Search

Start Over Subject h i line emission
281. WSRT Virgo HI filament survey
ID:
ivo://CDS.VizieR/J/A+A/527/A90
Title:
WSRT Virgo HI filament survey
Short Name:
J/A+A/527/A90
Date:
21 Oct 2021
Publisher:
CDS
Description:
Observations of neutral hydrogen can provide a wealth of information about the kinematics of galaxies. To learn more about the large-scale structures and accretion processes, the extended environment of galaxies have to be observed. Numerical simulations predict a cosmic web of extended structures and gaseous filaments. To observe the direct vicinity of galaxies, column densities have to be achieved that probe the regime of Lyman limit systems. Typically, HI observations are limited to a brightness sensitivity of N_HI_~10^19^cm^-2^, but this has to be improved by ~2 orders of magnitude. With the Westerbork Synthesis Radio Telescope (WSRT), we mapped the galaxy filament connecting the Virgo Cluster with the Local Group. About 1500 square degrees on the sky was surveyed with Nyquist sampled pointings. By using the WSRT antennas as single-dish telescopes instead of the more conventional interferometer, we were very sensitive to extended emission. The survey consists of a total of 22000 pointings, and each pointing was observed for two minutes with 14 antennas.
282. WSRT Virgo HI filament survey. II.
ID:
ivo://CDS.VizieR/J/A+A/528/A28
Title:
WSRT Virgo HI filament survey. II.
Short Name:
J/A+A/528/A28
Date:
21 Oct 2021
Publisher:
CDS
Description:
The extended environment of galaxies contains a wealth of information about the formation and life cycle of galaxies which are regulated by accretion and feedback processes. Observations of neutral hydrogen are routinely used to image the high brightness disks of galaxies and to study their kinematics. Deeper observations will give more insight into the distribution of diffuse gas in the extended halo of the galaxies and the inter-galactic medium, where numerical simulations predict a cosmic web of extended structures and gaseous filaments. To observe the extended environment of galaxies, column density sensitivities have to be achieved that probe the regime of Lyman limit systems. HI observations are typically limited to a brightness sensitivity of NHI~10^19^cm^-2^, but this must be improved upon by ~2 orders of magnitude.
283. WSRT wide-field HI survey. II.
ID:
ivo://CDS.VizieR/J/A+A/417/421
Title:
WSRT wide-field HI survey. II.
Short Name:
J/A+A/417/421
Date:
21 Oct 2021
Publisher:
CDS
Description:
We have used the Westerbork array to carry out an unbiased wide-field survey for HI emission features, achieving an RMS sensitivity of about 18mJy/Beam at a velocity resolution of 17km/s over 1800deg^2^ and between -1000<VHel<+6500km/s. The primary data consists of auto-correlation spectra with an effective angular resolution of 49' FWHM. The survey region is centered approximately on the position of Messier 31 and is Nyquist-sampled over 60x30deg in RAxDE. In this paper we present our HI detections at negative velocities which could be distinguished from the Galactic foreground. Fully 29% of the entire survey area has high velocity HI emission at a column density exceeding our 3-sigma limit of about 1.5x10^17cm^-2 over 30km/s. We tabulate the properties of 95 discrete HVC components in the field, corresponding to more than an order of magnitude increase in number over that known previously. The distribution of discrete object number with flux density has an inflection point near 12Jy.km/s which may correspond to a characteristic mass and distance for this population. A complete description of the observations and general methods of data reduction has already been given in Paper I (Braun et al., Cat. <J/A+A/406/829>).
284. WSRT ZoA Perseus-Pisces. HI catalogue
ID:
ivo://CDS.VizieR/J/MNRAS/460/923
Title:
WSRT ZoA Perseus-Pisces. HI catalogue
Short Name:
J/MNRAS/460/923
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present results of a blind 21cm HI-line imaging survey of a galaxy overdensity located behind the Milky Way at l, b ~= 160{deg}, 0.5{deg}. The overdensity corresponds to a zone-of-avoidance crossing of the Perseus-Pisces Supercluster filament. Although it is known that this filament contains an X-ray galaxy cluster (3C 129) hosting two strong radio galaxies, little is known about galaxies associated with this potentially rich cluster because of the high Galactic dust extinction. We mapped a sky area of ~9.6 deg^2^ using the Westerbork Synthesis Radio Telescope in a hexagonal mosaic of 35 pointings observed for 12h each, in the radial