NGC 4522 is a Virgo spiral that is currently undergoing active ram pressure stripping. In previous single-dish observations, 12CO emission was detected outside of the stellar disk, some of which coincides with the extraplanar H i gas and H patches. The extraplanar gas identified in multi-wavelength data makes this galaxy an ideal case to study the impact of pressure due to the cluster medium on the interstellar gas of various phases. In this Letter, we present the high-resolution 12CO(1-0) and 13CO(1-0) data of NGC 4522 obtained using the Atacama Large Millimeter/submillimeter Array (ALMA). In particular, we report here the extraplanar 13CO detection that has never before been seen in ram-pressure-stripped galaxies. As the main donor of 13C in the interstellar medium is evolved stars, the presence of 13CO strongly suggests that heavy elements likely originated from the galactic disk, not from the newly formed stars in situ. Even though it is still inconclusive whether it is stripped in atomic form or as molecules, this study provides evidence for the ram pressure stripping of heavy elements, which can chemically enrich the halo gas, and potentially the intracluster medium, in the case that they are pushed strongly enough to escape the galaxy.
Bibliographical noteFunding Information:
This Letter makes use of the following ALMA data: ADS/ JAO.ALMA#2015.1.01341.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/ NRAO and NAOJ. Support for this work was provided by the National Research Foundation of Korea to the Center for Galaxy Evolution Research (No. 2010-0027910) and NRF grant No. 2015R1D1A1A01060516 and 2018R1D1A1B07048314. We acknowledge the usage of the HyperLeda database (http:// leda.univ-lyon1.fr/). We acknowledge Bon-Chul Koo, O. Ivy Wong, and Susanne Aalto for useful comments and discussion, and the Korea ARC team for their help with the data.
© 2018. The American Astronomical Society. All rights reserved..
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science