462 research outputs found
Jaringan Detektif Anti-trafficking “J-track”: Upaya Membentuk Anak Siap Dan Tanggap Bahaya Trafficking
Indonesia was claimed as first ranked country trafficking victims contributor. Surabaya\u27s one of the cities in Indonesia with pretty high trafficking practices. There has been no senior high school (SMA/SMK) students act in preventing of trafficking, so as participatory approach is needed to encourage SMA/SMK students contributed actively to prevent him and others about trafficking menace. J-Track\u27s using guide training system method. This system aims to create an independent, softskilled, prepared, and responsive student. The increased shown in their changed attitude indicate this program output achievement\u27s success and expected this J-Track program will continue to grow for the sake of usefulnes
Bose Hubbard Model in a Strong Effective Magnetic Field: Emergence of a Chiral Mott Insulator Ground State
Motivated by experiments on Josephson junction arrays, and cold atoms in an
optical lattice in a synthetic magnetic field, we study the "fully frustrated"
Bose-Hubbard (FFBH) model with half a magnetic flux quantum per plaquette. We
obtain the phase diagram of this model on a two-leg ladder at integer filling
via the density matrix renormalization group approach, complemented by Monte
Carlo simulations on an effective classical XY model. The ground state at
intermediate correlations is consistently shown to be a chiral Mott insulator
(CMI) with a gap to all excitations and staggered loop currents which
spontaneously break time reversal symmetry. We characterize the CMI state as a
vortex supersolid or an indirect exciton condensate, and discuss various
experimental implications.Comment: 4 pages, 4 figs, Significantly revised version, to appear in
PRA-Rapi
Search for the isotropic stochastic background using data from Advanced LIGO's second observing run
The stochastic gravitational-wave background is a superposition of sources that are either too weak or too numerous to detect individually. In this study, we present the results from a cross-correlation analysis on data from Advanced LIGO’s second observing run (O2), which we combine with the results of the first observing run (O1). We do not find evidence for a stochastic background, so we place upper limits on the normalized energy density in gravitational waves at the 95% credible level of Ω GW < 6.0 × 10 − 8 for a frequency-independent (flat) background and Ω GW < 4.8 × 10 − 8 at 25 Hz for a background of compact binary coalescences. The upper limit improves over the O1 result by a factor of 2.8. Additionally, we place upper limits on the energy density in an isotropic background of scalar- and vector-polarized gravitational waves, and we discuss the implication of these results for models of compact binaries and cosmic string backgrounds. Finally, we present a conservative estimate of the correlated broadband noise due to the magnetic Schumann resonances in O2, based on magnetometer measurements at both the LIGO Hanford and LIGO Livingston observatories. We find that correlated noise is well below the O2 sensitivity
Searches for gravitational waves from known pulsars at two harmonics in 2015-2017 LIGO data
International audienceWe present a search for gravitational waves from 222 pulsars with rotation frequencies ≳10 Hz. We use advanced LIGO data from its first and second observing runs spanning 2015–2017, which provides the highest-sensitivity gravitational-wave data so far obtained. In this search we target emission from both the l = m = 2 mass quadrupole mode, with a frequency at twice that of the pulsar’s rotation, and the l = 2, m = 1 mode, with a frequency at the pulsar rotation frequency. The search finds no evidence for gravitational-wave emission from any pulsar at either frequency. For the l = m = 2 mode search, we provide updated upper limits on the gravitational-wave amplitude, mass quadrupole moment, and fiducial ellipticity for 167 pulsars, and the first such limits for a further 55. For 20 young pulsars these results give limits that are below those inferred from the pulsars’ spin-down. For the Crab and Vela pulsars our results constrain gravitational-wave emission to account for less than 0.017% and 0.18% of the spin-down luminosity, respectively. For the recycled millisecond pulsar J0711−6830 our limits are only a factor of 1.3 above the spin-down limit, assuming the canonical value of 1038 kg m2 for the star’s moment of inertia, and imply a gravitational-wave-derived upper limit on the star’s ellipticity of 1.2 × 10−8. We also place new limits on the emission amplitude at the rotation frequency of the pulsars
Constraints on dark photon dark matter using data from LIGO's and Virgo's third observing run
We present a search for dark photon dark matter that could couple to
gravitational-wave interferometers using data from Advanced LIGO and Virgo's
third observing run. To perform this analysis, we use two methods, one based on
cross-correlation of the strain channels in the two nearly aligned LIGO
detectors, and one that looks for excess power in the strain channels of the
LIGO and Virgo detectors. The excess power method optimizes the Fourier
Transform coherence time as a function of frequency, to account for the
expected signal width due to Doppler modulations. We do not find any evidence
of dark photon dark matter with a mass between eV/, which corresponds to frequencies between 10-2000
Hz, and therefore provide upper limits on the square of the minimum coupling of
dark photons to baryons, i.e. dark matter. For the
cross-correlation method, the best median constraint on the squared coupling is
at eV/; for the
other analysis, the best constraint is at eV/. These limits improve upon those obtained
in direct dark matter detection experiments by a factor of for
