1810.02212
Cosmological lensing ratios with DES Y1, SPT and Planck
Prat, et al
Correlations between tracers of the matter density field and gravitational lensing are sensitive to the evolution of the matter power spectrum and the expansion rate across cosmic time. Appropriately defined ratios of such correlation functions, on the other hand, depend only on the angular diameter distances to the tracer objects an to the gravitational lensing source places. Because of their simple cosmological dependence, such ratios can exploit available signal-to-noise down to small angular scales, even where directly modeling the correlation functions is difficult. Present a measurement of lensing ratios using galaxy position and lensing data from the DES, and CMB lensing data from SPT and Planck, obtaining the highest precision lensing ratio measurements to date. Relative to the concordance LCDM model, find a best lensing ratio amplitude of A=1.1±0.1. Use the ratio measurement to generate cosmological constraints, focusing on the curvature parameter. Demonstrate that photometrically selected galaxies can be used to measure lensing ratios, and argue that future lensing ratio measurements with data from a combination of LSST and Stage-4 CMB experiments can be used to place interesting cosmological constraints, even after considering the systematic uncertainties associated with photo-z and galaxy shear estimation.
1810.02374
Constraining neutrino mass with the tomographic weak lensing bispectrum
Coulton, et al
Explore the effect of massive neutrinos in the WL shear bispectrum ing the Cosmological Mssive Neutrino Simulations. Find that the primary effect of massive neutrinos is to suppress the amplitude of the bispectrum with limited effect on the bispectrum shape. The suppression of the bispectrum amplitude is a factor of 2 greater than the suppression of the small scale PS. For an LSST-like WL survey that observed half f the sky with five tomographic redshift bins, explore the constraining power of the bispectrum on 3 cosmological parameters: the sum of the neutrino mass Sum(m_nu), the matter density Omega_m, and the amplitude of primordial fluctuations A_s. Bispectrum measurements alone provide similar constraints to the PS measurements and combining the 2 probes leads to significant improvements than using the latter alone. Find that the joint constraints tighten the PS 95% constraints by ~32% for Sum(m_nu), 13% for Omega_m and 57% for A_s.
1810.02375
The dependence of halo bias on age, concentration and spin
Sato-Polito, et al
Halo bias is the main link between the matter distribution and DM haloes. In its simplest form, halo bias is determined by halo mass, but there are known additional dependencies on other halo properties which are of consequence for accurate modeling of galaxy clustering. Present the most precise measurement of these secondary-bias dependencies on halo age, concentration, and spin, for a wide range of halo masses spanning from 1e10.7 to 1e14.7 h^{-1} Msun. At the high-mass end, find no strong evidence of assembly bias for masses above M_vir ~1e14 h^{-1} Msun. Secondary bias exists, whoever, for halo concentration and spin, up to cluster-size haloes, in agreement with previous findings. For halo spin, report 2 different regimes: above M_vir~1e11.5 h^{-1} Msun, haloes with larger values of spin have larger bias, at fixed mass, with the effect reaching almost a factor 2. This trend reverses below this characteristic mass. In addition to these results, test the performance of a multi-tracer method for the determination of the relative bias between different subsets of haloes. Show that this method increases significantly the signal-to-noise of the secondary-bias measurement as compared to a traditional approach. This analysis serves as the basis for follow-up applications of the multi-tracer method to real data.
1810.02499
Dark Energy Survey Year 1 Results: constrains on extended cosmological models from galaxy clustering and weak lensing
DES Collaboration, et al
Present constraints on extension of the minimal cosmological models dominated by DM and DE, LCDM and wCDM, by using a combined analysis of galaxy clustering and WL from DES Y1 in combination with external data. Consider 4 extensions of the minimal DE-dominated scenarios: 1) nonzero curvature Omega_k, 2) number of relativistic species N_eff different from the standard value of 3.046, 3) time-varying equation-of-state of DE described by the parameters w_0 and w_a (alternative quoted by the values at the pivot redshift, w_p and w_a), and 4) modified gravity described by the parameters mu_0 and Sigma_0 that modify the metric potentials. Also consider e eternal information from Planck CMB measurements; BAO measurements from SDSS, 6dF, and BOSS; RSD measurements from BOSS; and SN1a information from the Pantheon compilation. Constraints on curvature and the number of relativistic species are dominated by the external data; when these are combined with DES Y1, find Omega_k=0.0020+0.0037-0.0032 at the 68% CL, and N_eff<3.28 (3.55) ad 68% (95%) CL. For the time-varying equation-of-state, find the pivot value (w_p, w_a)=(-0.91+0.19-0.23, -0.57+0.93-1.11) at pivot redshift z_p=0.27 from DES alone and (w_p, w_a)=(-1.01+0.04-0.04, -0.28+0.37-0.48) at pivot redshift z_p=0.20 from DES Y1 combined with external data; in either case, find no evidence for the temporal variation of the equation of state. For modified gravity, find the present-day value of the relevant parameters to be Sigma_0=0.45+0.28-0.29 from DES Y1 alone, and (Sigma_0, mu_0)=(0.06+0.08-0.07, -0.11+0.42-0.46) from DES Y1 combined with external data, consistent with predictions from GR.
