- ID:
- ivo://CDS.VizieR/J/ApJ/855/33
- Title:
- Compact clouds in a sensitive GBT HI survey
- Short Name:
- J/ApJ/855/33
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a new sensitive survey of neutral hydrogen above and below the Galactic Center with the Green Bank Telescope. The observations extend up to Galactic latitude |b|<10{deg} with an effective angular resolution of 9.5' and an average rms brightness temperature noise of 40mK in a 1km/s channel. The survey reveals the existence of a population of anomalous high-velocity clouds extending up to heights of about 1.5kpc from the Galactic plane and showing no signature of Galactic rotation. These clouds have local standard of rest velocities |V_LSR_|<~360km/s, and assuming a Galactic Center origin, they have sizes of a few tens of parsec and neutral hydrogen masses spanning 10-10^5^M_{sun}_. Accounting for selection effects, the cloud population is symmetric in longitude, latitude, and VLSR. We model the cloud kinematics in terms of an outflow expanding from the Galactic Center and find the population consistent with being material moving with radial velocity V_w_~330km/s distributed throughout a bicone with opening angle {alpha}>140{deg}. This simple model implies an outflow luminosity L_w_>3x10^40^erg/s over the past 10Myr, consistent with star formation feedback in the inner region of the Milky Way, with a cold gas mass-loss rate <~0.1M_{sun}_/yr. These clouds may represent the cold gas component accelerated in the nuclear wind driven by our Galaxy, although some of the derived properties challenge current theoretical models of the entrainment process.
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- ID:
- ivo://CDS.VizieR/J/A+A/503/469
- Title:
- Compact clusters in LMC catalogue of stars
- Short Name:
- J/A+A/503/469
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The LMC is an ideal environment for studying stellar MFs, because it contains a large population of compact clusters at different evolutionary stages. We aim to obtain constraints on the initial MFs (IMFs) of our sample clusters on the basis of their present-day MFs, combined with our understanding of their dynamical and photometric evolution. We use Hubble Space Telescope photometry for six rich, compact star clusters in the Large Magellanic Cloud (LMC), with ages ranging from 0.01 to 1.0Gyr, to derive the clusters' stellar mass functions (MFs) at their half-mass radii.
- ID:
- ivo://CDS.VizieR/J/A+A/578/A134
- Title:
- Compact early-type galaxies in SDSS
- Short Name:
- J/A+A/578/A134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Passive galaxies at high redshift are much smaller than equally massive early types today. If this size evolution is caused by stochastic merging processes, then a small fraction of the compact galaxies should persist until today. Up to now it has not been possible to systematically identify the existence of such objects in Sloan Digital Sky Survey (SDSS). We aim at finding potential survivors of these compact galaxies in SDSS, as targets for more detailed follow-up observations. From the virial theorem, it is expected that for a given mass, compact galaxies have stellar velocity dispersion higher than the mean owing to their smaller sizes. Therefore velocity dispersion, coupled with size (or mass), is an appropriate method of selecting relics, independent of the stellar population properties. Based on these considerations, we designed a set of criteria the use the distribution of early-type galaxies from SDSS on the log_10_(R_0_)-log_10_({sigma}_0_) plane to find the most extreme objects on it. We thus selected compact massive galaxy candidates by restricting them to high velocity dispersions {sigma}_0_>323.2km/s and small sizes R_0_<2.18kpc. We find 76 galaxies at 0.05<z<0.2, which have properties that are similar to the typical quiescent galaxies at high redshift. We discuss how these galaxies relate to average present-day early-type galaxies. We study how well these galaxies fit on well-known local universe relations of early-type galaxies, such as the fundamental plane, the red sequence, or mass-size relations. As expected from the selection criteria, the candidates are located in an extreme corner of the mass-size plane. However, they do not extend as deeply into the so-called zone of exclusion as some of the red nuggets found at high redshift, since they are a factor 2-3 less massive on a given intrinsic scale size. Several of our candidates are close to the size resolution limit of SDSS, but are not so small that they are classified as point sources. We find that our candidates are systematically offset on a scaling relation compared to the average early-type galaxies, but still within the general range of other early-type galaxies. Furthermore, our candidates are similar to the mass-size range expected for passive evolution of the red nuggets from their high redshift to the present. The 76 selected candidates form an appropriate set of objects for further follow-up observations. They do not constitute a separate population of peculiar galaxies, but form the extreme tail of a continuous distribution of early-type galaxies. We argue that selecting a high-velocity dispersion is the best way to find analogues of compact high redshift galaxies in the local universe.
- ID:
- ivo://CDS.VizieR/J/ApJS/166/526
- Title:
- Compact extragalactic radio sources
- Short Name:
- J/ApJS/166/526
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Very Large Array to search for compact milliarcsecond-size radio sources near methanol masers in high-mass star-forming regions. Such sources are required for very long baseline Interferometry phase-referencing observations. We conducted pointed observations of 234 compact sources found in the NVSS survey and find 92 sources with unresolved components and synchrotron spectral indexes. These sources are likely the cores of AGNs and, thus, are good candidates for astrometric calibrators.
