Testing Gravity on Large Scales with New Lensing Probes

Gravitational lensing has long served as a unique probe of the growth of structure, which is sensitive on large scales to the properties of dark energy and gravity.  In particular, lensing is instrumental in forming the statistic E_G, which is constructed to measure the growth rate of structure in a way independent of galaxy clustering bias.  Measurements of E_G using both CMB lensing and galaxy lensing have proliferated, but new challenges await as the data from upcoming surveys become more precise.  One such challenge is the bias on E_G due to the inhomogeneous magnification of galaxies.  In this talk, we will discuss how to identify this bias and calibrate it to remove from survey data.  We also consider a new tracer of gravitational lensing, namely upcoming 3D line intensity maps of emission lines such as the 21 cm line from neutral hydrogen.  Previous considerations of this new probe have assumed the flat-sky approximation, valid over small areas, where all light rays are assumed to come from the same direction.  We will present our extension of this treatment to the full-sky case which will be needed for large-area, 21 cm surveys such as HIRAX.  We will then discuss how this enhancement could improve intensity mapping probes of gravity.

Collection/Series: 
Event Type: 
Seminar
Scientific Area(s): 
Speaker(s): 
Event Date: 
Monday, September 10, 2018 - 11:00 to 12:30
Location: 
Space Room
Room #: 
400