Bulletin of the American Physical Society
APS April Meeting 2020
Volume 65, Number 2
Saturday–Tuesday, April 18–21, 2020; Washington D.C.
Session H10: Baryon Acoustic Oscillations, Early Universe, and Cosmological ConstantsLive
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Sponsoring Units: DAP Chair: Josh Frieman, Fermilab Room: Roosevelt 5 |
Sunday, April 19, 2020 10:45AM - 10:57AM Live |
H10.00001: Enhancing VRO/LSST Cosmology with Deep Spectroscopy Jeffrey Newman The LSST Survey from the Vera Rubin Observatory will provide a variety of measurements of cosmological parameters via deep imaging of more than half of the sky. However, LSST's cosmological constraining power can be greatly increased beyond its baseline capabilities using deep spectroscopic datasets from upcoming or proposed instruments and telescopes. In this talk I will provide an overview of how the work of the LSST Dark Energy Science Collaboration would benefit from additional data from spectroscopic facilities. I will particularly focus on the need for spectroscopy to train photometric redshift algorithms, which has the potential to improve dark energy constraints from VRO/LSST by \textasciitilde 40{\%}. I will summarize the landscape of facilities that may be available for this work over the next decade and the amount of time needed at any of the possible sites to accomplish these goals. [Preview Abstract] |
Sunday, April 19, 2020 10:57AM - 11:09AM Live |
H10.00002: Cosmological Constraints with Clusters from the SPT-SZ and SPTpol Extended Cluster Surveys Lindsey Bleem Clusters of galaxies selected by the Sunyaev-Zel’dovich (SZ) effect are powerful tools with which to constrain cosmological models. Here I will present the latest cosmological results using clusters identified by the South Pole Telescope (SPT) particularly focusing on results from the 2500 deg$^2$ SPT-SZ and new 2700 deg$^2$ SPTpol Extended Cluster Survey (SPT-ECS); with the publication of SPT-ECS, SPT has released over 1,000 optically-confirmed SZ-selected clusters. While the primary focus of the SPT effort has been on constraining cosmological models via cluster abundances, we have also explored in detail the overlap between the SPT cluster samples and the optical redMaPPer cluster samples from the Dark Energy Survey to derive constraints on the optical richness-mass relation. From this work we find significant (28\%, ~4 sigma) differences in the slope of the mass-richness relation compared to results from a weak lensing analysis of the DES clusters; to reconcile this difference would require a significant shift in the assumed cosmological parameters along the $\Omega_\textrm{matter}$-$\sigma_8$ degeneracy axis. In this talk I will provide an overview of this work as well as discuss next steps with the upcoming SPT-3G cluster samples. [Preview Abstract] |
Sunday, April 19, 2020 11:09AM - 11:21AM Live |
H10.00003: Cosmic controversies in galaxy clusters: weak lensing mass calibration Maria Elidaiana da Silva Pereira The abundance of galaxy clusters as a function of mass and redshift is potentially one of the most powerful cosmological probes. In particular, galaxy clusters are most sensitive to the combination of the matter fluctuation amplitude $\sigma_8$ and the matter density $\Omega_m$. In recent years, measurements of these parameters from different galaxy cluster samples are presenting a systematic lower value in comparison with the results from the Cosmic Microwave Background. However, these different measurements contain systematics that may explain this small shift in the $\sigma_8-\Omega_m$ plane. Currently, the mass calibration of galaxy clusters is the dominating source of systematics in cluster cosmology. In this talk, I will present the systematics involved in the weak-lensing mass calibration, show the latest results from the Dark Energy Survey for both a richness-based and a new stellar-mass based mass proxy. I will also discuss the improvements we need towards the per cent level uncertainties required for precise cluster cosmology. [Preview Abstract] |
Sunday, April 19, 2020 11:21AM - 11:33AM Live |
H10.00004: Effect of Distance-Inclination Angle Degeneracy on Hubble-Lemaitr\'e Constant Measurement Arnab Dhani, Anuradha Gupta, Archisman Ghosh, Sourabh Jha, B Sathyaprakash The discovery of GW170817 and its electromagnetic counterparts allowed the first independent measurement of Hubble-Lamaitr\'e constant ($H_0$) using gravitational waves (GWs). Such $H_0$ measurement, in the local universe, requires the correct estimation of the binary's distance from its GW signal and the redshift information of the host galaxy from optical observations. Though the measurement of host's redshift, if identified correctly, can be very accurate (within $\sim1\%$ error), the distance estimates through GWs suffer from large uncertainties mainly due to distance-inclination angle ($D_L-\iota$) degeneracy, hence, affecting the $H_0$ measurements. In this presentation, we exploit this degeneracy to constrain $H_0$ effectively. The distance posterior is asymmetric due to $D_L-\iota$ degeneracy and leads to an asymmeteric joint $H_0$ posterior for a population of binary neutron star (BNS) mergers. This results in uneven credible intervals measured from the maximum likelihood estimator of the $H_0$ posterior, left error bar being smaller than the right error bar. Using this feature of joint $H_0$ posterior, we show that the advanced LIGO-Virgo detector network will need only $\sim30$ BNS mergers (with counterparts) to rule-out Plank Collaboration's $H_0$ estimate. [Preview Abstract] |
Sunday, April 19, 2020 11:33AM - 11:45AM Live |
