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arXiv · 1506.03333

First Detection of HCO$^+$ Absorption in the Magellanic System

Claire E. Murray·Snežana Stanimirović·N. M. McClure-Griffiths·M. E. Putman·H. S. Liszt·Tony Wong·P. Richter·J. R. Dawson·John M. Dickey·Robert R. Lindner·Brian L. Babler·J. R. Allison
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Abstract

We present the first detection of HCO$^+$ absorption in the Magellanic System. Using the Australia Telescope Compact Array (ATCA), we observed 9 extragalactic radio continuum sources behind the Magellanic System and detected HCO$^+$ absorption towards one source located behind the leading edge of the Magellanic Bridge. The detection is located at LSR velocity of $v=214.0 \pm 0.4\rm\,km\,s^{-1}$, with a full width at half maximum of $\Delta v=4.5\pm 1.0\rm\,km\,s^{-1}$ and optical depth of $\tau(\rm HCO^+)=0.10\pm 0.02$. Although there is abundant neutral hydrogen (HI) surrounding the sightline in position-velocity space, at the exact location of the absorber the HI column density is low, $<10^{20}\rm\,cm^{-2}$, and there is little evidence for dust or CO emission from Planck observations. While the origin and survival of molecules in such a diffuse environment remains unclear, dynamical events such as HI flows and cloud collisions in this interacting system likely play an important role.

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Claire E. Murray, Snežana Stanimirović, N. M. McClure-Griffiths, M. E. Putman, H. S. Liszt, Tony Wong, P. Richter, J. R. Dawson, John M. Dickey, Robert R. Lindner, Brian L. Babler, J. R. Allison. 2015-06-10. First Detection of HCO$^+$ Absorption in the Magellanic System. https://doi.org/10.1088/0004-637x/808/1/41

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