- ID:
- ivo://CDS.VizieR/J/ApJS/130/177
- Title:
- Arecibo Dual-Beam Survey
- Short Name:
- J/ApJS/130/177
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Arecibo Dual-Beam Survey is a "blind" 21 cm search for galaxies covering ~430deg^2^ of sky. We present the data from the detection survey as well as from the follow-up observations to confirm detections and improve positions and flux measurements. We find 265 galaxies, many of which are extremely low surface brightness. Some of these previously uncatalogued galaxies lie within the zone of avoidance, where they are obscured by the gas and dust in our Galaxy. Eighty-one of these sources are not previously catalogued optically, and there are 11 galaxies that have no associated optical counterpart or are only tentatively associated with faint wisps of nebulosity on the Digitized Sky Survey images. We discuss the properties of the survey, and in particular we make direct determinations of the completeness and reliability of the sample. The behavior of the completeness and its dependencies is essential for determining the H I mass function. We leave the discussion of the mass function for a later paper, but do note that we find many low surface brightness galaxies and seven sources with M_HI_<10^8^M_{sun}_.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJS/183/214
- Title:
- Arecibo Legacy Fast Alfa Survey (ALFALFA) VIII.
- Short Name:
- J/ApJS/183/214
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a fourth catalog of HI sources from the Arecibo Legacy Fast ALFA (ALFALFA) Survey. We report 541 detections over 136deg^2^, within the region of the sky having 22h<RA<03h and 24<DE<26{deg}. This complements a previous catalog in the region 26<DE<28{deg}. We present here the detections falling into three classes: (1) extragalactic sources with signal-to-noise ratio (S/N)>6.5, where the reliability of the catalog is better than 95%; (2) extragalactic sources 5.0<S/N<6.5 and a previously measured optical redshift that corroborates our detection; or (3) High Velocity Clouds (HVCs), or subcomponents of such clouds, in the periphery of the Milky Way. Of the 541 objects presented here, 90 are associated with HVCs, while the remaining 451 are identified as extragalactic objects. Optical counterparts have been matched with all but one of the extragalactic objects.
- ID:
- ivo://CDS.VizieR/J/AJ/133/2569
- Title:
- Arecibo legacy fast ALFA survey III.
- Short Name:
- J/AJ/133/2569
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first installment of HI sources extracted from the Arecibo Legacy Fast ALFA (ALFALFA) extragalactic survey, initiated in 2005. Sources have been extracted from three-dimensional spectral data cubes exploiting a matched filtering technique and then examined interactively to yield global HI parameters. A total of 730 HI detections are cataloged within the solid angle 11h44<RA(J2000.0)<14h00 and +12{deg}<DE(J2000.0)<+16{deg} and redshift range -1600km/s<cz<18000km/s. In comparison, the HI Parkes All-Sky Survey (HIPASS, Meyer et al. 2004, Cat. VIII/73) detected 40 HI signals in the same region. Optical counterparts are assigned via examination of digital optical imaging databases.
- ID:
- ivo://CDS.VizieR/J/AJ/138/338
- Title:
- Arecibo Legacy Fast ALFA Survey. IX.
- Short Name:
- J/AJ/138/338
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the catalog of HI sources extracted from the ongoing Arecibo Legacy Fast ALFA (ALFALFA) extragalactic HI line survey, found within the sky region bounded by 9:36<RA<11:36 and +08<DE<+12. The HI catalog presented here for this 118deg^2^ region is combined with the ones derived from surrounding regions also covered by the ALFALFA survey to examine the large-scale structure in the complex Leo region. Because of the combination of wide sky coverage and superior sensitivity, spatial and spectral resolution, the ALFALFA HI catalog of the Leo region improves significantly on the numbers of low HI mass sources as compared with those found in previous HI surveys.
- ID:
- ivo://CDS.VizieR/J/AJ/135/588
- Title:
- Arecibo legacy fast ALFA survey V.
- Short Name:
- J/AJ/135/588
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a second catalog of HI sources detected in the Arecibo Legacy Fast ALFA Survey. We report 488 detections over 135deg^2^, within the region of the sky having 22<RA<03 and +26<DE<+28. We present here the detections that have either (a) S/N>6.5, where the reliability of the catalog is better than 95% or (b) 5.0<S/N<6.5 and a previously measured redshift that corroborates our detection. Of the 488 objects presented here, 49 are high-velocity clouds or clumps thereof with negative heliocentric recession velocities. These clouds are mostly very compact and isolated, while some of them are associated with large features such as Wright's Cloud or the northern extension of the Magellanic Stream. The remaining 439 candidate detections are identified as extragalactic objects and have all been matched with optical counterparts. Five of the six galaxies detected with M_HI_<10^7.5^ solMass are satellites of either the NGC672/IC1727 nearby galaxy pair or their neighboring dwarf irregular galaxy NGC784. The data of this catalog release include a slice through the Pisces-Perseus foreground void, a large nearby underdensity of galaxies. We report no detections within the void, where our catalog is complete for systems with HI masses of 10^8^M_{sun}_.
- ID:
- ivo://CDS.VizieR/J/AJ/136/713
- Title:
- Arecibo legacy fast ALFA survey. VI.