1810.02564
Can the CIB constrain the dark energy?
Maniyar, et al
[...] find that the ISW is not detected with the existing CIB maps over such small sky fractions [~11% of the sky].
1810.02595
GAIA Cepheid parallaxes and 'Local Hole' relieve $H_0$ tension
Shanks, Hogarth, Metcalfe
There has been much discussion of the tension between the values of H0 implied by the distance scale and fits to the microwave background's primordial power spectrum. While the latter is fitted by standard cosmological models with H0=67.4±0.5 km/s/Mpc, the distance scale gives H_0=73.45±1.66 km/s/Mpc, an ~10%, ~3.5 sigma discrepancy. Here, first show that GAIA parallax distances of MW Cepheids may be between 7-18% larger than previously estimated, with the potential to produce a corresponding reduction in the value of H_0. Then, show that the existence of an ~150 h^{-1} Mpc 'Local Hole' in the galaxy distribution around our position implies an outflow of ~500 km/s averaging over direction. Accounting for this in the recession velocities of SNIa standard candles out to z~0.1 reduces H0 by a further ~1.8%, while maintaining reasonable consistency with the SN Hubble diagram. Combining this result with even an ~7% increase in the Cepheid distance scale due to GAIA implies an ~9% reduction in the value of the Hubble constant, decreasing from H0 ~ 73.45 to 67.6 km/s/Mpc. This would leave the distance scale and Planck CMB values entirely consistent, thus potentially relieving the previous H0 tension.
Cosmological lensing ratios with DES Y1, SPT and Planck
Prat, et al
Correlations between tracers of the matter density field and gravitational lensing are sensitive to the evolution of the matter power spectrum and the expansion rate across cosmic time. Appropriately defined ratios of such correlation functions, on the other hand, depend only on the angular diameter distances to the tracer objects an to the gravitational lensing source places. Because of their simple cosmological dependence, such ratios can exploit available signal-to-noise down to small angular scales, even where directly modeling the correlation functions is difficult. Present a measurement of lensing ratios using galaxy position and lensing data from the DES, and CMB lensing data from SPT and Planck, obtaining the highest precision lensing ratio measurements to date. Relative to the concordance LCDM model, find a best lensing ratio amplitude of A=1.1±0.1. Use the ratio measurement to generate cosmological constraints, focusing on the curvature parameter. Demonstrate that photometrically selected galaxies can be used to measure lensing ratios, and argue that future lensing ratio measurements with data from a combination of LSST and Stage-4 CMB experiments can be used to place interesting cosmological constraints, even after considering the systematic uncertainties associated with photo-z and galaxy shear estimation.
1810.02374
Constraining neutrino mass with the tomographic weak lensing bispectrum
Coulton, et al
Explore the effect of massive neutrinos in the WL shear bispectrum ing the Cosmological Mssive Neutrino Simulations. Find that the primary effect of massive neutrinos is to suppress the amplitude of the bispectrum with limited effect on the bispectrum shape. The suppression of the bispectrum amplitude is a factor of 2 greater than the suppression of the small scale PS. For an LSST-like WL survey that observed half f the sky with five tomographic redshift bins, explore the constraining power of the bispectrum on 3 cosmological parameters: the sum of the neutrino mass Sum(m_nu), the matter density Omega_m, and the amplitude of primordial fluctuations A_s. Bispectrum measurements alone provide similar constraints to the PS measurements and combining the 2 probes leads to significant improvements than using the latter alone. Find that the joint constraints tighten the PS 95% constraints by ~32% for Sum(m_nu), 13% for Omega_m and 57% for A_s.
