- ID:
- ivo://CDS.VizieR/J/ApJS/245/3
- Title:
- HI 21cm and OH 18cm absorption search with the GBT
- Short Name:
- J/ApJS/245/3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a large search for intrinsic HI 21cm and OH 18cm absorption in 145 compact radio sources in the redshift range 0.02<z<3.8 with the Green Bank Telescope. We redetect HI 21cm absorption toward six known absorption systems, but detect no new HI or OH absorption in 102 interference-free sources. Seventy-nine sources have not previously been observed for HI 21cm absorption. We recover a mean optical depth limit of {tau}_3{sigma}_<0.023 for all the nondetections in the survey. Our results do not support the high intrinsic absorption rates found by previous studies in compact radio sources at low redshift. Our results do, however, support the hypothesis proposed by Curran+ (2019MNRAS.484.1182C) that high ultraviolet (UV) luminosity active galactic nuclei do not show intrinsic HI 21cm absorption, confirming a threshold of L_UV_=10^23^W/Hz, above which our intrinsic absorption fraction is zero (54 sources). The exact nature of the UV luminosity effect on HI absorption systems remains ambiguous. We additionally find no statistical correlation between the 1.4GHz radio luminosity or the source size and the 21cm absorption detection rate. We attribute the lack of intrinsic absorption in our survey to the UV luminosity effect caused by an optical selection bias and a decreased column density sensitivity with increasing redshift due to lower radio continuum flux densities, high radio frequency interference, and higher telescope system temperatures at low frequencies.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/173/85
- Title:
- HI 21cm forbidden-velocity wings
- Short Name:
- J/ApJS/173/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of a search for faint HI 21cm emission line wings at velocities forbidden by Galactic rotation in the Galactic plane using the Leiden/Dwingeloo HI Survey data and the HI Southern Galactic Plane Survey data. These "forbidden-velocity wings" (FVWs) appear as protruding excessive emission in comparison with their surroundings in limited (>~2{deg}) spatial regions over velocity extents of more than ~20km/s in large-scale (l,v) diagrams. Their high velocities imply that there should be some dynamical phenomena associated. We have identified 87 FVWs. We present their catalog and discuss their distribution and statistical properties. We found that 85% of FVWs are not coincident with known supernova remnants (SNRs), galaxies, or high-velocity clouds. Their natures are currently unknown.
- ID:
- ivo://CDS.VizieR/J/AJ/133/1104
- Title:
- HI 21cm observations of Pegasus galaxies
- Short Name:
- J/AJ/133/1104
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present neutral hydrogen observations of 54 galaxies in the Pegasus Cluster. The observations include single-dish HI measurements, obtained with the Arecibo telescope for all 54 galaxies in the sample, as well as HI images obtained with the Very Large Array (VLA) for 10 of these.
- ID:
- ivo://CDS.VizieR/J/A+A/650/A76
- Title:
- HI content in Coma cluster substructure
- Short Name:
- J/A+A/650/A76
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- Galaxy clusters are some of largest structures in the universe. These very dense environments tend to be home to higher numbers of evolved galaxies than found in lower-density environments. It is well known that dense environments can influence the evolution of galaxies through the removal of the neutral gas (HI) reservoirs that fuel star formation. It is unclear which environment has a stronger effect: the local environment (i.e. the substructure within the cluster), or the cluster itself. Using the new HI data from the Westerbork Coma Survey, we explore the average HI content of galaxies across the cluster comparing galaxies that reside in substructure to those that do not. We applied the Dressler-Shectman test to our newly compiled redshift catalogue of the Coma cluster to search for substructure. With so few of the Coma galaxies directly detected in HI, we used the HI stacking technique to probe the average HI content below what can be directly detected. Using the Dressler-Shectman test, we find 15 substructures within the footprint of the Westerbork Coma Survey. We compare the average HI content for galaxies within substructure to those not in substructure. Using the HI stacking technique, we find that those Coma galaxies not detected in HI are more than 10-50 times more HI deficient than expected, which supports the scenario of an extremely efficient and rapid quenching mechanism. By studying the galaxies that are not directly detected in HI, we also find Coma to be more HI deficient than previously thought.
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/217
- Title:
- HI cosmological mass density at z=5
- Short Name:
- J/MNRAS/452/217
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the largest homogeneous survey of z>4.4 damped Ly{alpha} systems (DLAs) using the spectra of 163 QSOs that comprise the Giant Gemini GMOS (GGG) survey. With this survey we make the most precise high-redshift measurement of the cosmological mass density of neutral hydrogen, Omega_HI_. At such high redshift, important systematic uncertainties in the identification of DLAs are produced by strong intergalactic medium absorption and QSO continuum placement. These can cause spurious DLA detections, result in real DLAs being missed or bias the inferred DLA column density distribution. We correct for these effects using a combination of mock and higher resolution spectra, and show that for the GGG DLA sample the uncertainties introduced are smaller than the statistical errors on Omega_HI_. We find Omega_HI_=0.98^+0.20^_-0.18_x10^-3^ at <z>=4.9, assuming a 20 percent contribution from lower column density systems below the DLA threshold. By comparing to literature measurements at lower redshifts, we show that Omega_HI_ can be described by the functional form Omega_HI_(z){prop.to}(1+z)^0.4^. This gradual decrease from z=5 to 0 is consistent with the bulk of HI gas being a transitory phase fuelling star formation, which is continually replenished by more highly ionized gas from the intergalactic medium and from recycled galactic winds.
