Transitioning from Stage-III to Stage-IV: cosmology from galaxy×CMB lensing and shear×CMB lensing

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.Comment: 18 pages, 13 figure

Constraints on dark matter to dark radiation conversion in the late universe with DES-Y1 and external data

84siWe study a class of decaying dark matter models as a possible resolution to the observed discrepancies between early- and late-time probes of the universe. This class of models, dubbed DDM, characterizes the evolution of comoving dark matter density with two extra parameters. We investigate how DDM affects key cosmological observables such as the CMB temperature and matter power spectra. Combining 3x2pt data from Year 1 of the Dark Energy Survey,Planck-2018 CMB temperature and polarization data, Supernova (SN) Type Ia data from Pantheon, and BAO data from BOSS DR12, MGS and 6dFGS, we place new constraints on the amount of dark matter that has decayed and the rate with which it converts to dark radiation. The fraction of the decayed dark matter in units of the current amount of dark matter, $zeta$, is constrained at 68% confidence level to be <0.32 for DES-Y1 3x2pt data, <0.030 for CMB+SN+BAO data, and <0.037 for the combined dataset. The probability that the DES and CMB+SN+BAO datasets are concordant increases from 4% for the $Lambda$CDM model to 8% (less tension) for DDM. Moreover, tension in $S_8=sigma_8sqrt{Omega_m/0.3}$ between DES-Y1 3x2pt and CMB+SN+BAO is reduced from 2.3$sigma$ to 1.9$sigma$. We find no reduction in the Hubble tension when the combined data is compared to distance-ladder measurements in the DDM model. The maximum-posterior goodness-of-fit statistics of DDM and $Lambda$CDM are comparable, indicating no preference for the DDM cosmology over $Lambda$CDM....partially_openopenChen, Angela; Huterer, Dragan; Lee, Sujeong; Ferté, Agnès; Weaverdyck, Noah; Alonso Alves, Otavio; Leonard, C. Danielle; MacCrann, Niall; Raveri, Marco; Porredon, Anna; Di Valentino, Eleonora; Muir, Jessica; Lemos, Pablo; Liddle, Andrew; Blazek, Jonathan; Campos, Andresa; Cawthon, Ross; Choi, Ami; Dodelson, Scott; Elvin-Poole, Jack; Gruen, Daniel; Ross, Ashley; Secco, Lucas F.; Sevilla, Ignacio; Sheldon, Erin; Troxel, Michael A.; Zuntz, Joe; Abbott, Tim; Aguena, Michel; Allam, Sahar; Annis, James; Avila, Santiago; Bertin, Emmanuel; Bhargava, Sunayana; Bridle, Sarah; Brooks, David; Carnero Rosell, Aurelio; Carrasco Kind, Matias; Carretero, Jorge; Costanzi, Matteo; Crocce, Martin; da Costa, Luiz; Elidaiana da Silva Pereira, Maria; Davis, Tamara; Doel, Peter; Eifler, Tim; Ferrero, Ismael; Fosalba, Pablo; Frieman, Josh; Garcia-Bellido, Juan; Gaztanaga, Enrique; Gerdes, David; Gruendl, Robert; Gschwend, Julia; Gutierrez, Gaston; Hinton, Samuel; Hollowood, Devon L.; Honscheid, Klaus; Hoyle, Ben; James, David; Jarvis, Mike; Kuehn, Kyler; Lahav, Ofer; Maia, Marcio; Marshall, Jennifer; Menanteau, Felipe; Miquel, Ramon; Morgan, Robert; Palmese, Antonella; Paz-Chinchon, Francisco; Plazas Malagón, Andrés; Roodman, Aaron; Sanchez, Eusebio; Scarpine, Vic; Schubnell, Michael; Serrano, Santiago; Smith, Mathew; Suchyta, Eric; Tarle, Gregory; Thomas, Daniel; To, Chun-Hao; Varga, Tamas Norbert; Weller, Jochen; Wilkinson, ReeseChen, Angela; Huterer, Dragan; Lee, Sujeong; Ferté, Agnès; Weaverdyck, Noah; Alonso Alves, Otavio; Leonard, C. Danielle; Maccrann, Niall; Raveri, Marco; Porredon, Anna; Di Valentino, Eleonora; Muir, Jessica; Lemos, Pablo; Liddle, Andrew; Blazek, Jonathan; Campos, Andresa; Cawthon, Ross; Choi, Ami; Dodelson, Scott; Elvin-Poole, Jack; Gruen, Daniel; Ross, Ashley; Secco, Lucas F.; Sevilla, Ignacio; Sheldon, Erin; Troxel, Michael A.; Zuntz, Joe; Abbott, Tim; Aguena, Michel; Allam, Sahar; Annis, James; Avila, Santiago; Bertin, Emmanuel; Bhargava, Sunayana; Bridle, Sarah; Brooks, David; Carnero Rosell, Aurelio; Carrasco Kind, Matias; Carretero, Jorge; Costanzi, Matteo; Crocce, Martin; da Costa, Luiz; Elidaiana da Silva Pereira, Maria; Davis, Tamara; Doel, Peter; Eifler, Tim; Ferrero, Ismael; Fosalba, Pablo; Frieman, Josh; Garcia-Bellido, Juan; Gaztanaga, Enrique; Gerdes, David; Gruendl, Robert; Gschwend, Julia; Gutierrez, Gaston; Hinton, Samuel; Hollowood, Devon L.; Honscheid, Klaus; Hoyle, Ben; James, David; Jarvis, Mike; Kuehn, Kyler; Lahav, Ofer; Maia, Marcio; Marshall, Jennifer; Menanteau, Felipe; Miquel, Ramon; Morgan, Robert; Palmese, Antonella; Paz-Chinchon, Francisco; Plazas Malagón, Andrés; Roodman, Aaron; Sanchez, Eusebio; Scarpine, Vic; Schubnell, Michael; Serrano, Santiago; Smith, Mathew; Suchyta, Eric; Tarle, Gregory; Thomas, Daniel; Chun-Hao, To; Varga, Tamas Norbert; Weller, Jochen; Wilkinson, Rees