1810.02375
The dependence of halo bias on age, concentration and spin
Sato-Polito, et al
Halo bias is the main link between the matter distribution and DM haloes. In its simplest form, halo bias is determined by halo mass, but there are known additional dependencies on other halo properties which are of consequence for accurate modeling of galaxy clustering. Present the most precise measurement of these secondary-bias dependencies on halo age, concentration, and spin, for a wide range of halo masses spanning from 1e10.7 to 1e14.7 h^{-1} Msun. At the high-mass end, find no strong evidence of assembly bias for masses above M_vir ~1e14 h^{-1} Msun. Secondary bias exists, whoever, for halo concentration and spin, up to cluster-size haloes, in agreement with previous findings. For halo spin, report 2 different regimes: above M_vir~1e11.5 h^{-1} Msun, haloes with larger values of spin have larger bias, at fixed mass, with the effect reaching almost a factor 2. This trend reverses below this characteristic mass. In addition to these results, test the performance of a multi-tracer method for the determination of the relative bias between different subsets of haloes. Show that this method increases significantly the signal-to-noise of the secondary-bias measurement as compared to a traditional approach. This analysis serves as the basis for follow-up applications of the multi-tracer method to real data.
1810.02499
Dark Energy Survey Year 1 Results: constrains on extended cosmological models from galaxy clustering and weak lensing
DES Collaboration, et al
Present constraints on extension of the minimal cosmological models dominated by DM and DE, LCDM and wCDM, by using a combined analysis of galaxy clustering and WL from DES Y1 in combination with external data. Consider 4 extensions of the minimal DE-dominated scenarios: 1) nonzero curvature Omega_k, 2) number of relativistic species N_eff different from the standard value of 3.046, 3) time-varying equation-of-state of DE described by the parameters w_0 and w_a (alternative quoted by the values at the pivot redshift, w_p and w_a), and 4) modified gravity described by the parameters mu_0 and Sigma_0 that modify the metric potentials. Also consider e eternal information from Planck CMB measurements; BAO measurements from SDSS, 6dF, and BOSS; RSD measurements from BOSS; and SN1a information from the Pantheon compilation. Constraints on curvature and the number of relativistic species are dominated by the external data; when these are combined with DES Y1, find Omega_k=0.0020+0.0037-0.0032 at the 68% CL, and N_eff<3.28 (3.55) ad 68% (95%) CL. For the time-varying equation-of-state, find the pivot value (w_p, w_a)=(-0.91+0.19-0.23, -0.57+0.93-1.11) at pivot redshift z_p=0.27 from DES alone and (w_p, w_a)=(-1.01+0.04-0.04, -0.28+0.37-0.48) at pivot redshift z_p=0.20 from DES Y1 combined with external data; in either case, find no evidence for the temporal variation of the equation of state. For modified gravity, find the present-day value of the relevant parameters to be Sigma_0=0.45+0.28-0.29 from DES Y1 alone, and (Sigma_0, mu_0)=(0.06+0.08-0.07, -0.11+0.42-0.46) from DES Y1 combined with external data, consistent with predictions from GR.
1810.02564
Can the CIB constrain the dark energy?
Maniyar, et al
[...] find that the ISW is not detected with the existing CIB maps over such small sky fractions [~11% of the sky].
1810.02595
GAIA Cepheid parallaxes and 'Local Hole' relieve $H_0$ tension
Shanks, Hogarth, Metcalfe
There has been much discussion of the tension between the values of H0 implied by the distance scale and fits to the microwave background's primordial power spectrum. While the latter is fitted by standard cosmological models with H0=67.4±0.5 km/s/Mpc, the distance scale gives H_0=73.45±1.66 km/s/Mpc, an ~10%, ~3.5 sigma discrepancy. Here, first show that GAIA parallax distances of MW Cepheids may be between 7-18% larger than previously estimated, with the potential to produce a corresponding reduction in the value of H_0. Then, show that the existence of an ~150 h^{-1} Mpc 'Local Hole' in the galaxy distribution around our position implies an outflow of ~500 km/s averaging over direction. Accounting for this in the recession velocities of SNIa standard candles out to z~0.1 reduces H0 by a further ~1.8%, while maintaining reasonable consistency with the SN Hubble diagram. Combining this result with even an ~7% increase in the Cepheid distance scale due to GAIA implies an ~9% reduction in the value of the Hubble constant, decreasing from H0 ~ 73.45 to 67.6 km/s/Mpc. This would leave the distance scale and Planck CMB values entirely consistent, thus potentially relieving the previous H0 tension.
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