- ID:
- ivo://CDS.VizieR/J/MNRAS/437/2017
- Title:
- HI-galaxy cross-correlation at z<~1
- Short Name:
- J/MNRAS/437/2017
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new optical spectroscopic survey of 1777 'star-forming' ('SF') and 366 'non-star-forming' ('non-SF') galaxies at redshifts z~0-1 (2143 in total), 22 AGN and 423 stars, observed by instruments such as the Deep Imaging Multi-Object Spectrograph, the Visible Multi-Object Spectrograph and the Gemini Multi-Object Spectrograph, in three fields containing five quasi-stellar objects (QSOs) with Hubble Space Telescope (HST) ultraviolet spectroscopy. We also present a new spectroscopic survey of 173 'strong' (10^14^<=N_HI_<~10^17^cm^-2^) and 496 'weak' (10^13^<~N_HI_<10^14^cm^-2^) intervening HI (Ly{alpha}) absorption-line systems at z<~1 (669 in total), observed in the spectra of eight QSOs at z~1 by the Cosmic Origins Spectrograph and the Faint Object Spectrograph on the HST. Combining these new data with previously published galaxy catalogues such as the Very Large Telescope Visible Multi-Object Spectrograph Deep Survey and the Gemini Deep Deep Survey, we have gathered a sample of 654 HI absorption systems and 17509 galaxies at transverse scales <~50Mpc, suitable for a two-point correlation function analysis. We present observational results on the HI-galaxy ({xi}_ag_) and galaxy-galaxy ({xi}_gg_) correlations at transverse scales r_perp_<~10Mpc, and the HI-HI autocorrelation ({xi}_aa_) at transverse scales r_perp_<~2Mpc.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/464/3796
- Title:
- HI gas mass fraction estimations
- Short Name:
- J/MNRAS/464/3796
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The application of artificial neural networks (ANNs) for the estimation of HI gas mass fraction (M_HI_/M*) is investigated, based on a sample of 13 674 galaxies in the Sloan Digital Sky Survey (SDSS) with HI detections or upper limits from the Arecibo Legacy Fast Arecibo L-band Feed Array (ALFALFA). We show that, for an example set of fixed input parameters (g-r colour and i-band surface brightness), a multidimensional quadratic model yields M_HI_/M* scaling relations with a smaller scatter (0.22dex) than traditional linear fits (0.32dex), demonstrating that non-linear methods can lead to an improved performance over traditional approaches. A more extensive ANN analysis is performed using 15 galaxy parameters that capture variation in stellar mass, internal structure, environment and star formation. Of the 15 parameters investigated, we find that g-r colour, followed by stellar mass surface density, bulge fraction and specific star formation rate have the best connection with M_HI_/M*. By combining two control parameters, that indicate how well a given galaxy in SDSS is represented by the ALFALFA training set (PR) and the scatter in the training procedure ({sigma}_fit_), we develop a strategy for quantifying which SDSS galaxies our ANN can be adequately applied to, and the associated errors in the M_HI_/M* estimation. In contrast to previous works, our M_HI_/M* estimation has no systematic trend with galactic parameters such as M*, g-r and star formation rate. We present a catalogue of M_HI_/M* estimates for more than half a million galaxies in the SDSS, of which ~150000 galaxies have a secure selection parameter with average scatter in the M_HI_/M* estimation of 0.22dex.
- ID:
- ivo://CDS.VizieR/J/other/JApA/25.143
- Title:
- High galactic latitude HI absorption survey
- Short Name:
- J/other/JApA/25.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have used the Giant Meterwave Radio Telescope (GMRT) to measure the Galactic HI 21-cm line absorption towards 102 extragalactic radio continuum sources, located at high (|b|>15{deg}) Galactic latitudes. The Declination coverage of the present survey is DE~-45{deg}. With a mean rms optical depth of ~0.003, this is the most sensitive Galactic HI 21-cm line absorption survey to date. To supplement the absorption data, we have extracted the HI 21-cm line emission profiles towards these 102 lines of sight from the Leiden Dwingeloo Survey of Galactic neutral hydrogen. We have carried out a Gaussian fitting analysis to identify the discrete absorption and emission components in these profiles. In this paper, we present the spectra and the components. A subsequent paper will discuss the interpretation of these results.
- ID:
- ivo://CDS.VizieR/J/ApJS/209/12
- Title:
- High-velocity clouds from GASS. I.
- Short Name:
- J/ApJS/209/12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a catalog of high-velocity clouds (HVCs) from the Galactic All Sky Survey (GASS) of southern sky neutral hydrogen, which has 57mK sensitivity and 1 km/s velocity resolution and was obtained with the Parkes Telescope. Our catalog has been derived from the stray-radiation-corrected second release of GASS. We describe the data and our method of identifying HVCs and analyze the overall properties of the GASS population. We catalog a total of 1693 HVCs at declinations <0{deg}, including 1111 positive velocity HVCs and 582 negative velocity HVCs. Our catalog also includes 295 anomalous velocity clouds (AVCs). The cloud line-widths of our HVC population have a median FWHM of ~19 km/s, which is lower than that found in previous surveys. The completeness of our catalog is above 95% based on comparison with the HIPASS catalog of HVCs upon which we improve by an order of magnitude in spectral resolution. We find 758 new HVCs and AVCs with no HIPASS counterpart. The GASS catalog will shed unprecedented light on the distribution and kinematic structure of southern sky HVCs, as well as delve further into the cloud populations that make up the anomalous velocity gas of the Milky Way.
