59,499 research outputs found
A note on linearized "New Massive Gravity" in arbitrary dimensions
By means of a triple master action we deduce here a linearized version of the
"New Massive Gravity" (NMG) in arbitrary dimensions. The theory contains a
4th-order and a 2nd-order term in derivatives. The 4th-order term is invariant
under a generalized Weyl symmetry. The action is formulated in terms of a
traceless mixed symmetry tensor
and corresponds to the massive
Fierz-Pauli action with the replacement
e_{\mu\nu}=\p^{\rho}\Omega_{\mu\nu\rho}. The linearized 3D and 4D NMG
theories are recovered via the invertible maps and respectively.
The properties and follow
from the traceless restriction. The equations of motion of the linearized NMG
theory can be written as zero "curvature" conditions \p_{\nu}T_{\rho\mu} -
\p_{\rho}T_{\nu\mu}=0 in arbitrary dimensions.Comment: 15 pages, no figures, few typos fixed, one more referenc
Elodie metallicity-biased search for transiting Hot Jupiters I. Two Hot Jupiters orbiting the slightly evolved stars HD118203 and HD149143
We report the discovery of a new planet candidate orbiting the subgiant star
HD118203 with a period of P=6.1335 days. The best Keplerian solution yields an
eccentricity e=0.31 and a minimum mass m2sin(i)=2.1MJup for the planet. This
star has been observed with the ELODIE fiber-fed spectrograph as one of the
targets in our planet-search programme biased toward high-metallicity stars,
on-going since March 2004 at the Haute-Provence Observatory. An analysis of the
spectroscopic line profiles using line bisectors revealed no correlation
between the radial velocities and the line-bisector orientations, indicating
that the periodic radial-velocity signal is best explained by the presence of a
planet-mass companion. A linear trend is observed in the residuals around the
orbital solution that could be explained by the presence of a second companion
in a longer-period orbit. We also present here our orbital solution for another
slightly evolved star in our metal-rich sample, HD149143, recently proposed to
host a 4-d period Hot Jupiter by the N2K consortium. Our solution yields a
period P=4.09 days, a marginally significant eccentricity e=0.08 and a
planetary minimum mass of 1.36MJup. We checked that the shape of the spectral
lines does not vary for this star as well.Comment: Accepted in A&A (6 pages, 6 figures
Tracking Vector Magnetograms with the Magnetic Induction Equation
The differential affine velocity estimator (DAVE) developed in Schuck (2006)
for estimating velocities from line-of-sight magnetograms is modified to
directly incorporate horizontal magnetic fields to produce a differential
affine velocity estimator for vector magnetograms (DAVE4VM). The DAVE4VM's
performance is demonstrated on the synthetic data from the anelastic
pseudospectral ANMHD simulations that were used in the recent comparison of
velocity inversion techniques by Welsch (2007). The DAVE4VM predicts roughly
95% of the helicity rate and 75% of the power transmitted through the
simulation slice. Inter-comparison between DAVE4VM and DAVE and further
analysis of the DAVE method demonstrates that line-of-sight tracking methods
capture the shearing motion of magnetic footpoints but are insensitive to flux
emergence -- the velocities determined from line-of-sight methods are more
consistent with horizontal plasma velocities than with flux transport
velocities. These results suggest that previous studies that rely on velocities
determined from line-of-sight methods such as the DAVE or local correlation
tracking may substantially misrepresent the total helicity rates and power
through the photosphere.Comment: 30 pages, 13 figure
Impact of stellar companions on precise radial velocities
Context: With the announced arrival of instruments such as ESPRESSO one can
expect that several systematic noise sources on the measurement of precise
radial velocity will become the limiting factor instead of photon noise. A
stellar companion within the fiber is such a possible noise source. Aims: With
this work we aim at characterizing the impact of a stellar companion within the
fiber to radial velocity measurements made by fiber-fed spectrographs. We
consider the contaminant star either to be part of a binary system whose
primary star is the target star, or as a background/foreground star. Methods:
To carry out our study, we used HARPS spectra, co-added the target with
contaminant spectra, and then compared the resulting radial velocity with that
obtained from the original target spectrum. We repeated this procedure and used
different tunable knobs to reproduce the previously mentioned scenarios.
Results: We find that the impact on the radial velocity calculation is a
function of the difference between individual radial velocities, of the
difference between target and contaminant magnitude, and also of their spectral
types. For the worst-case scenario in which both target and contaminant star
are well centered on the fiber, the maximum contamination for a G or K star may
be higher than 10 cm/s, on average, if the difference between target and
contaminant magnitude is < 10, and higher than 1 m/s if <
8. If the target star is of spectral type M, < 8 produces the same
contamination of 10 cm/s, and a contamination may be higher than 1 m/sComment: Accepted for publication in A&A on 29/12/2019 - 14 page
Deformation method for generalized Abelian Higgs-Chern-Simons models
We present an extension of the deformation method applied to self-dual
solutions of generalized Abelian Higgs-Chern-Simons models. Starting from a
model defined by a potential and a non-canonical kinetic term
whose analytical domain wall solutions are
known, we show that this method allows to obtain an uncountable number of new
analytical solutions of new models defined by other functions
and . We present some examples of deformation functions
leading to new families of models and their associated analytic solutions.Comment: 6 pages, 10 figure
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