Observations of clusters of galaxies suggest that they contain significantly fewer baryons (gas plus stars) than the cosmic baryon fraction. This `missing baryon' puzzle is especially surprising for the most massive clusters which are expected to be representative of the cosmic matter content of the universe (baryons and dark matter). Here we show that the baryons may not actually be missing from clusters, but rather are extended to larger radii than typically observed. The baryon deficiency is typically observed in the central regions of clusters (~0.5 the virial radius). However, the observed gas-density profile is significantly shallower than the mass-density profile, implying that the gas is more extended than the mass and that the gas fraction increases with radius. We use the observed density profiles of gas and mass in clusters to extrapolate the measured baryon fraction as a function of radius and as a function of cluster mass. We find that the baryon fraction reaches the cosmic value near the virial radius for all groups and clusters above 5e13 solar masses. This suggests that the baryons are not missing, they are simply located in cluster outskirts. Heating processes (shock-heating of the intracluster gas, plus supernovae and AGN feedback) that cause the gas to expand are likely explanations for these results. Upcoming observations should be able to detect these baryons.
The missing baryon problem may now be resolved, but the exact location and physical properties of the diffuse component remains unclear. This problem could be tractable, but requires the combination of new galaxy redshift surveys with new X-ray and radio facilities.
Galaxies are missing most of their baryons, and many models predict these baryons lie in a hot halo around galaxies. We establish observationally motivated constraints on the mass and radii of these haloes using a variety of independent arguments. First, the observed dispersion measure of pulsars in the Large Magellanic Cloud allows us to constrain the hot halo around the Milky Way: if it obeys the standard NFW profile, it must contain less than 4-5% of the missing baryons from the Galaxy. This is similar to other upper limits on the Galactic hot halo, such as the soft X-ray background and the…
We estimate the amount of the {\it missing baryons} detected by the \Planck\ measurements of the cosmic microwave background in the direction of Central Galaxies (CGs) identified in the Sloan galaxy survey. The peculiar motion of the gas inside and around the CGs unveils values of the Thomson optical depth $τ_{\rm T}$ in the range $0.2$--$2\times 10^{-4}$, indicating that the regions probed around CGs contain roughly half of the total amount of baryons in the Universe at the epoch where the CGs are found. If baryons follow dark matter, the measured $τ_{\rm T}$s are compatible with the detectio…
Context. A significant fraction of the predicted baryons remains undetected in the local universe. We adopted the common assumption that a large fraction of the missing baryons corresponds to the hot (log T(K) = 5.5-7) phase of the Warm Hot Intergalactic Medium (WHIM). We base our missing baryons search on the scenario whereby the WHIM has been heated up via accretion shocks and galactic outflows, and is concentrated towards the filaments of the Cosmic Web. Aims. Our aim is to improve the observational search of the poorly detected hot WHIM. Methods. We detect the filamentary structure within …
Tidal dwarf galaxies form during the interaction, collision or merger of massive spiral galaxies. They can resemble "normal" dwarf galaxies in terms of mass, size, and become dwarf satellites orbiting around their massive progenitor. They nevertheless keep some signatures from their origin, making them interesting targets for cosmological studies. In particular, they should be free from dark matter from a spheroidal halo. Flat rotation curves and high dynamical masses may then indicate the presence of an unseen component, and constrain the properties of the "missing baryons", known to exist bu…
The Milky Way and all other galaxies are missing most of their baryons in that the ratio of the known baryonic mass to the gravitating mass (within the virial radius), is several times less than the cosmic ratio determined from WMAP. This implies that either the baryons never fell into galaxies or that powerful galactic winds removed most of the baryons. It is possible to discriminate between these two pathways if we can discover the missing baryons and measure its properties: spatial distribution; temperature; and metallicity. The missing baryons from galaxies are expected to have temperature…
