1,133 research outputs found
Subjective Perception of Time and a Progressive Present Moment: The Neurobiological Key to Unlocking Consciousness
The conclusion of physics, within both a historical and more recent context, that an objectively progressive time and present moment are derivative notions without actual physical foundation in nature, illustrate that these perceived chronological features originate from subjective conscious experience and the neurobiological processes underlying it. Using this conclusion as a stepping stone, it is posited that the phenomena of an in-built subjective conception of a progressive present moment in time and that of conscious awareness are actually one and the same thing, and as such, are also the outcome of the same neurobiological processes. A possible explanation as to how this might be achieved by the brain through employing the neuronal induced nonconscious cognitive manipulation of a small interval of time is proposed. The CIP phenomenon, elucidated within the context of this study is also then discussed
A study of the compact group of galaxies Shahbazian 4
The radial velocities of members of Shakhbazian 4 are determined. It is found that the dispersion of the radial velocities is 440 km/s. The apparent and absolute magnitudes of galaxies in V color are obtained. It is found that the M/L ratio of the group is about 220 solar mass/solar luminosity. The crossing time for the Shakhbazian 4 group is equal to 47 Myr
High-Resolution Mid-Infrared Morphology of Cygnus A
We present subarcsecond resolution mid-infrared images at 10.8 and 18.2
microns of Cygnus A. These images were obtained with the University of Florida
mid-IR camera/spectrometer OSCIR at the Keck II 10-m telescope. Our data show
extended mid-IR emission primarily to the east of the nucleus with a possible
western extension detected after image deconvolution. This extended emission is
closely aligned with the bi-conical structure observed at optical and near-IR
wavelengths by the HST. This emission is consistent with dust heated from the
central engine of Cygnus A. We also marginally detect large-scale low level
emission extending > 1.5 kpc from the nucleus which may be caused by in-situ
star formation, line emission, and/or PAH contamination within the bandpass of
our wide N-band filter.Comment: 20 pages, 8 figures, accepted for publication in the Astrophysical
Journa
First optical light from the supernova remnant G 17.4-2.3
Deep optical CCD images of the supernova remnant G 17.4-2.3 were obtained and
faint emission has been discovered. The images, taken in the emission lines of
Halpha+[N II], [S II] and [O III], reveal filamentary structures in the east,
south-east area, while diffuse emission in the south and central regions of the
remnant is also present. The radio emission in the same area is found to be
well correlated with the brightest optical filament. The flux calibrated images
suggest that the optical filamentary emission originates from shock-heated gas
([S II]/Halpha > 0.4), while the diffuse emission seems to originate from an
HII region ([S II]/Halpha < 0.3). Furthermore, deep long-slit spectra were
taken at the bright [O III] filament and clearly show that the emission
originates from shock heated gas. The [O III] flux suggests shock velocities
into the interstellar "clouds" greater than 100 km/s, while the [S II]
6716/6731 ratio indicates electron densities ~240 cm^{-3}. Finally, the Halpha
emission has been measured to be between 7 to 20 x 10^{-17} erg s^{-1} cm^{-2}
arcsec^{-2}.Comment: 6 pages, 5 figures, accepted for publication in A&
Automatic detection of arcs and arclets formed by gravitational lensing
We present an algorithm developed particularly to detect gravitationally
lensed arcs in clusters of galaxies. This algorithm is suited for automated
surveys as well as individual arc detections. New methods are used for image
smoothing and source detection. The smoothing is performed by so-called
anisotropic diffusion, which maintains the shape of the arcs and does not
disperse them. The algorithm is much more efficient in detecting arcs than
other source finding algorithms and the detection by eye.Comment: A&A in press, 12 pages, 16 figure
Perturbative reconstruction of a gravitational lens: when mass does not follow light
The structure and potential of a complex gravitational lens is reconstructed
using the perturbative method presented in Alard 2007, MNRAS, 382L, 58; Alard
2008, MNRAS, 388, 375. This lens is composed of 6 galaxies belonging to a small
group. The lens inversion is reduced to the problem of reconstructing
non-degenerate quantities: the 2 fields of the perturbative theory of strong
gravitational lenses. Since in the perturbative theory the circular source
solution is analytical, the general properties of the perturbative solution can
be inferred directly from the data. As a consequence, the reconstruction of the
perturbative fields is not affected by degeneracy, and finding the best
solution is only a matter of numerical refinement. The local shape of the
potential and density of the lens are inferred from the perturbative solution,
revealing the existence of an independent dark component that does not follow
light. The most likely explanation is that the particular shape of the dark
halo is due to the merging of cold dark matter halos. This is a new result
illustrating the structure of dark halos at the scale of galaxies.Comment: Final version (Astronomy and Astrophysics in press
Searching (the) FIRST radio arcs near ACO clusters
Gravitational lensing (GL) of distant radio sources by galaxy clusters should
produce radio arc(let)s. We extracted radio sources from the FIRST survey near
Abell cluster cores and found their radio position angles to be uniformly
distributed with respect to the cluster centres. This result holds even when we
restrict the sample to the richest or most centrally condensed clusters, and to
sources with high S/N and large axial ratio. Our failure to detect GL with
statistical methods may be due to poor cluster centre positions. We did not
find convincing candidates for arcs either. Our result agrees with theoretical
estimates predicting that surveys much deeper than FIRST are required to detect
the effect. This is in apparent conflict with the detection of such an effect
claimed by Bagchi & Kapahi (1995).Comment: 6 pages; 8 figures and 1 style file are included; to appear in Proc.
"Observational Cosmology with the New Radio Surveys", eds. M. Bremer, N.
Jackson & I. Perez-Fournon, Kluwer Acad. Pres
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