DARK MATTER SEARCH USING CHANDRA OBSERVATIONS OF WILLMAN 1 AND A SPECTRAL FEATURE CONSISTENT WITH A DECAY LINE OF A 5 keV STERILE NEUTRINO

Journal Article · Sat May 01 04:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/714/1/652· OSTI ID:21448900

Loewenstein, Michael ^[1]; Kusenko, Alexander ^[2]

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1. Department of Astronomy, University of Maryland, College Park, MD (United States)
2. Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States)

We report the results of a search for an emission line from radiatively decaying dark matter in the Chandra X-ray Observatory spectrum of the ultra-faint dwarf spheroidal galaxy Willman 1. 99% confidence line flux upper limits over the 0.4-7 keV Chandra bandpass are derived and mapped to an allowed region in the sterile neutrino mass-mixing angle plane that is consistent with recent constraints from Suzaku X-ray Observatory and Chandra observations of the Ursa Minor and Draco dwarf spheroidals. A significant excess to the continuum, detected by fitting the particle-background-subtracted source spectrum, indicates the presence of a narrow emission feature with energy 2.51 {+-} 0.07(0.11) keV and flux [3.53 {+-} 1.95(2.77)] x 10{sup -6} photons cm{sup -2} s{sup -1} at 68% (90%) confidence. Interpreting this as an emission line from sterile neutrino radiative decay, we derive the corresponding allowed range of sterile neutrino mass and mixing angle using two approaches. The first assumes that dark matter is solely composed of sterile neutrinos, and the second relaxes that requirement. The feature is consistent with the sterile neutrino mass of 5.0 {+-} 0.2 keV and a mixing angle in a narrow range for which neutrino oscillations can produce all of the dark matter and for which sterile neutrino emission from the cooling neutron stars can explain pulsar kicks, thus bolstering both the statistical and physical significance of our measurement.

• OSTI ID: 21448900
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 714; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BOSONS
COSMIC RADIO SOURCES
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
DECAY
ELEMENTARY PARTICLES
ENERGY RANGE
FERMIONS
GALAXIES
KEV RANGE
KEV RANGE 01-10
LEPTONS
MASSLESS PARTICLES
MATTER
NEUTRINO OSCILLATION
NEUTRINOS
NEUTRON STARS
NONLUMINOUS MATTER
PARTICLE DECAY
PHOTONS
PULSARS
RADIATIVE DECAY
STARS
WEINBERG ANGLE
X-RAY GALAXIES