H [CSC]i[/CSC]–bright Galaxies in the Southern Zone of Avoidance

Henning, P. A.; Staveley‐Smith, L.; Ekers, R. D.; Green, Anne; Haynes, R. F.; Juraszek, S.; Kesteven, Michael; Koribalski, B. S.; Kraan-Korteweg, R. C.; Price, R. M.; Sadler, E. M.; Schröder, A. C.

doi:10.1086/301374

Cited by 60 publications

(100 citation statements)

References 27 publications

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“…HIPASS J0731-69; Ryder et al 2001). In addition, Parkes HI multibeam surveys of the Zone of Avoidance (ZOA) have catalogued more than 1000 galaxies (Staveley-Smith et al 1998;Henning et al 2000;Juraszek et al 2000;Donley et al 2005). Compact and extended populations of Galactic high-velocity clouds (HVCs) were catalogued by Putman et al (2002).…”

Section: Hipass Source Findingmentioning

confidence: 99%

Overview on Spectral Line Source Finding and Visualisation

Koribalski¹

2012

Publ. – Astron. Soc. Aust

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Here I will outline successes and challenges for finding spectral line sources in large data cubes that are dominated by noise. This is a 3D challenge as the sources we wish to catalog are spread over several spatial pixels and spectral channels. While 2D searches can be applied, e.g. channel by channel, optimal searches take into account the 3-dimensional nature of the sources. In this overview I will focus on HI 21-cm spectral line source detection in extragalactic surveys, in particular HIPASS, the HI Parkes All-Sky Survey and WALLABY, the ASKAP HI All-Sky Survey. I use the original HIPASS data to highlight the diversity of spectral signatures of galaxies and gaseous clouds, both in emission and absorption. Among others, I report the discovery of a 680 km s À1 wide HI absorption trough in the megamaser galaxy NGC 5793. Issues such as source confusion and baseline ripples, typically encountered in single-dish HI surveys, are much reduced in interferometric HI surveys. Several large HI emission and absorption surveys are planned for the Australian Square Kilometre Array Pathfinder (ASKAP): here we focus on WALLABY, the 21-cm survey of the sky (d , þ308; z , 0.26) which will take about one year of observing time with ASKAP. Novel phased array feeds ('radio cameras') will provide 30 deg 2 instantaneous field-of-view. WALLABY is expected to detect more than 500 000 galaxies, unveil their large-scale structures and cosmological parameters, detect their extended, low-surface-brightness disks as well as gas streams and filaments between galaxies. It is a precursor for future HI surveys with SKA Phase I and II, exploring galaxy formation and evolution. The compilation of highly reliable and complete source catalogs will require sophisticated source-finding algorithms as well as accurate source parametrisation.

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Section: Hipass Source Findingmentioning

confidence: 99%

Overview on Spectral Line Source Finding and Visualisation

Koribalski¹

2012

Publ. – Astron. Soc. Aust

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“…The HI searches for galaxies in the optical Zone of Avoidance carried out by, among others, Henning et al (1998) in the north, and by Henning et al (2000) and Juraszek (2000) in the south, were confined to |b| < 5…”

Section: Systematic Consequences Of Obscuration By H  In the Milky Waymentioning

confidence: 99%

An all–sky study of compact, isolated high–velocity clouds

Heij

Braun²,

Burton

2002

A&A

105

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Abstract.We combine the catalog of compact high-velocity H  clouds extracted by de Heij et al. (2002) from the Leiden/Dwingeloo Survey in the northern hemisphere with the catalog extracted by from the Parkes HIPASS data in the southern hemisphere, and analyze the all-sky properties of the ensemble. Compact high-velocity clouds are a subclass of the general high-velocity cloud phenomenon which are isolated in position and velocity from the extended high-velocity Complexes and Streams down to column densities below 1.5 × 10 18 cm −2 . Objects satisfying these criteria for isolation are found to have a median angular size of less than one degree. We discuss selection effects relevant to the two surveys; in particular the crucial role played by obscuration due to Galactic H . Five principal observables are defined for the CHVC population: (1) the spatial deployment of the objects on the sky, (2) the kinematic distribution, (3) the number distribution of observed H  column densities, (4) the number distribution of angular sizes, and (5) the number distribution of H  linewidth. Two classes of models are considered to reproduce the observed properties. The agreement of models with the data is judged by extracting these same observables from simulations, in a manner consistent with the sensitivities of the observations and explicitly taking account of Galactic obscuration. We show that models in which the CHVCs are the H  counterparts of dark-matter halos evolving in the Local Group potential provide a good match to the observables. The best-fitting populations have a maximum HI mass of 10 7 M , a power-law slope of the HI mass distribution in the range −1.7 to −1.8, and a Gaussian dispersion for their spatial distributions of between 150 and 200 kpc centered on both the Milky Way and M 31. Given its greater mean distance, only a small fraction of the M 31 sub-population is predicted to have been detected in present surveys. An empirical model for an extended Galactic halo distribution for the CHVCs is also considered. While reproducing some aspects of the population, this class of models does not account for some key systematic features of the population.

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“…Sorar (1994) and Spitzak & Schneider (1998) found optical counterparts to all their H i detections, and Rosenberg & Schneider (2000) find that most of their detections have an optical counterpart, although some have very low surface brightness. In addition, blind H i surveys have been conducted through the optically obscured zone of avoidance (ZOA; Henning et al 2000). Such surveys are important in determining the local large-scale structure, which is impossible to do optically in this region (Juraszek et al 2000).…”

Section: Introductionmentioning

confidence: 99%

A Catalog of H [CSC]i[/CSC]–selected Galaxies from the South Celestial Cap Region of Sky

Kilborn

Webster

Staveley‐Smith

et al. 2002

The Astronomical Journal

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The first deep catalog of the H i Parkes All Sky Survey (HIPASS) is presented, covering the south celestial cap (SCC) region. The SCC area is $2400 deg 2 and covers < À62. The average rms noise for the survey is 13 mJy beam À1 . Five hundred thirty-six galaxies have been cataloged according to their neutral hydrogen content, including 114 galaxies that have no previous cataloged optical counterpart. This is the largest sample of galaxies from a blind H i survey to date. Most galaxies in optically unobscured regions of sky have a visible optical counterpart; however, there is a small population of low-velocity H i clouds without visible optical counterparts whose origins and significance are unclear. The rms accuracy of the HIPASS positions is found to be 1<9. The H i mass range of galaxies detected is from $10 6 to $10 11 M . There are a large number of latetype spiral galaxies in the SCC sample (66%), compared with 30% for optically selected galaxies from the same region in the NASA Extragalactic Database. The average ratio of H i mass to B luminosity of the sample increases according to optical type, from 1.8 M /L for early types to 3.2 M /L for late-type galaxies. The H i-detected galaxies tend to follow the large-scale structure traced by galaxies found in optical surveys. From the number of galaxies detected in this region of sky, we predict the full HIPASS catalog will contain $5000 galaxies, to a peak flux density limit of $39 mJy (3 ), although this may be a conservative estimate as two large voids are present in the region. The H i mass function for this catalog is presented in a subsequent paper.

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H [CSC]i[/CSC]–bright Galaxies in the Southern Zone of Avoidance

Cited by 60 publications

References 27 publications

Overview on Spectral Line Source Finding and Visualisation

Overview on Spectral Line Source Finding and Visualisation

An all–sky study of compact, isolated high–velocity clouds

A Catalog of H [CSC]i[/CSC]–selected Galaxies from the South Celestial Cap Region of Sky

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