- ID:
- ivo://CDS.VizieR/J/MNRAS/447/1531
- Title:
- HI data collection update
- Short Name:
- J/MNRAS/447/1531
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cosmic Flows is an international multi-element project with the goal to map motions of galaxies in the local Universe. Kinematic information from observations in the radio HI line and photometry at optical or near-infrared bands are acquired to derive the large majority of distances that are obtained through the luminosity-linewidth or Tully-Fisher relation. This paper gathers additional observational radio data, frequently unpublished, retrieved from the archives of Green Bank, Parkes and Arecibo telescopes. Extracted HI profiles are consistently processed to produce linewidth measurements. Our current 'All-Digital HI Catalog' contains a total of 20343 HI spectra for 17738 galaxies with 14 802 galaxies with accurate linewidth measurement useful for Tully-Fisher galaxy distances. This addition of 4117 new measurements represents an augmentation of 34 percent compared to our last release.
- ID:
- ivo://CDS.VizieR/J/A+A/587/L3
- Title:
- HI datacubes if Pisces A and B
- Short Name:
- J/A+A/587/L3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Pisces A and Pisces B are the only two galaxies found via optical imaging and spectroscopy out of 22 HI clouds identified in the GALFAHI survey as dwarf galaxy candidates. We derive the HI content and kinematics of Pisces A and B. Our aperture synthesis HI observations used the seven-dish Karoo Array Telescope (KAT-7), which is a pathfinder instrument for MeerKAT, the South African precursor to the mid-frequency Square Kilometre Array (SKA-MID).
- ID:
- ivo://CDS.VizieR/J/A+A/582/A18
- Title:
- HI data cubes of 4 edge-on spiral galaxies
- Short Name:
- J/A+A/582/A18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Edge-on galaxies can offer important insight into galaxy evolution because they are the only systems where the distribution of the different components can be studied both radially and vertically. The HEROES project was designed to investigate the interplay between the gas, dust, stars, and dark matter (DM) in a sample of 7 massive edge-on spiral galaxies. In this second HEROES paper, we present an analysis of the atomic gas content of 6 out of 7 galaxies in our sample. The remaining galaxy was recently analysed according to the same strategy. The primary aim of this work is to constrain the surface density distribution, the rotation curve, and the geometry of the gas disks in a homogeneous way. In addition we identify peculiar features and signs of recent interactions. We have constructed detailed tilted-ring models of the atomic gas disks based on new GMRT 21-cm observations of NGC 973 and UGC 4277 and re-reduced archival HI data of NGC 5907, NGC 5529 IC 2531, and NGC 4217. Potential degeneracies between different models were resolved by requiring good agreement with the data in various representations of the data cubes. From our modelling we find that all but one galaxy are warped along the major axis. In addition, we identify warps along the line of sight in three galaxies. A flaring gas layer is required to reproduce the data for only one galaxy, but (moderate) flares cannot be ruled out for the other galaxies either. A coplanar ring-like structure is detected outside the main disk of NGC 4217, which we suggest could be the remnant of a recent minor merger event. We also find evidence of a radial inflow of 15 +/-5km/s in the disk of NGC 5529, which might be related to the ongoing interaction with two nearby companions. For NGC 5907 the extended, asymmetric, and strongly warped outer regions of the HI disk also suggest a recent interaction. In contrast, the inner disks of these three galaxies (NGC 4217, NGC 5529, and NGC 5907) show regular behaviour and seem largely unaffected by the interactions. Our models further support earlier claims of prominent spiral arms in the disks of IC 2531 and NGC 5529. Finally, we detect a dwarf companion galaxy at a projected distance of 36 kpc from the centre of NGC 973.
- ID:
- ivo://CDS.VizieR/J/A+A/113/61
- Title:
- HI data for 392 spiral galaxies
- Short Name:
- J/A+A/113/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 392 spiral galaxies with type Sb or later have been detected in the 21-cm line of neutral hydrogen with the Nancay radiotelescope, and among them 172 HI fluxes are obtained for the first time. The source of any possible bias has been carefully analyzed and only the Malmquist bias appears to be significant. In order to obviate this observational effect, the range of radial velocities has been properly truncated for all statistical studies. A mean value of each global parameter has been determined for each morphological type and compared to previous results.
- ID:
- ivo://CDS.VizieR/J/A+A/434/887
- Title:
- HI data of blue compact dwarf galaxies
- Short Name:
- J/A+A/434/887
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present HI-observations of 56 blue compact dwarf (BCD) galaxies of which 44 have been detected in the 21-cm line from neutral hydrogen with the 100-m radiotelescope at Effelsberg. Optical data (e.g., from NED) and HI data from other observers and telescopes are used to estimate the likelihood of confusion from other galaxies within the Effelsberg beam. The selected 29 BCD galaxies without any sign of confusion are used to infer several characteristic properties of the BCD galaxy population. In some respects, they resemble normal galaxies: e.g., the relations between global parameters like linear diameter A0 versus blue luminosity LB and the M_HI_/LB ratio vs. LB. At least five of these BCDGs emit milli-Jansky level radio continuum emission.