1805.03254
Implication of the shape of the EDGES signal for the 21cm power spectrum
Kaurov, Venumadhav, Dai, Zaldarriaga
Revisit the 21cm PS from the epoch of cosmic dawn in light of the recent EDGES detection of the 21cm global signal at frequencies corresponding to z~20. The shape of the signal suggests that the spin temperature of neutral hydrogen was coupled to the kinetic temperature of the gas relatively rapidly (19<~z<~21). Therefore consider models in which the UV photons were dominantly produced in the rarest and most massive haloes (M>~1e9Msun), since their abundance grows fast enough at those redshifts to account for this feature of the signal. Show that these models predict large power spectrum amplitudes during the inhomogeneous coupling, and then inhomogeneous heating by CMB and Ly-a photons due to the large shot noise associated with rare sources. The PS is enhanced by more than an order of magnitude compared to previous models which did not include the shot noise contribution, making it a promising target for upcoming radio interferometers that aim to detect high-redshift 21cm fluctuations.
1805.04114
The correspondence between convergence peaks from weak lensing and massive dark matter haloes
Wei, et al
The convergence peaks, constructed from galaxy shape measurement in WL, is a power probe of cosmology as the peaks can be connected with the underlined DM haloes. However, the capability of convergence peak statistic is affected by the noise in galaxy shape measurement, signal to noise ratio as well as the contribution form the projected mass distribution from the LSS along the LoS. In this paper, use the ray-tracing sim on a curved sky to investigate the correspondence between the convergence peak and the DM haloes at the LoS. Find that, in case of no noise and for source galaxies at z_s=1, more than 65% peaks with SNR >=3 are related to more than one massive haloes with mass larger than 1e13 Msun. Those massive haloes contribute 87.2% to high peaks (SNR>=5) with the remaining contributions are form the LSS. In the noise field where the shape noise is modeled as a gaussian distribution, about 60% high peaks (SNR>=5) are true peaks and the fraction decreases to 20% for lower peaks (3<= SNR <5). Furthermore, find that high peaks (SNR>=5) are dominated by very massive haloes larger than 1e14Msun.
1805.04511
Cosmological simulations for combined-probe analyses: covariance and neighbor-exclusion bias
Harnois-Deraps, et al
Present a public suite of WL mock data, extending the SLICS (Scinet Light Cone Simulations) to simulate cross-correlation analyses with different cosmological probes. These mocks include KIDS-450- and LSST-like lensing data, CMB lensing maps and simulated spectroscopic surveys that emulate the GAMA, BOSS and 2dFLenS galaxy surveys. With 817 independent realizations, the mocks are optimized for combined-probe covariance estimation, which is illustrated for the case of a joint measurement involving cosmic shear, gg lensing and galaxy clustering form KiDS-450 and BOSS data. With their high spatial resolution, the SLICS are also optimal for predicting the signal for novel lensing estimators, for the validation of analysis pipelines, and for testing a range of systematic effects such as the impact of neighbour-exclusion bias on the measured tomographic cosmic shear signal. For surveys like KiDS and DES, where the rejection of neighboring galaxies occurs within ~2 arc seconds, show that the measured cosmic shear signal will be biased low, but by less than a percent on the angular scales that are typically used in cosmic shear analyses. The amplitude of the neighbor exclusion bias doubles in deeper, LSST-like data. The simulation predicts described in this paper are made available at http://slicks.roe.ac.uk.
Implication of the shape of the EDGES signal for the 21cm power spectrum
Kaurov, Venumadhav, Dai, Zaldarriaga
Revisit the 21cm PS from the epoch of cosmic dawn in light of the recent EDGES detection of the 21cm global signal at frequencies corresponding to z~20. The shape of the signal suggests that the spin temperature of neutral hydrogen was coupled to the kinetic temperature of the gas relatively rapidly (19<~z<~21). Therefore consider models in which the UV photons were dominantly produced in the rarest and most massive haloes (M>~1e9Msun), since their abundance grows fast enough at those redshifts to account for this feature of the signal. Show that these models predict large power spectrum amplitudes during the inhomogeneous coupling, and then inhomogeneous heating by CMB and Ly-a photons due to the large shot noise associated with rare sources. The PS is enhanced by more than an order of magnitude compared to previous models which did not include the shot noise contribution, making it a promising target for upcoming radio interferometers that aim to detect high-redshift 21cm fluctuations.
1805.04114
The correspondence between convergence peaks from weak lensing and massive dark matter haloes
Wei, et al
The convergence peaks, constructed from galaxy shape measurement in WL, is a power probe of cosmology as the peaks can be connected with the underlined DM haloes. However, the capability of convergence peak statistic is affected by the noise in galaxy shape measurement, signal to noise ratio as well as the contribution form the projected mass distribution from the LSS along the LoS. In this paper, use the ray-tracing sim on a curved sky to investigate the correspondence between the convergence peak and the DM haloes at the LoS. Find that, in case of no noise and for source galaxies at z_s=1, more than 65% peaks with SNR >=3 are related to more than one massive haloes with mass larger than 1e13 Msun. Those massive haloes contribute 87.2% to high peaks (SNR>=5) with the remaining contributions are form the LSS. In the noise field where the shape noise is modeled as a gaussian distribution, about 60% high peaks (SNR>=5) are true peaks and the fraction decreases to 20% for lower peaks (3<= SNR <5). Furthermore, find that high peaks (SNR>=5) are dominated by very massive haloes larger than 1e14Msun.
1805.04511
Cosmological simulations for combined-probe analyses: covariance and neighbor-exclusion bias
Harnois-Deraps, et al
Present a public suite of WL mock data, extending the SLICS (Scinet Light Cone Simulations) to simulate cross-correlation analyses with different cosmological probes. These mocks include KIDS-450- and LSST-like lensing data, CMB lensing maps and simulated spectroscopic surveys that emulate the GAMA, BOSS and 2dFLenS galaxy surveys. With 817 independent realizations, the mocks are optimized for combined-probe covariance estimation, which is illustrated for the case of a joint measurement involving cosmic shear, gg lensing and galaxy clustering form KiDS-450 and BOSS data. With their high spatial resolution, the SLICS are also optimal for predicting the signal for novel lensing estimators, for the validation of analysis pipelines, and for testing a range of systematic effects such as the impact of neighbour-exclusion bias on the measured tomographic cosmic shear signal. For surveys like KiDS and DES, where the rejection of neighboring galaxies occurs within ~2 arc seconds, show that the measured cosmic shear signal will be biased low, but by less than a percent on the angular scales that are typically used in cosmic shear analyses. The amplitude of the neighbor exclusion bias doubles in deeper, LSST-like data. The simulation predicts described in this paper are made available at http://slicks.roe.ac.uk.
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