Cosmology overview II: current data, and some recent results

Eric Baxter University of Pennsylvania Two main cosmological probes

Large scale structure (LSS)

Cosmic microwave background (CMB) Extracting cosmology from the CMB: Primary Anisotropies Planck XI 2015

Credit: ESA (Planck)

Primary anisotropies in temperature and polarization are imprinted at time of recombination

Sensitive to geometry, matter content, extra light degrees of freedom, inflation… Extracting cosmology from the CMB: Secondary Anisotropies

Secondary anisotropies are imprinted after recombination: Gravitational lensing Sunyaev Zel’dovich effect Integrated Sachs Wolfe effect

Sensitive to expansion history, growth of structure, thermal history… Sunyaev- Zel’dovich effect Extracting cosmology from large scale structure

Distribution and time evolution of structure is sensitive to cosmological parameters

Many more modes than CMB (3D vs. 2D)

But nonlinear!

credit: Millennium simulation, Springel et al. 2005 Cross-correlations between the CMB and LSS

Secondary anisotropies induce correlation between CMB and LSS

Cross-correlation between tracers of large scale structure and CMB can be used to isolate contributions to secondary anisotropy as a function of redshift Cross-correlations between the CMB and LSS

Secondary anisotropies induce correlation between CMB and LSS

Galaxies narrowly distributed in redshift

Cross-correlation between tracers of large scale structure and CMB can be used to isolate contributions to secondary anisotropy as a function of redshift Cosmological datasets: CMB and optical imaging Advancing cosmological datasets: Cosmic Microwave Background

Deeper observations

Smaller angular scales • Needed to measure secondary anisotropies

Polarization sensitivity • Less foreground contamination • Inflationary B-modes CMB S4 science book Planck 143 GHz 50 deg2 SPTpol 150 GHz 50 deg2 6x finer angular resolution 6x deeper Advancing cosmological datasets: Large Scale Structure

Deeper, higher quality imaging, higher redshift

Wider area

More spectra

New data types: • 21 cm • Gravitational waves Galaxy image from the Sloan Digital Sky Survey (DR7)

H. Dominguez Sanchez et al. 2018 Same galaxy with DES (Year 1)

H. Dominguez Sanchez et al. 2018 Cosmological analyses: large vs. small

Large scales Easy to model Fewer modes per volume vs.

Small scales Lots of signal to noise Difficult to model Survey of recent results: large scales The South Pole Telescope and the Dark Energy Survey

Funded By:

Funded by: Recent CMB measurements: SPTpol 500 sq. deg. Henning et al. 2014

Most sensitive measurements to date of EE and TE power spectra at high ell Recent CMB measurements: gravitational lensing

Gravitational lensing leads to a distinctive distortion in the observed pattern of CMB fluctuations. Various estimators exploit this pattern to recover lensing signal.

Simard et al. 2018

CMB lensing power spectrum

SPT-SZ & Planck data

Omori et al. 2017 Recent LSS measurements:

DES two-point functions Elvin-Poole et al. 2017 f(ˆn)f(ˆn + ✓) h i

✖ Galaxy density Galaxy density Prat et al. 2017

✖ Galaxy density Galaxy lensing Troxel et al. 2017

✖ Galaxy lensing Galaxy lensing Recent LSS measurements: DES two-point functions 0 . 5

3) Shear = gravitational / 0 . lensing alone m ⌦ ( 8 = clustering and w + T

⌘ galaxy lensing 8

DES Year 1 two-point S analysis (3x2pt) DES Y1, Abbot et al. 2017 Tightest cosmological constraints from a single galaxy survey! Recent LSS x CMB measurements: Joint 2pt functions

Can also cross-correlate galaxy DES-only two-point functions survey measurements with with CMB lensing CMB lensing

FORECAST BLINDED

CMB lensing ✖ Galaxy density

Galaxy lensing CMB lensing ✖

Galaxy bias Shear calibration

Baxter et al. 2018a Survey of recent results: small scales Small scales are complicated

Helly, Cooper, Cole & Frenk, Institute for Computational Cosmology

Lots of interesting physics and signal-to-noise at small scales

However: small scales are more difficult to model Small scales: Splashback

Self similar collapse models predict that accreted matter piles up at first apoapsis after collapse (e.g. Fillmore & Goldreich 1984)

Splashback

Splashback radius Splashback with DES Chang, Baxter et al. 2017

For the first time we measure this feature using gravitational lensing Dwarf galaxies in DES Koposov et al. 2015

Ultra-faint dwarf galaxy discovered in DES data

Probe structure formation at small scales

Promising targets for indirect detection of dark matter Thank you!