We present a simple and efficient phenomenological model for the two-dimensional two-point galaxy correlation function that works well over a wide range of scales, from large scales down to scales as ...small as 25 h
−1 Mpc. Our model incorporates non-linear effects and a scale-dependent galaxy bias on small scales, and it allows the redshift-space distortions to be scale and direction dependent. We validate our model using LasDamas mock catalogues and apply it to the Sloan Digital Sky Survey (SDSS) Data Release Seven (DR7) luminous red galaxies (LRGs). Using only the monopole and quadrupole of the correlation function measured from the SDSS DR7 LRGs, we obtain improved measurements H(z)r
s
(z
d
)/c = 0.0433 ± 0.0042, D
A(z)/rs
(zd
) = 6.59 ± 0.46 and f (z)σ8(z) = 0.429 ± 0.089 at z = 0.35, using the scale range 25 < s < 120 h
−1 Mpc. We expect our results and model to be useful in tightening dark energy and gravity constraints from the full analysis of current and future galaxy clustering data.
ABSTRACT
We present a method for measuring the Hubble parameter, H(z), and angular diameter distance, DA(z), from the two‐dimensional two‐point correlation function and validate it using LasDamas ...mock galaxy catalogues. Applying our method to the sample of luminous red galaxies from the Sloan Digital Sky Survey Data Release 7, we measure H(z=0.35)≡H(0.35)=82.1−4.9+4.8 km s−1 Mpc −1 and DA(z=0.35)≡DA(0.35)=1048−58+60 Mpc without assuming a dark energy model or a flat universe. We find that the derived measurements of H(0.35) rs(zd)/c and DA(0.35)/rs(zd) where rs(zd) is the sound horizon at the drag epoch are nearly uncorrelated, have tighter constraints and are more robust with respect to possible systematic effects. Our galaxy clustering measurements of {H(0.35)rs(zd)/c,DA(0.35)/rs(zd)}={0.0434±0.0018,6.60±0.26} (with the correlation coefficient r = 0.0604) can be used to combine with cosmic microwave background and any other cosmological data sets to constrain dark energy. Our results represent the first measurements of H(z) and DA(z) (or H(z) rs(zd)/c and DA(0.35)/rs(zd)) from galaxy clustering data. Our work has significant implications for future surveys in establishing the feasibility of measuring both H(z) and DA(z) from galaxy clustering data.
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 present a new methodology to generate mock halo or galaxy catalogues, which have accurate clustering properties, nearly indistinguishable from full N-body solutions, in terms of the one-point, ...two-point, and three-point statistics. In particular, the agreement is remarkable, within 1 per cent up to k = 0.55 h Mpc... and down to r = 10 h... Mpc, for the power spectrum and two-point correlation function, respectively, while the bispectrum agrees in general within 20 per cent for different scales and shapes. Our approach is based on the Zel'dovich approximation, however, effectively including with the simple prescriptions the missing physical ingredients, and stochastic scale-dependent, non-local, and non-linear biasing contributions. The computing time and memory required to produce one mock is similar to that using the lognormal model. With high accuracy and efficiency, the effective Zel'dovich approximation mocks (EZmocks) provide a reliable and practical method to produce massive mock galaxy catalogues for the analysis of large-scale structure measurements. (ProQuest: ... denotes formulae/symbols omitted.)
We measure and analyse the clustering of the Baryon Oscillation Spectroscopic Survey (BOSS) relative to the line of sight (LOS), for LOWZ and CMASS galaxy samples drawn from the final Data Release ...12. The LOWZ sample contains 361 762 galaxies with an effective redshift of z
lowz = 0.32, and the CMASS sample 777 202 galaxies with an effective redshift of z
cmass = 0.57. From the power spectrum monopole and quadrupole moments around the LOS, we measure the growth of structure parameter f times the amplitude of dark matter density fluctuations σ8 by modelling the redshift-space distortion signal. When the geometrical Alcock–Paczynski effect is also constrained from the same data, we find joint constraints on fσ8, the product of the Hubble constant and the comoving sound horizon at the baryon-drag epoch H(z)r
s(z
d), and the angular distance parameter divided by the sound horizon D
A(z)/r
s(z
d). We find f(z
lowz)σ8(z
lowz) = 0.394 ± 0.062, D
A(z
lowz)/r
s(z
d) = 6.35 ± 0.19, H(z
lowz)r
s(z
d) = (11.41 ± 0.56) 103 km s− 1 for the LOWZ sample, and f(z
cmass)σ8(z
cmass) = 0.444 ± 0.038, D
A(z
cmass)/r
s(z
d) = 9.42 ± 0.15, H(z
cmass)r
s(z
d) = (13.92 ± 0.44) 103 km s− 1 for the CMASS sample. We find general agreement with previous BOSS DR11 measurements. Assuming the Hubble parameter and angular distance parameter are fixed at fiducial Λcold dark matter values, we find f(z
lowz)σ8(z
lowz) = 0.485 ± 0.044 and f(z
cmass)σ8(z
cmass) = 0.436 ± 0.022 for the LOWZ and CMASS samples, respectively.