velocity range cz=2400-16600km/s. The survey has a sensitivity of 0.36mJy/beam rms at a velocity resolution of 16.5km/s. We detected 211 galaxies, 62 per cent of which have a near-infrared counterpart in the UKIDSS Galactic Plane Survey. We present a catalogue of the HI properties and an HI atlas containing total intensity maps, position-velocity diagrams, global HI profiles and UKIDSS counterpart images. For the resolved galaxies we also present HI velocity fields and radial HI surface density profiles. A brief analysis of the structures outlined by these galaxies finds that 87 of them lie at the distance of the Perseus-Pisces Supercluster (cz~4000-8000km/s) and seem to form part of the 3C 129 cluster. Further 72 detections trace an overdensity at a velocity of cz~=10000km/s and seem to coincide with a structure predicted from mass density reconstructions in the first 2MASS Redshift Survey.
285. xCOLD GASS and xGASS. Metallicity gradients
ID:
ivo://CDS.VizieR/J/A+A/649/A39
Title:
xCOLD GASS and xGASS. Metallicity gradients
Short Name:
J/A+A/649/A39
Date:
22 Feb 2022
Publisher:
CDS
Description:
The xGASS and xCOLD GASS surveys have measured the atomic (HI) and molecular gas (H_2_) content of a large and representative sample of nearby galaxies (redshift range of 0.01<z<0.05). We present optical longslit spectra for a subset of the xGASS and xCOLD GASS galaxies to investigate the correlation between radial metallicity profiles and cold gas content. In addition to data from Moran et al. (2012ApJ...745...66M), this paper presents new optical spectra for 27 galaxies in the stellar mass range of 9.0<=logMstar[Msun]<=10.0. The longslit spectra were taken along the major axis of the galaxies, allowing us to obtain radial profiles of the gas-phase oxygen abundance (12+log(O/H)). The slope of a linear fit to these radial profiles is defined as the metallicity gradient. We investigated correlations between these gradients and global galaxy properties, such as star formation activity and gas content. In addition, we examined the correlation of local metallicity measurements and the global HI mass fraction. We obtained two main results: (i) the local metallicity is correlated with the global HI mass fraction, which is in good agreement with previous results. A simple toy model suggests that this correlation points towards a 'local gas regulator model'; (ii) the primary driver of metallicity gradients appears to be stellar mass surface density (as a proxy for morphology). This work comprises one of the few systematic observational studies of the influence of the cold gas on the chemical evolution of star-forming galaxies, as considered via metallicity gradients and local measurements of the gas-phase oxygen abundance. Our results suggest that local density and local HI mass fraction are drivers of chemical evolution and the gas-phase metallicity.
286. xGASS catalog
ID:
ivo://CDS.VizieR/J/MNRAS/476/875
Title:
xGASS catalog
Short Name:
J/MNRAS/476/875
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the extended GALEX Arecibo SDSS Survey (xGASS), a gas fraction-limited census of the atomic hydrogen (HI) gas content of 1179 galaxies selected only by stellar mass (M*=10^9^-10^11.5^M_{sun}_) and redshift (0.01<z<0.05). This includes new Arecibo observations of 208 galaxies, for which we release catalogues and HI spectra. In addition to extending the GASS HI scaling relations by one decade in stellar mass, we quantify total (atomic+molecular) cold gas fractions and molecular-to-atomic gas mass ratios, Rmol, for the subset of 477 galaxies observed with the IRAM 30m telescope. We find that atomic gas fractions keep increasing with decreasing stellar mass, with no sign of a plateau down to logM*/M_{sun}_=9. Total gas reservoirs remain HI-dominated across our full stellar mass range, hence total gas fraction scaling relations closely resemble atomic ones, but with a scatter that strongly correlates with Rmol, especially at fixed specific star formation rate. On average, Rmol weakly increases with stellar mass and stellar surface density {mu}*, but individual values vary by almost two orders of magnitude at fixed M* or {mu}*. We show that, for galaxies on the star-forming sequence, variations of Rmol are mostly driven by changes of the HI reservoirs, with a clear dependence on {mu}*. Establishing if galaxy mass or structure plays the most important role in regulating the cold gas content of galaxies requires an accurate separation of bulge and disc components for the study of gas scaling relations

Limit your search

more »

  • 2286