- ID:
- ivo://CDS.VizieR/VIII/89
- Title:
- Northern HI Parkes All Sky Survey Catalogue (HIPASS)
- Short Name:
- VIII/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Northern HIPASS catalogue (NHICAT) is the northern extension of the HIPASS catalogue, HICAT. This extension adds the sky area between the declination (Dec.) range of +2{deg}<DE<+25{deg}30' to HICAT's Dec. range of -90{deg}<DE<+2{deg}. HIPASS is a blind HI survey using the Parkes Radio Telescope covering 71 per cent of the sky (including this northern extension) and a heliocentric velocity range of -1280 to 12700km/s. The entire Virgo Cluster region has been observed in the Northern HIPASS. The galaxy catalogue, NHICAT, contains 1002 sources with v_hel_>300km/s. Sources with -300<v_hel_<300km/s were excluded to avoid contamination by Galactic emission. In total, the entire HIPASS survey has found 5317 galaxies identified purely by their HI content. The full galaxy catalogue is publicly available at http://hipass.aus-vo.org.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/252/1
- Title:
- OH and HI data in molecular clouds
- Short Name:
- J/ApJS/252/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a OH 18cm survey toward 141 molecular clouds in various environments, including 33 optical dark clouds, 98 Planck Galactic cold clumps (PGCCs), and 10 Spitzer dark clouds with the Arecibo telescope. The deviations from local thermal equilibrium are common for intensity ratios of both OH main lines and satellite lines. Line intensity of OH 1667MHz is found to correlate linearly with visual extinction A_V_ when A_V_ is less than 3mag. It was converted into OH column density by adopting the excitation temperature derived from Monte Carlo simulations with 1{sigma} uncertainty. The relationship between OH abundance X(OH) relative to H_2_ and A_V_ is found to follow an empirical formula, X(OH)/10^-7^=1.3_-0.4_^+0.4^+6.3_-0.5_^+0.5^*exp(-A_V_/2.9_-0.6_^+0.6^). Linear correlation is found between OH and ^13^CO intensity. Besides, nonthermal velocity dispersions of OH and ^13^CO are closely correlated. These results imply tight chemical evolution and spatial occupation between OH and ^13^CO. No obvious correlation is found between column density and nonthermal velocity dispersion of OH and HI narrow self-absorption (HINSA), indicating different chemical evolution and spatial volume occupation between OH and HINSA. Using the age information of HINSA analysis, OH abundance X(OH) is found to increase linearly with cloud age, which is consistent with previous simulations. Fourteen OH components without corresponding CO emission were detected, implying the effectiveness of OH in tracing the "CO-dark" molecular gas.
- ID:
- ivo://CDS.VizieR/J/A+A/473/399
- Title:
- Optical and HI data of 6 southern galaxy groups
- Short Name:
- J/A+A/473/399
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Multi-wavelength observations of Hickson's Compact Groups (HCGs) have shown that many of these groups are physical bound structures and are in different stage of evolution, from spiral-dominated systems to almost merged objects. Very few studies have analysed the Southern Compact Groups (SCGs) sample, which is thought to be younger that HCGs, due to an on average higher number of spiral galaxies. We present here the first results from optical and radio observations on a pilot sample of SCGs. Optical observations of SCGs obtained with ESO telescopes and radio data from the ATCA allow us to probe the distribution of the warm intra-group medium and the evolutionary stage of each group, by means of morphological studies and via measurements of star formation and other types of nuclear activity.
- ID:
- ivo://CDS.VizieR/J/AJ/144/16
- Title:
- Optical and HI properties of galaxies in voids
- Short Name:
- J/AJ/144/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have carefully selected a sample of 60 galaxies that reside in the deepest underdensities of geometrically identified voids within the Sloan Digital Sky Survey. HI imaging of 55 galaxies with the Westerbork Synthesis Radio Telescope reveals morphological and kinematic signatures of ongoing interactions and gas accretion. We probe a total volume of 485Mpc^3^ within the voids, with an angular resolution of 8kpc at an average distance of 85Mpc. We reach column density sensitivities of 5x10^19^/cm^-2^, corresponding to an HI mass limit of 3x10^8^M_{sun}_. We detect HI in 41 galaxies, with total masses ranging from 1.7x10^8^ to 5.5x10^9^M_{sun}_. The upper limits on the 14 non-detections are not inconsistent with their luminosities, given their expected HI mass-to-light ratios. We find that the void galaxies are generally gas-rich, low-luminosity, blue disk galaxies, with optical and HI properties that are not unusual for their luminosity and morphology. The sample spans a range of absolute magnitudes (-16.1>M_r_>-20.4) and colors (0.06<g-r<0.87), and includes disk and irregular galaxies. We also identify three as early-type galaxies, all of which are not detected in HI. All galaxies have stellar masses less than 3x10^10^M_{sun}_, and many have kinematic and morphological signs of ongoing gas accretion, suggesting that the void galaxy population is still in the process of assembling. The small-scale clustering in the void, within 600kpc and 200km/s, is similar to that in higher density regions, and we identify 18 HI-rich neighboring galaxies in the voids. Most are within 100kpc and 100km/s of the targeted galaxy, and we find no significant population of HI-rich low-luminosity galaxies filling the voids, contrary to what is predicted by simulations.