ABSTRACT
We perform a simulation with Galacticus, a semi-analytical galaxy formation model, to predict the number counts of H α and O iii emitting galaxies. With a state-of-the-art N-body simulation, ...UNIT, we first calibrate Galacticus with the current observation of H α luminosity function. The resulting model coupled with a dust attenuation model, can reproduce the current observations, including the H α luminosity function from HiZELS and number density from WISP. We extrapolate the model prediction to higher redshift and the result is found to be consistent with previous investigations. We then use the same galaxy formation model to predict the number counts for O iii emitting galaxies. The result provides further validation of our galaxy formation model and dust model. We present number counts of H α and O iii emission line galaxies for three different line flux limits: 5 × 10−17erg s−1 cm−2, 1 × 10−16 erg s−1 cm−2 (6.5σ nominal depth for WFIRST GRS), and 2 × 10−16 erg s−1 cm−2 (3.5σ depth of Euclid GRS). At redshift 2 < z < 3, our model predicts that WFIRST can observe hundreds of O iii emission line galaxies per square degree with a line flux limit of 1 × 10−16 erg s−1 cm−2. This will provide accurate measurement of large-scale structure to probe dark energy over a huge cosmic volume to an unprecedented high redshift. Finally, we compare the flux ratio of H α/O iii within the redshift range of 0 < z < 3. Our results show the known trend of increasing H α/O iii flux ratio with H α flux at low redshift, which becomes a weaker trend at higher redshifts.
We investigate the anisotropic clustering of the Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 12 sample, which consists of 1198 006 galaxies in the redshift range 0.2 < z < 0.75 and a ...sky coverage of 10 252 deg2. We analyse this data set in Fourier space, using the power-spectrum multipoles to measure redshift-space distortions simultaneously with the Alcock-Paczynski effect and the baryon acoustic oscillation scale. We include the power-spectrum monopole, quadrupole and hexadecapole in our analysis and compare our measurements with a perturbation-theory-based model, while properly accounting for the survey window function. To evaluate the reliability of our analysis pipeline, we participate in a mock challenge, which results in systematic uncertainties significantly smaller than the statistical uncertainties. While the high-redshift constraint on fs8 at zeff = 0.61 indicates a small (~1.4s) deviation from the prediction of the Planck ...CDM (... cold dark matter) model, the low-redshift constraint is in good agreement with Planck ...CDM. This paper is part of a set that analyses the final galaxy clustering data set from BOSS. The measurements and likelihoods presented here are combined with others in Alam et al. to produce the final cosmological constraints from BOSS. (ProQuest: ... denotes formulae/symbols omitted.)
ABSTRACT
We present measurements of the linear galaxy bias of Hα and O iii emission-line galaxies (ELGs) for the High Latitude Spectroscopic Survey (HLSS) of Nancy Grace Roman Space Telescope (or ...Roman), using galaxy mocks constructed using semi-analytical model for galaxy formation, Galacticus, with a large cosmic volume and redshift coverage. We compute the two-point statistics of galaxies in configuration space and measure linear bias within scales of 10–50 h−1 Mpc. We adopt different selection algorithms to investigate the impact of the Roman line flux cut, as well as the effect of dust model used to calibrate Galacticus, on the bias measurements. We consider galaxies with Hα and O iii emissions over the redshift range 1 < z < 3, as specified by the current baseline for the Roman HLSS. We find that the linear bias for the Hα and O iii ELGs can be expressed as a linear function with respect to redshift: b ≃ 0.9z + 0.5 for H$\alpha \, (1\lt z\lt 2)$, and b ≃ z + 0.5 for O iii (2 < z < 3). We have also measured the halo occupation distributions of these Hα and O iii ELGs to understand their distribution within dark matter haloes. Our results provide key input to enable the reliable forecast of dark energy and cosmology constraints from Roman.
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