Casey Watson's Research Interests
Dark Matter
While the particle nature of dark matter remains mysterious,
it is possible to directly constrain the mass m_s of sterile neutrinos,
a particularly promising warm dark matter candidate,
based on their radiative decay to X-rays.
Zhiyuan Li (UMASS), Hasan Yuksel (Delaware), John Beacom (OSU), and I
have used the Chandra unresolved (total minus point source) X-ray emission from the Andromeda galaxy
to set the most stringent (95% C.L.) upper bound on m_s to date in the Dodelson-Widrow (DW)
scenario: m_s < 2.6 keV, thereby restricting the DW sterile neutrino mass
to the narrow range:
0.4 keV < m_s < 2.6 keV (95% C.L.), using only our constraints and the
Tremaine-Gunn lower bound. Even more importantly, our results restrict alternative
sterile neutrino production scenarios at very small active-sterile neutrino mixing angles.
For the draft of our most recent paper,
click here (pdf) or here (ps).
Galaxy Evolution: Star Formation and Supermassive Black Hole Growth
I am working with Chris Kochanek (of the OSU Astronomy Department)
and members of the CXO/NOAO and AGES
collaborations to develop a better understanding of the
star formation and accretion histories of the Universe based on the cosmological evolution of galactic
X-ray emission from z ~ 1 to the present.
For the draft of our most recent paper,
click here (pdf) or here (ps).
Gravitational Lensing
Neal Dalal (Princeton IAS, CITA) and I considered the environments of lens galaxies
as a possible means of reconciling the small external shear values typically predicted in simulations
with the large values required to correctly model many observed strong lensing systems.
Dark Energy
I have studied the low redshift behavior of Inverse Power Law Quintessence
with Bob Scherrer (Vanderbilt University) and remain interested in the study of new
theoretical explanations for and observational signatures of dark energy.
View my papers on SPIRES.
Contact me at
crwatson@millikin.edu.
This page was last updated August 10, 2008.