An H I survey of high-velocity clouds in nearby disk galaxies

Schulman, Eric; Bregman, Joel N.; Roberts, M. S.

doi:10.1086/173797

Cited by 38 publications

(31 citation statements)

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“…While this difference might not be significant it shows that if anything, NGC 5668 has a larger HI content than the average of the spiral galaxy population of its type. Schulman et al (1994) found in NGC 5668 a weak bar or oval inner structure of 12 ′′ size visible in both optical and near-infrared images. Athanassoula (1994) found that in spiral galaxies having oval structures or weak bars star formation can occur prolifically along them, especially in the central parts and at the two ends of the bar region.…”

Section: Bar Formation In Ngc 5668mentioning

confidence: 82%

Integral Field Spectroscopy and Multi-Wavelength Imaging of the Nearby Spiral Galaxy NGC 5668: An Unusual Flattening in Metallicity Gradient

Marino

Paz

Castillo-Morales

et al. 2012

ApJ

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We present the analysis of the full bi-dimensional optical spectral cube of the nearby spiral galaxy NGC 5668, observed with the PPAK IFU at the Calar Alto observatory 3.5m telescope. We make use of broad-band imaging to provide further constraints on the evolutionary history of the galaxy. This dataset will allow us to improve our understanding of the mechanisms that drive the evolution of disks. We investigated the properties of 62 H II regions and concentric rings in NGC 5668 and derived maps in ionized-gas attenuation and chemical (oxygen) abundances. We find that, while inwards of r ∼ 36 ′′ ∼ 4.4kpc ∼ 0.36 ( D25 2 ) the derived O/H ratio follows the radial gradient typical of spiral galaxies, the abundance gradient beyond r∼ 36 ′′ flattens out. The analysis of the multi-wavelength surface brightness profiles of NGC 5668 is performed by fitting these profiles with those predicted by chemo-spectrophotometric evolutionary models of galaxy disks. From this, we infer a spin and circular velocity of λ=0.053 and v c =167 km s −1 , respectively. The metallicity gradient and rotation curve predicted by this best-fitting galaxy model nicely match the values derived from the IFU observations, especially within r ∼ 36 ′′ . The same is true for the colors despite of some small offsets and a reddening in the bluest colors beyond that radius. On the other hand, deviations of some of these properties in the outer disk indicate that a secondary mechanism, possibly gas transfer induced by the presence of a young bar, must have played a role in shaping the recent chemical and star formation histories of NGC 5668. 2 They adopted a distance of 30 Mpc consistent with a cosmology with H 0 = 50 km s −1 Mpc −1 .

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Section: Bar Formation In Ngc 5668mentioning

confidence: 82%

Integral Field Spectroscopy and Multi-Wavelength Imaging of the Nearby Spiral Galaxy NGC 5668: An Unusual Flattening in Metallicity Gradient

Marino

Paz

Castillo-Morales

et al. 2012

ApJ

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“…Additionally, we note that there is excess H I 21-cm emission in the extreme blue wing of the Arecibo H I 21-cm profile (∼ −80 km s −1 ) that cannot be explained by a simple rotating disc model. Excess emission in the wings have been explained by high velocity clouds as seen in our Galaxy or a warped H I disc (Schulman et al 1994). Deeper H I 21-cm emission observations are required to derive the distribution and kinematics of H I gas in UGC 00439, and distinguish between these scenarios.…”

Section: Structure and Kinematics Of The H I Gas Associated With Ugc mentioning

confidence: 98%

Mapping kiloparsec-scale structures in the extended H i disc of the galaxy UGC 000439 by H i 21-cm absorption

Dutta¹,

Gupta²,

Srianand³

et al. 2016

Mon. Not. R. Astron. Soc.

