416 research outputs found
Approximating the inspiral of test bodies into Kerr black holes
We present a new approximate method for constructing gravitational radiation
driven inspirals of test-bodies orbiting Kerr black holes. Such orbits can be
fully described by a semi-latus rectum , an eccentricity , and an
inclination angle ; or, by an energy , an angular momentum component
, and a third constant . Our scheme uses expressions that are exact
(within an adiabatic approximation) for the rates of change (,
, ) as linear combinations of the fluxes (,
, ), but uses quadrupole-order formulae for these fluxes.
This scheme thus encodes the exact orbital dynamics, augmenting it with
approximate radiation reaction. Comparing inspiral trajectories, we find that
this approximation agrees well with numerical results for the special cases of
eccentric equatorial and circular inclined orbits, far more accurate than
corresponding weak-field formulae for (, , ). We
use this technique to study the inspiral of a test-body in inclined, eccentric
Kerr orbits. Our results should be useful tools for constructing approximate
waveforms that can be used to study data analysis problems for the future LISA
gravitational-wave observatory, in lieu of waveforms from more rigorous
techniques that are currently under development.Comment: 15 pages, 5 figures, submitted to PR
Metabolomics of reef benthic interactions reveals a bioactive lipid involved in coral defence
Infants rely more on gaze cues from own-race than other-race adults for learning under uncertainty
Differential experience leads infants to have perceptual processing advantages for own- over other-race faces, but whether this experience has down-stream consequences is unknown. Three experiments examined whether 7-month-olds (Range = 5.9-8.5 months, N = 96) use gaze from own- versus other-race adults to anticipate events. When gaze predicted an eventâs occurrence with 100% reliability, 7-month-olds followed both adults equally; with 25% (chance) reliability, neither was followed. However, with 50% (uncertain) reliability, infants followed own- over other-race gaze. Differential face race experience may thus affect how infants use social cues from own- versus other-race adults for learning. Such findings suggest that infants integrate online statistical reliability information with prior knowledge of own- versus other-race to guide social interaction and learning
Three-Dimensional Molecular Cartography of the Caribbean Reef-Building Coral<i> Orbicella faveolata</i>
Three-Dimensional Molecular Cartography of the Caribbean Reef-Building Coral<i> Orbicella faveolata</i>
Tess hunt for young and maturing exoplanets (thyme). II. a 17 myr old transiting hot jupiter in the sco-cen association
We present the discovery of a transiting hot Jupiter orbiting HIP 67522 (T eff ⌠5650 K; M â ⌠1.2M oË) in the 10-20 Myr old Sco-Cen OB association. We identified the transits in the TESS data using our custom notch filter planet search pipeline and characterize the system with additional photometry from Spitzer; spectroscopy from SOAR/Goodman, SALT/HRS, LCOGT/NRES, and SMARTS/CHIRON; and speckle imaging from SOAR/HRCam. We model the photometry as a periodic Gaussian process with transits to account for stellar variability and find an orbital period of 6.9596+0.0000150-000016days and radius of10.02-0.53+0.54Râ. We also identify a single transit of an additional candidate planet with radius 8.01-0.710.75R â that has an orbital period of âȘ23 days. The validated planet HIP 67522b is currently the youngest transiting hot Jupiter discovered and is an ideal candidate for transmission spectroscopy and radial velocity follow-up studies, while also demonstrating that some young giant planets either form in situ at small orbital radii or else migrate promptly from formation sites farther out in the disk
Search for Higgs bosons decaying to tautau pairs in ppbar collisions at sqrt(s) = 1.96 TeV
We present a search for the production of neutral Higgs bosons decaying into
tautau pairs in ppbar collisions at a center-of-mass energy of 1.96 TeV. The
data, corresponding to an integrated luminosity of 5.4 fb-1, were collected by
the D0 experiment at the Fermilab Tevatron Collider. We set upper limits at the
95% C.L. on the product of production cross section and branching ratio for a
scalar resonance decaying into tautau pairs, and we then interpret these limits
as limits on the production of Higgs bosons in the minimal supersymmetric
standard model (MSSM) and as constraints in the MSSM parameter space.Comment: 7 pages, 5 figures, submitted to PL
Measurement of the photon-jet production differential cross section in collisions at \sqrt{s}=1.96~\TeV
We present measurements of the differential cross section dsigma/dpT_gamma
for the inclusive production of a photon in association with a b-quark jet for
photons with rapidities |y_gamma|< 1.0 and 30<pT_gamma <300 GeV, as well as for
photons with 1.5<|y_gamma|< 2.5 and 30< pT_gamma <200 GeV, where pT_gamma is
the photon transverse momentum. The b-quark jets are required to have pT>15 GeV
and rapidity |y_jet| < 1.5. The results are based on data corresponding to an
integrated luminosity of 8.7 fb^-1, recorded with the D0 detector at the
Fermilab Tevatron Collider at sqrt(s)=1.96 TeV. The measured cross
sections are compared with next-to-leading order perturbative QCD calculations
using different sets of parton distribution functions as well as to predictions
based on the kT-factorization QCD approach, and those from the Sherpa and
Pythia Monte Carlo event generators.Comment: 10 pages, 9 figures, submitted to Phys. Lett.
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