Observed galaxy clustering exhibits local transverse statistical isotropy around the line of sight (LOS). The variation of the LOS across a galaxy survey complicates the measurement of the observed ...clustering as a function of the angle to the LOS, as fast Fourier transforms (FFTs) based on Cartesian grids, cannot individually allow for this. Recent advances in methodology for calculating LOS-dependent clustering in Fourier space include the realization that power spectrum LOS-dependent moments can be constructed from sums over galaxies, based on approximating the LOS to each pair of galaxies by the LOS to one of them. We show that we can implement this method using multiple FFTs, each measuring the LOS-weighted clustering along different axes. The Nlog N nature of FFTs means that the computational speed-up is a factor of >1000 compared with summing over galaxies. This development should be beneficial for future projects such as DESI and Euclid which will provide an order of magnitude more galaxies than current surveys.
We measure and analyse the bispectrum of the final data release 12 (DR12), galaxy sample provided by the Baryon Oscillation Spectroscopic Survey, splitting by selection algorithm into LOWZ and CMASS ...galaxies. The LOWZ sample contains 361 762 galaxies with an effective redshift of z sub( LOWZ) = 0.32, and the CMASS sample contains 777 202 galaxies with an effective redshift of z sub( CMASS) = 0.57. Combining the power spectrum, measured relative to the line of sight, with the spherically averaged bispectrum, we are able to constrain the product of the growth of structure parameter, f, and the amplitude of dark matter density fluctuations, ..., along with the geometric Alcock-Paczynski parameters, the product of the Hubble constant and the comoving sound horizon at the baryon drag epoch, H(z)r sub( s)(z sub( d)), and the angular distance parameter divided by the sound horizon, D sub( A)(z)/r sub( s)(z sub( d)). After combining pre-reconstruction RSD analyses of the power spectrum monopole, quadrupole and bispectrum monopole with post-reconstruction analysis of the BAO power spectrum monopole and quadrupole, we find f(z sub( LOWZ))...(z sub( LOWZ)) = 0.427 plus or minus 0.056, D sub( A)(z sub( LOWZ))/r sub( s)(z sub( d)) = 6.60 plus or minus 0.13, H(z sub( LOWZ))r sub( s)(z sub( d)) = (11.55 plus or minus 0.38)10 super( 3) km s super( -1) for the LOWZ sample, and f(z sub( CMASS))...(z sub( CMASS)) = 0.426 plus or minus 0.029, D sub( A)(z sub( CMASS))/r sub( s)(z sub( d)) = 9.39 plus or minus 0.10, H(z sub( CMASS))r sub( s)(z sub( d)) = (14.02 plus or minus 0.22)10 super( 3) km s super( -1) for the CMASS sample. We find general agreement with previous Baryon Oscillation Spectroscopic Survey DR11 and DR12 measurements. Combining our data set with Planck15 we perform a null test of General Relativity through the ...-parametrization finding ...=0.733..., which is ~2.7... away from the General Relativity predictions. (ProQuest: ... denotes formulae/symbols omitted.)
We examine the cosmological implications of the measurements of the linear growth rate of cosmological structure obtained in a companion paper from the power spectrum and bispectrum monopoles of the ...Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey Data Release 11, CMASS galaxies. This measurement was of f 0.43σ8, where σ8 is the amplitude of dark matter density fluctuations, and f is the linear growth rate, at the effective redshift of the survey, z
eff = 0.57. In conjunction with cosmic microwave background (CMB) data, interesting constraints can be placed on models with non-standard neutrino properties and models where gravity deviates from General Relativity on cosmological scales. In particular, the sum of the masses of the three species of the neutrinos is constrained to m
ν < 0.49 eV (at 95 per cent confidence level) when the f 0.43σ8 measurement is combined with state-of-the-art CMB measurements. Allowing the effective number of neutrinos to vary as a free parameter does not significantly change these results. When we combine the measurement of f 0.43σ8 with the complementary measurement of fσ8 from the monopole and quadrupole of the two-point correlation function, we are able to obtain an independent measurements of f and σ8. We obtain f = 0.63 ± 0.16 and σ8 = 0.710 ± 0.086 (68 per cent confidence level). This is the first time when these parameters have been able to be measured independently using the redshift-space power spectrum and bispectrum measurements from galaxy clustering data only.
A tale of two (or more) h's Brieden, Samuel; Gil-Marín, Héctor; Verde, Licia
Journal of cosmology and astroparticle physics,
04/2023, Letnik:
2023, Številka:
4
Journal Article
ABSTRACT
Cosmological studies of large-scale structure have relied on two-point statistics, not fully exploiting the rich structure of the cosmic web. In this paper we show how to capture some of ...this cosmic web information by using the minimum spanning tree (MST), for the first time using it to estimate cosmological parameters in simulations. Discrete tracers of dark matter such as galaxies, N-body particles or haloes are used as nodes to construct a unique graph, the MST, that traces skeletal structure. We study the dependence of the MST on cosmological parameters using haloes from a suite of COmoving Lagrangian Acceleration (COLA) simulations with a box size of $250\ h^{-1}\, {\rm Mpc}$, varying the amplitude of scalar fluctuations (As), matter density (Ωm), and neutrino mass (∑mν). The power spectrum P and bispectrum B are measured for wavenumbers between 0.125 and 0.5 $h\, {\rm Mpc}^{-1}$, while a corresponding lower cut of ∼12.6 $h^{-1}\, {\rm Mpc}$ is applied to the MST. The constraints from the individual methods are fairly similar but when combined we see improved 1σ constraints of $\sim 17{{\ \rm per\ cent}}$ ($\sim 12{{\ \rm per\ cent}}$) on Ωm and $\sim 12{{\ \rm per\ cent}}$ ($\sim 10{{\ \rm per\ cent}}$) on As with respect to P (P + B) thus showing the MST is providing additional information. The MST can be applied to current and future spectroscopic surveys (BOSS, DESI, Euclid, PSF, WFIRST, and 4MOST) in 3D and photometric surveys (DES and LSST) in tomographic shells to constrain parameters and/or test systematics.
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