Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userEnvironmental dependence of X-ray and optical properties of galaxy clusters
73
0
0.0
(
0
)
Added by
Maria Manolopoulou Miss
Publication date
2020
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
Galaxy clusters are widely used to constrain cosmological parameters through their properties, such as masses, luminosity and temperature distributions. One should take into account all kind of biases that could affect these analyses in order to obtain reliable constraints. In this work, we study the difference in the properties of clusters residing in different large scale environments, defined by their position within or outside of voids, and the density of their surrounding space. We use both observational and simulation cluster and void catalogues, i.e. XCS and redMaPPer clusters, BOSS voids, and Magneticum simulations. We devise two different environmental proxies for the clusters and study their redshift, richness, mass, X-ray luminosity and temperature distributions as well as some properties of their galaxy populations. We use the Kolmogorov-Smirnov two-sample test to discover that richer and more massive clusters are more prevalent in overdense regions and outside of voids. We also find that clusters of matched richness and mass in overdense regions and outside voids tend to have higher X-ray luminosities and temperatures. These differences could have important implications for precision cosmology with clusters of galaxies, since cluster mass calibrations can vary with environment.
rate research
Read More
We use SDSS data to investigate the scaling relations of 127 NoSOCS and 56 CIRS galaxy clusters at low redshift ($z le 0.10$). We show that richness and both optical and X-ray luminosities are reliable mass proxies. The scatter in mass at fixed observable is $sim$ 40%, depending on the aperture, sample and observable considered. For example, for the massive CIRS systems $sigma_{lnM500|N500}$ = 0.33 $pm$ 0.05 and $sigma_{lnM500|Lx}$ = 0.48 $pm$ 0.06. For the full sample $sigma_{lnM500|N500}$ = 0.43 $pm$ 0.03 and $sigma_{lnM500|Lx}$ = 0.56 $pm$ 0.06. We estimate substructure using two and three dimensional optical data, verifying that substructure has no significant effect on the cluster scaling relations (intercepts and slopes), independent of which substructure test we use. For a subset of twenty-one clusters, we estimate masses from the M-T$_X$ relation using temperature measures from BAX. The scaling relations derived from the optical and X-ray masses are indeed very similar, indicating that our method consistently estimates the cluster mass and yields equivalent results regardless of the wavelength from which we measure mass. For massive systems, we represent the mass-richness relation by a function with the form ${rm ln (M_{200}) = A + B times ln(N_{200}/60)}$, with M$_{200}$ being expressed in units of 10$^{14}$ M$_{odot}$. Using the virial mass, for CIRS clusters, we find A = (1.39 $pm$ 0.07) and B = (1.00 $pm$ 0.11). The relations based on the virial mass have a scatter of $sigma_{lnM200|N200}$ = 0.37 $pm$ 0.05, while $sigma_{lnM200|N200}$ = 0.77 $pm$ 0.22 for the caustic mass and $sigma_{lnM200|N200}$ = 0.34 $pm$ 0.08 for the temperature based mass (abridged).
We study the stellar mass distribution for galaxies in 160 X-ray detected groups of 10^13<Log(M_200/M_sun)<2x10^14 and compare it with that of galaxies in the field, to investigate the action of environment on the build up of the stellar mass. We highlight differences in the build up of the passive population in the field, which imprint features in the distribution of stellar mass of passive galaxies at Log(M/M_sun)< 10.5. The gradual diminishing of the effect when moving to groups of increasing total masses indicates that the growing influence of the environment in bound structures is responsible for the build up of a quenched component at Log(M/M_sun)< 10.5. Differently, the stellar mass distribution of star forming galaxies is similar in shape in all the environments, and can be described by a single Schechter function both in groups and in the field. Little evolution is seen up to redshift 1. Nevertheless at z=0.2-0.4 groups with M_200<6x10^13 Msun (low mass groups) tend to have a characteristic mass for star forming galaxies which is 50% higher than in higher mass groups; we interpret it as a reduced action of environmental processes in such systems. Furthermore we analyse the distribution of sSFR--Log(M) in groups and in the field, and find that groups show on average a lower sSFR (by ~0.2 dex) at z<0.8. Accordingly, we find that the fraction of star forming galaxies is increasing with redshift in all environments, but at a faster pace in the denser ones. Finally our analysis highlights that low mass groups have a higher fraction (by 50%) of the stellar mass locked in star forming galaxies than higher mass systems (i.e. 2/3 of their stellar mass).
