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Herschel Spectroscopy of the Taffy Galaxies (UGC 12914/12915 = VV 254): Enhanced [C ii] Emission in the Collisionally Formed Bridge.
- Source :
- Astrophysical Journal; 3/10/2018, Vol. 855 Issue 2, p1-1, 1p
- Publication Year :
- 2018
-
Abstract
- Using the PACS and SPIRE spectrometers on board Herschel, we obtained observations of the Taffy galaxies (UGC 12914/12915) and bridge. The Taffy system is believed to be the result of a face-on collision between two gas-rich galaxies, in which the stellar disks passed through each other, but the gas was dispersed into a massive H i and molecular bridge between them. Emission is detected and mapped in both galaxies and the bridge in the [C ii]157.7 μm and [O i]63.2 μm fine-structure lines. Additionally, SPIRE FTS spectroscopy detects the [C i] and [C i] neutral carbon lines, and weakly detects high-J CO transitions in the bridge. These results indicate that the bridge is composed of a warm multi-phase medium consistent with shock and turbulent heating. Despite low star formation rates in the bridge, the [C ii] emission appears to be enhanced, reaching [C ii]/FIR ratios of 3.3% in parts of the bridge. Both the [C ii] and [O i] lines show broad intrinsic multi-component profiles, similar to those seen in previous CO (1–0) and H i observations. The [C ii] emission shares similar line profiles with both the double-peaked H i profiles and shares a high-velocity component with single-peaked CO profiles in the bridge, suggesting that the [C ii] emission originates in both the neutral and molecular phases. We show that it is feasible that a combination of turbulently heated H<subscript>2</subscript> and high column-density H i, resulting from the galaxy collision, is responsible for the enhanced [C ii] emission. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0004637X
- Volume :
- 855
- Issue :
- 2
- Database :
- Complementary Index
- Journal :
- Astrophysical Journal
- Publication Type :
- Academic Journal
- Accession number :
- 128534637
- Full Text :
- https://doi.org/10.3847/1538-4357/aaac2c