Astrophysics

A number of ground based CMB surveys that will survey large fractions of the sky to high sensitivity are currently in the planning stages.  I will give an overview of what can be learned from these surveys about the Universe since recombination, focussing on gravitational lensing science.  I will also discuss some new CMB observables that would be accessible with even more futuristic surveys.

Cosmology has seen great progress thanks to precision measurements and is bound to greatly benefit from upcoming Large Scale Structure and Cosmic Microwave Background data. I will point out a number of interesting directions. In particular, I discuss how the microphysics of inflation may be tested in galaxy surveys through “fossil” signatures originating from squeezed primordial correlations. I further elaborate on the constraining power of CMB spectral distortions on small-scale cosmological fluctuations and on particle decays in the very early Universe in relation to reheating. I also describe some of the possible constraints on inflation and reheating from future B-mode observations.

I will describe the Dark Energy Spectroscopic Instrument (DESI), an instrument currently being built to carry out a large galaxy redshift survey.  DESI is the next step beyond the SDSS and BOSS surveys, mapping over 30 million galaxies.  I will focus in particular on the amazing engineering challenges of the DESI instrument itself, which includes a 5,000-robot army and 250 kilometers of fiber optics.  I will conclude by briefly describing the work I am personally involved in: a large imaging survey that will measure the galaxies from which DESI will select targets for follow-up spectroscopic observation.

Modified gravitation known as Scalar-Tensor- Vector-Gravity (STVG) and MOG and its consequences for dark matter and dark energy in astrophysics and cosmology and black holes is reviewed. A variable speed of light (VSL) cosmology is compared to inflation. MOG predictions for gravitational waves are compared to the LIGO/Virgo collaboration data. MOG – black hole predictions for the sizes of the Sagittarius A* shadow are compared to the sizes predicted by the Schwarzschild and Kerr solutions. A possible void cosmology is compared to the standard cosmology based on dark energy and the cosmological constant.

Current constraints on spatial curvature demonstrate it to be dynamically negligible at late times. However, neglecting it as a cosmological parameter would be premature, as it offers a valuable test of eternal inflation models and probes novel large-scale structure phenomena. I will discuss a recent project in which a broad and conservative approach was employed to systematically forecast spatial curvature constraints from a suite of upcoming cosmology surveys, while also examining important degeneracies with cosmological parameters and potential sources of systematic error.

Pulsars are some of physics and astrophysics’ most exotic objects, and they have already earned two Nobel Prizes. We currently know of about 2500 of them in our Galaxy, but a small subset, the millisecond pulsars (MSPs), are truly remarkable. These systems are notoriously hard to detect, yet their numbers have more than doubled in the past 5 years via surveys using the world’s most sensitive
telescopes, new instrumentation, and huge amounts of computing. Specialized “timing” observations of these systems, accounting for each and every one of the billions of rotations of the stars, are providing fantastic results in basic physics. In this talk I’ll focus on the efforts to directly detect gravitational waves from super-massive black hole binaries, make strong-field tests of general relativity, and determine the nature of the densest form of matter known in the universe.