AGC 226178 and NGVS 3543: Two Deceptive Dwarfs toward Virgo

This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.The two sources AGC 226178 and NGVS 3543, an extremely faint, clumpy, blue stellar system and a low surface brightness dwarf spheroidal, are adjacent systems in the direction of the Virgo cluster. Both have been studied in detail previously, with it being suggested that they are unrelated normal dwarf galaxies or that NGVS 3543 recently lost its gas through ram pressure stripping and AGC 226178 formed from this stripped gas. However, with Hubble Space Telescope Advanced Camera for Surveys imaging, we demonstrate that the stellar population of NGVS 3543 is inconsistent with being at the distance of the Virgo cluster and that it is likely a foreground object at approximately 10 Mpc, whereas the stellar population of AGC 226178 is consistent with it being a very young (10–100 Myr) object in the Virgo cluster. Through a reanalysis of the original ALFALFA H i detection, we show that AGC 226178 likely formed from gas stripped from the nearby dwarf galaxy VCC 2034, a hypothesis strengthened by the high metallicity measured with MUSE VLT observations. However, it is unclear whether ram pressure or a tidal interaction is responsible for stripping the gas. Object AGC 226178 is one of at least five similar objects now known toward Virgo. These objects are all young and unlikely to remain visible for over ∼500 Myr, suggesting that they are continually produced in the cluster. © 2022. The Author(s). Published by the American Astronomical Society.This work is based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. These observations are associated with program No. HST-GO-15183. Support for program No. HST-GO-15183 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. It is also based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO program 0101.B-0376A. This work used archival data from the Karl G. Jansky Very Large Array. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The data were observed as part of program 13A-028 (PI: J. Cannon). The work used images from the Dark Energy Camera Legacy Survey (DECaLS; proposal ID 2014B-0404; PIs: David Schlegel and Arjun Dey). Full acknowledgment at https://www.legacysurvey.org/acknowledgment/. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society, and the Higher Education Funding Council for England. The SDSS website is http://www.sdss.org/. D.J.S. acknowledges support from NSF grants AST-1821967 and 1813708. M.B. acknowledges financial support of this research from INAF Main Stream grant 1.05.01.86.28 assigned to the program The Smallest Scale of the Hierarchy (SSH). K.S. acknowledges support from the Natural Sciences and Engineering Research Council of Canada (NSERC). B.M.P. is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-2001663. E.A.K.A. is supported by the WISE research program, which is financed by the Dutch Research Council (NWO). G.B. acknowledges financial support through grant (AEI/FEDER, UE) AYA2017-89076-P, as well as by the Ministerio de Ciencia, Innovación y Universidades through the state budget and by the Consejería de Economía, Industria, Comercio y Conocimiento of the Canary Islands Autonomous Community through the regional budget. J.S. acknowledges support from the Packard Foundation. M.P.H. acknowledges support from NSF/AST-1714828 and grants from the Brinson Foundation. J.M.C., J.F., and J.L.I. are supported by NST/AST 2009894. R.R.M. gratefully acknowledges support from project ANID PIA/BASAL FB210003. Research by D.C. is supported by NSF grant AST-1814208. AK acknowledges financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award to the Instituto de Astrofísica de Andalucía (SEV-2017-0709).Peer reviewe