10,514 research outputs found
Localizing merging black holes with sub-arcsecond precision using gravitational-wave lensing
The current gravitational-wave localization methods rely mainly on sources
with electromagnetic counterparts. Unfortunately, a binary black hole does not
emit light. Due to this, it is generally not possible to localize these objects
precisely. However, strongly lensed gravitational waves, which are forecasted
in this decade, could allow us to localize the binary by locating its lensed
host galaxy. Identifying the correct host galaxy is challenging because there
are hundreds to thousands of other lensed galaxies within the sky area spanned
by the gravitational-wave observation. However, we can constrain the lensing
galaxy's physical properties through both gravitational-wave and
electromagnetic observations. We show that these simultaneous constraints allow
one to localize quadruply lensed waves to one or at most a few galaxies with
the LIGO/Virgo/Kagra network in typical scenarios. Once we identify the host,
we can localize the binary to two sub-arcsec regions within the host galaxy.
Moreover, we demonstrate how to use the system to measure the Hubble constant
as a proof-of-principle application.Comment: 5 pages (main text) + 5 pages (methods+references), 5 figures.
Accepted to MNRA
Topological interactions in systems of mutually interlinked polymer rings
The topological interaction arising in interlinked polymeric rings such as
DNA catenanes is considered. More specifically, the free energy for a pair of
linked random walk rings is derived where the distance between two segments
each of which is part of a different ring is kept constant. The topology
conservation is imposed by the Gauss invariant. A previous approach (M.Otto,
T.A. Vilgis, Phys.Rev.Lett. {\bf 80}, 881 (1998)) to the problem is refined in
several ways. It is confirmed, that asymptotically, i.e. for large
where is average size of single random walk ring, the effective
topological interaction (free energy) scales .Comment: 16 pages, 3 figur
Doppler Shift in Andreev Reflection from a Moving Superconducting Condensate in Nb/InAs Josephson Junctions
We study narrow ballistic Josephson weak links in a InAs quantum wells
contacted by Nb electrodes and find a dramatic magnetic-field suppression of
the Andreev reflection amplitude, which occurs even for in-plane field
orientation with essentially no magnetic flux through the junction. Our
observations demonstrate the presence of a Doppler shift in the energy of the
Andreev levels, which results from diamagnetic screening currents in the hybrid
Nb/InAs-banks. The data for conductance, excess and critical currents can be
consistently explained in terms of the sample geometry and the McMillan energy,
characterizing the transparency of the Nb/InAs-interface.Comment: 4 pages, 5 figures, title modifie
Automatic structures for semigroup constructions
We survey results concerning automatic structures for semigroup
constructions, providing references and describing the corresponding automatic
structures. The constructions we consider are: free products, direct products,
Rees matrix semigroups, Bruck-Reilly extensions and wreath products.Comment: 22 page
lensingGW: a Python package for lensing of gravitational waves
Advanced LIGO and Advanced Virgo could observe the first lensed gravitational
waves in the coming years, while the future Einstein Telescope could observe
hundreds of lensed events. Ground-based gravitational-wave detectors can
resolve arrival time differences of the order of the inverse of the observed
frequencies. As LIGO/Virgo frequency band spans from a few to a few , the typical time resolution of current interferometers is of the
order of milliseconds. When microlenses are embedded in galaxies or galaxy
clusters, lensing can become more prominent and result in observable time
delays at LIGO/Virgo frequencies. Therefore, gravitational waves could offer an
exciting alternative probe of microlensing. However, currently, only a few
lensing configurations have been worked out in the context of
gravitational-wave lensing. In this paper, we present lensingGW, a Python
package designed to handle both strong and microlensing of compact binaries and
the related gravitational-wave signals. This synergy paves the way for
systematic parameter space investigations and the detection of arbitrary lens
configurations and compact sources. We demonstrate the working mechanism of
lensingGW and its use to study microlenses embedded in galaxies.Comment: 11 pages, 10 figure
Improving Detection of Gravitational wave Microlensing Using Repeated Signals Induced by Strong Lensing
Microlensing imprints by typical stellar mass lenses on gravitational waves
are challenging to identify in the LIGO and Virgo frequency band because such
effects are weak. However, stellar mass lenses are generally embedded in lens
galaxies such that strong lensing accompanies microlensing. Therefore, events
that are strongly lensed in addition to being microlensed may significantly
improve the inference of the latter. We present a proof of principle
demonstration of how one can use parameter estimation results from one strongly
lensed signal to enhance the inference of the microlensing effects of the other
signal with the Bayesian inference method currently used in gravitational wave
astronomy. We expect this to significantly enhance our future ability to detect
the weak imprints from stellar mass objects on gravitational-wave signals from
colliding compact objects.Comment: 8 pages, 5 figures, presented at TAUP 202
Interferometric Astrometry of the Low-mass Binary Gl 791.2 (= HU Del) Using Hubble Space Telescope Fine Guidance Sensor 3: Parallax and Component Masses
With fourteen epochs of fringe tracking data spanning 1.7y from Fine Guidance
Sensor 3 we have obtained a parallax (pi_abs=113.1 +- 0.3 mas) and perturbation
orbit for Gl 791.2A. Contemporaneous fringe scanning observations yield only
three clear detections of the secondary on both interferometer axes. They
provide a mean component magnitude difference, Delta V = 3.27 +- 0.10. The
period (P = 1.4731 yr) from the perturbation orbit and the semi-major axis (a =
0.963 +- 0.007 AU) from the measured component separations with our parallax
provide a total system mass M_A + M_B = 0.412 +- 0.009 M_sun. Component masses
are M_A=0.286 +- 0.006 M_sun and M_B = 0.126 +- 0.003 M_sun. Gl 791.2A and B
are placed in a sparsely populated region of the lower main sequence
mass-luminosity relation where they help define the relation because the masses
have been determined to high accuracy, with errors of only 2%.Comment: 19 pages, 5 figures. The paper is to appear in August 2000 A
Topological Entanglement of Polymers and Chern-Simons Field Theory
In recent times some interesting field theoretical descriptions of the
statistical mechanics of entangling polymers have been proposed by various
authors. In these approaches, a single test polymer fluctuating in a background
of static polymers or in a lattice of obstacles is considered. The extension to
the case in which the configurations of two or more polymers become non-static
is not straightforward unless their trajectories are severely constrained. In
this paper we present another approach, based on Chern--Simons field theory,
which is able to describe the topological entanglements of two fluctuating
polymers in terms of gauge fields and second quantized replica fields.Comment: 16 pages, corrected some typos, added two new reference
Extreme Dark Matter Tests with Extreme Mass Ratio Inspirals
Future space-based laser interferometry experiments such as LISA are expected
to detect (100--1000) stellar-mass compact objects (e.g., black holes,
neutron stars) falling into massive black holes in the centers of galaxies, the
so-called extreme-mass-ratio inspirals (EMRIs). If dark matter forms a "spike"
due to the growth of the massive black hole, it will induce a gravitational
drag on the inspiraling object, changing its orbit and gravitational-wave
signal. We show that detection of even a single dark matter spike from the
EMRIs will severely constrain several popular dark matter candidates, such as
ultralight bosons, keV fermions, MeV--TeV self-annihilating dark matter, and
sub-solar mass primordial black holes, as these candidates would flatten the
spikes through various mechanisms. Future space gravitational wave experiments
could thus have a significant impact on the particle identification of dark
matter.Comment: 10 pages (main body: 5 pages), 2 figure
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