Recently, Thornton and coworkers (2013) confirmed a class of millisecond radio bursts likely of extragalactic origin that is well-suited for estimating dispersion measures (DMs). We calculate the probability distribution of DM(z) in different models for how the cosmic baryons are distributed (both analytically and with cosmological simulations). We show that the distribution of DM is quite sensitive to whether the "missing" baryons lie around the virial radius of 10^11-10^13 Msun halos or further out, which is not easily constrained with other observational techniques. The intrinsic contributi…
Radio galaxies with bent jets are predominantly located in groups and clusters of galaxies. We use bent-double radio sources, under the assumption that their jets are bent by ram-pressure, to probe intragroup medium (IGM) gas densities in galaxy groups. This method provides a direct measurement of the intergalactic gas density and allows us to probe IGM gas at large radii and in systems whose IGM is too cool to be detected by the current generation of X-ray telescopes. We find gas with densities of 10^(-3)-10^(-4) per cubic centimeter at group radii from 15-700 kpc. A rough estimate of the tot…
We present a new method for detecting the missing baryons by generating a template for the kinematic Sunyaev-Zel'dovich effect. The template is computed from the product of a reconstructed velocity field with a galaxy field; we find that the combination of a galaxy redshift survey such as SDSS and a CMB survey such as ACT and PLANCK can detect the kSZ, and thus the ionized gas, at significant signal-to-noise. Unlike other techniques that look for hot gas or metals, this approach directly detects the electrons in the IGM through their signature on the CMB. The estimated signal-to-noise for dete…
For low-redshift cosmology and galaxy formation rates, it is important to account for all the baryons synthesized in the Big Bang. Although galaxies and clusters contain 10% of the baryons, many more reside in the photoionized Lyman-alpha forest and shocked-heated warm-hot intergalactic medium (WHIM) at T = 10^5 to 10^7 K. Current tracers of WHIM at 10^5 to 10^6 K include the O VI 1032, 1038 absorption lines, together with broad Lyman-alpha absorbers (BLAs) and EUV/X-ray absorption lines from Ne VIII, O VII, and O VIII. We improve the O VI baryon surveys with corrections for oxygen metallicity…
We present predictions for galactic halo baryon fractions from cosmological hydrodynamic simulations with a well-constrained model for galactic outflows. Without outflows, halos contain roughly the cosmic fraction of baryons, slightly lowered at high masses owing to pressure support from hot gas. The star formation efficiency is large and increases monotonically to low masses, in disagreement with data. With outflows, the baryon fraction is increasingly suppressed in halos to lower masses. A Milky Way-sized halo at z=0 has about 60% of the cosmic fraction of baryons, so "missing" halo baryons …
The baryon content of high-density regions in the universe is relevant to two critical unanswered questions: the workings of nurture effects on galaxies and the whereabouts of the missing baryons. In this paper, we analyze the distribution of dark matter and semianalytical galaxies in the Millennium Simulation to investigate these problems. Applying the same density field reconstruction schemes as used for the overall matter distribution to the matter locked in halos we study the mass contribution of halos to the total mass budget at various background field densities, i.e., the conditional ha…
Observations of galaxies and galaxy clusters in the local universe can account for only $\sim\,10\%$ of the total baryon content. Cosmological simulations predict that the `missing baryons' are spread throughout filamentary structures in the cosmic web, forming a low-density gas with temperatures of $10^5-10^7\,\!$K. We search for this warm-hot intergalactic medium (WHIM) by stacking the Planck Compton $y$-parameter map of the thermal Sunyaev-Zel'dovich (tSZ) effect for 1,002,334 pairs of CMASS galaxies from the Sloan Digital Sky Survey. We model the contribution from the galaxy halo pairs ass…
The missing baryon problem is one of the major unsolved problems in astronomy. Fast radio bursts (FRBs) are bright millisecond pulses with unknown origins. The dispersion measure of FRBs is defined as the electron column density along the line of sight, and accounts for every ionized baryon. Here we measure the baryon content of the Universe using 22 localized FRBs. Unlike previous works that fixed the value of dispersion measure of FRB host galaxies and ignored the inhomogeneities of the intergalactic medium (IGM), we use the probability distributions of dispersion measures contributed by hos…
