# Difference between revisions of "UChicago-2020: JuniorScientistTalks"

Junior Scientist Talks Organized by the CMB-S4 Junior Scientist Advancement Committee
These talks are highlighting the recent work of graduate students and postdocs in cosmology.

## Connection Details

Zoom: https://fnal.zoom.us/j/97391022720?pwd=QTE4ZzBzcml4MmlZQ1crWjZib0R1dz09 One-tap: +13126266799,,97391022720#,,,,,,0#,,695564# US (Chicago)

Time/Date: 8:00am - 12:15pm Pacific Time / Friday August 14, 2020

Organizers: Darcy Barron for the CMB-S4 Junior Scientist Advancement Committee

## Agenda

Session 1: 8:00am - 10:15am PDT

• Yuto Minami - Simultaneous determination of the cosmic birefringence and miscalibrated polarization angles File:20200814 SimultaneousDetermination CMBS4 upload ver2.7.pdf
• Dongwon 'DW' Han - The Atacama Cosmology Telescope: Delensed Power Spectra and Parameters File:Han CMB-S4 JRT.pdf
• Suvodip Mukherjee - Peering into patchy reionization using kSZ and B-mode polarization
• Omar Darwish - ACTPol lensing maps and foreground-cleaned galaxy correlations
• Heather McCarrick - The Simons Observatory uMux detector modules
• Benjamin Beringue - Cosmology with Rayleigh scattering File:RS CMB S4 beringue.pdf
• Max Abitbol - Robust B-mode foreground analysis for ground-based experiments Slides
• Jahmour J. Givans - Lyman-alpha forest perturbative modeling and improved CMB constraining power
• Lindsay Ng Lowry - Development and Characterization of the POLARBEAR-2b Receiver for the Simons Array
• Shouvik Roy Choudhury - Neutrino Mass and Mass Hierarchy from Cosmology
• Ruby Byrne - Enabling Precision EoR Calibration
BREAK 10:15am - 10:30am PDT


Session 2: 10:30am - 12:15pm

• Anna Ho - The Landscape of Relativistic Stellar Explosions
• Charles Hill - A cryogenic half-wave plate for POLARBEAR-2b
• Tucker Elleflot - DfMux Readout for CMB Experiments
• Kirit Karkare - Cosmology with Next-Generation Millimeter-Wave Spectrometers
• Theodore Macioce - Realistic Mock kSZ Observations to Forecast Constraints on Structure Formation and Cosmic Acceleration
• John Groh - Development and deployment of the Simons Array CMB polarization experiment
• Tyler St Germaine - Beam Systematics in BICEP3 and the Keck Array CMB Polarimeters
• Tashalee Billings - Extracting Optical Depth from Simulated 21cm Data

