9 research outputs found
Resonant scattering of the OVII X-ray emission line in the circumgalactic medium of TNG50 galaxies
We study the impact of resonantly scattered X-ray line emission on the
observability of the hot circumgalactic medium (CGM) of galaxies. We apply a
Monte Carlo radiative transfer post-processing analysis to the high-resolution
TNG50 cosmological magnetohydrodynamical galaxy formation simulation. This
allows us to model the resonant scattering of OVII(r) X-ray photons within the
complex, multi-phase, multi-scale CGM. The resonant transition of the OVII
He-like triplet is one of the brightest, and most promising, X-ray emission
lines for detecting the hot CGM and measuring its physical properties. We focus
on galaxies with stellar masses 10 < log(M*/Msun) < 11 at z ~ 0. After
constructing a model for OVII(r) emission from the central galaxy as well as
from CGM gas, we forward model these intrinsic photons to derive observable
surface brightness maps. We find that scattering significantly boosts the
observable OVII(r) surface brightness of the extended and diffuse CGM. This
enhancement can be large -- an order of magnitude on average at a distance of
200 projected kpc for high-mass M* = 10^10.7 Msun galaxies. The enhancement is
larger for lower mass galaxies, and can even reach a factor of 100, across the
extended CGM. Galaxies with higher star formation rates, AGN luminosities, and
central OVII(r) luminosities all have larger scattering enhancements, at fixed
stellar mass. Our results suggest that next-generation X-ray spectroscopic
missions including XRISM, LEM, ATHENA, and HUBS -- which aim to detect the hot
CGM in emission -- could specifically target halos with significant
enhancements due to resonant scattering.Comment: Published in MNRAS. See https://www.lem-observatory.org/ and
https://www.tng-project.org/ for more details; 2023MNRAS.522.3665
Circumgalactic Medium on the Largest Scales: Detecting X-ray Absorption Lines with Large-Area Microcalorimeters
The circumgalactic medium (CGM) plays a crucial role in galaxy evolution as
it fuels star formation, retains metals ejected from the galaxies, and hosts
gas flows in and out of galaxies. For Milky Way-type and more massive galaxies,
the bulk of the CGM is in hot phases best accessible at X-ray wavelengths.
However, our understanding of the CGM remains largely unconstrained due to its
tenuous nature. A promising way to probe the CGM is via X-ray absorption
studies. Traditional absorption studies utilize bright background quasars, but
this method probes the CGM in a pencil beam, and, due to the rarity of bright
quasars, the galaxy population available for study is limited. Large-area, high
spectral resolution X-ray microcalorimeters offer a new approach to exploring
the CGM in emission and absorption. Here, we demonstrate that the cumulative
X-ray emission from cosmic X-ray background sources can probe the CGM in
absorption. We construct column density maps of major X-ray ions from the
Magneticum simulation and build realistic mock images of nine galaxies to
explore the detectability of X-ray absorption lines arising from the
large-scale CGM. We conclude that the OVII absorption line is detectable around
individual massive galaxies at the confidence level. For
Milky Way-type galaxies, the OVII and OVIII absorption lines are detectable at
the and levels even beyond the virial radius
when co-adding data from multiple galaxies. This approach complements emission
studies, does not require additional exposures, and will allow probing of the
baryon budget and the CGM at the largest scales.Comment: 16 pages, 8 figures, accepted for publication in Ap
Diagnostic différentiel des tuméfactions cervico-faciales survenant au cours et au décours d'un geste dentaire
STRASBOURG-Medecine (674822101) / SudocSudocFranceF
Tuméfactions cervico-faciales per et post-opératoires immédiates en chirurgie bucco-dentaire
Il nâest pas rare que le chirurgien-dentiste soit confrontĂ© Ă une tumĂ©faction
cervico-faciale (TCF) per ou post-opĂ©ratoire immĂ©diate. Bien quâil sâagisse gĂ©nĂ©ralement
dâun phĂ©nomĂšne bĂ©nin, il est souvent source dâinquiĂ©tude pour le praticien et le patient.
