Cold Mode Gas Accretion on Two Galaxy Groups at z∼\sim2

We present Keck Cosmic Web Imager (KCWI) integral field spectroscopy (IFS) observations of rest-frame UV emission lines $\rm Ly\alpha$, C IV $\lambda \lambda$ 1548 \AA, 1550\AA and He II 1640 \AA observed in the circumgalactic medium (CGM) of two $z=2$ radio-loud quasar host galaxies. We detect extended emission on 80-90 kpc scale in $\rm Ly\alpha$ in both systems with C IV, and He II emission also detected out to 30-50 kpc. All emission lines show kinematics with a blue and redshifted gradient pattern consistent with velocities seen in massive dark matter halos and similar to kinematic patterns of inflowing gas seen in hydrodynamical simulations. Using the kinematics of both resolved $\rm Ly\alpha$ emission and absorption, we can confirm that both kinematic structures are associated with accretion. Combining the KCWI data with molecular gas observations with Atacama Large Millimeter/submillimeter Array (ALMA) and high spatial resolution of ionized gas with Keck OSIRIS, we find that both quasar host galaxies reside in proto-group environments at $z=2$. We estimate $1-6\times10^{10}$M$_\odot$ of warm-ionized gas within 30-50 kpc from the quasar that is likely accreting onto the galaxy group. We estimate inflow rates of 60-200 M$_\odot$yr$^{-1}$, within an order of magnitude of the outflow rates in these systems. In the 4C 09.17 system, we detect narrow gas streams associated with satellite galaxies, potentially reminiscent of ram-pressure stripping seen in local galaxy groups and clusters. We find that the quasar host galaxies reside in dynamically complex environments, with ongoing mergers, gas accretion, ISM stripping, and outflows likely playing an important role in shaping the assembly and evolution of massive galaxies at cosmic noon.Comment: 24 pages, 11 figures, 6 tabes. Accepted for publication in MNRA

Re-imagining the futures of geographical thought and praxis

The question of geography\u27s future has recurred throughout the history of geographical thought, and responses to it often presume a linear trajectory from the past and present to a possible future. Yet one of the major contributions that geographers have made to understanding spatio-temporality is reconceiving both space and time as plural, fluid, and co-constituted through multiple space–time trajectories simultaneously. Amidst the ongoing crises of the present, this article opens the current special issue with a call to pluralize geography\u27s futures by diversifying the voices speaking in the name of ‘geography’ and broadening the horizon of possibilities for the futures of geographical thought and praxis. We have assembled the contributions in this collection with the aim of raising important theoretical, methodological, and empirical questions about how geography\u27s past and present shape the conditions of possibility for its potential futures. In doing so, we seek to demonstrate how the worlding of geography\u27s futures is fundamentally a matter of transforming its disciplinary reproduction in the here-and-now

Circumgalactic Environments Around Distant Quasars 3C 9 and 4C 05.84

We present results from the Quasar hosts Unveiled by high Angular Resolution Techniques survey studying the circumgalactic medium (CGM) by observing rest-frame UV emission lines Ly α , C iv , and He ii around two radio-loud quasars, 3C 9 ( z = 2.02) and 4C 05.84 ( z = 2.32), using the Keck Cosmic Web Imager. We detect large-scale Ly α nebulae around both quasars with projected diameters ∼100 kpc, with spatially resolved, embedded 15–30 kpc He ii and C iv nebulae around both quasars as well as kinematically distinct He ii and C iv nebulae at a physical separation of ∼15 kpc from both quasars. Observations of H α , H β , and [O iii ] emission using Keck MOSFIRE spectroscopically confirm that the Ly α nebulae extend to companion galaxies and that these quasars are in a protogroup/protocluster environment. We confirm that the He ii and C iv emission is kinematically and spatially coincident with the companion galaxies. We estimate the virial masses of the companion galaxies, their metallicities, and star formation rates, and investigate the sources of ionization. We measure the dynamical mass of the host dark matter halos and estimate that the dark matter halos of these systems will grow to a mass of 2 × 10 ^14 M _⊙ (3C 9) and 2 × 10 ^13 M _⊙ (4C 05.84) by z = 0. The combined CGM and companion galaxies observations indicate Ly α substructure can indicate the presence of companion galaxies in the CGM