Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract： While the probability density function (PDF) of the cosmic microwave background (CMB) convergence field approximately follows a Gaussian distribution, small contributions from structures at low redshifts make the overall distribution slightly non-Gaussian. Some of this late-time component can be modelled using the distribution of galaxies and subtracted off from the original CMB lensing map to produce a map of matter distribution at high redshifts. Using this high-redshift mass map, we are able to directly study the early phases of structure formation and look for deviations from our standard model. In this work, we forecast the detectability of signatures of non-Gaussianity due to nonlinear structure formation at $z>1.2$. Although we find that detecting such signatures using ongoing surveys will be challenging, we forecast that future experiments such as the CMB-S4 will be able to make detections of $\sim$ 7$\sigma$.
Peer Review Status:
Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract： While the probability density function (PDF) of the cosmic microwave background (CMB) convergence field approximately follows a Gaussian distribution, small contributions from structures at low redshifts make the overall distribution slightly non-Gaussian. Some of this late-time component can be modelled using the distribution of galaxies and subtracted off from the original CMB lensing map to produce a map of matter distribution at high redshifts. Using this high-redshift mass map, we are able to directly study the early phases of structure formation and look for deviations from our standard model. In this work, we forecast the detectability of signatures of non-Gaussianity due to nonlinear structure formation at $z>1.2$. Although we find that detecting such signatures using ongoing surveys will be challenging, we forecast that future experiments such as the CMB-S4 will be able to make detections of $\sim$ 7$\sigma$.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Abstract： We introduce deep-field METACALIBRATION, a new technique that reduces the pixel noise in METACALIBRATION estimators of weak lensing shear signals by using a deeper imaging survey for calibration. In standard METACALIBRATION, when estimating the object's shear response, extra noise is added to correct the effect of shearing the noise in the image, increasing the uncertainty on shear estimates by ~ 20%. Our new deep-field METACALIBRATION technique leverages a separate, deeper imaging survey to calculate calibrations with less degradation in image noise. We demonstrate that weak lensing shear measurement with deep-field METACALIBRATION is unbiased up to second-order shear effects. We provide algorithms to apply this technique to imaging surveys and describe how to generalize it to shear estimators that rely explicitly on object detection (e.g., METACALIBRATION). For the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST), the improvement in weak lensing precision will depend on the somewhat unknown details of the LSST Deep Drilling Field (DDF) observations in terms of area and depth, the relative point-spread function properties of the DDF and main LSST surveys, and the relative contribution of pixel noise vs. intrinsic shape noise to the total shape noise in the survey. We conservatively estimate that the degradation in precision is reduced from 20% for METACALIBRATION to ~ 5% or less for deep-field METACALIBRATION, which we attribute primarily to the increased source density and reduced pixel noise contributions to the overall shape noise. Finally, we show that the technique is robust to sample variance in the LSST DDFs due to their large area, with the equivalent calibration error being ~ 0.1%. The deep-field METACALIBRATION technique provides higher signal-to-noise weak lensing measurements while still meeting the stringent systematic error requirements of future surveys.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Zhuoqi Zhang
Chihway Chang
Patricia Larsen
Lucas F. Secco
Joe Zuntz
the LSST Dark Energy Science Collaboration
Abstract： We examine the cosmological constraining power from two cross-correlation probes between galaxy and CMB surveys: the cross-correlation of lens galaxy density with CMB lensing convergence $\langle\delta\kappa\rangle$, and source galaxy weak lensing shear with CMB lensing convergence $\langle\gamma\kappa\rangle$. These two cross-correlation probes provide an independent cross-check of other large-scale structure constraints and are insensitive to galaxy-only or CMB-only systematic effects. In addition, when combined with other large-scale structure probes, the cross-correlations can break degeneracies in cosmological and nuisance parameters, improving both the precision and robustness of the analysis. In this work, we study how the constraining power of $\langle\delta\kappa\rangle+\langle\gamma\kappa\rangle$ changes from Stage-III (ongoing) to Stage-IV (future) surveys. Given the flexibility in selecting the lens galaxy sample, we also explore systematically the impact on cosmological constraints when we vary the redshift range and magnitude limit of the lens galaxies using mock galaxy catalogs. We find that in our setup, the contribution to cosmological constraints from $\langle\delta\kappa\rangle$ and $\langle\gamma\kappa\rangle$ are comparable in the Stage-III datasets; but in Stage-IV surveys, the noise in $\langle\delta\kappa\rangle$ becomes subdominant to cosmic variance, preventing $\langle\delta\kappa\rangle$ to further improve the constraints. This implies that to maximize the cosmological constraints from future $\langle\delta\kappa\rangle+\langle\gamma\kappa\rangle$ analyses, we should focus more on the requirements on $\langle\gamma\kappa\rangle$ instead of $\langle\delta\kappa\rangle$. Furthermore, the selection of the lens sample should be optimized in terms of our ability to characterize its redshift or galaxy bias instead of its number density.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Sean D. Johnson
Joop Schaye
Gregory L. Walth
Jennifer I-Hsiu Li
Gwen C. Rudie
Hsiao-Wen Chen
Mandy C. Chen
Benoît Epinat
Massimo Gaspari
Sebastiano Cantalupo
Wolfram Kollatschny
Zhuoqi
Liu
Sowgat Muzahid
Abstract： We report the discovery of giant (50-100 kpc) [O II] emitting nebulae with the Multi-Unit Spectroscopic Explorer (MUSE) in the field of TXS 0206-048, a luminous quasar at z=1.13. Down-the-barrel UV spectra of the quasar show absorption at velocities coincident with those of the extended nebulae, enabling new insights into inflows and outflows around the quasar host. One nebula exhibits a filamentary morphology extending over 120 kpc from the halo toward the quasar and intersecting with another nebula surrounding the quasar host with a radius of 50 kpc. This is the longest cool filament observed to-date and arises at higher redshift and in a less massive system than those in cool-core clusters. The filamentary nebula has line-of-sight velocities >300 km/s from nearby galaxies but matches that of the nebula surrounding the quasar host where they intersect, consistent with accretion of cool inter- or circum-galactic medium or cooling hot halo gas. The kinematics of the nebulae surrounding the quasar host are unusual and complex, with redshifted and blueshifted spiral-like structures. The emission velocities at 5-10 kpc from the quasar match those of inflowing absorbing gas observed in UV spectra of the quasar. Together, the extended nebulae and associated redshifted absorption represent a compelling case of cool, filamentary gas accretion from halo scales into the extended interstellar medium and toward the nucleus of a massive quasar host. The inflow rate implied by the combined emission and absorption constraints is well below levels required to sustain the quasar's radiative luminosity, suggesting anisotropic or variable accretion.
Peer Review Status:Awaiting Review
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