6,501,911 research outputs found
Gravitational-Wave Fringes at LIGO: Detecting Compact Dark Matter by Gravitational Lensing
Utilizing gravitational-wave (GW) lensing opens a new way to understand the
small-scale structure of the universe. We show that, in spite of its coarse
angular resolution and short duration of observation, LIGO can detect the GW
lensing induced by compact structures, in particular by compact dark matter
(DM) or primordial black holes of , which remain
interesting DM candidates. The lensing is detected through GW frequency
chirping, creating the natural and rapid change of lensing patterns:
\emph{frequency-dependent amplification and modulation} of GW waveforms. As a
highest-frequency GW detector, LIGO is a unique GW lab to probe such light
compact DM. With the design sensitivity of Advanced LIGO, one-year observation
by three detectors can optimistically constrain the compact DM density fraction
to the level of a few percent.Comment: 6 pages, 5 figures, v2: published version, Fig.5 updated with Poisson
distribution, improved discussion on the optical dept
Magnetogenesis from a rotating scalar: \`a la scalar chiral magnetic effect
The chiral magnetic effect (CME) is a phenomenon in which an electric current
is induced parallel to an external magnetic field in the presence of chiral
asymmetry in a fermionic system. In this paper, we show that the electric
current induced by the dynamics of a pseudo-scalar field which anomalously
couples to electromagnetic fields can be interpreted as closely analogous to
the CME. In particular, the velocity of the pseudo-scalar field, which is the
phase of a complex scalar, indicates that the system carries a global U(1)
number asymmetry as the source of the induced current. We demonstrate that an
initial kick to the phase-field velocity and an anomalous coupling between the
phase-field and gauge fields are naturally provided, in a set-up such as the
Affleck-Dine mechanism. The resulting asymmetry carried by the Affleck-Dine
field can give rise to instability in the (electro)magnetic field. Cosmological
consequences of this mechanism are also investigated.Comment: 35 pages, 1 figure; v2: extended discussions, comments and references
added, matches version accepted for publication in JHE
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