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Note that if the talk's pdf or ppt is available after the talk, you can get it by clicking on the talk title.

Physics/Astronomy C290C Cosmology and Cosmology-BCCP Seminar
The Physics/Astronomy C290C series consists of the Cosmology-BCCP LBNL-Physics-Astronomy Cosmology seminars held Tuesdays 1:10-2:00 pm via ZOOM.
Please mail Joanne Cohn if you need the ZOOM login information (before 1 pm for sure, and the earlier the better), or to add to this list or to suggest speakers.

This seminar is intended for BCCP members and Berkeley graduate students pursuing their dissertation research in cosmology. Other LBL, Berkeley Astronomy and and Berkeley Physics Department members are welcome.

Speaker/Visitor Info is here.





BOSS and Nyx
(Image by C. Stark)

Note that there are also other talks which might be of interest, including:


July 2020
July 9, Thursday
4 pm (RPM LBL)
Kyle Dawson, Utah By ZOOM
“The Completed SDSS-IV extended Baryon Oscillation Spectroscopic Survey: Cosmological Implications from two Decades of Spectroscopic Surveys at the Apache Point observatory”
The Extended Baryon Oscillation Spectroscopic Survey (eBOSS) concluded observations of the cosmic distance scale and the growth of structure in February, 2019. The three dimensional clustering in all samples from the Sloan Digital Sky Survey (SDSS) was used to make 15 distinct, high precision measurements of Baryon Acoustic Oscillations (BAO) to an effective redshift z<2.4 and six measurements of redshift space distortions (RSD) to z<1.5. With this redshift coverage and sensitivity, the SDSS experiment is unparalleled in its ability to explore models of dark energy. Using available cosmological samples, we provide new constraints on the cosmological model with an emphasis on the role of the final BAO and RSD clustering measurements in advancing the cosmological model. In this talk, I will give a brief overview of the BAO and RSD measurements and present the highlights of the advances in modeling dark energy, the local expansion rate, tests of general relativity, neutrino masses, and the overall cosmological model.
Results webpages:
https://www.sdss.org/science/final-bao-and-rsd-measurements/
https://www.sdss.org/science/cosmology-results-from-eboss/

September 2020
Sep 1, Tuesday
1:10 pm (BCCP/Cosmology)
Elisa Chisari, Leiden
By ZOOM
Cosmology and galaxy evolution from galaxy shapes
Two phenomena contribute to correlating galaxy shapes across the Universe: the deviation of photons from a straight path due to the spacetime curvature ("gravitational lensing”), and tidal interactions (“intrinsic alignments”). Modelling both accurately is crucial to obtaining unbiased constraints on the cosmological model from forthcoming surveys, particularly in the context of elucidating the origin of accelerated expansion of the Universe. In this talk, I will cover recent advances in our understanding of the intrinsic alignments of galaxies. While these alignments are typically regarded as a contaminant to weak gravitational lensing, I will also discuss how they might become a cosmological and galaxy evolution probe of their own in the near future.
Sep 2, Wednesday
12 noon (sharp, LBL DESI group lunch)
Anand Raichoor, newly arriving
By ZOOM

