- ID:
- ivo://CDS.VizieR/J/A+A/584/A113
- Title:
- Gas dynamics in tidal dwarf galaxies
- Short Name:
- J/A+A/584/A113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tidal dwarf galaxies (TDGs) are recycled objects that form within the collisional debris of interacting and merging galaxies. They are expected to be devoid of non-baryonic dark matter, since they can only form from dissipative material ejected from the discs of the progenitor galaxies. We investigate the gas dynamics in a sample of six bona fide TDGs around three interacting and post-interacting systems: NGC 4694, NGC 5291, and NGC 7252 ("Atoms for Peace"). For NGC 4694 and NGC 5291, we analyse existing HI data from the Very Large Array (VLA), while for NGC 7252 we present new HI observations from the Jansky VLA, together with long-slit and integral-field optical spectroscopy. For all six TDGs, the HI emission can be described by rotating disc models. These HI discs, however, have undergone less than a full rotation since the time of the interaction/merger event, raising the question of whether they are in dynamical equilibrium. Assuming that these discs are in equilibrium, the inferred dynamical masses are consistent with the observed baryonic masses, implying that TDGs are devoid of dark matter. This puts constraints on putative "dark discs" (either baryonic or non-baryonic) in the progenitor galaxies. Moreover, TDGs seem to systematically deviate from the baryonic Tully-Fisher relation. These results provide a challenging test for alternative theories like MOND.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/131/47
- Title:
- Gas-rich dwarfs from the POSS-II. III.
- Short Name:
- J/ApJS/131/47
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Arecibo neutral hydrogen data on a sample of optically selected dwarf galaxies. The sample ranges in H I mass from 10^6^ to 5x10^9^M_{sun}_, with a mean of 7.9x10^8^M_{sun}_. Using estimated H I radii, the H I surface densities range from 0.6 to 20M_{sun}_/pc^2^, all well below the critical threshold for star formation (Kennicutt, 1998ApJ...498..541K). M_HI_/L values of the LSB dwarfs range from 0.3 to 12 with a mean value of 2.0. Dynamical masses, calculated from the H I profile widths, range from 10^8^ to 10^11^M_{sun}_. There is a strong correlation between optical luminosity and dynamical mass for LSB dwarfs implying that the dark matter (whether baryonic or nonbaryonic) follows the detectable baryonic matter.
- ID:
- ivo://CDS.VizieR/J/MNRAS/443/1044
- Title:
- GBT HI observations of 1194 spirals
- Short Name:
- J/MNRAS/443/1044
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present HI 21cm observations of 1194 galaxies out to a redshift of 10000km/s selected as inclined spirals (i>~60{deg}) from the 2MASS redshift survey. These observations were carried out at the National Radio Astronomy Observatory Robert C. Byrd Green Bank Telescope (GBT). This observing programme is part of the 2MASS Tully-Fisher (2MTF) survey. This project will combine Hi widths from these GBT observations with those from further dedicated observing at the Parkes Telescope, from the Arecibo Legacy Fast Arecibo L-band Feed Array survey at Arecibo, and S/N>10 and spectral resolution v_res_<10km/s published widths from a variety of telescopes. We will use these Hi widths along with 2MASS photometry to estimate Tully-Fisher distances to nearby spirals and investigate the peculiar velocity field of the local Universe. In this paper, we report on detections of neutral hydrogen in emission in 727 galaxies, and measure good signal to noise and symmetric HI global profiles suitable for use in the Tully-Fisher relation in 484.
- ID:
- ivo://CDS.VizieR/J/ApJS/65/485
- Title:
- 1.49GHz Atlas of Spiral Galaxies
- Short Name:
- J/ApJS/65/485
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The VLA has been used in its most compact D- and C/D-configurations to make low-resolution ({theta}~0.9FWHM) 1.49GHz maps of the spiral galaxies north of DE=-45{deg} and brighter than B_T_=+12, the completeness limit of the Revised Shapley-Ames Catalog (Cat. VII/51). Most of these maps are confusion-limited at {sigma}>=0.1mJy per beam, and at least 94% of the galaxies were detected with S>=1mJy. The maps have sufficient sensitivity to low-brightness emission that accurate radio "photometry" is possible. An atlas of contour maps, a table of total flux densities plus other radio source parameters, and references to published radio maps are given.
- ID:
- ivo://CDS.VizieR/J/ApJS/73/359
- Title:
- 1.49 GHz atlas of the IRAS bright galaxies
- Short Name:
- J/ApJS/73/359
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains 1.49 GHz VLA observations of sources from the IRAS Bright Galaxy Sample. The original IRAS Bright Galaxy Sample (Soifer et al., 1987ApJ...320..238S) comprises 324 extragalactic objects with 60 micron flux densities above 5.4 Jy. It is the infrared analog of the radio 3CR or optical Shapley-Ames samples. Recalibration of the IRAS flux densities led to a revised Bright Galaxy Sample (Soifer et al., 1989AJ.....98..766S) containing 313 sources stronger than 5.24 Jy at 60 microns. Only one source from these samples was not detected (NGC1377) at 1.49 GHz. For most sources, multiple observations were conducted with different synthesized beam areas. Thus, for a given galaxy there may be several rows in the table reporting data at different angular resolution or reporting different radio components of the object. A low-resolution observation was used to yield an accurate total flux density and a high-resolution observation was used to resolve the brightest components clearly. These observations were originally presented in Condon, et al., (1990ApJS...73..359C).