- ID:
- ivo://CDS.VizieR/J/ApJS/140/331
- Title:
- High-velocity HI observations at 21cm
- Short Name:
- J/ApJS/140/331
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Very sensitive HI 21cm observations have been made in 860 directions at {delta}>=-43{deg} in search of weak, Galactic, high-velocity HI emission lines at moderate and high Galactic latitudes.
- ID:
- ivo://CDS.VizieR/J/A+AS/142/25
- Title:
- High velocity HI Southern Survey
- Short Name:
- J/A+AS/142/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new high-sensitivity HI survey of the southern sky was made south of Declination -25{deg}, at the Instituto Argentino de Radioastronomia (IAR), on a half-degree grid in galactic coordinates. A total of 50980 positions were observed. One of the goals of this survey was to search for high velocity clouds (HVCs). The HI profiles have been smoothed to a velocity resolution of 8km/s. The resulting rms noise falls in the range 0.015 to 0.020K. We have detected 6848 high velocity (HV) components.
- ID:
- ivo://CDS.VizieR/J/AJ/141/23
- Title:
- HI holes in THINGS galaxies
- Short Name:
- J/AJ/141/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the properties of HI holes detected in 20 galaxies that are part of "The HI Nearby Galaxy Survey." We detected more than 1000 holes in total in the sampled galaxies. Where they can be measured, their sizes range from about 100pc (our resolution limit) to about 2kpc, their expansion velocities range from 4 to 36km/s, and their ages are estimated to range between 3 and 150Myr. The holes are found throughout the disks of the galaxies, out to the edge of the HI disk; 23% of the holes fall outside R25. We find that shear limits the age of holes in spirals (shear is less important in dwarf galaxies) which explains why HI holes in dwarfs are rounder, on average than in spirals.
- ID:
- ivo://CDS.VizieR/J/A+AS/139/1
- Title:
- HI in Byurakan blue compact galaxies
- Short Name:
- J/A+AS/139/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a neutral hydrogen survey of 79 galaxies from a statistical sample of 88 Blue Compact Galaxies (BCGs) selected from the First and Second Byurakan objective prism surveys to have a HII region-like spectrum, an equivalent width of the [O III] {lambda}5007 line larger than ~50{AA}, and a velocity <=6000km/s. The detection rate for the statistical sample is 74%. HI masses range between 4x10^7^M_{sun}_ and 5x10^9^M_{sun}_ with the HI mass distribution peaking at 3x10^8^M_{sun}_. The full width at half-maximum of the HI profile varies between ~30km/s and 160km/s, with a mean of ~92km/s. These small widths are characteristic of dwarf galaxies. For comparison, we have also observed an additional 92 BCGs with weaker star formation and/or larger distances, and/or interesting astrophysical properties. These in general have larger widths and HI masses.
- ID:
- ivo://CDS.VizieR/J/A+A/506/677
- Title:
- HI in Local Supercluster dwarf galaxies
- Short Name:
- J/A+A/506/677
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have observed 71 dwarf galaxies of low surface brightness using the 100-m radio telescope at Effelsberg in a search for new members of 27 northern galaxy groups with characteristic distances of 8 to 15Mpc. We present radial velocities, HI-fluxes, and HI line widths for 17 detected galaxies as well as upper limits for the remaining undetected objects.
- ID:
- ivo://CDS.VizieR/J/A+A/604/A43
- Title:
- HI in nearby radio sources
- Short Name:
- J/A+A/604/A43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an analysis of the properties of neutral hydrogen (HI) in 248 nearby (0.02<z<0.25) radio galaxies with S_1.4GHz_>30mJy and for which optical spectroscopy is available. The observations were carried out with the Westerbork Synthesis Radio Telescope as the last large project before the upgrade of the telescope with phased array feed receivers (Apertif). The sample covers almost four orders of magnitude in radio power from logP_1.4GHz_=22.5W/Hz and 26.2W/Hz. We detect HI in absorption in 27%+/-5.5% of the objects. The detections are found over the full range of radio power. However, the distribution and kinematics of the absorbing HI gas appear to depend on radio power, the properties of the radio continuum emission, and the dust content of the sources. Among the sources where HI is detected, gas with kinematics deviating from regular rotation is more likely found as the radio power increases.In the great majority of these cases, the HI profile is asymmetric with a significant blue-shifted component. This is particularly common for sources with logP_1.4GHz_>24W/Hz, where the radio emission is small, possibly because these radio sources are young. The same is found for sources that are bright in the mid-infrared, i.e. sources rich in heated dust.In these sources, the HI is outflowing likely under the effect of the interaction with the radio emission. Conversely, in dust-poor galaxies, and in sources with extended radio emission, at all radio powers we only detect HI distributed in a rotating disk. Stacking experiments show that in sources for which we do not detect HI in absorption directly, the HI has a column density that is lower than 3.5x10^17^(T_spin_/c_f_)cm^-2^. We use our results to predict the number and type of HI absorption lines that will be detected by the upcoming surveys of the Square Kilometre Array precursors and pathfinders (Apertif, MeerKAT, and ASKAP).