Une revue de littérature se propose de présenter les différentes étiologies de
tumĂ©factions cervico-faciales per et post-opĂ©ratoires, et dâapporter les Ă©lĂ©ments
pratiques pour leur diagnostic. Parmi ces tumĂ©factions, lâemphysĂšme sous-cutanĂ© est un
évÚnement banal, bénin et facile à diagnostiquer mais souvent méconnu, ce dont témoigne le
nombre de cas rapportés. Plus rares, mais potentiellement graves, il convient également de
citer lâhĂ©matome du plancher buccal et lâangiĆdĂšme qui peuvent ĂȘtre la consĂ©quence du
geste bucco-dentaire ou des médicaments. Dans ce cadre, il est en effet nécessaire de
savoir reconnaĂźtre les prodromes dâune dĂ©tresse respiratoire. Enfin, la fasciite
nĂ©crosante cervico-faciale se doit dâĂȘtre reconnue tĂŽt du fait de son extrĂȘme gravitĂ©,
dâautant que son incidence paraĂźt croissante. Un tableau rĂ©capitulatif prĂ©sente les
principales causes de TCF per et post-opératoires aprÚs chirurgie dentaire, leur
chronologie, leurs principaux symptÎmes et les mesures thérapeutiques à mettre en
Ćuvre
Structural basis of nanobody recognition of grapevine fanleaf virus and of virus resistance loss
International audienceGrapevine fanleaf virus (GFLV) is a picorna-like plant virus transmitted by nematodes that affects vineyards worldwide. Nanobody (Nb)-mediated resistance against GFLV has been created recently, and shown to be highly effective in plants, including grapevine, but the underlying mechanism is unknown. Here we present the high-resolution cryo electron microscopy structure of the GFLV-Nb23 complex, which provides the basis for molecular recognition by the Nb. The structure reveals a composite binding site bridging over three domains of one capsid protein (CP) monomer. The structure provides a precise mapping of the Nb23 epitope on the GFLV capsid in which the antigen loop is accommodated through an induced-fit mechanism. Moreover, we uncover and characterize several resistance-breaking GFLV isolates with amino acids mapping within this epitope, including C-terminal extensions of the CP, which would sterically interfere with Nb binding. Escape variants with such extended CP fail to be transmitted by nematodes linking Nb-mediated resistance to vector transmission. Together, these data provide insights into the molecular mechanism of Nb23-mediated recognition of GFLV and of virus resistance loss
Mapping the imprints of stellar and AGN feedback in the circumgalactic medium with X-ray microcalorimeters
The Astro2020 Decadal Survey has identified the mapping of the circumgalactic
medium (CGM, gaseous plasma around galaxies) as a key objective. We explore the
prospects for characterizing the CGM in and around nearby galaxy halos with
future large grasp X-ray microcalorimeters. We create realistic mock
observations from hydrodynamical simulations (EAGLE, IllustrisTNG, and Simba)
that demonstrate a wide range of potential measurements, which will address the
open questions in galaxy formation and evolution. By including all background
and foreground components in our mock observations, we show why it is
impossible to perform these measurements with current instruments, such as
X-ray CCDs, and only microcalorimeters will allow us to distinguish the faint
CGM emission from the bright Milky Way (MW) foreground emission lines.
We find that individual halos of MW mass can, on average, be traced out to
large radii, around R500, and for larger galaxies even out to R200, using the
OVII, OVIII, or FeXVII emission lines. Furthermore, we show that emission line
ratios for individual halos can reveal the radial temperature structure.
Substructure measurements show that it will be possible to relate azimuthal
variations to the feedback mode of the galaxy. We demonstrate the ability to
construct temperature, velocity, and abundance ratio maps from spectral fitting
for individual galaxy halos, which reveal rotation features, AGN outbursts, and
enrichment.Comment: 38 pages, 18 figures, submitted to Ap
Line Emission Mapper (LEM): Probing the physics of cosmic ecosystems
The Line Emission Mapper (LEM) is an X-ray Probe for the 2030s that will answer the outstanding questions of the Universe's structure formation. It will also provide transformative new observing capabilities for every area of astrophysics, and to heliophysics and planetary physics as well. LEM's main goal is a comprehensive look at the physics of galaxy formation, including stellar and black-hole feedback and flows of baryonic matter into and out of galaxies. These processes are best studied in X-rays, and emission-line mapping is the pressing need in this area. LEM will use a large microcalorimeter array/IFU, covering a 30x30' field with 10" angular resolution, to map the soft X-ray line emission from objects that constitute galactic ecosystems. These include supernova remnants, star-forming regions, superbubbles, galactic outflows (such as the Fermi/eROSITA bubbles in the Milky Way and their analogs in other galaxies), the Circumgalactic Medium in the Milky Way and other galaxies, and the Intergalactic Medium at the outskirts and beyond the confines of galaxies and clusters. LEM's 1-2 eV spectral resolution in the 0.2-2 keV band will make it possible to disentangle the faintest emission lines in those objects from the bright Milky Way foreground, providing groundbreaking measurements of the physics of these plasmas, from temperatures, densities, chemical composition to gas dynamics. While LEM's main focus is on galaxy formation, it will provide transformative capability for all classes of astrophysical objects, from the Earth's magnetosphere, planets and comets to the interstellar medium and X-ray binaries in nearby galaxies, AGN, and cooling gas in galaxy clusters. In addition to pointed observations, LEM will perform a shallow all-sky survey that will dramatically expand the discovery space