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We study the properties of H I gas in the outer regions (∼2r 25 ) of a spiral galaxy, UGC 00439 (z = 0.01769), using H I 21-cm absorption towards different components of an extended background radio source, J0041−0043 (z = 1.679). The radio source exhibits a compact core coincident with the optical quasar and two lobes separated by ∼7 kpc, all at an impact parameter ∼25 kpc. The H I 21-cm absorption detected towards the southern lobe is found to extend over ∼2 kpc 2 . The absorbing gas shows sub-kpc-scale structures with the line-of-sight velocities dominated by turbulent motions. Much larger optical depth variations over 4-7 kpc-scale are revealed by the non-detection of H I 21-cm absorption towards the radio core and the northern lobe, and the detection of Na I and Ca II absorption towards the quasar. This could reflect a patchy distribution of cold gas in the extended H I disc. We also detect H I 21-cm emission from UGC 00439 and two other galaxies within ∼150 kpc to it, that probably form an interacting group. However, no H I 21-cm emission from the absorbing gas is detected. Assuming a linear extent of ∼4 kpc, as required to cover both the core and the southern lobe, we constrain the spin temperature 300 K for the absorbing gas. The kinematics of the gas and the lack of signatures of any ongoing in situ star formation are consistent with the absorbing gas being at the kinematical minor axis and corotating with the galaxy. Deeper H I 21-cm observations would help to map in greater detail both the large-and small-scale structures in the H I gas associated with UGC 00439.

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“…Early evidence of anomalous H I appeared in the face-on galaxies M 101 (van der Hulst & Sancisi 1988;Kamphuis et al 1991), NGC 628 (Kamphuis & Briggs 1992), and NGC 6946 (Kamphuis & Sancisi 1993), with detections of a few clouds of mass M HI > 10 7 M ⊙ . Integrated H I profiles from a sample of 14 face-on galaxies show evidence for high-velocity gas in 10 of the systems (Schulman et al 1994). More recent observations of inclined galaxies have uncovered anomalous H I gas in every target imaged with sufficient depth.…”

Section: Introductionmentioning

confidence: 95%

High-Velocity Clouds in the Nearby Spiral Galaxy M 83

Miller

Bregman

Wakker

2009

ApJ

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We present deep H I 21-cm and optical observations of the face-on spiral galaxy M 83 obtained as part of a project to search for high-velocity clouds (HVCs) in nearby galaxies. Anomalous-velocity neutral gas is detected toward M 83, with 5.6×10 7 M ⊙ of H I contained in a disk rotating 40-50 km s −1 more slowly in projection than the bulk of the gas. We interpret this as a vertically extended thick disk of neutral material, containing 5.5% of the total H I within the central 8 kpc. Using an automated source detection algorithm to search for small-scale H I emission features, we find eight distinct, anomalous-velocity H I clouds with masses ranging from 7×10 5 to 1.5×10 7 M ⊙ and velocities differing by up to 200 km s −1 compared to the H I disk. Large on-disk structures are coincident with the optical spiral arms, while unresolved off-disk clouds contain no diffuse optical emission down to a limit of 27 r ′ mag per square arcsec. The diversity of the thick H I disk and larger clouds suggests the influence of multiple formation mechanisms, with a galactic fountain responsible for the slowlyrotating disk and on-disk discrete clouds, and tidal effects responsible for off-disk cloud production. The mass and kinetic energy of the H I clouds are consistent with the mass exchange rate predicted by the galactic fountain model. If the HVC population in M 83 is similar to that in our own Galaxy, then the Galactic HVCs must be distributed within a radius of less than 25 kpc.

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An H I survey of high-velocity clouds in nearby disk galaxies

Cited by 38 publications

References 0 publications

Integral Field Spectroscopy and Multi-Wavelength Imaging of the Nearby Spiral Galaxy NGC 5668: An Unusual Flattening in Metallicity Gradient

Integral Field Spectroscopy and Multi-Wavelength Imaging of the Nearby Spiral Galaxy NGC 5668: An Unusual Flattening in Metallicity Gradient

Mapping kiloparsec-scale structures in the extended H i disc of the galaxy UGC 000439 by H i 21-cm absorption

High-Velocity Clouds in the Nearby Spiral Galaxy M 83

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