分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： To assume hydrostatic equilibrium between the intracluster medium and the gravitational potential of galaxy clusters is an extensively used method to investigate their total masses. We want to test hydrostatic masses obtained with an observational code in the context of the SRG/eROSITA survey. We use the hydrostatic modeling code MBProj2 to fit surface-brightness profiles to simulated clusters with idealized properties as well as to a sample of 93 clusters taken from the Magneticum Pathfinder simulations. We investigate the latter under the assumption of idealized observational conditions and also for realistic eROSITA data quality. The comparison of the fitted cumulative total mass profiles and the true mass profiles provided by the simulations allows to gain knowledge about the reliability of our approach. Furthermore, we use the true profiles for gas density and pressure to compute hydrostatic mass profiles based on theory for every cluster. For an idealized cluster that was simulated to fulfill perfect hydrostatic equilibrium, we find that the cumulative total mass at the true $r_{500}$ and $r_{200}$ can be reproduced with deviations of less than 7%. For the clusters from the Magneticum Pathfinder simulations under idealized observational conditions, the median values of the fitted cumulative total masses at the true $r_{500}$ and $r_{200}$ are in agreement with our expectations, taking into account the hydrostatic mass bias. Nevertheless, we find a tendency towards a too high steepness of the cumulative total mass profiles in the outskirts. For realistic eROSITA data quality, this steepness problem intensifies for clusters with high redshifts and thus leads to too high cumulative total masses at $r_{200}$. For the hydrostatic masses based on the true profiles known from the simulations, we find a good agreement with our expectations concerning the hydrostatic mass.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Elizabeth Lee
Dhayaa Anbajagane
Priyanka Singh
Jens Chluba
Daisuke Nagai
Scott T. Kay
Weiguang Cui
Klaus Dolag
Gustavo Yepes
摘要： The Sunyaev-Zeldovich (SZ) effect is a powerful tool in modern cosmology. With future observations promising ever improving SZ measurements, the relativistic corrections to the SZ signals from galaxy groups and clusters are increasingly relevant. As such, it is important to understand the differences between three temperature measures: (a) the average relativistic SZ (rSZ) temperature, (b) the mass-weighted temperature relevant for the thermal SZ (tSZ) effect, and (c) the X-ray spectroscopic temperature. In this work, we compare these cluster temperatures, as predicted by the {\sc Bahamas} \& {\sc Macsis}, {\sc Illustris-TNG}, {\sc Magneticum}, and {\sc The Three Hundred Project} simulations. Despite the wide range of simulation parameters, we find the SZ temperatures are consistent across the simulations. We estimate a $\simeq 10\%$ level correction from rSZ to clusters with $Y\simeq10^{-4}$~Mpc$^{-2}$. Our analysis confirms a systematic offset between the three temperature measures; with the rSZ temperature $\simeq 20\%$ larger than the other measures, and diverging further at higher redshifts. We demonstrate that these measures depart from simple self-similar evolution and explore how they vary with the defined radius of haloes. We investigate how different feedback prescriptions and resolution affect the observed temperatures, and discover the SZ temperatures are rather insensitive to these details. The agreement between simulations indicates an exciting avenue for observational and theoretical exploration, determining the extent of relativistic SZ corrections. We provide multiple simulation-based fits to the scaling relations for use in future SZ modelling.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Pierre A. Burger
Oliver Friedrich
Joachim Harnois-Déraps
Peter Schneider
Marika Asgari
Maciej Bilicki
Hendrik Hildebrandt
Angus H. Wright
Tiago Castro
Klaus Dolag
Catherine Heymans
Benjamin Joachimi
Konrad Kuijken
Nicolas Martinet
HuanYuan Shan
Tilman Tröster
摘要： Context. Weak lensing and clustering statistics beyond two-point functions can capture non-Gaussian information about the matter density field, thereby improving the constraints on cosmological parameters relative to the mainstream methods based on correlation functions and power spectra. Aims. This paper presents a cosmological analysis of the fourth data release of the Kilo Degree Survey based on the density split statistics, which measures the mean shear profiles around regions classified according to foreground densities. The latter is constructed from a bright galaxy sample, which we further split into red and blue samples, allowing us to probe their respective connection to the underlying dark matter density. Methods. We use the state-of-the-art model of the density splitting statistics and validate its robustness against mock data infused with known systematic effects such as intrinsic galaxy alignment and baryonic feedback. Results. After marginalising over the photometric redshift uncertainty and the residual shear calibration bias, we measure for the full KiDS-bright sample a structure growth parameter of $S_8 = \sigma_8 \sqrt{\Omega_\mathrm{m}/0.3} = 0.74^{+0.03}_{-0.02}$ that is competitive to and consistent with two-point cosmic shear results, a matter density of $\Omega_\mathrm{m} = 0.28 \pm 0.02$, and a constant galaxy bias of $b = 1.32^{+0.12}_{-0.10}$.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Helen Shao
Natalí S. M de Santi
Francisco Villaescusa-Navarro
Romain Teyssier
Yueying Ni
Daniel Angles-Alcazar
Shy Genel
Lars Hernquist