The angular power spectrum and polarization of the cosmic microwave background radiation (CMB), the relative abundances of primordial hydrogen, deuterium and helium isotopes, and the large-scale structure of the universe all indicate that 4.5% of the current mass density of the universe consists of baryons. However, only a small fraction of these baryons can be accounted for in stars and gas inside galaxies, galaxy groups and galaxy clusters, and in spectral-line absorbing gas in the intergalactic medium (IGM). Too hot to show up in Lyman-absorption, too cool to cause detectable spectral disto…
Almost a third of the cosmic baryons are "missing" at low redshifts, as they reside in the invisible warm-hot intergalactic medium (WHIM). The thermal Sunyaev-Zeldovich (tSZ) effect, which measures the line-of-sight integral of the plasma pressure, can potentially detect this WHIM, although its expected signal is hidden below the noise. Extragalactic dispersion measures (DMs)---obtained through observations of fast radio bursts (FRBs)---are excellent tracers of the WHIM, as they measure the column density of plasma, regardless of its temperature. Here we propose cross correlating DMs and tSZ m…
Baryons constitute about 4% of our universe, but most of them are missing and we do not know where and in what form they are hidden. This constitute the so-called missing baryon problem. A possibility is that part of these baryons are hidden in galactic halos. We show how the 7-year data obtained by the WMAP satellite may be used to trace the halo of the nearby giant spiral galaxy M31. We detect a temperature asymmetry in the M31 halo along the rotation direction up to about 120 kpc. This could be the first detection of a galactic halo in microwaves and may open a new way to probe hidden baryo…
We present the detection of the kinetic Sunyaev-Zel'dovich effect (kSZE) signals from groups of galaxies as a function of halo mass down to $\log (M_{500}/{\rm M_\odot}) \sim 12.3$, using the {\it Planck} CMB maps and stacking about $40,000$ galaxy systems with known positions, halo masses, and peculiar velocities. The signals from groups of different mass are constrained simultaneously to take care of projection effects of nearby halos. The total kSZE flux within halos estimated implies that the gas fraction in halos is about the universal baryon fraction, even in low-mass halos, indicating t…
The backbone of the large-scale structure of the Universe is determined by processes on a cosmological scale and by the gravitational interaction of the dominant dark matter. However, the mobile baryon population shapes the appearance of these structures. Theory predicts that most of the baryons reside in vast unvirialized filamentary structures that connect galaxy groups and clusters, but the observational evidence is currently lacking. Because the majority of the baryons are supposed to exist in a large-scale, hot and dilute gaseous phase, X-rays provide the ideal tool to progress our unders…
Tracing Missing Baryons in the Cosmic Filaments with tSZ and CMB-Lensing Stacking
School of Physics and Astronomy, Sun Yat-sen University（中山大学物理学院）；CSST Science Center for the Guangdong-Hong kong-Macau Greater Bay Area, SYSU（中山大学粤港澳大湾区深空探测科学中心）
The current observational status of the hot (log T(K) > 5.5) warm-hot intergalactic medium (WHIM) remains incomplete. While recent observations from stacking large numbers of Cosmic Web filaments have yielded statistically significant detections, direct measurements of single objects remain scarce. The lack of such a sample currently prevents a robust analysis of the cosmic baryon content composed of the hot WHIM, which could help solve the cosmological missing baryons problem. To improve the search for the missing baryons, we used the EAGLE simulation. Our aim is to understand the metal enric…
It has been demonstrated that the inclusion of baryonic physics can alter the dark matter densities in the centers of low-mass galaxies, making the central dark matter slope more shallow than predicted in pure cold dark matter simulations. This flattening of the dark matter profile can occur in the most luminous subhalos around Milky Way-mass galaxies. Zolotov et al. (2012) have suggested a correction to be applied to the central masses of dark matter-only satellites in order to mimic the affect of (1) the flattening of the dark matter cusp due to supernova feedback in luminous satellites, and…
We report the first results of the MUSIC project. It consists of two data sets of resimulates clusters extracted from two large dark matter only simulations: Marenostrum Universe and Multidark. In total, the MUSIC contains more than 400 clusters resimulated with high resolution both with radiative and non-radiative physics included. Here we present the first results on the properties of the baryon content and the Sunyaev Zeldovich scaling relations.
