Sunyaev-Zeldovich Cluster Surveys Research Articles

Constraints on neutrino mass from Sunyaev-Zeldovich cluster surveys

The presence of massive neutrinos has a characteristic impact on the growth of large scale structures such as galaxy clusters. We forecast on the capability of the number count and power spectrum measured from the ongoing and future Sunyaev-Zeldovich cluster surveys, combined with cosmic microwave background (CMB) observation to constrain the total neutrino mass ${M}_{\ensuremath{\nu}}$ in a flat $\ensuremath{\Lambda}\mathrm{CDM}$ cosmology. We adopt self-calibration for the mass-observable scaling relation and evaluate constraints for the South Pole Telescope normally and with polarization, Planck, and Atacama Cosmology Telescope Polarization surveys. We find that a sample of $\ensuremath{\approx}1000$ clusters obtained from the Planck cluster survey plus extra information from CMB lensing extraction could tighten the current upper bound on the sum of neutrino masses to ${\ensuremath{\sigma}}_{{M}_{\ensuremath{\nu}}}=0.17\text{ }\text{ }\mathrm{eV}$ at 68% C.L. Our analysis shows that cluster number counts and the power spectrum provide complementary constraints, and as a result they help reducing the error bars on ${M}_{\ensuremath{\nu}}$ by a factor of 4--8 when both probes are combined. We also show that the main strength of cluster measurements in constraining ${M}_{\ensuremath{\nu}}$ is when good control of cluster systematics is available. When applying a weak prior on the mass-observable relations, which can be at reach in the upcoming cluster surveys, we obtain ${\ensuremath{\sigma}}_{{M}_{\ensuremath{\nu}}}=0.48\text{ }\text{ }\mathrm{eV}$ using cluster only probes and, more interestingly, ${\ensuremath{\sigma}}_{{M}_{\ensuremath{\nu}}}=0.08\text{ }\text{ }\mathrm{eV}$ using cluster $+$ CMB, which corresponds to a $S/N\ensuremath{\approx}4$ detection for ${M}_{\ensuremath{\nu}}\ensuremath{\ge}0.3\text{ }\text{ }\mathrm{eV}$. We analyze and discuss the degeneracies of ${M}_{\ensuremath{\nu}}$ with other parameters and investigate the sensitivity of neutrino mass constraints with various surveys specifications.

Constraints on non-Gaussianity from Sunyaev-Zeldovich cluster surveys

We perform a Fisher matrix analysis to forecast the capability of ongoing and future Sunyaev-Zeldovich cluster surveys in constraining the deviations from Gaussian distribution of primordial density perturbations. We use the constraining power of the cluster number counts and clustering properties to forecast limits on the ${f}_{\mathrm{NL}}$ parameter. The primordial non-Gaussianity (NG) effects on the mass function and halo bias are considered. We adopt self-calibration for the mass-observable scaling relation and evaluate constraints for the South Pole Telescope, Planck, CCAT-like, South Pole Telescope polarization survey, and Atacama Cosmology Telescope polarization survey. We show that the scale dependence of the halo bias induced by the local NG provides strong constraints on ${f}_{\mathrm{NL}}$, while the results from number count are two orders of magnitude worse. When combining information from number counts and the power spectrum, the Planck cluster catalog provides the tightest constraint with ${\ensuremath{\sigma}}_{{f}_{\mathrm{NL}}}=7$ (68% C.L.) even for relatively conservative assumptions on the expected cluster yields and systematics. This value is a factor of 2 smaller than the $1\ensuremath{\sigma}$ error as measured by WMAP cosmic microwave background measurements and comparable to what is expected from Planck. We find that the results are mildly sensitive to the mass threshold of the surveys but strongly depend on the survey coverage; a full-sky survey like Planck is more favorable because it can probe longer wavelength modes that are most sensitive to NG effects. In addition, the constraints are largely insensitive to priors on nuisance parameters as they are mainly driven by the power spectrum probe, which has a mild dependence on the mass-observable relations.

