Odd radio circles (ORCs) are a newly discovered class of extended faint radiosources of unknown origin. We report the first detection of diffuse X-ray gasat the location of a low-redshift ORC (z=0.046) known as Cloverleaf ORC. Thisobservation was performed with the XMM-Newton X-ray telescope. The physicalextent of the diffuse X-ray emission corresponds to a region of approximately230 kpc by 160 kpc, lying perpendicular to the radio emission detected byASKAP. The X-ray spectrum shows characteristics of thermal multiphase gas withtemperatures of 1.10+/-0.08 keV and 0.22+/-0.01 keV and a central density of$(4.9\pm0.6)\times10^{-4}$ cm$^{-3}$, indicating that the Cloverleaf ORCresides in a low-mass galaxy group. Using X-ray observations, with hydrostaticequilibrium and isothermal assumptions, we measure the galaxy group to have agas mass and a total mass of $(7.7\pm 0.8) \times 10^{11}$ M$_{\rm sun}$ and$2.6\pm0.3\times10^{13}$~$M_{\rm sun}$ within the overdensity radius R$_{500}$.The presence of a high-velocity subgroup identified in optical data, theorientation of the brightest cluster galaxy, the disturbed morphologies ofgalaxies toward the east of the Cloverleaf ORC, and the irregular morphology ofthe X-ray emission suggest that this system is undergoing a galaxy groupmerger. The radio power of the ORC could be explained by the shockreacceleration of fossil cosmic rays generated by a previous episode of blackhole activity in the central active galactic nucleus.

Based on the integral field unit (IFU) data from Mapping Nearby Galaxies atApache Point Observatory (MaNGA) survey, we develop a new method to selectgalaxies with biconical ionized structures, building a sample of 142 edge-onbiconical ionized galaxies. We classify these 142 galaxies into 81 star-forminggalaxies, 31 composite galaxies, and 30 AGNs (consisting of 23 Seyferts and 7LI(N)ERs) according to the {\nii}-BPT diagram. The star-forming bicones havebar-like structures while AGN bicones display hourglass structures, andcomposite bicones exhibit transitional morphologies between them due to bothblack hole and star-formation activities. Star-forming bicones have intensestar-formation activities in their central regions, and the primary driver ofbiconical structures is the central star formation rate surface density. Thelack of difference in the strength of central black hole activities (traced bydust attenuation corrected {\oiii}$\lambda$5007 luminosity and Eddington ratio)between Seyfert bicones and their control samples can be naturally explained asthat the accretion disk and the galactic disk are not necessarily coplanar.Additionally, the biconical galaxies with central LI(N)ER-like line ratios areedge-on disk galaxies that show strong central dust attenuation. The radialgradients of {\ha} surface brightness follow the $r^{-2.35}$ relation, roughlyconsistent with $r^{-2}$ profile, which is expected in the case ofphotoionization by a central point-like source. These observations indicateobscured AGNs or AGN echoes as the primary drivers of biconical structures inLI(N)ERs.

Simulations and observations find long tails in jellyfish galaxies, which arecommonly thought to originate from ram-pressure stripped gas of theinterstellar medium (ISM) in the immediate galactic wake. While at largerdistances from the galaxy, they have been claimed to form in situ owing tothermal instability and fast radiative cooling of mixed ISM and intraclustermedium (ICM). In this paper, we use magneto-hydrodynamical windtunnelsimulations of a galaxy with the arepo code to study the origin of gas in thetails of jellyfish galaxies. To this end, we model the galaxy orbit in acluster by accounting for a time-varying galaxy velocity, ICM density andturbulent magnetic field. Tracking gas flows between the ISM, thecircumgalactic medium (CGM) and the ICM, we find contrary to popular opinionthat the majority of gas in the tail originated in the CGM. Prior to thecentral passage of the jellyfish galaxy in the cluster, the CGM is directlytransported to the clumpy jellyfish tail that has been shattered into smallcloudlets. After the central cluster passage, gas in the tail originates bothfrom the initial ISM and the CGM, but that from the latter was accreted to thegalactic ISM before being ram-pressure stripped to form filamentary tentaclesin the tail. Our simulation shows a declining gas metallicity in the tail as afunction of downstream distance from the galaxy. We conclude that the CGM playsan important role in shaping the tails of jellyfish galaxies.