13,253 research outputs found
The Scalar Sector in 331 Models
We calculate the exact tree-level scalar mass matrices resulting from
symmetry breaking using the most general gauge-invariant scalar potential of
the 331 model, both with and without the condition that lepton number is
conserved. Physical masses are also obtained in some cases, as well as
couplings to standard and exotic gauge bosons.Comment: LaTex, 15 page
3D Velocity and Density Reconstructions of the Local Universe with Cosmicflows-1
This paper presents an analysis of the local peculiar velocity field based on
the Wiener Filter reconstruction method. We used our currently available
catalog of distance measurements containing 1,797 galaxies within 3000 km/s:
Cosmicflows-1. The Wiener Filter method is used to recover the full 3D peculiar
velocity field from the observed map of radial velocities and to recover the
underlying linear density field. The velocity field within a data zone of 3000
km/s is decomposed into a local component that is generated within the data
zone and a tidal one that is generated by the mass distribution outside that
zone. The tidal component is characterized by a coherent flow toward the
Norma-Hydra-Centaurus (Great Attractor) region while the local component is
dominated by a flow toward the Virgo Cluster and away from the Local Void. A
detailed analysis shows that the local flow is predominantly governed by the
Local Void and the Virgo Cluster plays a lesser role. The analysis procedure
was tested against a mock catalog. It is demonstrated that the Wiener Filter
accurately recovers the input velocity field of the mock catalog on the scale
of the extraction of distances and reasonably recovers the velocity field on
significantly larger scales. The Bayesian Wiener Filter reconstruction is
carried out within the ?CDM WMAP5 framework. The Wiener Filter reconstruction
draws particular attention to the importance of voids in proximity to our
neighborhood. The prominent structure of the Local Supercluster is wrapped in a
horseshoe collar of under density with the Local Void as a major component.Comment: Accepted for ApJ, August 6, 201
Cosmicflows-2: SNIa Calibration and H0
The construction of the Cosmicflows-2 compendium of distances involves the
merging of distance measures contributed by the following methods: (Cepheid)
Period-Luminosity, Tip of the Red Giant Branch (TRGB), Surface Brightness
Fluctuation (SBF), Luminosity-Linewidth (TF), Fundamental Plane (FP), and Type
Ia supernova (SNIa). The method involving SNIa is at the top of an
interconnected ladder, providing accurate distances to well beyond the expected
range of distortions to Hubble flow from peculiar motions. In this paper, the
SNIa scale is anchored by 36 TF spirals with Cepheid or TRGB distances, 56 SNIa
hosts with TF distances, and 61 groups or clusters hosting SNIa with Cepheid,
SBF, TF, or FP distances. With the SNIa scale zero point set, a value of the
Hubble Constant is evaluated over a range of redshifts 0.03 < z < 0.5, assuming
a cosmological model with Omega_m = 0.27 and Omega_Lambda = 0.73. The value
determined for the Hubble Constant is H0 = 75.9 \pm 3.8 km s-1 Mpc-1.Comment: Accepted for publication in The Astrophysical Journal. 11 pages,
8Figures, 5 Table
The mid-infrared Tully-Fisher relation: Spitzer Surface Photometry
The availability of photometric imaging of several thousand galaxies with the
Spitzer Space Telescope enables a mid-infrared calibration of the correlation
between luminosity and rotation in spiral galaxies. The most important
advantage of the new calibration in the 3.6 micron band, IRAC ch.1, is
photometric consistency across the entire sky. Additional advantages are
minimal obscuration, observations of flux dominated by old stars, and
sensitivity to low surface brightness levels due to favorable backgrounds.