- ID:
- ivo://CDS.VizieR/J/MNRAS/459/220
- Title:
- Optical redshifts of OH- and HI-emitting galaxies
- Short Name:
- J/MNRAS/459/220
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- OH megamasers (OHMs) are rare, luminous molecular masers that are typically observed in (ultra) luminous infrared galaxies and serve as markers of major galaxy mergers. In blind emission line surveys such as the Arecibo Legacy Fast Arecibo L-Band Feed Array (ALFALFA) survey for neutral hydrogen (HI), OHMs at z~0.2 can mimic z~0.05 HI lines. We present the results of optical spectroscopy of ambiguous HI detections in the ALFALFA 40 per cent data release detected by the Wide Field Infrared Survey Explorer (WISE) but with uncertain optical counterparts. The optical redshifts, obtained from observations at the Apache Point Observatory, revealed five new OHMs and identified 129 HI optical counterparts. 60 candidates remain ambiguous. The new OHMs are the first detected in a blind spectral line survey. The number of OHMs in ALFALFA is consistent with predictions from the OH luminosity function. Additionally, the mid-infrared magnitudes and colours of the OHM host galaxies found in a blind survey do not seem to differ from those found in previous targeted surveys. This validates the methods used in previous IR-selected OHM surveys and indicates there is no previously unknown OHM-producing population at z~0.2. We also provide a method for future surveys to separate OH megamasers from 99 per cent of HI line emitters without optical spectroscopy by using WISE infrared colours and magnitudes. Since the fraction of OHMs found in flux-limited HI surveys is expected to increase with the survey's redshift, this selection method can be applied to future flux-limited high-redshift hydrogen surveys.
- ID:
- ivo://CDS.VizieR/J/AJ/161/71
- Title:
- Paramaters for 40 LITTLE THINGS galaxies
- Short Name:
- J/AJ/161/71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The stellar, gaseous and young stellar disks in the LITTLE THINGS sample of nearby dwarf irregular galaxies are fitted with functions to search for correlations between the parameters. We find that the HI radial profiles are generally flatter in the center and fall faster in the outer regions than the V-band profiles, while young stars are more centrally concentrated, especially if the HI is more centrally flat. This pattern suggests that the HI is turning into molecules in the center, and the molecular clouds are forming stars and FUV. A model that assumes the molecular surface density is proportional to the total gas surface density to a power of 1.5 or 2, in analogy with the Kennicutt-Schmidt relation, reproduces the relationship between the ratio of the visible to the HI scale length and the HI Sersic index. The molecular fraction is estimated as a function of radius for each galaxy by converting the FUV to a molecular surface density using conventional calibrations. The average molecular fraction inside 3RD is 23%{+/-}17%. However, the break in the stellar surface brightness profile has no unified tracer related to star formation.
- ID:
- ivo://CDS.VizieR/J/ApJ/899/15
- Title:
- Parameters for the 58 {tau}HI(v) sightlines
- Short Name:
- J/ApJ/899/15
- Date:
- 14 Mar 2022 07:09:23
- Publisher:
- CDS
- Description:
- Resolving the phase structure of neutral hydrogen (HI) is crucial for understanding the life cycle of the interstellar medium (ISM). However, accurate measurements of HI temperature and density are limited by the availability of background continuum sources for measuring HI absorption. Here we test the use of deep learning for extracting HI properties over large areas without optical depth information. We train a 1D convolutional neural network using synthetic observations of 3D numerical simulations of the ISM to predict the fraction (f_CNM_) of cold neutral medium (CNM) and the correction to the optically thin HI column density for optical depth (R_H_I__) from 21cm emission alone. We restrict our analysis to high Galactic latitudes (|b|>30{deg}), where the complexity of spectral line profiles is minimized. We verify that the network accurately predicts f_CNM_ and R_H_I__ by comparing the results with direct constraints from 21cm absorption. By applying the network to the GALFA-HI survey, we generate large-area maps of f_CNM_ and R_H_I__. Although the overall contribution to the total HI column of CNM-rich structures is small (~5%), we find that these structures are ubiquitous. Our results are consistent with the picture that small-scale structures observed in 21cm emission aligned with the magnetic field are dominated by CNM. Finally, we demonstrate that the observed correlation between HI column density and dust reddening (E(B-V)) declines with increasing R_H_I__, indicating that future efforts to quantify foreground Galactic E(B-V) using HI, even at high latitudes, should increase fidelity by accounting for HI phase structure.