- ID:
- ivo://CDS.VizieR/J/A+A/625/A19
- Title:
- 33 GHz continuum map of M51
- Short Name:
- J/A+A/625/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It remains unclear what sets the efficiency with which molecular gas transforms into stars. Here we present a new VLA map of the spiral galaxy M51 in 33GHz radio continuum, an extinction-free tracer of star formation, at 3" scales (~100pc). We combined this map with interferometric PdBI/NOEMA observations of CO(1-0) and HCN(1-0) at matched resolution for three regions in M51 (central molecular ring, northern and southern spiral arm segments). While our measurements roughly fall on the well-known correlation between total infrared and HCN luminosity, bridging the gap between Galactic and extragalactic observations, we find systematic offsets from that relation for different dynamical environments probed in M51, e.g. the southern arm segment is more quiescent due to low star formation efficiency (SFE) of the dense gas, despite having a high dense gas fraction. Combining our results with measurements from the literature at 100pc scales, we find that the SFE of the dense gas and the dense gas fraction anti-correlate and correlate, respectively, with the local stellar mass surface density. This is consistent with previous kpc-scale studies. In addition, we find a significant anti-correlation between the SFE and velocity dispersion of the dense gas. Finally, we confirm that a correlation also holds between star formation rate surface density and the dense gas fraction, but it is not stronger than the correlation with dense gas surface density. Our results are hard to reconcile with models relying on a universal gas density threshold for star formation and suggest that turbulence and galactic dynamics play a major role in setting how efficiently dense gas converts into stars.
- ID:
- ivo://CDS.VizieR/J/AJ/127/1959
- Title:
- 1.4GHz emission of KISS emission-line galaxies
- Short Name:
- J/AJ/127/1959
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have searched the Faint Images of the Radio Sky at Twenty centimeters (FIRST, <VIII/71>) and the NRAO VLA Sky Survey (NVSS, <VIII/65>) 1.4GHz radio surveys for sources that are coincident with emission-line galaxy (ELG) candidates from the KPNO International Spectroscopic Survey (KISS). A total of 207 of the 2157 KISS ELGs (~10%) in the first two H{alpha}-selected survey lists (Cats <J/AJ/121/66>, <J/AJ/127/1943>) were found to possess radio detections in FIRST, NVSS, or both. Follow-up spectra exist for all of the radio detections, allowing us to determine the activity type (star-forming vs. active nucleus) for the entire sample. We explore the properties of the radio-detected KISS galaxies in order to gain a better insight into the nature of radio-emitting galaxies in the local universe (z<0.1). Because of the selection technique used for KISS, our radio ELGs represent a quasivolume-limited sample, which allows us to develop a clearer picture of the radio galaxy population at low redshift. Nearly two-thirds of the KISS radio galaxies are starburst or star-forming galaxies, which is in stark contrast to the results of flux-limited radio surveys, which are dominated by active galactic nuclei (AGNs) and elliptical galaxies (i.e., classical radio galaxies).
- ID:
- ivo://CDS.VizieR/J/A+A/424/371
- Title:
- 1.4GHz First Look Survey (FLS)
- Short Name:
- J/A+A/424/371
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The First Look Survey (FLS) is the first scientific product to emerge from the Spitzer Space Telescope. A small region of this field (the verification strip) has been imaged very deeply, permitting the detection of cosmologically distant sources. We present Westerbork Synthesis Radio Telescope (WSRT) observations of this region, encompassing a 1 sq. deg field, centred on the verification strip (J2000 RA=17:17:00.00, DE=59:45:00.000). The radio images reach a noise level of 8.5 microJy per beam - the deepest WSRT image made to date. We summarise here the first results from the project, and present the final mosaic image, together with a list of detected sources. The effect of source confusion on the position, size and flux density of the faintest sources in the source catalogue are also addressed. The results of a serendipitous search for HI emission in the field are also presented. Using a subset of the data, we clearly detect HI emission associated with four galaxies in the central region of the FLSv. These are identified with nearby, massive galaxies.
- ID:
- ivo://CDS.VizieR/J/AJ/125/2427
- Title:
- 1.4GHz flux densities of Abell 2255 galaxies
- Short Name:
- J/AJ/125/2427
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Deep VLA 1.4GHz radio continuum imaging of Abell 2255 is presented. This cluster is among the better nearby candidates for rich cluster-cluster merger systems, with evidence including an elongated X-ray morphology, the presence of a radio halo, and substructure present in its galaxy distribution. Our radio observations reach an rms sensitivity of ~40{mu}Jy/beam, enabling us to detect (at 5{sigma}) star formation rates as low as 1.4M_{sun}_/yr from the center of the cluster out to a radial distance of 3h^-1^_75_Mpc. The radio data are complemented by optical imaging and a large spectroscopic database, allowing us to separate all galaxies with M_Rc_<=-20 0 into cluster members and foreground/background galaxies. The spectra are also used to associate the galaxies' radio emission with either star formation or active galactic nuclei (AGNs). We compare the resulting cluster radio galaxy population with those of 19 other nearby Abell clusters and find strong evidence for an increase in the frequency of radio galaxies in Abell 2255. This increase is seen in two separate types of galaxies: powerful radio AGNs and optically faint star-forming galaxies. The optical spectra of the latter often indicate current or recent starbursts, and these galaxies appear to be distributed along an axis perpendicular to the probable merger axis. We assess these factors in light of models of galaxy evolution and suggest that the cluster-cluster merger is responsible for triggering galaxy activity in Abell 2255.
- ID:
- ivo://CDS.VizieR/J/A+A/419/71
- Title:
- 1.4GHz obs. and optical ident. in A3558
- Short Name:
- J/A+A/419/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present Very Large Array (VLA) 1.4GHz (21cm) observations of the region between the centres of A3558 and A3562, in the major cluster merger complex of the Shapley Concentration. Our final catalogue includes a total of 174 radio sources above the flux density limit of 0.25 mJy/b. By cross-correlation with optical and spectroscopic catalogues we found 33 optical counterparts belonging to the Shapley Concentration.
