FGC 1287 and its enigmatic 250 kpc long HI tail in the outskirts of Abell 1367

Abstract

We present H i and radio continuum, narrow–band Hα imaging, IFU spectroscopy, and X–ray observations of the FGC 1287 triplet projected ∼ 1.8 Mpc west of the galaxy cluster Abell 1367. One triplet member, FGC 1287, displays an exceptionally long, 250 kpc H i tail and an unperturbed stellar disk which are the typical signatures of ram pressure stripping (RPS). To generate detectable RPS signatures the presence of an Intra–cluster medium ICM/intra–group medium IGM with sufficient density to produce RPS at a realistic velocity relative to the ICM/IGM is a prerequisite. However, XMM–Newton observations were not able to detect X–ray emission from the triplet, implying that if a hot ICM/IGM is present, its density, ne, is less than 2.6× 10−5 cm−3. Higher–resolution VLA H i data presented here show FGC 1287’s H i disk is truncated and significantly warped whereas the H i tail is clumpy. TNG Hα imaging identified three star forming clumps projected within 20 kpc of FGC 1287’s disk, with VIMOS–IFU data confirming two of these are counterparts to H i clumps in the tail. The triplet’s H i kinematics, together with Hα and radio continuum imaging suggests an interaction may have enhanced star formation in FGC 1287’s disk, but cannot readily account for the origin of the long H i tail. We consider several scenarios which might reconcile RPS with the non–detection of ICM/IGM X–ray emission but none of these unambiguously explains the origin of the long H i tail.

Young, Blue, and Isolated Stellar Systems in the Virgo Cluster. II. A New Class of Stellar System

“…As a closing remark for this discussion we also note that despite the apparently simple requirement for ram pressure stripping (i.e., sufficient ram pressure to overcome the gravitational attraction of the gas disk) and extensive efforts to simulate this process in increasing detail, there remain systems that are challenging to explain. In particular, the recent discovery of an enormous (apparently) ram-pressure-stripped H I tail in a system outside of a cluster, where no significant intergalatic medium could be detected (Scott et al 2022), poses difficult questions regarding its origin and could even suggest that some BC-like objects might exist outside of clusters.…”

Dust in Clusters of Galaxies

“…Long HI tails > ∼ 100 kpc are also seen in the galaxies NGC 4388 [192] and NGC 4424 in the Virgo cluster; a lower limit of the tail length is because of a limited flux sensitivity [193]. An example of an exceptionally long HI tail in the Virgo-500 kpc driven by ram pressure has been demonstrated by Koopmann et al [194], and another of length 250 kpc has been found recently in the outskirts of the Abell 1367 cluster [195]. In general, a 100 kpc length of ram pressure-driven tail does not seem to be an overestimate, both for Hα and HI tails [98,189,196].…”

Discovery of a Large-scale H i Plume in the NGC 7194 Group

“…Thus it is likely that a considerable fraction of present-day cluster galaxies have experienced morphological transformation in galaxy groups, which allow more violent mergers between galaxies (preprocessing; Zabludoff & Mulchaey 1998;De Lucia et al 2012). Recent observational and theoretical studies emphasize the importance of galaxy groups as the environments for preprocessing (Cortese et al 2006;Just et al 2019;Kleiner et al 2021;Scott et al 2022).…”