The accumulation of redshifts provides a significant observational bottleneck when using galaxy cluster surveys to constrain cosmological parameters. We propose a simple method to allow the use of samples where there is a fraction of the redshifts that are not known. The simplest assumption is that the missing redshifts are randomly extracted from the catalogue, but the method also allows one to take into account known selection effects in the accumulation of redshifts. We quantify the reduction in statistical precision of cosmological parameter constraints as a function of the fraction of mis…
The halo mass function from N-body simulations of collisionless matter is generally used to retrieve cosmological parameters from observed counts of galaxy clusters. This neglects the observational fact that the baryonic mass fraction in clusters is a random variable that, on average, increases with the total mass (within an overdensity of 500). Considering a mock catalog that includes tens of thousands of galaxy clusters, as expected from the forthcoming generation of surveys, we show that the effect of a varying baryonic mass fraction will be observable with high statistical significance. Th…
A large fraction of baryons predicted from the standard cosmology has been missing observationally. Although previous numerical simulations have indicated that most of the missing baryons reside in large-scale filaments in the form of Warm Hot Intergalactic Medium (WHIM), it is generally very difficult to detect signatures from such a diffuse gas. In this work, we focus on the hyperfine transition of neutral hydrogen (HI) called 21-cm line as a tool to trace the WHIM. For the purpose, we first construct the map of the 21-cm signals by using the data provided by the state-of-the-art cosmologica…
Locating the missing baryons in the warm-hot intergalactic medium with fast radio bursts and the Sunyaev-Zel'dovich effect
School of Astronomy and Space Science, Nanjing University（南京大学天文与空间科学学院）；Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education（教育部现代天文与天体物理重点实验室（南京大学））；Department of Astronomy, School of Physical Sciences, University of Science and Technology of China（中国科学技术大学物理科学学院天文学系）；Center for Cosmology and Computational Astrophysics, Zhejiang University（浙江大学宇宙学与计算天体物理中心）
Modified Newtonian Dynamics (MOND) is a gravitational framework designed to explain the astronomical observations in the Universe without the inclusion of particle dark matter. Modified Newtonian Dynamics, in its current form, cannot explain the missing mass in galaxy clusters without the inclusion of some extra mass, be it in the form of neutrinos or non-luminous baryonic matter. We investigate whether the MOND framework can be generalized to account for the missing mass in galaxy clusters by boosting gravity in high gravitational potential regions. We examine and review Extended MOND (EMOND)…
Weak gravitational lensing depends on the integrated mass along the line of sight. Baryons contribute to the mass distribution of galaxy clusters and the resulting mass estimates from lensing analysis. We use the cosmo-OWLS suite of hydrodynamic simulations to investigate the impact of baryonic processes on the bias and scatter of weak lensing mass estimates of clusters. These estimates are obtained by fitting NFW profiles to mock data using MCMC techniques. In particular, we examine the difference in estimates between dark matter-only runs and those including various prescriptions for baryoni…
It is commonly believed that galaxies use, throughout the Hubble time, a very small fraction of the baryons associated to their dark matter halos to form stars. This so-called low "star formation efficiency" $f_\star\equiv M_\star/f_{\rm b} M_{\rm halo}$, where $f_{\rm b}\equivΩ_{\rm b}/Ω_{\rm c}$ is the cosmological baryon fraction, is expected to reach its peak at nearly $L^\ast$ (at efficiency $\approx 20\%$) and decline steeply at lower and higher masses. We have tested this using a sample of nearby star-forming galaxies, from dwarfs ($M_\star\simeq 10^7 M_\odot$) to high-mass spirals ($M_…