- Short Name:
- J/AJ/136/713
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the third installment of HI sources extracted from the Arecibo Legacy Fast ALFA extragalactic survey. This data set continues the work of the Virgo ALFALFA catalog. The catalogs and spectra published here consist of data obtained during the 2005 and 2006 observing sessions of the survey. The catalog consists of 578 HI detections within the range 11h36m<RA(J2000)<13h52m and +08{deg}<DE(J2000)<+12{deg}, and cz_{sun}_<18000km/s. The catalog entries are matched with optical counterparts where possible through the examination of digitized optical images. The catalog detections can be classified into three categories: (a) detections of high reliability with a signal-to-noise ratio (S/N)>6.5; (b) high-velocity clouds in the Milky Way or its periphery; and (c) signals of lower S/N which coincide spatially with an optical object and known redshift. 75% of the sources are newly published HI detections. Of particular note is a complex of HI clouds projected between M87 and M49 that do not coincide with any optical counterparts. Candidate objects without optical counterparts are few. Position corrections for telescope pointing errors are applied to the data set by comparing the ALFALFA continuum centroid with those cataloged in the NRAO VLA Sky Survey (NVSS, Cat. VIII/65). The uncorrected positional accuracy averages 27"(21" median) for all sources with S/N>6.5 and is of order ~21"(16" median) for signals with S/N>12. Uncertainties in distances toward the Virgo cluster can affect the calculated HI mass distribution.
- ID:
- ivo://CDS.VizieR/VIII/9
- Title:
- Argentina High-Latitude H I Survey
- Short Name:
- VIII/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This survey consists of H I 21-cm spectra covering the southern sky with absolute galactic latitude |b|>10 degrees and a declination dec<-25 degrees. The observations were made with the 30m telescope of the Instituto Argentino de Radioastronomia during 1973 to 1977 and were described in Colomb et al. (1977A&AS...29...89C). The data were obtained by keeping the telescope fixed on the meridian at the desired declination and letting the sky drift through the field. The individual spectra were obtained with a 56-channel filterbank and covering the velocity range from about -40 to +40km/s. The velocity resolution is 2km/s, and the beamwidth is 30arcmin.
- ID:
- ivo://CDS.VizieR/J/A+A/391/159
- Title:
- A search for Compact High-Velocity Clouds
- Short Name:
- J/A+A/391/159
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An automated search is applied to the Leiden/Dwingeloo HI Survey (LDS) for high-velocity clouds north of Dec.=-28{deg}. From the general catalog we extract a sample of relatively small (less than about 8{deg}) and isolated high-velocity clouds, CHVCs: anomalous-velocity HI clouds which are sharply bounded in angular extent with no kinematic or spatial connection to other HI features down to a limiting column density of 1.5x10^18cm^-2. Unambiguously isolated objects are given the "CHVC" designation, while those with some degree of ambiguity in this classification or designated "CHVC:" or "CHVC?". The vast majority of features show diffuse connections at low column densities with the extended HVC complexes and are simply designated as "HVC" features. The automated search algorithm has been applied to the HIPASS and to the Leiden/Dwingeloo data sets. The results from the LDS are described here; Putman et al. (2002, Cat. <J/AJ/123/873>) describe application of this algorithm to the HIPASS material. Only those catalog entries which have and additional ID listed have been confirmed in independent data.
- ID:
- ivo://CDS.VizieR/J/ApJ/806/95
- Title:
- A search for ultra-compact HVC counterparts
- Short Name:
- J/ApJ/806/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report five Local Volume dwarf galaxies (two of which are presented here for the first time) uncovered during a comprehensive archival search for optical counterparts to ultra-compact high-velocity clouds (UCHVCs). The UCHVC population of HI clouds are thought to be candidate gas-rich, low-mass halos at the edge of the Local Group and beyond, but no comprehensive search for stellar counterparts to these systems has been presented. Careful visual inspection of all publicly available optical and ultraviolet imaging at the position of the UCHVCs revealed six blue, diffuse counterparts with a morphology consistent with a faint dwarf galaxy beyond the Local Group. Optical spectroscopy of all six candidate dwarf counterparts show that five have an H{alpha}-derived velocity consistent with the coincident HI cloud, confirming their association; the sixth diffuse counterpart is likely a background object. The size and luminosity of the UCHVC dwarfs is consistent with other known Local Volume dwarf irregular galaxies. The gas fraction (M_HI_/M_star_) of the five dwarfs are generally consistent with that of dwarf irregular galaxies in the Local Volume, although ALFALFA-Dw1 (associated with ALFALFA UCHVC HVC274.68+74.70-123) has a very high M_HI_/M_star_~40. Despite the heterogeneous nature of our search, we demonstrate that the current dwarf companions to UCHVCs are at the edge of detectability due to their low surface brightness, and that deeper searches are likely to find more stellar systems. If more sensitive searches do not reveal further stellar counterparts to UCHVCs, then the dearth of such systems around the Local Group may be in conflict with {Lambda}CDM simulations.
- ID:
- ivo://CDS.VizieR/J/ApJS/244/7
- Title:
- ATCA HI absorption survey in Magellanic clouds. I.
- Short Name:
- J/ApJS/244/7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first results from the Small Magellanic Cloud portion of a new Australia Telescope Compact Array HI absorption survey of both of the Magellanic Clouds, comprising over 800hr of observations. Our new HI absorption line data allow us to measure the temperature and fraction of cold neutral gas in a low-metallicity environment. We observed 22 separate fields, targeting a total of 55 continuum sources, against 37 of which we detected HI absorption; from this we measure a column-density-weighted mean average spin temperature of <Ts>=150K. Splitting the spectra into individual absorption line features, we estimate the temperatures of different gas components and find an average cold gas temperature of ~30K for this sample, lower than the average of ~40K in the Milky Way. The HI appears to be evenly distributed throughout the SMC, and we detect absorption in 67% of the lines of sight in our sample, including some outside the main body of the galaxy (N_HI_>2x10^21^cm^-2^). The optical depth and temperature of the cold neutral atomic gas show no strong trend with location spatially or in velocity. Despite the low-metallicity environment, we find an average cold gas fraction of ~20%, not dissimilar from that of the Milky Way.