Constraints on modified gravity from Sunyaev-Zeldovich cluster surveys

We investigate the constraining power of current and future Sunyaev-Zeldovich cluster surveys on the $f(R)$ gravity model. We use a Fisher matrix approach, adopt self-calibration for the mass-observable scaling relation, and evaluate constraints for the South Pole Telescope (SPT), Planck, SPT polarimeter (SPTpol), and Atacama Cosmology Telescope polarimeter (ACTpol) surveys. The modified gravity effects on the mass function, halo bias, matter power spectrum, and mass-observable relation are taken into account. We show that, relying on number counts only, the Planck cluster catalog is expected to reduce current upper limits by about a factor of 4, to ${\ensuremath{\sigma}}_{{f}_{R0}}=2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ (68% confidence level) while SPT, SPTpol, and ACTpol yield about $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$. Adding the cluster power spectrum further improves the constraints to ${\ensuremath{\sigma}}_{{f}_{R0}}=5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ for Planck and ${\ensuremath{\sigma}}_{{f}_{R0}}=2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ for SPTpol, pushing cluster constraints significantly beyond the limit where number counts have no constraining power due to the chameleon screening mechanism. Further, the combination of both observables breaks degeneracies, especially with the expansion history (effective dark energy density and equation of state). The constraints are only mildly worsened by the use of self-calibration but depend on the mass threshold and redshift coverage of the cluster samples.

Dynamics and constraints of the dissipative Liouville cosmology

In this article we investigate the properties of the FLRW flat cosmological models in which the cosmic expansion of the Universe is affected by a dilaton dark energy (Liouville scenario). In particular, we perform a detailed study of these models in the light of the latest cosmological data, which serves to illustrate the phenomenological viability of the new dark energy paradigm as a serious alternative to the traditional scalar field approaches. By performing a joint likelihood analysis of the recent supernovae type Ia data (SNIa), the differential ages of passively evolving galaxies, and the baryonic acoustic oscillations (BAOs) traced by the Sloan Digital Sky Survey (SDSS), we put tight constraints on the main cosmological parameters. Furthermore, we study the linear matter fluctuation field of the above Liouville cosmological models. In this framework, we compare the observed growth rate of clustering measured from the optical galaxies with those predicted by the current Liouville models. Performing various statistical tests we show that the Liouville cosmological model provides growth rates that match well with the observed growth rate. To further test the viability of the models under study, we use the Press–Schechter formalism to derive their expected redshift distribution of cluster-size halos that will be provided by future X-ray and Sunyaev–Zeldovich cluster surveys. We find that the Hubble flow differences between the Liouville and the LambdaCDM models provide a significantly different halo redshift distribution, suggesting that the models can be observationally distinguished.

Hubble expansion and structure formation in the ``running FLRW model'' of the cosmic evolution

A new class of Friedmann-Lemaître-Robertson-Walker (FLRW)cosmological models with time-evolving fundamental parameters shouldemerge naturally from a description of the expansion of the universebased on the first principles of quantum field theory and stringtheory. Within this general paradigm, one expects that both thegravitational Newton's coupling G and the cosmological term Λshould not be strictly constant but appear rather as smoothfunctions of the Hubble rate H(t).This scenario (``running FLRW model'') predicts, in a natural way,the existence of dynamical dark energy without invoking theparticipation of extraneous scalar fields.In this paper, we perform a detailed study of some of these modelsin the light of the latest cosmological data, which serves toillustrate the phenomenological viability of the new dark energyparadigm as a serious alternative to the traditional scalar fieldapproaches. By performing a joint likelihood analysis of the recentsupernovae type Ia data (SNIa), the Cosmic Microwave Background(CMB) shift parameter, and the Baryonic Acoustic Oscillations (BAOs)traced by the Sloan Digital Sky Survey (SDSS), we put tightconstraints on the main cosmological parameters. Furthermore, wederive the theoretically predicted dark-matter halo mass functionand the corresponding redshift distribution of cluster-size halosfor the ``running'' models studied. Despite the fact that thesemodels closely reproduce the standard ΛCDM Hubble expansion,their normalization of the perturbation's power-spectrum varies,imposing, in many cases, a significantly different cluster-sizehalo redshift distribution. This fact indicates that it should berelatively easy to distinguish between the ``running'' models andthe ΛCDM using realistic future X-ray and Sunyaev-Zeldovichcluster surveys.