We propose a new method to use the kinematic Sunyaev-Zeldovich for measuring the baryon fraction in cluster of galaxies. In this proposal we need a configuration in which a supernova Type Ia resides in a brightest cluster galaxy of intermediate redshift clusters. We show this supernova Type Ia can be used to measure the bulk velocity of a galaxy cluster. We assert that the redshift range of $0.4<z<0.6$ is suitable for this proposal. The main contribution to the deviation of standard candles distance modulus from cosmological background prediction in this redshift range comes from peculiar velo…
Based on constraints from Big Bang nucleosynthesis and the cosmic microwave background, the baryon content of the high-redshift Universe can be precisely determined. However, at low redshift, about one-third of the baryons remain unaccounted for, which poses the long-standing missing baryon problem. The missing baryons are believed to reside in large-scale filaments in the form of warm-hot intergalactic medium (WHIM). In this work, we employ a novel stacking approach to explore the hot phases of the WHIM. Specifically, we utilize the 470 ks Chandra LETG data of the luminous quasar, H1821+643, …
We study the effect of baryonic processes on the halo mass function in the galaxy cluster mass range using a catalogue of 153 high resolution cosmological hydrodynamical simulations performed with the AMR code ramses. We use the results of our simulations within a simple analytical model to gauge the effects of baryon physics on the halo mass function. Neglect of AGN feedback leads to a significant boost in the cluster mass function similar to that reported by other authors. However, including AGN feedback not only gives rise to systems that are similar to observed galaxy clusters, but they al…
We study the relationship between two major baryonic components in galaxy clusters, namely the stars in galaxies, and the ionized gas in the intracluster medium (ICM), using 94 clusters that span the redshift range 0-0.6. Accurately measured total and ICM masses from Chandra observations, and stellar masses derived from the Wide-field Infrared Survey Explorer and the Two-Micron All-Sky Survey allow us to trace the evolution of cluster baryon content in a self-consistent fashion. We find that, within r_{500}, the evolution of the ICM mass--total mass relation is consistent with the expectation …
In order to be efficient, spectroscopic galaxy redshift surveys do not obtain redshifts for all galaxies in the population targeted. The missing galaxies are often clustered, commonly leading to a lower proportion of successful observations in dense regions. One example is the close-pair issue for SDSS spectroscopic galaxy surveys, which have a deficit of pairs of observed galaxies with angular separation closer than the hardware limit on placing neighbouring fibers. Spatially clustered missing observations will exist in the next generations of surveys. Various schemes have previously been sug…
We present the first simulated galaxy clusters (M_200 > 10^14 Msun) with both self-interacting dark matter (SIDM) and baryonic physics. They exhibit a greater diversity in both dark matter and stellar density profiles than their counterparts in simulations with collisionless dark matter (CDM), which is generated by the complex interplay between dark matter self-interactions and baryonic physics. Despite variations in formation history, we demonstrate that analytical Jeans modelling predicts the SIDM density profiles remarkably well, and the diverse properties of the haloes can be understood in…
We present BAHAMAS-SIDM, the first large-volume, (400/h Mpc)^3, cosmological simulations including both self-interacting dark matter (SIDM) and baryonic physics. These simulations are important for two primary reasons: 1) they include the effects of baryons on the dark matter distribution 2) the baryon particles can be used to make mock observables that can be compared directly with observations. As is well known, SIDM haloes are systematically less dense in their centres, and rounder, than CDM haloes. Here we find that that these changes are not reflected in the distribution of gas or stars w…