We present the X-ray properties and scaling relations of a large sample of clusters extracted from the Marenostrum MUltidark SImulations of galaxy Clusters (MUSIC) dataset. We focus on a sub-sample of 179 clusters at redshift z~0.11, with 3.2e14M_sun/h<M_vir<2e15Msun/h, complete in mass. We employed the X-ray photon simulator PHOX to obtain synthetic Chandra Observations and derive observable-like global properties of the intracluster medium (ICM), as X-ray temperature (T_X) and luminosity (L_X). T_X is found to slightly under-estimate the true mass-weighted temperature, although tracing fairly well the cluster total mass. We also study the effects of T_X on scaling relations with cluster intrinsic properties: total (M_500) and gas (M_g500) mass; integrated Compton parameter (Y_SZ) of the Sunyaev-Zeldovich (SZ) thermal effect; Y_X=M_g500 T_X. We confirm that Y_X is a very good mass proxy, with a scatter on M_500-Y_X and Y_SZ-Y_X lower than 5%. The study of scaling relations among X-ray, intrinsic and SZ properties indicates that MUSIC clusters reasonably resemble the self-similar prediction, especially for correlations involving T_X. The observational approach also allows for a more direct comparison with real clusters, from which we find deviations mainly due to the physical description of the ICM, affecting T_X and, particularly, L_X.
Galaxy clusters have their unique advantages for cosmology. Here we collect a new sample of 10 lensing galaxy clusters with X-ray observations to constrain cosmological parameters.The redshifts of lensing clusters lie between 0.1 and 0.6, and the redshift range of their arcs is from 0.4 to 4.9. These clusters are selected carefully from strong gravitational lensing systems which have both X-ray satellite observations and optical giant luminous arcs with known redshift. Giant arcs usually appear in the central region of clusters, where mass can be traced with luminosity quite well. Based on gravitational lensing theory and cluster mass distribution model we can derive an Hubble constant independent ratio between two angular diameter distances. One is the distance of lensing source and the other is that between the deflector and the source. Since angular diameter distance relies heavily on cosmological geometry, we can use these ratios to constrain cosmological models. Meanwhile X-ray gas fractions of galaxy clusters can also be a cosmological probe. Because there are a dozen parameters to be fitted, we introduce a new analytic algorithm, Powells UOBYQA (Unconstrained Optimization By Quadratic Approximation), to accelerate our calculation. Our result proves that this algorithm is an effective fitting method for such continuous multi-parameter constraint. We find an interesting fact that these two approaches are sensitive to $Omega_{Lambda}$ and $Omega_{M}$ separately. Combining them we can get quite good fitting values of basic cosmological parameters: $Omega_{M}=0.26_{-0.04}^{+0.04}$, and $Omega_{Lambda}=0.82_{-0.16}^{+0.14}$ .
We used optical imaging and spectroscopic data to derive substructure estimates for local Universe ($z < 0.11$) galaxy clusters from two different samples. The first was selected through the Sunyaev-Zeldovich (SZ) effect by the Planck satellite and the second is an X-ray selected sample. In agreement to X-ray substructure estimates we found that the SZ systems have a larger fraction of substructure than the X-ray clusters. We have also found evidence that the higher mass regime of the SZ clusters, compared to the X-ray sample, explains the larger fraction of disturbed objects in the Planck data. Although we detect a redshift evolution in the substructure fraction, it is not sufficient to explain the different results between the higher-z SZ sample and the X-ray one. We have also verified a good agreement ($sim$60$%$) between the optical and X-ray substructure estimates. However, the best level of agreement is given by the substructure classification given by measures based on the brightest cluster galaxy (BCG), either the BCG$-$X-ray centroid offset, or the magnitude gap between the first and second BCGs. We advocate the use of those two parameters as the most reliable and cheap way to assess cluster dynamical state. We recommend an offset cut of $sim$0.01$times$R$_{500}$ to separate relaxed and disturbed clusters. Regarding the magnitude gap the separation can be done at $Delta m_{12} = 1.0$. The central galaxy paradigm (CGP) may not be valid for $sim$20$%$ of relaxed massive clusters. This fraction increases to $sim$60$%$ for disturbed systems.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
