UNDER PRESSURE: STAR CLUSTERS AND THE NEUTRAL HYDROGEN MEDIUM OF TIDAL TAILS

Journal Article · Fri May 10 04:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/768/2/194· OSTI ID:22126699

Mullan, B.; Charlton, J. C.; Gronwall, C. ^[1]; Kepley, A. A. ^[2]; Maybhate, A. ^[3]; English, J. ^[4]; Knierman, K. ^[5]; Hibbard, J. E. ^[6]; Bastian, N. ^[7]; Durrell, P. R. ^[8]; Elmegreen, D. ^[9]

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1. Department of Astronomy and Astrophysics, Pennsylvania State University, 525 Davey Lab, University Park, PA 16803 (United States)
2. Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325 (United States)
3. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
4. Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba R3T 2N2 (Canada)
5. Arizona State University, School of Earth and Space Exploration, Bateman Physical Sciences Center F-wing Room 686, Tempe, AZ 85287-1404 (United States)
6. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States)
7. Excellence Cluster Universe, Technische Universitaet Muenchen, Boltzmannstrasse 2, D-85748 Garching (Germany)
8. Department of Physics and Astronomy, Youngstown State University, Youngstown, OH 44555 (United States)
9. Department of Physics and Astronomy, Vassar College, Box 745, Poughkeepsie, NY 12604 (United States)

Using archival data from ATCA, WHISP, and the Very Large Array, we have analyzed the H I emission of 22 tidal tail regions of the Mullan et al. sample of pairwise interacting galaxies. We have measured the column densities, line-of-sight velocity dispersions, and kinetic energy densities on {approx}kpc scales. We also constructed a tracer of the line-of-sight velocity gradient over {approx}10 kpc scales. We compared the distributions of these properties between regions that do and do not contain massive star cluster candidates (M{sub V} < -8.5; {approx}10{sup 4}-10{sup 6} M{sub Sun} as observed in Hubble Space Telescope WFPC2 VI data). In agreement with Maybhate et al., we find that a local, {approx}kpc-scale column density of log N{sub H{sub I}} {approx}> 20.6 cm{sup -2} is frequently required for detecting clustered star formation. This H I gas also tends to be turbulent, with line-of-sight velocity dispersions {sigma}{sub los} Almost-Equal-To 10-75 km s{sup -1}, implying high kinetic energy densities (log {Sigma}{sub KE} > 46 erg pc{sup -2}). Thus, high H I densities and pressures, partly determined by the tail dynamical age and other interaction characteristics, are connected to large-scale cluster formation in tidal tails overall. Last, we find that the high mechanical energy densities of the gas are likely not generally due to feedback from star formation. Rather, these properties are more likely to be a cause of star formation than a result.

• OSTI ID: 22126699
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 768; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DENSITY
DISPERSIONS
DISTRIBUTION
EMISSION
ENERGY DENSITY
FEEDBACK
GALAXIES
GAMMA-GAMMA LOGGING
HYDROGEN
INTERACTIONS
KINETIC ENERGY
SPACE
STAR CLUSTERS
STARS
TELESCOPES