- ID:
- ivo://CDS.VizieR/J/ApJ/645/228
- Title:
- Velocities of satellites of external disk galaxies
- Short Name:
- J/ApJ/645/228
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze the angular distribution and the orbital rotation directions of a sample of carefully selected satellite galaxies about disk galaxy primaries extracted from the Sloan Digital Sky Survey (SDSS). We complement this analysis with a theoretical study of these statistics in an N-body simulation of cosmological structure formation set within the {Delta}CDM paradigm under various assumptions for the orientations of disk angular momenta.
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- ID:
- ivo://CDS.VizieR/J/MNRAS/433/L30
- Title:
- Velocity gradient and brightness in disc galaxies
- Short Name:
- J/MNRAS/433/L30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For disc galaxies, a close relation exists between the distribution of light and the shape of the rotation curve. We quantify this relation by measuring the inner circular-velocity gradient d_R_V(0) for spiral and irregular galaxies with high-quality rotation curves. We find that d_R_V(0) correlates with the central surface brightness {mu}_0_ over more than two orders of magnitude in d_R_V(0) and four orders of magnitudes in {mu}_0_. This is a scaling relation for disc galaxies. It shows that the central stellar density of a galaxy closely relates to the inner shape of the potential well, also for low-luminosity and low-surface-brightness galaxies that are expected to be dominated by dark matter.
- ID:
- ivo://CDS.VizieR/J/A+A/420/147
- Title:
- Velocity in 6 spiral galaxies
- Short Name:
- J/A+A/420/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- High resolution Fabry-Perot data of six spiral galaxies are presented. Those data extend the previous sample of spiral galaxies studied with high resolution 3-D spectroscopy to earlier morphological types. All the galaxies in the sample have available HI data at 21cm from the VLA or Westerbork. Velocity fields are analyzed and H{alpha} rotation curves are computed and compared to HI curves. The kinematics of NGC 5055 central regions are looked at more closely. Its peculiar kinematics can be interpreted either as a bipolar outflow or as a counter-rotating disk, possibly hosting a 9+/-2x10^8^M_{sun}-compact object. Most of the H{alpha} rotation curves present a significantly steeper inner slope than their HI counterparts. The 21cm data thus seems affected by moderate to strong beam smearing. The beam smearing has an effect at higher scale-length/beam-width than previously thought (up to 20km/s at a ratio of 8.5).
- ID:
- ivo://CDS.VizieR/J/A+A/561/A28
- Title:
- WSRT HI data cubes of the dwarf galaxy UGCA 105
- Short Name:
- J/A+A/561/A28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Owing to their shallow stellar potential, dwarf galaxies possess thick gas disks, which makes them good candidates for studies of the galactic vertical kinematical structure. We present 21cm line observations of the isolated nearby dwarf irregular galaxy UGCA 105, taken with the Westerbork Synthesis Radio Telescope (WSRT), and analyse the geometry of its neutral hydrogen (HI) disk and its kinematics. The galaxy shows a fragmented HI distribution. It is more extended than the optical disk, and hence allows one to determine its kinematics out to very large galacto- centric distances. The HI kinematics and morphology are well-ordered and symmetric for an irregular galaxy. The HI is sufficiently extended to observe a substantial amount of differential rotation. Moreover, UGCA 105 shows strong signatures for the presence of a kinematically anomalous gas component. Performing tilted-ring modelling by use of the least-squares fitting routine TiRiFiC, we found that the HI disk of UGCA 105 has a moderately warped and diffuse outermost part. Probing a wide range of parameter combinations, we succeeded in modelling the data cube as a disk with a strong vertical gradient in rotation velocity (~-60km/s/kpc), as well as vertically increasing inwards motion (~-70km/s/kpc) within the radius of the stellar disk. The inferred radial gas inflow amounts to 0.06M_{sun}_/yr, which is similar to the star formation rate of the galaxy. The observed kinematics are hence compatible with direct or indirect accretion from the intergalactic medium, an extreme backflow of material that has formerly been expelled from the disk, or a combination of both.
- ID:
- ivo://CDS.VizieR/J/MNRAS/366/144
- Title:
- 0.06<=z<=1.20 galaxies Tully-Fisher relation
- Short Name:
- J/MNRAS/366/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carried out spectroscopic observations in four cluster fields using Subaru's FOCAS multislit spectrograph and obtained spectra for 103 bright disc field and cluster galaxies at 0.06<=z<=1.20. 77 of these show emission lines, and 33 provide reasonably secure determinations of the galaxies' rotation velocity. The rotation velocities, luminosities, colours and emission-line properties of these galaxies are used to study the possible effects of the cluster environment on the star formation history of the galaxies.