Baryonic feedback effects consist of a major systematic for upcoming weak-lensing and galaxy-clustering surveys. In this paper, we present an emulator for the baryonic suppression of the matter power spectrum. The emulator is based on the baryonification model, containing seven free parameters that are connected to the gas profiles and stellar abundances in haloes. We show that with the baryonic emulator, we can not only recover the power spectra of hydro-dynamical simulations at sub-percent precision but also establish a connection between the baryonic suppression of the power spectrum and th…
We re-analyse a combined 198 ks Chandra observation of NGC4696, the brightest galaxy of the Centaurus cluster. We extract temperature and metallicity profiles from the data, and we confirm the presence of a sharp drop in iron abundance, from ~1.8 Zsolar to ~0.4 Zsolar, within the central 5 kpc of the cluster. We estimate that this abundance drop corresponds to a total "missing" iron mass of 1.4e06 Msolar. We propose that part of this missing iron is locked up in cool (~19 K) far-IR emitting dust, as found by Spitzer and Herschel observations. This can occur if the iron injected by stellar mass…
To assess the effect of baryonic ``pinching'' of galaxy cluster dark matter (DM) haloes, cosmological (LCDM) TreeSPH simulations of the formation and evolution of two galaxy clusters have been performed, with and without baryons included. The simulations with baryons invoke star formation, chemical evolution with non-instantaneous recycling, metallicity dependent radiative cooling, strong star-burst, driven galactic super-winds and the effects of a meta-galactic UV field, including simplified radiative transfer. The two clusters have T_X~3 and 6 keV, respectively, and, at z~0, both host a prom…
It has been known for decades that the observed number of baryons in the local universe falls about 30-40% short of the total number of baryons predicted by Big-Bang Nucleosynthesis, as inferred from density fluctuations of the Cosmic Microwave Background and seen during the first 2-3 billion years of the universe in the so called Lyman-alpha Forest. A theoretical solution to this paradox locates the missing baryons in the hot and tenuous filamentary gas between galaxies, known as the warm-hot intergalactic medium. However, it is difficult to detect them there because the largest by far consti…
A large portion of the baryons at low redshifts are still missing from detection. Most of the missing baryons are believed to reside in large scale cosmic filaments. Understanding the distribution of baryons in filaments is crucial for the search for missing baryons. We investigate the properties of cosmic filaments since $z=4.0$ in a cosmological hydrodynamic simulation, focusing on the density and temperature profiles perpendicular to the filament spines. Our quantitative evaluation confirm the rapid growth of thick and prominent filaments after $z=2$. We find that the local linear density o…
Gravitational lensing is a powerful probe of the mass distribution of galaxy clusters and cosmology. However, accurate measurements of the cluster mass profiles are limited by uncertainties in cluster astrophysics. In this work, we present a physically motivated model of baryonic effects on the cluster mass profiles, which self-consistently takes into account the impact of baryons on the concentration as well as mass accretion histories of galaxy clusters. We calibrate this model using the Omega500 hydrodynamical cosmological simulations of galaxy clusters with varying baryonic physics. Our mo…
We propose a new approach to the missing baryons problem. Building on the common assumption that the missing baryons are in the form of the Warm Hot Intergalactic Medium (WHIM), we further assumed here that the galaxy luminosity density can be used as a tracer of the WHIM. The latter assumption is supported by our finding of a significant correlation between the WHIM density and the galaxy luminosity density in the hydrodynamical simulations of Cui et al. (2012). We further found that the fraction of the gas mass in the WHIM phase is substantially (by a factor of $\sim$1.6) higher within the l…
Revisiting the missing mass problem in MOND for nearby galaxy clusters
Helmholtz-Institut für Strahlen-und Kernphysik (HISKP), Universität Bonn（波恩大学亥姆霍兹辐射与核物理研究所）；Department of Physics, Institute for Advanced Studies in Basic Sciences (IASBS)（基础科学高等研究院物理系）；Charles University in Prague, Faculty of Mathematics and Physics, Astronomical Institute（布拉格查理大学数学物理学院天文研究所）
