156 research outputs found
Elliptic CMB Sky
The ellipticity of the anisotropy spots of the Cosmic Microwave Background
measured by the Wilkinson Microwave Anisotropy Probe (WMAP) has been studied.
We find an average ellipticity of about 2, confirming with a far larger
statistics similar results found first for the COBE-DMR CMB maps, and then for
the BOOMERanG CMB maps. There are no preferred directions for the obliquity of
the anisotropy spots. The average ellipticity is independent of temperature
threshold and is present on scales both smaller and larger than the horizon at
the last scattering. The measured ellipticity characteristics are consistent
with being the effect of geodesics mixing occurring in an hyperbolic Universe,
and can mark the emergence of CMB ellipticity as a new observable constant
describing the Universe. There is no way of simulating this effect. Therefore
we cannot exclude that the observed behavior of the measured ellipticity can
result from a trivial topology in the popular flat -CDM model, or from
a non-trivial topology.Comment: 10 pages, 5 figures, the version to appear in Mod.Phys.Lett.
Messier 81's Planck view vs its halo mapping
This paper is a follow-up of a previous paper about the M82 galaxy and its
halo based on Planck observations. As in the case of M82, so also for the M81
galaxy a substantial North-South and East-West temperature asymmetry is found,
extending up to galactocentric distances of about . The temperature
asymmetry is almost frequency independent and can be interpreted as a
Doppler-induced effect related to the M81 halo rotation and/or triggered by the
gravitational interaction of the galaxies within the M81 Group. Along with the
analogous study of several nearby edge-on spiral galaxies, the CMB temperature
asymmetry method thus is shown to act as a direct tool to map the galactic
haloes and/or the intergalactic bridges, invisible in other bands or by other
methods.Comment: 5 pages, 3 figures, in press in Astronomy and Astrophysics, Main
Journa
Planck's confirmation of the M31 disk and halo rotation
Planck's data acquired during the first 15.4 months of observations towards
both the disk and halo of the M31 galaxy are analyzed. We confirm the existence
of a temperature asymmetry, previously detected by using the 7-year WMAP data,
along the direction of the M31 rotation, therefore indicative of a
Doppler-induced effect. The asymmetry extends up to about 10 degrees (about 130
kpc) from the M31 center. We also investigate the recent issue raised in Rubin
and Loeb (2014) about the kinetic Sunyaev-Zeldovich effect from the diffuse hot
gas in the Local Group, predicted to generate a hot spot of a few degrees size
in the CMB maps in the direction of M31, where the free electron optical depth
gets the maximum value. We also consider the issue whether in the opposite
direction with respect to the M31 galaxy the same effect induces a minimum in
temperature in the Planck's maps of the sky. We find that the Planck's data at
100 GHz show an effect even larger than that expected.Comment: 4 pages, 1 table, 2 figures, in press as a Letter in A&
Planck view of the M82 galaxy
Planck data towards the galaxy M82 are analyzed in the 70, 100 and 143 GHz
bands. A substantial north-south and East-West temperature asymmetry is found,
extending up to 1 degree from the galactic center. Being almost
frequency-independent, these temperature asymmetries are indicative of a
Doppler-induced effect regarding the line-of-sight dynamics on the halo scale,
the ejections from the galactic center and, possibly, even the tidal
interaction with M81 galaxy. The temperature asymmetry thus acts as a
model-independent tool to reveal the bulk dynamics in nearby edge-on spiral
galaxies, like the Sunyaev-Zeldovich effect for clusters of galaxies.Comment: 4 pages, 3 figures, in press on A&
Planck revealed bulk motion of Centaurus A lobes
Planck data towards the active galaxy Centaurus A are analyzed in the 70, 100
and 143 GHz bands. We find a temperature asymmetry of the northern radio lobe
with respect to the southern one that clearly extends at least up to 5 degrees
from the Cen A center and diminishes towards the outer regions of the lobes.
That transparent parameter - the temperature asymmetry - thus has to carry a
principal information, i.e. indication on the line-of-sight bulk motion of the
lobes, while the increase of that asymmetry at smaller radii reveals the
differential dynamics of the lobes as expected at ejections from the center.Comment: 4 pages, 3 figures, Astronomy & Astrophysics, Letter to the Editor
(in press
Detection of X-ray galaxy clusters based on the Kolmogorov method
The detection of clusters of galaxies in large surveys plays an important
part in extragalactic astronomy, and particularly in cosmology, since cluster
counts can give strong constraints on cosmological parameters. X-ray imaging is
in particular a reliable means to discover new clusters, and large X-ray
surveys are now available. Considering XMM-Newton data for a sample of 40 Abell
clusters, we show that their analysis with a Kolmogorov distribution can
provide a distinctive signature for galaxy clusters. The Kolmogorov method is
sensitive to the correlations in the cluster X-ray properties and can therefore
be used for their identification, thus allowing to search reliably for clusters
in a simple way
Triangulum galaxy viewed by Planck
We used Planck data to study the M33 galaxy and find a substantial
temperature asymmetry with respect to its minor axis projected onto the sky
plane. This temperature asymmetry correlates well with the HI velocity field at
21 cm, at least within a galactocentric distance of 0.5 degree, and it is found
to extend up to about 3 degrees from the galaxy center. We conclude that the
revealed effect, that is, the temperature asymmetry and its extension, implies
that we detected the differential rotation of the M33 galaxy and of its
extended baryonic halo.Comment: 8 pages, 8 figures, in press on Astronomy and Astrophysics, main
journa
Is there a common origin for the WMAP low multipole and for the ellipticity in BOOMERanG CMB maps?
We have measured the ellipticity of several degree scale anisotropies in the
BOOMERanG maps of the Cosmic Microwave Background (CMB) at 150 GHz. The average
ellipticity is around 2.6-2.7. The biases of the estimator of the ellipticity
and for the noise are small in this case. Large spot elongation had been
detected also for COBE-DMR maps. If this effect is due to geodesic mixing, it
would indicate a non precisely zero curvature of the Universe which is among
the discussed reasons of the WMAP low multipole anomaly. Both effects are
related to the diameter of the Universe: the geodesics mixing through
hyperbolic geometry, low multipoles through boundary conditions.This common
reason can also be related with the origin of the the cosmological constant:
the modes of vacuum fluctuations conditioned by the boundary conditions lead to
a value of the cosmological constant being in remarkable agreement with the
supernovae observations.Comment: Added: two co-authors and a comment on the possible relation of the
discussed CMB properties with the origin of the observed value of the
cosmological constan
WMAP confirming the ellipticity in BOOMERanG and COBE CMB maps
The recent study of BOOMERanG 150 GHz Cosmic Microwave Background (CMB)
radiation maps have detected ellipticity of the temperature anisotropy spots
independent on the temperature threshold. The effect has been found for spots
up to several degrees in size, where the biases of the ellipticity estimator
and of the noise are small. To check the effect, now we have studied, with the
same algorithm and in the same sky region, the WMAP maps. We find ellipticity
of the same average value also in WMAP maps, despite of the different
sensitivity of the two experiments to low multipoles. Large spot elongations
had been detected also for the COBE-DMR maps. If this effect is due to geodesic
mixing and hence due to non precisely zero curvature of the hyperbolic
Universe, it can be linked to the origin of WMAP low multipoles anomaly.Comment: More explanations and two references adde
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