Ulrich P. Steinwandel
Tiago Castro
Elena Hernandez-Martınez
Klaus Dolag
Christopher C. Lovell
Eli Visbal
Lehman H. Garrison
Mihir Kulkarni
摘要： We discover analytic equations that can infer the value of $\Omega_{\rm m}$ from the positions and velocity moduli of halo and galaxy catalogues. The equations are derived by combining a tailored graph neural network (GNN) architecture with symbolic regression. We first train the GNN on dark matter halos from Gadget N-body simulations to perform field-level likelihood-free inference, and show that our model can infer $\Omega_{\rm m}$ with $\sim6\%$ accuracy from halo catalogues of thousands of N-body simulations run with six different codes: Abacus, CUBEP$^3$M, Gadget, Enzo, PKDGrav3, and Ramses. By applying symbolic regression to the different parts comprising the GNN, we derive equations that can predict $\Omega_{\rm m}$ from halo catalogues of simulations run with all of the above codes with accuracies similar to those of the GNN. We show that by tuning a single free parameter, our equations can also infer the value of $\Omega_{\rm m}$ from galaxy catalogues of thousands of state-of-the-art hydrodynamic simulations of the CAMELS project, each with a different astrophysics model, run with five distinct codes that employ different subgrid physics: IllustrisTNG, SIMBA, Astrid, Magneticum, SWIFT-EAGLE. Furthermore, the equations also perform well when tested on galaxy catalogues from simulations covering a vast region in parameter space that samples variations in 5 cosmological and 23 astrophysical parameters. We speculate that the equations may reflect the existence of a fundamental physics relation between the phase-space distribution of generic tracers and $\Omega_{\rm m}$, one that is not affected by galaxy formation physics down to scales as small as $10~h^{-1}{\rm kpc}$.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Natalí S. M. de Santi
Helen Shao
Francisco Villaescusa-Navarro
L. Raul Abramo
Romain Teyssier
Pablo Villanueva-Domingo
Yueying Ni
Daniel Anglés-Alcázar
Shy Genel
Elena Hernandez-Martinez
Ulrich P. Steinwandel
Christopher C. Lovell
Klaus Dolag
Tiago Castro
Mark Vogelsberger
摘要： We train graph neural networks to perform field-level likelihood-free inference using galaxy catalogs from state-of-the-art hydrodynamic simulations of the CAMELS project. Our models are rotationally, translationally, and permutation invariant and have no scale cutoff. By training on galaxy catalogs that only contain the 3D positions and radial velocities of approximately $1,000$ galaxies in tiny volumes of $(25~h^{-1}{\rm Mpc})^3$, our models achieve a precision of approximately $12$% when inferring the value of $\Omega_{\rm m}$. To test the robustness of our models, we evaluated their performance on galaxy catalogs from thousands of hydrodynamic simulations, each with different efficiencies of supernova and AGN feedback, run with five different codes and subgrid models, including IllustrisTNG, SIMBA, Astrid, Magneticum, and SWIFT-EAGLE. Our results demonstrate that our models are robust to astrophysics, subgrid physics, and subhalo/galaxy finder changes. Furthermore, we test our models on 1,024 simulations that cover a vast region in parameter space - variations in 5 cosmological and 23 astrophysical parameters - finding that the model extrapolates really well. Including both positions and velocities are key to building robust models, and our results indicate that our networks have likely learned an underlying physical relation that does not depend on galaxy formation and is valid on scales larger than, at least, $~\sim10~h^{-1}{\rm kpc}$.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Weiguang Cui
Romeel Dave
Alexander Knebe
Elena Rasia
Meghan Gray
Frazer Pearce
Chris Power
Gustavo Yepes
Dhayaa Anbajagane
Daniel Ceverino
Ana Contreras-Santos
Daniel de Andres
Marco De Petris
Stefano Ettori
Roan Haggar
Qingyang Li
Yang Wang
Xiaohu Yang
Stefano Borgani
Klaus Dolag
摘要： We introduce \textsc{Gizmo-Simba}, a new suite of galaxy cluster simulations within \textsc{The Three Hundred} project. \textsc{The Three Hundred} consists of zoom re-simulations of 324 clusters with $M_{200}\gtrsim 10^{14.8}M_\odot$ drawn from the MultiDark-Planck $N$-body simulation, run using several hydrodynamic and semi-analytic codes. The \textsc{Gizmo-Simba} suite adds a state-of-the-art galaxy formation model based on the highly successful {\sc Simba} simulation, mildly re-calibrated to match $z=0$ cluster stellar properties. Comparing to \textsc{The Three Hundred} zooms run with \textsc{Gadget-X}, we find intrinsic differences in the evolution of the stellar and gas mass fractions, BCG ages, and galaxy colour-magnitude diagrams, with \textsc{Gizmo-Simba} generally providing a good match to available data at $z \approx 0$. \textsc{Gizmo-Simba}'s unique black hole growth and feedback model yields agreement with the observed BH scaling relations at the intermediate-mass range and predicts a slightly different slope at high masses where few observations currently lie. \textsc{Gizmo-Simba} provides a new and novel platform to elucidate the co-evolution of galaxies, gas, and black holes within the densest cosmic environments.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Ralph Kraft
Maxim Markevitch
Caroline Kilbourne
Joseph S. Adams
Hiroki Akamatsu
Mohammadreza Ayromlou
Simon R. Bandler
Douglas A. Bennett
Anil Bhardwaj
Veronica Biffi
Dennis Bodewits
Akos Bogdan
Massimiliano Bonamente
Stefano Borgani
Graziella Branduardi-Raymont
Joel N. Bregman
Joseph N. Burchett
Jenna Cann
Jenny Carter
Priyanka Chakraborty
摘要： 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.
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