eV/, and are, in absolute terms, the
most stringent constraint so far in a large mass range eV/.Comment: 20 pages, 7 figure
The population of merging compact binaries inferred using gravitational waves through GWTC-3
We report on the population properties of 76 compact binary mergers detected with gravitational waves below a false alarm rate of 1 per year through GWTC-3. The catalog contains three classes of binary mergers: BBH, BNS, and NSBH mergers. We infer the BNS merger rate to be between 10 and 1700 and the NSBH merger rate to be between 7.8 and 140 , assuming a constant rate density versus comoving volume and taking the union of 90% credible intervals for methods used in this work. Accounting for the BBH merger rate to evolve with redshift, we find the BBH merger rate to be between 17.9 and 44 at a fiducial redshift (z=0.2). We obtain a broad neutron star mass distribution extending from to . We can confidently identify a rapid decrease in merger rate versus component mass between neutron star-like masses and black-hole-like masses, but there is no evidence that the merger rate increases again before 10 . We also find the BBH mass distribution has localized over- and under-densities relative to a power law distribution. While we continue to find the mass distribution of a binary's more massive component strongly decreases as a function of primary mass, we observe no evidence of a strongly suppressed merger rate above . The rate of BBH mergers is observed to increase with redshift at a rate proportional to with for . Observed black hole spins are small, with half of spin magnitudes below . We observe evidence of negative aligned spins in the population, and an increase in spin magnitude for systems with more unequal mass ratio
All-sky search for long-duration gravitational-wave bursts in the third Advanced LIGO and Advanced Virgo run
After the detection of gravitational waves from compact binary coalescences, the search for transient gravitational-wave signals with less well-defined waveforms for which matched filtering is not well suited is one of the frontiers for gravitational-wave astronomy. Broadly classified into “short” ≲1 s and “long” ≳1 s duration signals, these signals are expected from a variety of astrophysical processes, including non-axisymmetric deformations in magnetars or eccentric binary black hole coalescences. In this work, we present a search for long-duration gravitational-wave transients from Advanced LIGO and Advanced Virgo’s third observing run from April 2019 to March 2020. For this search, we use minimal assumptions for the sky location, event time, waveform morphology, and duration of the source. The search covers the range of 2–500 s in duration and a frequency band of 24–2048 Hz. We find no significant triggers within this parameter space; we report sensitivity limits on the signal strength of gravitational waves characterized by the root-sum-square amplitude hrss as a function of waveform morphology. These hrss limits improve upon the results from the second observing run by an average factor of 1.8
Search for gravitational-wave transients associated with magnetar bursts in Advanced LIGO and Advanced Virgo data from the third observing run
Gravitational waves are expected to be produced from neutron staroscillations associated with magnetar giant flares and short bursts. We presentthe results of a search for short-duration (milliseconds to seconds) andlong-duration ( 100 s) transient gravitational waves from 13 magnetarshort bursts observed during Advanced LIGO, Advanced Virgo and KAGRA's thirdobservation run. These 13 bursts come from two magnetars, SGR 19352154 andSwift J1818.01607. We also include three other electromagnetic burst eventsdetected by Fermi GBM which were identified as likely coming from one or moremagnetars, but they have no association with a known magnetar. No magnetargiant flares were detected during the analysis period. We find no evidence ofgravitational waves associated with any of these 16 bursts. We place upperbounds on the root-sum-square of the integrated gravitational-wave strain thatreach at 100 Hz for theshort-duration search and at Hzfor the long-duration search, given a detection efficiency of 50%. For aringdown signal at 1590 Hz targeted by the short-duration search the limit isset to . Using the estimated distanceto each magnetar, we derive upper bounds on the emitted gravitational-waveenergy of erg ( erg) for SGR19352154 and erg ( erg) for SwiftJ1818.01607, for the short-duration (long-duration) search. Assumingisotropic emission of electromagnetic radiation of the burst fluences, weconstrain the ratio of gravitational-wave energy to electromagnetic energy forbursts from SGR 19352154 with available fluence information. The lowest ofthese ratios is .<br
GW190521 : a binary black hole merger with a total mass of 150 M⊙
On May 21, 2019 at 03:02:29 UTC Advanced LIGO and Advanced Virgo observed a short duration gravitational-wave signal, GW190521, with a three-detector network signal-to-noise ratio of 14.7, and an estimated false-alarm rate of 1 in 4900 yr using a search sensitive to generic transients. If GW190521 is from a quasicircular binary inspiral, then the detected signal is consistent with the merger of two black holes with masses of 85+21−14 M⊙ and 66+17−18 M⊙ (90% credible intervals). We infer that the primary black hole mass lies within the gap produced by (pulsational) pair-instability supernova processes, with only a 0.32% probability of being below 65 M⊙. We calculate the mass of the remnant to be 142+28−16 M⊙, which can be considered an intermediate mass black hole (IMBH). The luminosity distance of the source is 5.3+2.4−2.6 Gpc, corresponding to a redshift of 0.82+0.28−0.34. The inferred rate of mergers similar to GW190521 is 0.13+0.30−0.11 Gpc−3 yr−1
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