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Register a new userOn the kinetic Sunyaev-Zeldovich effect as an observational probe for halo spin bias
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Antonio D. Montero-Dorta Dr.
Publication date
2020
fields
Physics
and research's language is
English
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We explore the potential of the kinetic Sunyaev-Zeldovich (kSZ) effect as the cornerstone of a future observational probe for halo spin bias, the secondary dependence of halo clustering on halo spin at fixed halo mass. Using the IllustrisTNG magneto-hydrodynamical cosmological simulation, we measure both the kSZ and the thermal SZ (tSZ) effects produced by the baryonic content of more than 50,000 haloes within the halo mass range $11 < log_{10} ({rm M_{vir}}/ h^{-1} {rm M_{odot}}) lesssim 14.5$. First, we confirm that the magnitude of both effects depends strongly on the total gas and virial mass of the haloes, and that the integrated kSZ signal displays a significant correlation with the angular momentum of the intra-halo gas, particularly for massive haloes. Second, we show that both the integrated kSZ signal and the ratio of the integrated kSZ and tSZ signals trace total halo spin, even though significant scatter exists. Finally, we demonstrate that, in the absence of observational and instrumental uncertainties, these SZ-related statistics can be used to recover most of the underlying IllustrisTNG halo spin bias signal. Our analysis represents the first attempt to develop a future observational probe for halo spin bias, bringing forward alternative routes for measuring the secondary bias effects.
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We propose a novel technique to separate the late-time, post-reionization component of the kinetic Sunyaev-Zeldovich (kSZ) effect from the contribution to it from a (poorly understood and probably patchy) reionization history. The kSZ effect is one of the most promising probe of the {em missing baryons} in the Universe. We study the possibility of reconstructing it in three dimensions (3D), using future spectroscopic surveys such as the Euclid survey. By reconstructing a 3D template from galaxy density and peculiar velocity fields from spectroscopic surveys we cross-correlate the estimator against CMB maps. The resulting cross-correlation can help us to map out the kSZ contribution to CMB in 3D as a function of redshift thereby extending previous results which use tomographic reconstruction. This allows the separation of the late time effect from the contribution owing to reionization. By construction, it avoids contamination from foregrounds, primary CMB, tSZ effect as well as from star forming galaxies. Due to a high number density of galaxies the signal-to-noise (S/N) for such cross-correlational studies are higher, compared to the studies involving CMB power spectrum analysis. Using a spherical Bessel-Fourier (sFB) transform we introduce a pair of 3D power-spectra: ${cal C}^{parallel}_ell(k)$ and ${cal C}^{perp}_ell(k)$ that can be used for this purpose. We find that in a future spectroscopic survey with near all-sky coverage and a survey depth of $zapprox 1$, reconstruction of ${cal C}^{perp}_ell(k)$ can be achieved in a few radial wave bands $kapprox(0.01-0.5 h^{-1}rm Mpc)$ with a S/N of upto ${cal O}(10)$ for angular harmonics in the range $ell=(200-2000)$ (abrdiged).
We review recent results of Sunyaev-Zeldovich effect (SZE) observations toward galaxy clusters. Using cm-wave receivers mounted on the OVRO and BIMA mm-wave arrays we have obtained high signal to noise images of the effect for more than 20 clusters. We present current estimates of the Hubble constant and cosmological parameters and discuss the potential of conducting statistical studies with large SZE cluster samples.
We propose a new method to determine the electron velocity (EV) distribution function in the intracluster gas (ICG) in clusters of galaxies based on the frequency dependence of the Sunyaev-Zeldovich (SZ) effect. It is generally accepted that the relativistic equilibrium EV distribution is the one suggested by Juttner. However, there is an ongoing debate on the foundation of relativistic kinetic theory, and other distributions have also been proposed. The mildly relativistic intracluster gas (ICG) provides a unique laboratory to test relativistic kinetic theories. We carried out Monte Carlo simulations to generate SZ signal from a single-temperature gas assuming the Juttner EV distribution assuming a few per cent errors. We fitted SZ models based on non-relativistic Maxwellian, and its two relativistic generalizations, the Juttner and modified Juttner distributions. We found that a 1% error in the SZ signal is sufficient to distinguish between these distributions with high significance based on their different best-fit temperatures. However, in any LOS in a cluster, the ICG contains a range of temperatures. Using our N-body/hydrodynamical simulation of a merging galaxy cluster and assuming a 1% error in the SZ measurements in a LOS through a bow shock, we find that it is possible to distinguish between Juttner and modified Juttner distributions with high significance. Our results suggest that deriving ICG temperatures from fitting to SZ data assuming different EV distribution functions and comparing them to the temperature in the same cluster obtained using other observations would enable us to distinguish between the different distributions.11 pages, 8 figures, and 1 table, accepted for publication in the Astrophysical Journal
We propose the use of the kinetic Sunyaev-Zeldovich (kSZ) effect to probe the circumgalactic medium (CGM), with the aid of a spectroscopic survey covering the same area of a SZ survey. One can design an optimal estimator of the kSZ effect of the CGM with a matched filter, and construct the cross correlation between the estimator and the peculiar velocity recovered from the galaxy survey, which can be measured by stacking a number of galaxies. We investigate two compelling profiles for the CGM, the MB profile (Maller & Bullock 2004) and the $beta$ profile, and estimate the detectability against the synergy of a fiducial galaxy survey with number density $10^{-3}h^3,$ Mpc$^{-3}$ and an ACT-like SZ survey. We show that the shape of the filter does not change much with redshift for the $beta$ profile, while there are significant side lobes at $z<0.1$ for the MB profile. By stacking $sim 10^4$ Milky Way-size halos around z $sim 0.5$, one can get $gtrsim$ 1 $sigma$ signal to noise (S/N) for the both profiles. The S/N increases with decreasing redshift before it reaches a maximum ($sim$ 7.5 at z $simeq$ 0.15 for the MB profile, $sim 19$ at $zsimeq 0.03$ for the $beta$ profile). Due to the large beam size, a Planck-like CMB survey can marginally detect the kSZ signal by stacking the same number of galaxies at $z<0.1$. The search for the CGM in realistic surveys will involve dividing the galaxies into subsamples with similar redshift and mass of host halos, and scaling the results presented here to obtain the S/N.
We report the direct detection of the kinetic Sunyaev-Zeldovich (kSZ) effect in galaxy clusters with a 3.5 sigma significance level. The measurement was performed by stacking the Planck map at 217 GHz at the positions of galaxy clusters from the Wen-Han-Liu (WHL) catalog. To avoid the cancelation of positive and negative kSZ signals, we used the large-scale distribution of the Sloan Digital Sky Survey (SDSS) galaxies to estimate the peculiar velocities of the galaxy clusters along the line of sight and incorporated the sign in the velocity-weighted stacking of the kSZ signals. Using this technique, we were able to measure the kSZ signal around galaxy clusters beyond 3R500. Assuming a standard beta-model, we also found that the gas fraction within R500 is fgas,500 = 0.12 +- 0.04 for the clusters with the mass of M500 ~ 1e14 Msun/h. We compared this result to predictions from the Magneticum cosmological hydrodynamic simulations as well as other kSZ and X-ray measurements, most of which show a lower gas fraction than the universal baryon fraction for the same mass of clusters. Our value is statistically consistent with results from the measurements and simulations and also with the universal value within our measurement uncertainty.
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