- ID:
- ivo://CDS.VizieR/J/MNRAS/441/224
- Title:
- Compact FIR-bright sources in M33
- Short Name:
- J/MNRAS/441/224
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a multiwavelength study of a sample of far-infrared (FIR) sources detected on the Herschel broad-band maps of the nearby galaxy M33. We perform source photometry on the FIR maps as well as mid-infrared (MIR), H{alpha}, far-ultraviolet and integrated Hi and CO line emission maps. By fitting MIR/FIR dust emission spectra, the source dust masses, temperatures and luminosities are inferred. The sources are classified based on their H{alpha} morphology (sub-structured versus not-substructured) and on whether they have a significant CO detection (S/N>3{sigma}). We find that the sources have dust masses in the range 10^2^-10^4^M_{sun}_ and that they present significant differences in their inferred dust/star formation/gas parameters depending on their H{alpha} morphology and CO detection classification. The results suggests differences in the evolutionary states or in the number of embedded HII regions between the sub-samples. The source background-subtracted dust emission seems to be predominantly powered by local star formation, as indicated by a strong correlation between the dust luminosity and the dust-corrected H{alpha} luminosity and the fact that the extrapolated young stellar luminosity is high enough to account for the observed dust emission. Finally, we do not find a strong correlation between the dust-corrected H{alpha} luminosity and the dust mass of the sources, consistent with previous results on the breakdown of simple scaling relations at sub-kpc scales. However, the scatter in the relation is significantly reduced by correcting the H{alpha} luminosity for the age of the young stellar populations in the star-forming regions.
- ID:
- ivo://CDS.VizieR/J/ApJ/720/723
- Title:
- Compact galaxies in the local universe
- Short Name:
- J/ApJ/720/723
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We set out to test the claim that the recently identified population of compact, massive, and quiescent galaxies at z~2.3 must undergo significant size evolution to match the properties of galaxies found in the local universe. Using data from the Sloan Digital Sky Survey (SDSS; Data Release 7), we have conducted a search for local red sequence galaxies with sizes and masses comparable to those found at z~2.3. The SDSS spectroscopic target selection algorithm excludes high surface brightness objects; we show that this makes incompleteness a concern for such massive, compact galaxies, particularly for low redshifts (z<~0.05). We have identified 63 M_*_>10^10.7^M_{sun}_ (~5x10^10^M_{sun}_) red sequence galaxies at 0.066<z_spec_<0.12 which are smaller than the median size-mass relation by a factor of 2 or more. Consistent with expectations from the virial theorem, the median offset from the mass-velocity dispersion relation for these galaxies is 0.12 dex. We do not, however, find any galaxies with sizes and masses comparable to those observed at z~2.3, implying a decrease in the comoving number density of these galaxies, at fixed size and mass, by a factor of >~5000. This result cannot be explained by incompleteness: in the 0.066<z<0.12 interval, we estimate that the SDSS spectroscopic sample should typically be >~75% complete for galaxies with the sizes and masses seen at high redshift, although for the very smallest galaxies it may be as low as ~20%. In order to confirm that the absence of such compact massive galaxies in SDSS is not produced by spectroscopic selection effects, we have also looked for such galaxies in the basic SDSS photometric catalog, using photometric redshifts. While we do find signs of a slight bias against massive, compact galaxies, this analysis suggests that the SDSS spectroscopic sample is missing at most a few objects in the regime we consider.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A157
- Title:
- Compact Groups in SDSSDR12
- Short Name:
- J/A+A/618/A157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A catalogue of compact groups identified on the SDSS DR12 is provided. Compact Groups were identified in redshift space with a modified Hickson-like algorithm. The catalogue comprises 462 compact groups of which 406 clearly fulfil all the compact group requirements: compactness, isolation and velocity concordance of all of their members. The remaining 56 groups need further redshift information of potentially contaminating sources.
- ID:
- ivo://CDS.VizieR/J/A+A/391/35
- Title:
- Compact Groups in the UZC galaxy sample
- Short Name:
- J/A+A/391/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Applying an automatic neighbour search algorithm to the 3D UZC galaxy catalogue (Falco et al., 1999, Cat. <J/PASP/111/438>) we have identified 291 compact groups (CGs) with radial velocity between 1000 and 10000km/s. The sample is analysed to investigate whether Triplets display kinematical and morphological characteristics similar to higher order CGs (Multiplets). It is found that Triplets constitute low velocity dispersion structures, have a gas-rich galaxy population and are typically retrieved in sparse environments. Conversely Multiplets show higher velocity dispersion, include few gas-rich members and are generally embedded structures. Evidence hence emerges indicating that Triplets and Multiplets, though sharing a common scale, correspond to different galaxy systems. Triplets are typically field structures whilst Multiplets are mainly subclumps (either temporarily projected or collapsing) within larger structures. Simulations show that selection effects can only partially account for differences, but significant contamination of Triplets by field galaxy interlopers could eventually induce the observed dependences on multiplicity.
- ID:
- ivo://CDS.VizieR/VII/89B
- Title:
- Compact groups of compact galaxies
- Short Name:
- VII/89B
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The catalog is a compilation of ten published lists of compact groups of compact galaxies found on the Palomar Sky Survey red charts. The catalog contains 377 groups of compact galaxies and includes identifications, equatorial coordinates, numbers of constituent galaxies, magnitudes of the brightest member, sizes of the groups as a whole, and coefficients of relative compactness.
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/296
- Title:
- Compact Groups of galaxies from 2MASX
- Short Name:
- J/MNRAS/426/296
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a photometric catalogue of compact groups of galaxies (p2MCGs) automatically extracted from the Two-Micron All Sky Survey (2MASS) extended source catalogue. A total of 262 p2MCGs are identified, following the criteria defined by Hickson, of which 230 survive visual inspection (given occasional galaxy fragmentation and blends in the 2MASS parent catalogue). Only one quarter of these 230 groups were previously known compact groups (CGs). Among the 144 p2MCGs that have all their galaxies with known redshifts, 85 (59%) have four or more accordant galaxies. This v2MCG sample of velocity-filtered p2MCGs constitutes the largest sample of CGs (with N>=4) catalogued to date, with both well-defined selection criteria and velocity filtering, and is the first CG sample selected by stellar mass. It is fairly complete up to K_group_~9 and radial velocity of ~6000km/s.