We report the discovery of a complete Einstein ring around the ellipticalgalaxy NGC 6505, at $z=0.042$. This is the first strong gravitational lensdiscovered in Euclid and the first in an NGC object from any survey. Thecombination of the low redshift of the lens galaxy, the brightness of thesource galaxy ($I_\mathrm{E}=18.1$ lensed, $I_\mathrm{E}=21.3$ unlensed), andthe completeness of the ring make this an exceptionally rare strong lens,unidentified until its observation by Euclid. We present deep imaging data ofthe lens from the Euclid Visible Camera (VIS) and Near-Infrared Spectrometerand Photometer (NISP) instruments, as well as resolved spectroscopy from theKeck Cosmic Web Imager (KCWI). The Euclid imaging in particular presents one ofthe highest signal-to-noise ratio optical/near-infrared observations of astrong gravitational lens to date. From the KCWI data we measure a sourceredshift of $z=0.406$. Using data from the Dark Energy Spectroscopic Instrument(DESI) we measure a velocity dispersion for the lens galaxy of$\sigma_\star=303\pm15\,\mathrm{kms}^{-1}$. We model the lens galaxy light indetail, revealing angular structure that varies inside the Einstein ring. Aftersubtracting this light model from the VIS observation, we model the stronglylensed images, finding an Einstein radius of 2.5 arcsec, corresponding to$2.1\,\mathrm{kpc}$ at the redshift of the lens. This is small compared to theeffective radius of the galaxy, $R_\mathrm{eff}\sim 12.3\,\mathrm{arcsec}$.Combining the strong lensing measurements with analysis of the spectroscopicdata we estimate a dark matter fraction inside the Einstein radius of$f_\mathrm{DM} = (11.1_{-3.5}^{+5.4})\%$ and a stellar initial mass-function(IMF) mismatch parameter of $\alpha_\mathrm{IMF} = 1.26_{-0.08}^{+0.05}$,indicating a heavier-than-Chabrier IMF in the centre of the galaxy.

We report the discovery of the first example of an Einstein zig-zag lens, anextremely rare lensing configuration. In this system, J1721+8842, six images ofthe same background quasar are formed by two intervening galaxies, one atredshift $z_1 = 0.184$ and a second one at $z_2 = 1.885$. Two out of the sixmultiple images are deflected in opposite directions as they pass the firstlens galaxy on one side, and the second on the other side -- the optical pathsforming zig-zags between the two deflectors. In this letter, we demonstratethat J1721+8842, previously thought to be a lensed dual quasar, is in fact acompound lens with the more distant lens galaxy also being distorted as an arcby the foreground galaxy. Evidence supporting this unusual lensing scenarioincludes: 1- identical light curves in all six lensed quasar images obtainedfrom two years of monitoring at the Nordic Optical Telescope; 2- detection ofthe additional deflector at redshift $z_2 = 1.885$ in JWST/NIRSpec IFU data;and 3- a multiple-plane lens model reproducing the observed image positions.This unique configuration offers the opportunity to combine two major lensingcosmological probes: time-delay cosmography and dual source-plane lensing sinceJ1721+8842 features multiple lensed sources forming two distinct Einstein radiiof different sizes, one of which being a variable quasar. We expect tightconstraints on the Hubble constant and the equation of state of dark energy bycombining these two probes on the same system. The $z_2 = 1.885$ deflector, aquiescent galaxy, is also the highest-redshift strong galaxy-scale lens with aspectroscopic redshift measurement.

In the centers of many galaxy clusters, the hot ($\sim$10$^7$ K) intraclustermedium (ICM) can become dense enough that it should cool on short timescales.However, the low measured star formation rates in massive central galaxies andabsence of soft X-ray lines from cooling gas suggest that most of this gasnever cools - this is known as the "cooling flow problem." The latestobservations suggest that black hole jets are maintaining the vast majority ofgas at high temperatures. A cooling flow has yet to be fully mapped through allgas phases in any galaxy cluster. Here, we present new observations of thePhoenix cluster using the James Webb Space Telescope to map the [Ne VI]$\lambda$7.652$\mu$m emission line, allowing us to probe gas at 10$^{5.5}$ K onlarge scales. These data show extended [Ne VI] emission cospatial with (i) thecooling peak in the ICM, (ii) the coolest gas phases, and (iii) sites of activestar formation. Taken together, these imply a recent episode of rapid cooling,causing a short-lived spike in the cooling rate which we estimate to be5,000-23,000 M$_\odot$ yr$^{-1}$. These data provide the first large-scale mapof gas at temperatures between 10$^5$-10$^6$ K in a cluster core, and highlightthe critical role that black hole feedback plays in not only regulating butalso promoting cooling.

The main fuelling processes for Active Galactic Nuclei (AGN) are currentlyunknown. Previous work showed that galaxies with a large kinematic misalignmentbetween their stellar and gas reservoirs have a higher AGN fraction thangalaxies without misalignment. Such misalignment is a strong indication of apast galaxy interaction or an external accretion event. In this work we useintegral field spectroscopy data from the SAMI and MaNGA surveys to investigatethe AGN luminosity as a function of kinematic misalignment angle. Our sample ofAGN exhibit bolometric luminosities in the range 10^40 to 10^43 erg/s,indicative of low to moderate luminosity AGN. We find no correlation betweenAGN luminosity as a function of misalignment for AGN host galaxies from bothsurveys. We find some differences between the AGN luminosity of early- andlate-type AGN host galaxies (ETGs, LTGs). AGN in LTG hosts have a widerluminosity range, with most LTG hosts showing aligned stellar to gaskinematics. AGN in ETG hosts have a luminosity range that does not depend onmisalignment angle, suggesting AGN in ETG hosts are consistent with beingfuelled by external accretion events, irrespective of their stellar to gaskinematic misalignment. While all the AGN in ETGs in our sample are consistentwith being activated and fuelled by external gas, the range of observed AGNluminosities is likely caused by secondary factors such as the amount of freshgas brought into the galaxy by the external interaction.