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Authors_;
* Mr. Rupak Bhattacharya-Bsc(cal)Msc(JU) of Residence 7/51 purbapalli,Po-sodepur, Dist 24 parganas(north),Kol-110,West Bengal, India**ProfessorPranab kumar BhattacharyaMD(cal) FIC Path(India); Professor and Head of Department of Pathology [course coordinator of DCP course of West Bengal University of Health sciences(WBUHS); member secretary of Board of Studies for DCP course and member of Board of Studies for undergraduate, Post graduate & Doctoral courses in Pathology Discipline of WBUHS],School of Tropical Medicine, 108 CR Avenue ,Kolkata-73, West Bengal , India,** Miss Upasana Bhattacharya- Student, Mahamayatala, Garia, kol-86, Only daughter of Prof.PK Bhattacharya ***Mr.Ritwik Bhattacharya B.com(cal) of Residence 7/51 Purbapalli, Po-Sodepur, Dist 24 parganas(north) , Kolkata-110,WestBengal, India **** Mrs. Dalia Mukherjee BA(hons) Cal, Swamiji Road, South Habra, 24 Parganas(north) West Bengal, India**** Miss Oaindrila Mukherjee- BA(hons)cal Student, ****Miss Ayshi Mukherjee –Student of residence Swamiji Road, South Habra, 24 Parganas(north), West Bengal, India ***Miss Rupsa Bhattacharya and ***Mr Somyak Bhattacharya BHM(IGNOU) Msc student(PUSHA) of 7/51 Purbapalli PO-Sodepur Dist 24 Parganas(north) Kolkata-110 West Bengal, India and Mrs Runa Mitra of BK Mitra Social Worker Barrackpore
* Mr. Rupak Bhattacharya-Bsc(cal)Msc(JU) of Residence 7/51 purbapalli,Po-sodepur, Dist 24 parganas(north),Kol-110,West Bengal, India**ProfessorPranab kumar BhattacharyaMD(cal) FIC Path(India); Professor and Head of Department of Pathology [course coordinator of DCP course of West Bengal University of Health sciences(WBUHS); member secretary of Board of Studies for DCP course and member of Board of Studies for undergraduate, Post graduate & Doctoral courses in Pathology Discipline of WBUHS],School of Tropical Medicine, 108 CR Avenue ,Kolkata-73, West Bengal , India,** Miss Upasana Bhattacharya- Student, Mahamayatala, Garia, kol-86, Only daughter of Prof.PK Bhattacharya ***Mr.Ritwik Bhattacharya B.com(cal) of Residence 7/51 Purbapalli, Po-Sodepur, Dist 24 parganas(north) , Kolkata-110,WestBengal, India **** Mrs. Dalia Mukherjee BA(hons) Cal, Swamiji Road, South Habra, 24 Parganas(north) West Bengal, India**** Miss Oaindrila Mukherjee- BA(hons)cal Student, ****Miss Ayshi Mukherjee –Student of residence Swamiji Road, South Habra, 24 Parganas(north), West Bengal, India ***Miss Rupsa Bhattacharya and ***Mr Somyak Bhattacharya BHM(IGNOU) Msc student(PUSHA) of 7/51 Purbapalli PO-Sodepur Dist 24 Parganas(north) Kolkata-110 West Bengal, India and Mrs Runa Mitra of BK Mitra Social Worker Barrackpore
A “giant hole” in
the universe had been a discovered by astronomers from Minnesota in 2009 January. Investigating an
area of the sky known as the WMAP Cold Spot, Lawrence Rudnick and colleagues
found a void empty of stars, gas and even dark matter. As AP’s widely
circulating report notes, the hole is big: an “expanse of nearly 6 billion
trillion miles of emptiness” Astronomers have long known that there are big
voids in the universe, and think they can explain them with their theories as
to how large scale structures first formed.[ Plenty of nothing - August 24, 2007The Great Beyond Nature.Com
http://blogs.nature.com/cgi-bin/mt/mt-tb.cgi/3329].our Galaxy, the Milky Way, contains also disks
of ‘dark matter. Dark’ matter is always invisible but its
presence can be inferred through its gravitational influence on its
surroundings. Dark matter particles is neutral it does not couple directly to
the electromagnetic field, and hence annihilations straight into two
monochromatic photons (or a photon and a Z boson) are typically strongly
suppressed. γ-rays can be a
significant by-product of dark matter annihilations, since they can arise
either from the decay of neutral pions produced in the hadronization of the
annihilation products, or through internal bremsstrahlung associated into charged
particles, with annihilations into charged particles,
interactions of energetic leptons. In the Lattanzi & Silk models the annihilation
results in two neutral Z bosons Or a pair
of W+ and W. bosons, and the dominant source of γ-rays is neutral
pion decay. Form_ = 4.5 TeV, every annihilation results in 26
photons with energies between 3 and 300GeV.