Starting from the 1970s, some relations connecting dark matter and baryons were discovered, such as the Tully-Fisher relation. However, many of the relations found in galaxies are quite different from that found in galaxy clusters. Here, we report two new mysterious universal relations connecting dark matter and baryons in both galaxies and galaxy clusters. The first relation indicates that the total dynamical mass of a galaxy or a galaxy cluster $M_{500}$ has a power-law relation with its total baryonic mass $M_b$ within the `virial region': $M_{500} \propto M_b^a$, with $a \approx 3/4$. The …
We present one-dimensional models of the hot gas in dark-matter halos, which both predict the existence of cool cores and explain their structure. Our models are directly applicable to semi-analytic models (SAMs) of galaxy formation. We have previously argued that filaments of cold (~10^4 K) gas condense out of the intracluster medium (ICM) in hydrostatic and thermal equilibrium when the ratio of the thermal instability timescale to the free-fall time $t_{TI}/t_{ff}$ falls below 5-10. This criterion corresponds to an upper limit on the density of the ICM and motivates a model in which a densit…
Accurate estimation of the merger timescale of galaxy clusters is important to understand the cluster merger process and further the formation and evolution of the large-scale structure of the universe. In this paper, we explore a baryonic effect on the merger timescale of galaxy clusters by using hydrodynamical simulations. We find that the baryons play an important role in accelerating the merger process. The merger timescale decreases with increasing the gas fraction of galaxy clusters. For example, the merger timescale is shortened by a factor of up to 3 for merging clusters with gas fract…
We present the baryon fractions of 2MASS groups and clusters as a function of cluster richness using total and gas masses measured from stacked ROSAT X-ray data and stellar masses estimated from the infrared galaxy catalogs. We detect X-ray emission even in the outskirts of clusters, beyond r_200 for richness classes with X-ray temperatures above 1 keV. This enables us to more accurately determine the total gas mass in these groups and clusters. We find that the optically selected groups and clusters have flatter temperature profiles and higher stellar-to-gas mass ratios than the individually …
We introduce a new set of simulations of Milky Way-sized galaxies using the AMR code ART + hydrodynamics in a $Λ$CDM cosmogony. The simulation series is named GARROTXA and follow the formation of a halo/galaxy from z~$=$~60 to z~$=$~0. The final virial mass of the system is $\sim$7.4$\times$10$^{11}$M$_{\odot}$. Our results are as follows: (a) contrary to many previous studies, the circular velocity curve shows no central peak and overall agrees with recent MW observations. (b) Other quantities, such as M$\_{*}$(6$\times$10$^{10}$M$_\odot$) and R$_d$ (2.56 kpc), fall well inside the observatio…
The role of baryon models played in hydrodynamic simulations is still unclear. Future surveys that use cluster statistics to precisely constrain cosmology models require a better understanding of that. With the hydro-simulated galaxy clusters from different baryon models (Gadget-MUSIC, Gadget-X and Gizmo-SIMBA) from the THREEHUNDRED project, we can look into more details of this question. We find that the galaxy cluster mass change due to different baryon models is at a few per cent level. However, the mass changes can be positive or negative, which is depending on the baryon models. Such a sm…
Most of the baryons from galaxies have been "missing" and several studies have attempted to map the circumgalactic medium (CGM) of galaxies in their quest. Recent studies with the Hubble Space Telescope have shown that many galaxies contain a large reservoir of ionized gas with temperatures of about 10^5 K. Here we report on X-ray observations made with the Chandra X-ray Observatory probing an even hotter phase of the CGM of our Milky Way at about 10^6 K. We show that this phase of the CGM is massive, extending over a large region around the Milky Way, with a radius of over 100 kpc. The mass c…