Through Spitzer cycle 7 roughly 3000 galaxies had been observed and images of
these are available at the Spitzer archive. In cycle 8 a program called Cosmic
Flows with Spitzer has been initiated that will increase by 1274 the available
sample of spiral galaxies with inclinations greater than 45 degrees from
face-on suitable for distance measurements. This paper describes procedures
based on the photometry package Archangel that are being employed to analyze
both the archival and the new data in a uniform way. We give results for 235
galaxies, our calibrator sample for the Tully-Fisher relation. Galaxy
magnitudes are determined with uncertainties held below 0.05 mag for normal
spiral systems. A subsequent paper will describe the calibration of the [3.6]
luminosity-rotation relation.Comment: Accepted for publication in The Astronomical Journal, 12 pages, 9
figure
Cosmicflows-2: I-band Luminosity - HI Linewidth Calibration
In order to measure distances with minimal systematics using the correlation
between galaxy luminosities and rotation rates it is necessary to adhere to a
strict and tested recipe. We now derive a measure of rotation from a new
characterization of the width of a neutral Hydrogen line profile. Additionally,
new photometry and zero point calibration data are available. Particularly the
introduction of a new linewidth parameter necessitates the reconstruction and
absolute calibration of the luminosity-linewidth template. The slope of the new
template is set by 267 galaxies in 13 clusters. The zero point is set by 36
galaxies with Cepheid or Tip of the Red Giant Branch distances. Tentatively, we
determine H0 = 75 km s-1 Mpc-1. Distances determined using the
luminosity-linewidth calibration will contribute to the distance compendium
Cosmicflows-2.Comment: Accepted for publication in The Astrophysical Journal, 27 pages, 18
figure
Derivation of Distances with the Tully-Fisher Relation: The Antlia Cluster
The Tully-Fisher relation is a correlation between the luminosity and the HI
21cm line width in spiral galaxies (LLW relation). It is used to derive galaxy
distances in the interval 7 to 100 Mpc. Closer, the Cepheids, TRGB and Surface
Brightness Fluctuation methods give a better accuracy. Further, the SNIa are
luminous objects still available for distance measurement purposes, though with
a dramatically lower density grid of measurements on the sky. Galaxies in
clusters are all at the same distance from the observer. Thus the distance of
the cluster derived from a large number of galaxies (N) has an error reduced
according to the square root of N. However, not all galaxies in a cluster are
suitable for the LLW measurement. The selection criteria we use are explained
hereafter; the important point being to avoid Malmquist bias and to not
introduce any systematics in the distance measurement.Comment: Moriond0
Cosmic Bulk Flow and the Local Motion from Cosmicflows-2
Full sky surveys of peculiar velocity are arguably the best way to map the
large scale structure out to distances of a few times 100 Mpc/h. Using the
largest and most accurate ever catalog of galaxy peculiar velocities
"Cosmicflows-2", the large scale structure has been reconstructed by means of
the Wiener filter and constrained realizations assuming as a Bayesian prior
model the LCDM model with the WMAP inferred cosmological parameters. The
present paper focuses on studying the bulk flow of the local flow field,
defined as the mean velocity of top-hat spheres with radii ranging out to R=500
Mpc/h. The estimated large scale structures, in general, and the bulk flow, in
particular, are determined by the tension between the observational data and
the assumed prior model. A prerequisite for such an analysis is the requirement
that the estimated bulk flow is consistent with the prior model. Such a
consistency is found here. At R=50(150) Mpc/h the estimated bulk velocity is
250+/-21 (239+/-38) km/s. The corresponding cosmic variance at these radii is
126(60)km/s, which implies that these estimated bulk flows are dominated by the
data and not by the assumed prior model. The estimated bulk velocity is
dominated by the data out to R~200 Mpc/h, where the cosmic variance on the
individual Supergalactic Cartesian components (of the r.m.s. values) exceeds
the variance of the Constrained Realizations by at least a factor of 2. The
supergalactic SGX and SGY components of the CMB dipole velocity are recovered
