HSC-SSP
- Short Name:
- J/ApJ/857/104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of extended low surface brightness galaxies (LSBGs) identified in the Wide layer of the Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP). Using the first ~200deg^2^ of the survey, we have uncovered 781 LSBGs, spanning red (g-i>=0.64) and blue (g-i<0.64) colors and a wide range of morphologies. Since we focus on extended galaxies (r_eff_=2.5"-14"), our sample is likely dominated by low-redshift objects. We define LSBGs to have mean surface brightnesses \bar{mu}_eff_(g)>24.3mag/arcsec^2^, which allows nucleated galaxies into our sample. As a result, the central surface brightness distribution spans a wide range of {mu}_0_(g)=18-27.4mag/arcsec^2^, with 50% and 95% of galaxies fainter than 24.3 and 22mag/arcsec^2^, respectively. Furthermore, the surface brightness distribution is a strong function of color, with the red distribution being much broader and generally fainter than that of the blue LSBGs, and this trend shows a clear correlation with galaxy morphology. Red LSBGs typically have smooth light profiles that are well characterized by single-component Sersic functions. In contrast, blue LSBGs tend to have irregular morphologies and show evidence for ongoing star formation. We cross-match our sample with existing optical, HI, and ultraviolet catalogs to gain insight into the physical nature of the LSBGs. We find that our sample is diverse, ranging from dwarf spheroidals and ultradiffuse galaxies in nearby groups to gas-rich irregulars to giant LSB spirals, demonstrating the potential of the HSC-SSP to provide a truly unprecedented view of the LSBG population.
- ID:
- ivo://CDS.VizieR/J/MNRAS/437/2607
- Title:
- Low X-ray luminosity galaxy clusters
- Short Name:
- J/MNRAS/437/2607
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This is the second of a series of papers on low X-ray luminosity galaxy clusters, in which we present the r', g' and i' photometry obtained with Gemini Multi-Object Spectrograph IMAGE at Gemini North and South telescopes for seven systems in the redshift range of 0.18 to 0.70. Optical magnitudes, colours and morphological parameters, namely, concentration index, ellipticity and visual morphological classification, are also given. At lower redshifts, the presence of a well-defined red cluster sequence extending by more than 4mag showed that these intermediate-mass clusters had reached a relaxed stage. This was confirmed by the small fraction of blue galaxy members observed in the central regions of ~0.75Mpc. In contrast, galaxy clusters at higher redshifts had a less important red cluster sequence. We also found that the galaxy radial density profiles in these clusters were well fitted by a single power law. At 0.18<z<0.70, we observed an increasing fraction of blue galaxies and a decreasing fraction of lenticulars, with the early-type fraction remaining almost constant. Overall, the results of these intermediate-mass clusters are in agreement with those for high-mass clusters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/476/4488
- Title:
- LSBG HI and optical properties
- Short Name:
- J/MNRAS/476/4488
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of the HI and optical properties of nearby (z<=0.1) Low Surface Brightness galaxies (LSBGs). We started with a literature sample of ~900 LSBGs and divided them into three morphological classes: spirals, irregulars, and dwarfs. Of these, we could use ~490 LSBGs to study their HI and stellar masses, colours, and colour-magnitude diagrams, and local environment, compare them with normal, High Surface Brightness (HSB) galaxies and determine the differences between the three morphological classes. We found that LSB and HSB galaxies span a similar range in HI and stellar masses, and have a similar M_HI_/M_{star}_-M_{star}_ relationship. Among the LSBGs, as expected, the spirals have the highest average HI and stellar masses, both of about 10^9.8^M_{sun}_. The LSGBs' (g-r) integrated colour is nearly constant as function of HI mass for all classes. In the colour-magnitude diagram, the spirals are spread over the red and blue regions whereas the irregulars and dwarfs are confined to the blue region. The spirals also exhibit a steeper slope in the M_HI_/M_{star}_-M_{star}_ plane. Within their local environment, we confirmed that LSBGs are more isolated than HSB galaxies, and LSB spirals more isolated than irregulars and dwarfs. Kolmogorov-Smirnov statistical tests on the HI mass, stellar mass, and number of neighbours indicate that the spirals are a statistically different population from the dwarfs and irregulars. This suggests that the spirals may have different formation and HI evolution than the dwarfs and irregulars.
- ID:
- ivo://CDS.VizieR/J/A+A/458/341
- Title:
- LSBG in Arecibo HI Strip Survey
- Short Name:
- J/A+A/458/341
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to estimate the contribution of low surface brightness (LSB) galaxies to the local (z<=0.1) galaxy number density, we performed an optical search for LSB candidates in a 15.5{deg}^2^ part of the region covered by the 65{deg}^2^ blind Arecibo HI Strip Survey (AHISS)
- ID:
- ivo://CDS.VizieR/J/ApJ/804/34
- Title:
- Luminous AGNs and early-type SDSS galaxies
- Short Name:
- J/ApJ/804/34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is not yet clear what triggers the activity of active galactic nuclei (AGNs), but galaxy merging has been suspected to be one of the main mechanisms fueling the activity. Using deep optical images taken at various ground-based telescopes, we investigate the fraction of galaxy mergers in 39 luminous AGNs (M_R_<~-22.6mag) at z<=0.3 (a median redshift of 0.155), for which the host galaxies are generally considered as early-type galaxies. Through visual inspection of the images, we find that 17 of 39 AGN host galaxies (43.6%) show evidence for current or past mergers like tidal tails, shells, and disturbed morphology. In order to see if this fraction is abnormally high, we also examined the merging fraction of normal early-type galaxies in the Sloan Digital Sky Survey (SDSS) Stripe 82 data (a median redshift of 0.04), of which the surface-brightness limit is comparable to our imaging data. To correct for the effects related to the redshift difference of the two samples, we performed an image simulation by putting a bright point source as an artificial AGN in the images of SDSS early-type galaxies and placing them onto the redshifts of AGNs. The merging fraction in this realistic sample of simulated AGNs is only ~5-15% (1/4 to 1/8 of that of real AGNs). Our result strongly suggests that luminous AGN activity is associated with galaxy merging.