H10.00005: Cosmic shear: internal consistency and results from three years of Dark Energy Survey Data Daniel Gruen I present measurements and methodological progress on gravitational shear two-point correlation functions from three years of Dark Energy Survey Data, i.e. over the full footprint. As one major upgrade, a new formalism allows us to make principled use of spectroscopic information for the calibration of galaxy redshift distributions, including a comprehensive suite of tests of internal consistency. Passing these, our measurements provide the most precise and accurate constraints to date on late-time structure in the cosmos. I discuss cosmological implications of these results and review the most relevant systematic uncertainties requiring continued effort for upcoming data sets. [Preview Abstract] |
Sunday, April 19, 2020 11:45AM - 11:57AM On Demand |
H10.00006: Extracting the BAO Length Scale from the Galaxy Correlation Function Chad Popik, Zachery Brown, Regina Demina Dark energy is the mysterious substance that is responsible for the accelerating expansion of our universe, and although it constitutes around 68\% of the total energy density in our universe, we know little of its true nature. To study dark energy, scientists have been observing important physical processes in the early universe known as the baryon acoustic oscillations (BAO’s), which leave imprints on large scale structure that act as standard rulers in cosmology. In our research, we have developed methods of data analysis to identify and extract the BAO length scale from galaxy surveys such as the Sloan Digital Sky Survey’s (SDSS) Baryon Oscillation Spectroscopic Survey (BOSS). More specifically, we use Markov Chain Monte Carlo methods to fit the galaxy two point correlation function. These methods of data analysis are being constructed for the Dark Energy Spectroscopic Instrument (DESI), which will observe over ten times the number of galaxies as BOSS and go out to over twice the redshift, giving us a more detailed look into our universe and hopefully into dark energy. [Preview Abstract] |
Sunday, April 19, 2020 11:57AM - 12:09PM |
H10.00007: CenterFinder: Locating over-dense centers of baryon acoustic oscillations Zachery Brown, Yujie Liu, Gebri Mishtaku, Regina Demina Acoustic waves in the primordial Universe (baryon acoustic oscillations, BAO) generated spherical shells of matter over-density, which can be detected today as a preferential length scale between galaxies in redshift surveys. We propose a new algorithm, CenterFinder, which extends BAO detection beyond a simple length scale, to include the cosmic locations of these primordial over-densities. Our method creates a model template of the expected matter distribution around over-dense BAO centers, then convolves it with the matter distribution as traced by redshift surveys to achieve this goal. Using mock galaxy catalogs, we evaluate the success and robustness of the algorithm by cross-correlating our found BAO centers with the galaxies themselves. We hope to apply our method to future surveys like DESI, and to investigate cross-correlations between our BAO centers and other cosmic objects like clusters, voids, or other matter tracers. [Preview Abstract] |
Sunday, April 19, 2020 12:09PM - 12:21PM |
H10.00008: Measuring the Hubble Constant with dark standard sirens Antonella Palmese, Kenneth Herner, James Annis, Marcelle Soares-Santos, Alyssa Garcia In this talk we will present the latest dark siren measurement of the Hubble constant with multiple gravitational wave source detections from LIGO/Virgo using the Dark Energy Survey (DES) galaxy photometric redshift catalog. The DES collaboration has a dedicated effort to follow up gravitational wave events, and it led to the independent discovery of the kilonova associated to GW170817. We have followed up several binary black hole mergers and one neutron star-black hole merger, finding no compelling evidence for an electromagnetic counterpart. In the absence of a confirmed host galaxy redshift, we use the standard siren distances of these events to measure the Hubble constant by a statistical redshift method that takes into account all the potential host galaxies observed with DES. We extend the photometric redshift analysis to incorporate partial spectroscopic redshift coverage. By combining information from several events we expect to improve several-fold on the precision of the first such measurement on a single event (GW170814) reported in 2019. [Preview Abstract] |
Sunday, April 19, 2020 12:21PM - 12:33PM On Demand |
H10.00009: Computer Simulations of the Early Universe David Garrison We are now able to simulate much of the early universe from the time of the Electro-Weak Phase Transition through the end of primordial nucleosynthesis. This simulation is performed using a General Relativistic Magnetohydrodynamic code based on the Cactus framework. It solves both the relativistic magnetohydrodynamic equations and Einstein's equations of General Relativity. As a result, it can simulate: magnetogenesis, primordial gravitational waves, turbulence, primordial perturbations and the role of dark matter in the early universe. Future work will involve extrapolating this work to the present epoch. [Preview Abstract] |
Sunday, April 19, 2020 12:33PM - 12:45PM |
H10.00010: Cosmology at Low Redshift with the Dark Energy Spectroscopic Instrument Segev BenZvi, Antonella Palmese During the next five years, the Dark Energy Spectroscopic Instrument (DESI) will produce a detailed 3D map of the universe, with 25 million galaxies, quasars, and Lyman-alpha quasars observed at redshifts between 0.4 and 3. These data will enable unprecedented measurements of the expansion history of the universe using baryon acoustic oscillations, as well as the growth of structure using redshift space distortions. During bright time, DESI will also carry out an extensive survey of 10 million galaxies at $z<0.4$ down to a magnitude of $r<19.5$. DESI's low-redshift bright galaxy survey, when combined with transient catalogs from photometric and multimessenger observatories, will provide precision measurements of the growth of structure and the late-time expansion of the universe. In this contribution we describe the prospects for low-$z$ cosmology with DESI and the synergies possible with the next generation of imaging and multimessenger detectors. [Preview Abstract] |
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