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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-2158
DTSTART:20110428T210000Z
DURATION:PT1H0M0S
DTSTAMP:20240328T134323Z
LAST-MODIFIED:20110413T121936Z
LOCATION:4274 Chamberlin Hall
SUMMARY:A Holistic View of Unstable Dark Matter: Spectral and Anisotro
py Signatures in Astrophysical Backgrounds\, NPAC (Nuclear/Particle/As
tro/Cosmo) Forum\, Le Zhang\, UW-Madison/Hamburg University/DESY
DESCRIPTION:The nature of dark matter is one of the key outstanding pr
oblems in both particle and astrophysics. If dark matter decays or ann
ihilates into electrons and positrons\, it can affect diffuse radiatio
n backgrounds observed in astrophysics. We present a new\, more gener
al analysis of constraints on dark matter models. For any decaying dar
k matter model\, constraints on mass and lifetime can be obtained by f
olding the specific dark matter decay spectrum with a response functio
n. These response functions are derived from full-sky radio surveys an
d Fermi-LAT gamma-ray observations and apply them to place constraints
on some specific dark matter decay models. We also discuss the influe
nce of astrophysical uncertainties on the response function\, such as
the uncertainties from propagation models and from the spatial distrib
ution of the dark matter.
\n
\nMoreover\, an anisotro
py analysis of full-sky emission gamma-ray and radio maps is performed
to identify possible signatures of annihilating dark matter. We calcu
late angular power spectra of the cosmological background of synchrotr
on emission from dark matter annihilations into electron-positron pair
s. We compare the power spectra with the anisotropy of astrophysical a
nd cosmological radio backgrounds\, from normal galaxies\, radio-galax
ies\, galaxy cluster accretion shocks\, the cosmic microwave backgroun
d and Galactic foregrounds. In addition\, we develop a numerical tool
to compute gamma-ray emission from such electrons and positrons diffus
ing in the smooth host halo and in substructure halos with masses down
to earth mass. We show that\, unlike the total gamma-ray angular powe
r spectrum observed by Fermi-LAT\, the angular power spectrum from the
inverse Compton scattering is exponentially suppressed below an angul
ar scale determined by the diffusion length of electrons and positrons
.
URL:https://www.physics.wisc.edu/events/?id=2158
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