Multi-messenger observations of a binary neutron star merger

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of ~1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg2 at a luminosity distance of 40+8-8 Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 Mo. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at ~40 Mpc) less than 11 hours after the merger by the One- Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ~10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position ~9 and ~16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta

Constraints on dark matter to dark radiation conversion in the late universe with DES-Y1 and external data

We study a phenomenological class of models where dark matter converts to dark radiation in the low redshift epoch. This class of models, dubbed DMDR, characterizes the evolution of comoving dark-matter density with two extra parameters, and may be able to help alleviate the observed discrepancies between early and late-time probes of the Universe. We investigate how the conversion affects key cosmological observables such as the cosmic microwave background (CMB) temperature and matter power spectra. Combining 3x2pt data from Year 1 of the Dark Energy Survey, Planck-2018 CMB temperature and polarization data, supernovae (SN) Type Ia data from Pantheon, and baryon acoustic oscillation (BAO) data from BOSS DR12, MGS and 6dFGS, we place new constraints on the amount of dark matter that has converted to dark radiation and the rate of this conversion. The fraction of the dark matter that has converted since the beginning of the Universe in units of the current amount of dark matter, ζ, is constrained at 68% confidence level to be <0.32 for DES-Y1 3x2pt data, <0.030 for CMB+SN+BAO data, and <0.037 for the combined dataset. The probability that the DES and CMB+SN+BAO datasets are concordant increases from 4% for the ΛCDM model to 8% (less tension) for DMDR. The tension in S8=σ8√Ωm/0.3 between DES-Y1 3x2pt and CMB+SN+BAO is slightly reduced from 2.3σ to 1.9σ. We find no reduction in the Hubble tension when the combined data is compared to distance-ladder measurements in the DMDR model. The maximum-posterior goodness-of-fit statistics of DMDR and ΛCDM model are comparable, indicating no preference for the DMDR cosmology over ΛCDM

Dark Energy Survey Year 3 Results: clustering redshifts – calibration of the weak lensing source redshift distributions with redMaGiC and BOSS/eBOSS

ABSTRACT We present the calibration of the Dark Energy Survey Year 3 (DES Y3) weak lensing (WL) source galaxy redshift distributions n(z) from clustering measurements. In particular, we cross-correlate the WL source galaxies sample with redMaGiC galaxies (luminous red galaxies with secure photometric redshifts) and a spectroscopic sample from BOSS/eBOSS to estimate the redshift distribution of the DES sources sample. Two distinct methods for using the clustering statistics are described. The first uses the clustering information independently to estimate the mean redshift of the source galaxies within a redshift window, as done in the DES Y1 analysis. The second method establishes a likelihood of the clustering data as a function of n(z), which can be incorporated into schemes for generating samples of n(z) subject to combined clustering and photometric constraints. Both methods incorporate marginalization over various astrophysical systematics, including magnification and redshift-dependent galaxy-matter bias. We characterize the uncertainties of the methods in simulations; the first method recovers the mean z of tomographic bins to RMS (precision) of ∼0.014. Use of the second method is shown to vastly improve the accuracy of the shape of n(z) derived from photometric data. The two methods are then applied to the DES Y3 data