Sep 8, Tuesday
1:10 pm (BCCP/Cosmology)
Omar Darwish, Cambridge
By ZOOM
Reconstructing cosmic mass with new CMB lensing methods
Current and future high significance CMB lensing-galaxy cross-correlations will soon precisely probe the growth of structure and provide powerful tests for parameter tensions, non-Gaussianity, and modifications to LCDM and gravity. However, such cross-correlations are sensitive to CMB foreground contamination, and the resulting biases represent an important challenge for cosmological analyses. In the first part of this talk, I will describe new CMB lensing cross-correlation measurements and new techniques to mitigate foreground effects in lensing maps. In particular, I will present a tSZ cleaned cross-spectrum between Atacama Cosmology Telescope lensing and BOSS galaxies using a modified version of the standard quadratic estimator that retains most of the signal-to-noise. I will also discuss work on upcoming correlations with Advanced ACT CMB lensing maps (which can reach up to 100 sigma significance) and on further improvements to foreground mitigation. In the second part of this talk, I will turn to the three-dimensional large scale structure of the Universe probed by galaxy surveys. I will show how we can reconstruct the large-scale density field from galaxy modes using CMB lensing-inspired methods and use this reconstruction to improve constraints on local non-Gaussianity.
Sep 10, Thursday
4 pm (LBL)
Yacine Ali-Haimoud, NYU
By ZOOM
"Hunting for Dark Matter in the Early Universe"
It is now well established that the dominant part of non-relativistic matter in the Universe is some substance which appears to be oblivious to any force but gravity. The nature of this dark matter remains a nagging puzzle, and several candidates remain in the running. For instance, dark matter might be a new particle, as light as an electron, which might weakly interact with standard particles. Or it could be partly made of primordial black holes as massive as many Suns, born in the very early Universe from the gravitational collapse of enhanced primordial fluctuations. In this talk, I will describe how one can try and tease out some of the properties of dark matter from the Cosmic Microwave Background (CMB), both through its frequency spectrum, and its angular fluctuations. After reviewing the basic physics underlying the CMB, I will highlight how it can constrain interacting particles and primordial black holes. If time allows, I will discuss what LIGO may be able to tell us about primordial-black holes.
Sep 15, Tuesday
1:10 pm (BCCP/Cosmology)
Ethan Nadler, Stanford/SLAC
By ZOOM
The Faintest Galaxies and Their Dark Matter Halos
As luminous tracers of the smallest dark matter halos, ultra-faint dwarf galaxies offer a unique window into the physics of galaxy formation and dark matter. Our census of these extremely faint systems has drastically improved in recent years as a result of detailed searches in deep photometric datasets, including those from the Dark Energy Survey. In this talk, we describe recent advances in our understanding of these systems, focusing on their implications for 1) the galaxy--halo connection, reionization physics, and high-redshift galaxy formation, and 2) the microphysical properties of dark matter. We show that the lack of a cutoff in the observed abundance of ultra-faint galaxies yields among the strongest astrophysical constraints to date on the warmth, Standard Model couplings, and de Broglie wavelength of dark matter, and we discuss the implications of these constraints for particle models including sterile neutrinos and ultra-light axions.
Sep 16, Wednesday
12 noon (sharp, LBL DESI group lunch)
Andres Salcedo, OSU
By ZOOM
Cosmological Forecasting with Cluster Cross-Correlations and Constraining Galaxy Assembly Bias in SDSS
Cluster weak lensing is a sensitive probe of cosmology, particularly the amplitude of matter clustering and matter density parameter. The main nuisance parameter in a cluster weak lensing cosmological analysis is the scatter between the true halo mass and the relevant cluster observable. We show that combining cluster weak lensing with the projected cluster-galaxy cross-correlation function and galaxy auto correlation function can break the degeneracy between cosmology and the cluster mass-observable relation to achieve tight, percent level constraints on the amplitude of matter clustering. For our fiducial scenario of combining these three observables measured over 0.3 - 30.0 Mpc/h, for clusters at z = 0.35-0.55, we forecast a 1.4% constraint on the amplitude of matter clustering while marginalizing over the scatter in the cluster mass-observable relation and all HOD parameters. I will present these and other results on cluster cosmology in the first section of the talk. In the second section of the talk I will discuss work on the connection between the properties and bias of haloes with their proximity to massive neighbors and more recent work on constraining the level of galaxy assembly bias in SDSS.
Sep 22, Tuesday
1:10 pm (BCCP/Cosmology)
Shivam Pandey, Penn
By ZOOM
Precise constraints on cosmology and gas physics: small scales modeling using DES, ACT and Planck
Small scale correlations between the tracers of large scale structure (LSS) carry the majority of the information but are challenging to model due to complex astrophysics. The correlations constructed out of galaxy positions, galaxy shear, and Sunyaev-Zeldovich effect can be used to constrain these processes. The first half of the talk will be focussed on describing galaxy clustering and galaxy-galaxy lensing correlations down to scales of 4Mpc/h using an effective perturbation theory model. I will describe the validation of the model using the DES-like simulations and its applications to the imminent cosmology results from DES Year 3 data. The second half will focus on describing the cross-correlations between shear/galaxy-positions from DES Year 3 data with the Compton-y maps from ACT and Planck. I will describe the constraints on the evolution of the average thermal energy of the Universe, preliminary constraints on the pressure profile, and comparison with hydrodynamical simulations.
Sep 29, Tuesday
1:10 pm (BCCP/Cosmology)
Chun-Hao To, Stanford
By ZOOM


October 2020
Oct 6, Tuesday
1:10 pm (BCCP/Cosmology)
Christina Kreisch, Princeton
By ZOOM

Oct 13, Tuesday
1:10 pm (BCCP/Cosmology)
Zack Li, Princeton
By ZOOM

Oct 14, Wednesday
12 noon (sharp, LBL DESI group lunch)
Ellen Hang, ROE
By ZOOM

Oct 15, Thursday
4 pm (LBL RPM)
Andrej Obuljen, Waterloo
By ZOOM

Oct 20, Tuesday
1:10 pm (BCCP/Cosmology)
Stephon Alexander, Brown
By ZOOM

Oct 21, Wednesday
12 noon (sharp, LBL DESI group lunch)
Sandy Yuan, Harvard
By ZOOM

Oct 27, Tuesday
1:10 pm (BCCP/Cosmology)
Alexandra Amon, Stanford/SLAC
By ZOOM


November 2020
Nov 3, Tuesday
1:10 pm (BCCP/Cosmology)
, held
By ZOOM

Nov 10, Tuesday
1:10 pm (BCCP/Cosmology)
Ana Diaz Rivero, Harvard
By ZOOM

Nov 17, Tuesday
1:10 pm (BCCP/Cosmology)
Jahmour Givans, OSU
By ZOOM

Nov 24
1:10 pm (BCCP/Cosmology)
NO TALK

December 2020
Dec 1, Tuesday
1:10 pm (BCCP/Cosmology)
Yun-Ting Cheng, Caltech
By ZOOM







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