## Speaker Information (in order of talks)

 Name Short Bio Talk Title Abstract Yuto Minami I'm postdoc fellow of High Energy Accelerator Research Organization (KEK) in Japan. I'm members of LiteBIRD and Simons Array. My research history is here: https://inspirehep.net/authors/1238534. Simultaneous determination of the cosmic birefringence and miscalibrated polarization angles We show that the cosmic birefringence and miscalibrated polarization angles can be determined simultaneously by cosmic microwave background (CMB) experiments using the cross-correlation between E- and B-mode polarization data. This is possible because the polarization angles of the CMB are rotated by both the cosmic birefringence and miscalibration effects, whereas those of the Galactic foreground emission are rotated only by the latter. Our method does not require prior knowledge of the E- and B-mode power spectra of the foreground emission, but uses only the knowledge of the CMB polarization spectra. Specifically, we relate the observed EB correlation to the difference between the observed E- and B-mode spectra in the sky, and use different multipole dependences of the CMB (given by theory) and foreground spectra (given by data) to derive the likelihood for the miscalibration angle α and the birefringence angle β⁠. We show that a future satellite mission similar to LiteBIRD can determine β with a precision of 6 arcmin. Dongwon 'DW' Han A PhD student at Stony Brook University studying CMB data analysis with Dr. Neelima Sehgal The Atacama Cosmology Telescope: Delensed Power Spectra and Parameters We present LCDM cosmological parameter constraints obtained from delensed microwave background power spectra. Lensing maps from a subset of DR4 data from the Atacama Cosmology Telescope (ACT) are used to undo the lensing effect in ACT spectra observed at 150 and 98 GHz. At 150 GHz, we remove the lensing distortion with an effective efficiency of 30% (TT), 30% (EE), 26% (TE) and 20% (BB); this results in detections of the delensing effect at 8.7 sigma (TT), 5.1 sigma (EE), 2.6 sigma (TE), and 2.4 sigma (BB) significance. The combination of 150 and 98 GHz TT, EE, and TE delensed spectra is well fit by a standard LCDM model. We also measure the shift in best-fit parameters when fitting delensed versus lensed spectra; while this shift does not inform our ability to measure cosmological parameters, it does provide a three-way consistency check among the lensing inferred from the best-fit parameters, the lensing in the CMB power spectrum, and the reconstructed lensing map. This shift is predicted to be zero when fitting with the correct model since both lensed and delensed spectra originate from the same region of sky. Fitting with a LCDM model and marginalizing over foregrounds, we find that the shift in cosmological parameters is consistent with zero. Our results show that gravitational lensing of the microwave background is internally consistent within the framework of the standard cosmological model. Suvodip Mukherjee University of Amsterdam, GRAPPA postdoctoral fellow, https://staff.fnwi.uva.nl/s.mukherjee/ Peering into patchy reionization using kSZ and B-mode polarization The epoch of cosmic reionization can be probed using the secondary anisotropies induced in the cosmic microwave background (CMB) temperature and polarization field. I will discuss the impact of patchy reionization on CMB temperature and polarization anisotropies using the results obtained from semi-numerical simulations. I will introduce two new scaling relations to connect the kSZ power spectrum and secondary B-mode power spectrum with the scenarios of patchy reionization and is going to discuss its utility for the ongoing/upcoming CMB experiments. By using a physically motivated model of reionization, I will show the first constraints on patchiness during reionization from the current kSZ measurement and will present the corresponding upper bound on the amplitude of secondary B-mode polarization. I will also discuss the advantage of a joint study of the kSZ signal and secondary B-mode polarization from the upcoming CMB experiments to unveil the reionization history. Omar Darwish University of Cambridge, Blake Sherwin, PhD, CMB Lensing cross correlations, LSS reconstruction, https://www.maths.cam.ac.uk/person/od261 ACTPol lensing maps and foreground-cleaned galaxy correlations We construct cosmic microwave background lensing mass maps using data from the 2014 and 2015 seasons of observations with the Atacama Cosmology Telescope (ACT). These maps cover 2100 square degrees of sky and overlap with a wide variety of optical surveys. The maps are signal dominated on large scales and have fidelity such that their correlation with the cosmic infrared background is clearly visible by eye. We also create lensing maps with thermal Sunyaev-Zel’dovich contamination removed using a novel cleaning procedure that only slightly degrades the lensing signal-to-noise ratio. The cross-spectrum between the cleaned lensing map and the BOSS CMASS galaxy sample is detected at 10-σ significance, with an amplitude of A = 1.02±0.10 relative to the Planck best-fit LCDM cosmological model with fiducial linear galaxy bias. Our measurement lays the foundation for lensing cross-correlation science with current ACT data and beyond. Heather McCarrick I am a postdoc at Princeton, advised by Suzanne Staggs. I primarily work on the Simons Observatory with a focus on the readout, detectors, and focal plane module design. The Simons Observatory uMux detector modules The Simons Observatory (SO) will be a cosmic microwave background (CMB) survey experiment with four small-aperture telescopes and one large-aperture telescope, which will observe from the Atacama Desert. In total, SO will field over 60,000 transition-edge sensor (TES) bolometers in six spectral bands centered between 27 and 280 GHz in order to achieve the sensitivity necessary to measure or constrain numerous cosmological quantities, as outlined in The Simons Observatory Collaboration et al. (2019). SO will use a microwave SQUID multiplexing (uMux) readout with an initial multiplexing factor of 1000. Comparatively, current CMB experiments use a multiplexing