by the Wiener filter velocity field down to a very few km/s. The SGZ component
of the estimated velocity, the one that is most affected by the Zone of
Avoidance, is off by 126 km/s (an almost 2 sigma discrepancy).Comment: 10 pages, accepted for MNRA
Cosmological fluctuation growth in bimetric MOND
I look at the growth of weak density inhomogeneities of nonrelativistic
matter, in bimetric-MOND (BIMOND) cosmology. I concentrate on
matter-twin-matter-symmetric versions of BIMOND, and assume that, on average,
the universe is symmetrically populated in the two sectors. MOND effects are
absent in an exactly symmetric universe, apart from the appearance of a
cosmological constant, Lambda~(a0/c)^2. MOND effects-local and cosmological-do
enter when density inhomogeneities that differ in the two sectors appear and
develop. MOND later takes its standard form in systems that are islands
dominated by pure matter. I derive the nonrelativistic equations governing
small-scale fluctuation growth. The equations split into two uncoupled systems,
one for the sum, the other for the difference, of the fluctuations in the two
sectors. The former is governed strictly by Newtonian dynamics. The latter is
governed by MOND dynamics, which entails stronger gravity, and nonlinearity
even for the smallest of perturbations. These cause the difference to grow
faster than the sum, conducing to matter-twin-matter segregation. The
nonlinearity also causes interaction between nested perturbations on different
scales. Because matter and twin matter (TM) repel each other in the MOND
regime, matter inhomogeneities grow not only by their own self gravity, but
also through shepherding by flanking TM overdensitie. The relative importance
of gravity and pressure in the MOND system depends also on the strength of the
perturbation. The development of structure in the universe, in either sector,
thus depends crucially on two initial fluctuation spectra: that of matter alone
and that of the matter-TM difference. I also discuss the back reaction on
cosmology of BIMOND effects that appear as "phantom matter" resulting from
inhomogeneity differences between the two sectors.Comment: 14 pages. Some clarifications added. Version published in Phys. Rev.
The Mid-Infrared Tully-Fisher Relation: Calibration of the SNIa Scale and Ho
This paper builds on a calibration of the SNIa absolute distance scale begun
with a core of distances based on the correlation between galaxy rotation rates
and optical Ic band photometry. This new work extends the calibration through
the use of mid-infrared photometry acquired at 3.6 microns with Spitzer Space
Telescope. The great virtue of the satellite observations is constancy of the
photometry at a level better than 1% across the sky. The new calibration is
based on 39 individual galaxies and 8 clusters that have been the sites of well
observed SNIa. The new 3.6 micron calibration is not yet as extensively based
as the Ic band calibration but is already sufficient to justify a preliminary
report. Distances based on the mid-infrared photometry are 2% greater in the
mean than reported at Ic band. This difference is only marginally significant.
The Ic band result is confirmed with only a small adjustment. Incorporating a
1% decrease in the LMC distance, the present study indicates Ho = 75.2 +/- 3.0
km/s/Mpc.Comment: Accepted for publication in The Astrophysical Journal Letters, 6
pages, 2 figure
The Velocity Field from Type Ia Supernovae Matches the Gravity Field from Galaxy Surveys
We compare the peculiar velocities of nearby SNe Ia with those predicted by
the gravity fields of full sky galaxy catalogs. The method provides a powerful
test of the gravitational instability paradigm and strong constraints on the
density parameter beta = Omega^0.6/b. For 24 SNe Ia within 10,000 km/s we find
the observed SNe Ia peculiar velocities are well modeled by the predictions
derived from the 1.2 Jy IRAS survey and the Optical Redshift Survey (ORS). Our
best is 0.4 from IRAS, and 0.3 from the ORS, with beta>0.7 and
beta<0.15 ruled out at 95% confidence levels from the IRAS comparison.
Bootstrap resampling tests show these results to be robust in the mean and in
its error. The precision of this technique will improve as additional nearby
SNe Ia are discovered and monitored.Comment: 16 pages (LaTex), 3 postscript figure
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