Dynamics and constraints of the massive graviton dark matter flat cosmologies

We discuss the dynamics of the Universe within the framework of the massive graviton cold dark matter scenario (MGCDM) in which gravitons are geometrically treated as massive particles. In this modified gravity theory, the main effect of the gravitons is to alter the density evolution of the cold dark matter component in such a way that the Universe evolves to an accelerating expanding regime, as presently observed. Tight constraints on the main cosmological parameters of the MGCDM model are derived by performing a joint likelihood analysis involving the recent supernovae type Ia data, the cosmic microwave background shift parameter, and the baryonic acoustic oscillations as traced by the Sloan Digital Sky Survey red luminous galaxies. The linear evolution of small density fluctuations is also analyzed in detail. It is found that the growth factor of the MGCDM model is slightly different ($\ensuremath{\sim}1--4%$) from the one provided by the conventional flat $\ensuremath{\Lambda}\mathrm{CDM}$ cosmology. The growth rate of clustering predicted by MGCDM and $\ensuremath{\Lambda}\mathrm{CDM}$ models are confronted to the observations and the corresponding best fit values of the growth index ($\ensuremath{\gamma}$) are also determined. By using the expectations of realistic future x-ray and Sunyaev-Zeldovich cluster surveys we derive the dark matter halo mass function and the corresponding redshift distribution of cluster-size halos for the MGCDM model. Finally, we also show that the Hubble flow differences between the MGCDM and the $\ensuremath{\Lambda}\mathrm{CDM}$ models provide a halo redshift distribution departing significantly from the those predicted by other dark energy models. These results suggest that the MGCDM model can observationally be distinguished from $\ensuremath{\Lambda}\mathrm{CDM}$ and also from a large number of dark energy models recently proposed in the literature.

Probing the largest cosmological scales with the correlation between the cosmic microwave background and peculiar velocities

Cross correlation between the cosmic microwave background (CMB) and large-scale structure is a powerful probe of dark energy and gravity on the largest physical scales. We introduce a novel estimator, the CMB-velocity correlation, that has most of its power on large scales and that, at low redshift, delivers up to a factor of 2 higher signal-to-noise ratio than the recently detected CMB-dark matter density correlation expected from the integrated Sachs-Wolfe effect. We propose to use a combination of peculiar velocities measured from supernovae type Ia and kinetic Sunyaev-Zeldovich cluster surveys to reveal this signal and forecast dark energy constraints that can be achieved with future surveys. We stress that low redshift peculiar velocity measurements should be exploited with complementary deeper large-scale structure surveys for precision cosmology.

The hybrid SZ power spectrum: combining cluster counts and SZ fluctuations to probe gas physics

Sunyaev-Zeldovich (SZ) effect from a cosmological distribution of clusters carry information on the underlying cosmology as well as the cluster gas physics. In order to study either cosmology or clusters one needs to break the degeneracies between the two. We present a toy model showing how complementary informations from SZ power spectrum and the SZ flux counts, both obtained from upcoming SZ cluster surveys, can be used to mitigate the strong cosmological influence (especially that of sigma_8) on the SZ fluctuations. Once the strong dependence of the cluster SZ power spectrum on sigma_8 is diluted, the cluster power spectrum can be used as a tool in studying cluster gas structure and evolution. The method relies on the ability to write the Poisson contribution to the SZ power spectrum in terms the observed SZ flux counts. We test the toy model by applying the idea to simulations of SZ surveys.

Expectations for Sunyaev‐Zeldovich Cluster Counts: Mass Function versus X‐Ray Luminosity Function

We present a comparison of the Sunyaev-Zeldovich (SZ) cluster counts predicted by the Press-Schechter (PS) mass function (MF) and the X-ray luminosity function (XLF) of clusters. The employment of the cluster XLF, together with the observationally determined X-ray luminosity-temperature (LX-T) relation, may allow us to estimate the SZ cluster counts in a more realistic manner, although such an empirical approach depends sensitively on our current knowledge of the dynamical properties of intracluster gas and its cosmic evolution. Using both the nonevolving and evolving XLFs of clusters suggested by X-ray observations, we calculate the expectations for SZ surveys of clusters with X-ray luminosity LX ≥ 3 × 1044 ergs s-1 and LX ≥ 1 × 1043 ergs s-1 in the 0.5-2.0 band, respectively. The nonevolving XLF results in a significant excess of SZ cluster counts at high redshifts as compared with the evolving XLF, while a slightly steeper LX-T relation than the observed one is needed to reproduce the distributions of SZ clusters predicted by the standard PS formalism. It is pointed out that uncertainties in the cosmological application of future SZ cluster surveys via the standard PS formalism should be carefully studied.