Serendipitous Catch of a Giant Jellyfish: an Ionized Nebula around 3C 275.1 with 170 kpc Long Tails

TL;DR

This paper reports the discovery of an enormous ionized nebula with 170 kpc long tails around quasar 3C 275.1, revealing complex interactions possibly involving ram pressure stripping, tidal forces, or AGN outflows.

Contribution

It presents the first detailed analysis of a giant, elongated ionized nebula around a quasar, highlighting unusual features not fully explained by existing models.

Findings

Nebula extends over 100 kpc with non-flattening rotation curve.

Tails are longer and more ionized than typical jellyfish galaxy tails.

Additional ionization sources beyond the quasar are required to explain the gas state.

Abstract

3C 275.1 is a blue quasar at $z=0.55522$, hosting powerful outflows and residing in a complex environment. We present a serendipitously detected giant nebula surrounding 3C 275.1, which shows morphological features resembling those of objects known as "jellyfish galaxy", with extremely long tails of ionized gas extending to 170 kpc in projection. We analyze its optical spectra taken by the MUSE on the VLT. The brighter part of this giant nebula exceeds 100 kpc, whose rotation curve does not flatten out, is very different from those of normal spiral galaxies. This system shares some characteristics common to those formed via ram pressure stripping (RPS), yet its long narrow tails and higher ionization are unusual compared to known tails in jellyfish galaxies, not fully consistent with a simple RPS scenario. Our photoionization simulation and the inferred short recombination timescale both suggest that besides the quasar 3C 275.1, an extra source of ionization is necessary to keep the gas ionized at such distance from the nucleus, which could be related to RPS, tidal interaction or AGN outflow, providing new evidence of active dynamical interaction of a galaxy with the intracluster medium.