- ID:
- ivo://CDS.VizieR/VIII/8A
- Title:
- Parkes High-Latitude H I Survey
- Short Name:
- VIII/8A
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This survey consists of HI 21-cm spectra covering the southern sky with absolute galactic latitude |b|>=10 degrees and declination dec<=-30 degrees. The observations were made with the Parkes Radio Observatory (CSIRO) 60-foot telescope. The receiver back end was the Parkes 64-channel spectrometer. The velocity resolution was 7km/s (33kHz) and the beamwidth (HPBW) was 48arcmin. Drift scans at constant declination were used with continuous integration in right ascension for -80<=declination<=-30 degrees. For declination<-80 degrees a grid of positions spaced 1 degree apart in declination and one beam-width apart in right ascension were observed. The survey was made in two parts. Part 1 included b>=-25 degrees, |b|>=10 degrees and declination dec<=-30 degrees. Part 2 included b<=-25 degrees and dec<=-30 degrees. The scans in Part 1 were spaced at 1 degree intervals in declination and the velocity coverage was from -148 to +300km/s. The scans in Part 2 were spaced at 2 degrees and the velocity coverage was from -230 to +218km/s. Each spectrum or record consists of a header followed by 64 antenna temperatures. The header contains the galactic longitude, galactic latitude, right ascension, declination, central velocity (LSR), and quality factor. The catalog contains a total of 9891 spectra.
- ID:
- ivo://CDS.VizieR/J/AJ/122/3155
- Title:
- Peculiar HI cloud near galactic plane
- Short Name:
- J/AJ/122/3155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An H I cloud with a double-lobed structure and a radial velocity of +50km/s has been found near l=92{deg}, b=-4{deg} in a low-resolution H I survey carried out at the Dominion Radio Astrophysical Observatory (DRAO). This velocity is forbidden for circular Galactic rotation. Because of its unusual morphology and small variation in radial velocity over the cloud, further observations of the area were made with the DRAO Synthesis Telescope, both in the H I line and in the radio continuum. The cloud has dimensions of about 3.3{deg}x0.5{deg}, and has a morphology somewhat similar to high-velocity H I clouds (HVCs). Several possible associations with other objects are examined in this paper. A variable inverted-spectrum radio continuum source exists near the morphological center of the H I cloud. It is probably a rare example of a gigahertz peaked spectrum (GPS) extragalactic source having a peak above 5GHz. A luminous B star is found close to the peculiar H I cloud, and the cloud is also located near the center of an H I supershell, supposedly located at a distance of about 9kpc. Energetic and other considerations lead to the conclusion that the cloud is probably not related to the HVC phenomenon nor to any of the above objects but is a relic of a nearby (D~1kpc) supernova event, all other evidence of which has now dissipated. Maps of continuum radio emission (at 1420 and 408MHz) in the area around the cloud are presented, as well as lists of continuum radio sources. A few isolated high-velocity knots of H I emission have also been detected in the vicinity of the cloud.
- ID:
- ivo://CDS.VizieR/J/ApJ/793/132
- Title:
- Perseus cloud sources Gaussian parameters
- Short Name:
- J/ApJ/793/132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the Arecibo Observatory, we have obtained neutral hydrogen (HI) absorption and emission spectral pairs in the direction of 26 background radio continuum sources in the vicinity of the Perseus molecular cloud. Strong absorption lines were detected in all cases, allowing us to estimate spin temperature (T_s_) and optical depth for 107 individual Gaussian components along these lines of sight. Basic properties of individual H I clouds (spin temperature, optical depth, and the column density of the cold and warm neutral medium (CNM and WNM), respectively) in and around Perseus are very similar to those found for random interstellar lines of sight sampled by the Millennium H I survey. This suggests that the neutral gas found in and around molecular clouds is not atypical. However, lines of sight in the vicinity of Perseus have, on average, a higher total H I column density and the CNM fraction, suggesting an enhanced amount of cold H I relative to an average interstellar field. Our estimated optical depth and spin temperature are in stark contrast with the recent attempt at using Planck data to estimate properties of the optically thick H I. Only ~15% of lines of sight in our study have a column density weighted average spin temperature lower than 50 K, in comparison with >~85% of Planck's sky coverage. The observed CNM fraction is inversely proportional to the optical depth weighted average spin temperature, in excellent agreement with the recent numerical simulations by Kim et al. (2014ApJ...786...64K). While the CNM fraction is, on average, higher around Perseus relative to a random interstellar field, it is generally low, between 10%-50%. This suggests that extended WNM envelopes around molecular clouds and/or significant mixing of CNM and WNM throughout molecular clouds are present and should be considered in the models of molecule and star formation. Our detailed comparison of H I absorption with CO emission spectra shows that only 3 of the 26 directions are clear candidates for probing the CO-dark gas as they have N(H I)>10^21^/cm2 yet no detectable CO emission.
