UChicago-2020: JuniorScientistTalks

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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


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

  • Yuto Minami - Simultaneous determination of the cosmic birefringence and miscalibrated polarization angles
  • Dongwon 'DW' Han - The Atacama Cosmology Telescope: Delensed Power Spectra and Parameters
  • 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
  • Max Abitbol - Robust B-mode analysis for ground-based experiments
  • 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
  • Marcel Schmittfull - Future cosmology with CMB lensing and galaxy clustering
  • 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 - Characterization of Multiplexed Transition Edge Sensor Bolometers for the POLARBEAR-2 Cosmic Microwave Background Experiment
  • Zachary Martinot - Interferometric Visibililty Simulations for HERA Data Analysis
  • 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 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 2<z<6 where galaxies are more difficult to resolve, the Lyman-alpha forest is an excellent probe of structure. In this talk I will present my work on using perturbation theory beyond leading order to model Lyman-alpha forest flux fluctuations. This improved model is a first step toward obtaining a nonlinear Lyman-alpha forest power spectrum model without using any fitting functions. I then discuss how measurements of this power spectrum by DESI can be combined with future CMB data to place tighter constraints on the sum of neutrino masses and test for primordial non-Gaussianity.
Lindsay Ng Lowry My name is Lindsay Ng Lowry and I am currently a grad student at UC San Diego working on the Simons Array with Professor Brian Keating as my advisor. I joined the group in 2014 and have been focused on hardware development and testing for the POLARBEAR-2b receiver as well as site preparation for the Simons Array's three telescopes. Aside from research, I love participating in physics outreach and mentoring programs such as giving shows with UCSD's portable planetarium and leading the graduate Women in Physics group. Development and Characterization of the POLARBEAR-2b Receiver for the Simons Array POLARBEAR-2b (PB-2b) is the receiver to be installed in the second telescope of the Simons Array. The cryogenic receiver was developed and characterized at UC San Diego where it was also integrated with its detectors (7,588 transition edge sensor bolometers with lenslet-coupled sinuous antennas), readout system (frequency-division multiplexing utilizing LC resonators and SQUID series array amplifiers), and optical elements (reimaging lenses and cryogenic, continuously rotating half-wave plate). I will describe the results of this lab work along with the current status and future plans for PB-2b.
Shouvik Roy Choudhury I am currently a Postdoctoral fellow (Feb 2020 - present) at the Indian Institute of Technology Bombay (IIT B), India, where my current advisor is Prof. Vikram Rentala. I did my PhD (defended: Feb 2020) from Harish-Chandra Research Institute (HRI), Allahabad, India with Prof. Sandhya Choubey as my supervisor. My research work involves cosmological parameter estimation with a strong focus on neutrino cosmology. Currently, my research interests also include dark energy, dark matter, the Hubble tension, etc. Link to my publications list: http://old.inspirehep.net/author/profile/Shouvik.Roy.Choudhury.1 Neutrino Mass and Mass Hierarchy from Cosmology In this talk I shall discuss results from my paper (arXiv: 1907.12598, published in JCAP) where we update the bounds on the sum of neutrino masses, $\sum m_{\nu}$ from latest publicly available cosmological data and likelihoods using Bayesian analysis, while explicitly considering particular neutrino mass hierarchies. In the minimal $\Lambda\textrm{CDM}+\sum m_{\nu}$ model with most recent CMB data from Planck 2018 TT,TE,EE, lowE, and lensing; and BAO data from BOSS DR12, MGS, and 6dFGS, we find that at 95\% C.L. the bounds are: $\sum m_{\nu}<0.12$ eV (degenerate), $\sum m_{\nu}<0.15$ eV (normal), $\sum m_{\nu}<0.17$ eV (inverted). The bounds vary across the different mass orderings due to different priors on $\sum m_{\nu}$. Also, we find that the normal hierarchy is very mildly preferred relative to the inverted, using both minimum $\chi^2$ values and Bayesian Evidence ratios. We also provide bounds on $\sum m_{\nu}$ considering different neutrino mass hierarchies in various extended cosmological models: $\Lambda\textrm{CDM}+\sum m_{\nu}+r$, $w\textrm{CDM}+\sum m_{\nu}$, $w_0 w_a \textrm{CDM}+\sum m_{\nu}$, $w_0 w_a \textrm{CDM}+\sum m_{\nu}$ with $w(z)\geq -1$, $\Lambda \textrm{CDM} + \sum m_{\nu} + \Omega_k$, and $\Lambda \textrm{CDM} + \sum m_{\nu} + A_{\textrm{Lens}}$. We do not find any strong evidence of normal hierarchy over inverted hierarchy in the extended models either.
Marcel Schmittfull Postdoc at IAS working with Matias Zaldarriaga. Projects include large-scale structure and CMB lensing theory, simulations and analysis. Future cosmology with CMB lensing and galaxy clustering Next-generation Cosmic Microwave Background experiments such as the Simons Observatory, CMB-S4 and PICO aim to measure gravitational lensing of the Cosmic Microwave Background an order of magnitude better than current experiments. The lensing signal will be highly correlated with measurements of galaxy clustering from next-generation galaxy surveys such as LSST. This will help us understand whether cosmic inflation was driven by a single field or by multiple fields. It will also allow us to accurately measure the growth of structure as a function of time, which is a powerful probe of dark energy and the sum of neutrino masses. I will discuss the prospects for this, as well as recent progress on the theoretical modeling of galaxy clustering, which is key to realize the full potential of these anticipated datasets.