factor of ~64. The focal plane modules contain the uMUX readout, TES bias circuitry and detectors. The focal plane module design is both critical to the readout performance and allows for close-packing of the modules within the focal plane. In this talk, I will discuss the evolved SO focal plane module design and status. Benjamin Beringue My name is Benjamin Beringue, I am a third year PhD student at the University of Cambridge under the supervision of Dr Daan Meerburg. I have been working on several aspects of CMB data analysis from forecasting detectability of Rayleigh scattering of the CMB to implementing component separation methods for SO. Cosmology with Rayleigh scattering "The cosmic microwave background (CMB) has been a treasure trove for cosmology. Over the next decade, current and planned CMB experiments are expected to exhaust nearly all primary CMB information. However, CMB photons can be affected after recombination, which can be a nuisance in extracting the primary modes, but will also provide valuable cosmological information. Well-studied examples include deflection of CMB photons by gravitational lensing and the Sunyaev-Zel'dovich effects describing scattering by free electrons in collapsed objects. Several of these effects have been detected and have been, or will be, used for cosmological inference. Among these secondaries, Rayleigh scattering of the CMB is a less studied yet potentially powerful probe of the recombination history. Scattering of CMB photons off neutral species right after recombination presents a distinctive $\nu^4$ scaling with frequency as well as a strong correlation with the primary CMB. These unique features should guarantee its detection by the next generation of CMB experiments. We will present detectability forecasts combining the Simons Observatory and CCAT-prime telescopes as well as more futuristic space missions. Finally, we will present potential cosmological implications of the detection of this signal by studying improvement of parameter constrains." Max Abitbol I am a postdoc at University of Oxford working with David Alonso on CMB B-mode foregrounds and systematics for Simons Observatory. Robust B-mode foreground analysis for ground-based experiments In this talk I will discuss foreground and instrument systematic modeling for upcoming ground-based B-mode searches. I will begin by introducing a moment-expansion method, which aims to address the problem of spatially varying foreground SEDs by adding physically motivated parameters to the SEDs. Next I will summarize the power-spectrum domain foreground and systematic cleaning pipeline for the Simons Obsevatory. Using this framework we have quantified calibration requirements on bandpass and polarization angle systematics for the SO target of $\sigma_r\approx 10^{-3}$. We show that we can explicitly model and marginalize over systematic parameters without a large penalty on $\sigma_r$. The pipeline was validated on simulations and BICEP data. We also propagated these systematic requirements into instrument design choices. Finally, I will present preliminary results from a new power-spectrum domain moment-expansion based foreground modeling procedure. This method combines the practicality of power-spectrum domain cleaning with the expressiveness of additional foreground moment parameters to allow for robust foreground subtraction and CMB B-mode identification. Jahmour J. Givans I am a fifth-year graduate student at The Ohio State University working under Chris Hirata. I am a member of the DESI Lyman-alpha forest working group and the Roman Space Telescope image simulation group. My previous and current projects are related to Lyman-alpha forest perturbation theory, the relative velocity effect on the H I power spectrum, and modeling detector effects as a source of weak lensing systematics. You can read more about me at https://u.osu.edu/givans.2/ Lyman-alpha forest perturbative modeling and improved CMB constraining power Efforts to improve the constraining power of CMB measurements by incorporating probes of large-scale structure have primarily focused on synergies between the CMB and galaxies or clusters. Over redshifts 2P) leakage in our latest data including all observations from 2010 through 2018 (BK18). In this talk, I present measured per-detector far-field beam maps and differential beam mismatch, and preliminary maps of the T—>P leakage present in the BK18 data set. I also discuss recent effort in linking together physical optics simulations and real beam measurements, in the context of validating the design simulated performance of the CMB-S4 Small Aperture Telescopes. Tashalee Billings I am a 5th year PhD candidate at the University of Pennsylvania in the Department of Physics and Astronomy. My thesis advisor is Dr. James Aguirre. My projects include calibration and imaging techniques using CASA and using machine learning techniques to extract reionization parameters. Extracting Optical Depth from Simulated 21cm Data Upcoming measurements of the high-redshift 21 cm signal from the Epoch of Reionization (EoR) is a promising probe of cosmological information and parameters. One parameter in particular is the optical depth to the cosmic microwave background (CMB). Previous proposals for extracting this parameter from future 21 cm datasets used semi-numerical models to compare to power spectra and reconstruct the reionization history. A robust measurement of the optical depth would help eliminate it as a nuisance parameter from CMB data analysis, and provide tighter constraints on other cosmological parameters. We present here an application of convolution neural networks (CNNs) to mock images of the 21 cm signal from the EoR. We show that well-trained CNNs are able to recover optical depth values with typical error values of 3% or better. Furthermore, we show that this level of accuracy is achievable even when removing Fourier modes that are expected to be corrupted by bright foreground contamination of the 21 cm signal. We also perform automated hyperparameter optimization of the CNNs used in this analysis, and demonstrate that the accuracy of the results are not very sensitive to the precise architecture chosen.