HIPASS High-Velocity Clouds: Properties of the Compact and Extended Populations

By M. Putman, V. De Heij, L. Staveley-Smith, R. Braun, Kenneth C. Freeman, B. Gibson, W. B. Burton, David G. Barnes, G. Banks, R. Bhathal and 22 more. 2001

159 citations recorded by the source corpus.

A catalog of southern anomalous-velocity H I clouds at decl. < +2° is presented. This catalog is based on data from the H I Parkes All-Sky Survey (HIPASS) reprocessed with the MINMED5 procedure and searched with a new high-velocity cloud-finding algorithm. The improved sensitivity (5 σ: ΔTB = 0.04 K), resolution (15.′5), and velocity range (-500 km s-1 < VLSR < +500 km s-1) of the HIPASS data result in a substantial increase in the number of individual clouds (1956, as well as 41 galaxies) compared with what was known from earlier southern data. The method of cataloging the anomalous-velocity objects is described, and a catalog of key cloud parameters, including velocity, angular size, peak column density, total flux, position angle, and degree of isolation, is presented. The data are characterized into several classes of anomalous-velocity H I emission. Most high-velocity emission features are HVCs and have a filamentary morphology and are loosely organized into large complexes extending over tens of degrees. In addition, 179 compact and isolated anomalous-velocity objects, CHVCs, are identified based on their size and degree of isolation. Of the CHVCs originally classified by Braun & Burton, 25% are reclassified based on the HIPASS data. The properties of all the high-velocity emission features and only the CHVCs are investigated, and distinct similarities and differences are found. Both populations have typical H I masses of ∼4.5D2kpc M⊙ and have similar slopes for their column density and flux distributions. On the other hand, the CHVCs appear to be clustered and the population can be broken up into three spatially distinct groups, while the entire population of clouds is more uniformly distributed with a significant percentage aligned with the Magellanic Stream. The median velocities are VGSR = -38 km s-1 for the CHVCs and -30 km s-1 for all the anomalous-velocity clouds. Based on the catalog sizes, high-velocity features cover 19% of the southern sky, and CHVCs cover 1%.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

The Parkes HI survey of the Magellanic System (2004, background): “◦3) at vLSR = 110 km s−1 that were classified as compact high-velocity clouds (HVCs) by Putman et al. (2002).”
On the Continuing Formation of the Andromeda Galaxy: Detection of H I Clouds in the M31 Halo (2003, background): “The high negative velocities of some clouds (e.g., −515 km s−1) are also more extreme than any seen previously in Galactic HVC surveys (v > −466 km s−1) (Putman et al. 2002; de Heij et al. 2002b).”
The Magellanic Stream, High-Velocity Clouds, and the Sculptor Group (2002, background): “For more details on the cataloging see Putman et al. (2002) and de Heij et al. (2002).”
GASS: THE PARKES GALACTIC ALL-SKY SURVEY. I. SURVEY DESCRIPTION, GOALS, AND INITIAL DATA RELEASE (2009, methodology): “There have been extensive searches for high velocity gas (see Wakker & van Woerden 1997 for a review, or recent surveys by Putman et al. 2002 and Lockman et al. 2002b).”
Gaseous Galaxy Halos (2012, methodology): “…clouds in these catalogs ranges from ∼ 600 over the entire sky in the lowest resolution surveys (35′ beam; Wakker & van Woerden, 1991), to 2000 in just the southern sky (15.5′ beam; Putman et al., 2002), to ∼ 700 clouds smaller than 20′ in 7600 deg2 of the sky (4′ beam; Saul et al., 2012).”
Highly Ionized High-Velocity Gas in the Vicinity of the Galaxy (2002, background): “…andMrk 205 The class of high-velocity H i clouds classified as ‘‘ compact and isolated ’’ based on their morphological properties is a difficult group of clouds to study in absorption at ultraviolet wavelengths since their sky covering factor is low (d1% for those cataloged by Putman et al. 2002).”
The HIPASS catalogue - I. Data presentation (2004, methodology): “First, all candidates with vgsr < 300 kms −1 are removed to avoid Galactic Hi emission and HVCs (HVCs in Hipass are catalogued separately, see Putman et al. 2002).”
Misaligned angular momentum in hydrodynamic cosmological simulations: warps, outer discs and thick discs (2010, methodology): “(4) We assume in this estimate that the clouds in our simulation are analogous to compact high-velocity clouds (CHVCs) observed in the halo of the Milky Way and other nearby systems (e.g. Putman et al. 2002; Westmeier, Brüns & Kerp 2005; Pisano et al. 2007).”
A Catalog of Neighboring Galaxies (2004, unknown): “68 11 10 Putman et al. 2002; ph: Parodi et al. 2002 07 34 11.3 ......”