Physicists
today believe that dark matter makes up 22% of the mass of the Universe
(compared with the 4% of normal matter and 74% comprising the mysterious ‘dark
energy’). But, despite its pervasive influence, even today no-one is sure what
dark matter consists of. It was thought that dark matter forms in roughly
spherical lumps called ‘halos’, one of which envelopes the Milky Way and other
spiral galaxies. Stars and gas are thought to have settled into disks very
early on in the life of the Universe and this affected how smaller dark matter
halos formed. Such a theory suggest that
most lumps of dark matter in our locality actually merged to form a halo around
the Milky Way. But the largest lumps were preferentially dragged towards the
galactic disk and were then torn apart, creating a disk of dark matter within
the Galaxy. The presence of unseen haloes of Dark matter had long been inferred
from high rotation speed of Gas and stars in outer part of spiral galaxies. The
volume of density of these dark matter decreases less quickly from the galactic
center than does heat luminous mass such as that in stars meaning that dark
matter dominates the mass from the center of galaxies. A spiral galaxy is
composed of thin disk of young stars called( population I stars) whose local
surface brightness falls exponentially with cylindrical distances from galactic
center and with height above galactic plane.
How did the cosmic Dark Age
ended and when did the first star lit up in the universe in a few hundred
millions years after the Big Bang?
According to the standard Model of Big Bang
Star formation in the early universe was very different from the present now.
Star today form in the giant clouds of molecular gas and dust embedded in the
disk of large galaxies like our milky ways. Where as the first stars evolved
inside “Mini holes” agglomerates of primoriadial gas and dark matter with a
total mass of millions times of our Sun. Another difference arises for the initial
absences of elements, other then hydrogen and helium that were synthesized in
the big bang. Gas clouds today be efficiently via radiation emitted by atoms
molecule or dust grains that contain heavy elements. Because the primoridial
gas lacked those coolants it remained comparatively hot. For gravity to
overcome when the higher thermal pressure, the mass of all first stars must had
been larger as well. The emergence of first stars fundamentally changed the
early universe at the end of cosmic dark ages. Owing to the high masses these
stars were copious. They also produced many ultraviolet photons that were
energetic enough to ionize hydrogen, the most abundant element in the universe.
Thus began the extended process ”re-Ionization” which transformed the universe
from the completely cooled and dark material state into fully ionized medium.
Observation of CMB due to scattering of CMB photons of free electrons, phase constrains
in the onset of re-ionization. How the first stars formed and how they affected
the evolution of cosmos assumes that dark matter is made up of WIMP-yet
undetected because they interact with normal matter only via gravity and weak
nuclear interactions. A possible WIMP candidate is the Neutrions particles, the
lightest super partner in mass super symmetry theory but not zero mass
particles. Super symmetry postulated that for every known particle there must
be a super partner thus affectively doubling mass of the elementary particles.
Most of the super particles that were produced after the Big Bang (including Rupak
particles also] were unstable and decayed. The neutrinos is expected to be
rather massive having roughly the mass of hundred of protons, so are a part of
cosmos.
Most of the matter in the universe did not
interact then with light except gravitationally. These dark matter assumed to
be very intensively cold, that is its velocity dispersion was sufficiently
small for density perturbation imprinted in the early universe to persist in a
very small sale. Dark matter has yet to be detected in the human laboratories.
However there might exist some viable
dark matter candidates from particle physics that were not cold. They may be
termed as Warm Dark Matter(WDM) as per present authors .Warm dark matter
particles had intensive thermal velocities and there motion quench the growth
of structure bellow a “ free streaming scale”{ the distances over which a
typical WDM particles travel}, which depend on the nature of the particle,
because small and dark haloes do not form better then free streaming scale. The
dark matter haloes that formed the galaxies in a WDM model had far less
substructures and were less concentrated as compared to the cold dark
matter(CDM) counterparts. The first generation of stars in the universe formed
when primoridial gas compressed by falling into these small dark matter
potential wells. Large scale partner in the spectrum of density perturbation
causes progenitors of present day clusters of galaxies to be among the first
objects to condense out of the initially almost smooth mass distribution.
Lang Gao & Tom Thennus[science 317:14th
Sept:Page1527:2007] did studied the early star formation in the red shift Z=0
and they concluded that pristine gas heat and it falls into the dark matter
potential Well [halos) cools radiatively because of formation of molecular
hydrogen and became self gravitating. They told
another important particle- called- Gravitinos_ a popular WDM candidate
particle with mass MWDM=3Kev-a. a free streaming particle of few +_ evs of
kelopersec and first stars at red shift Z~200 and the growth structure
re-simulation in the led to a pattern of
filaments and sheets which is familiar form the local large scale distribution
of Galaxies. In assumed Gaussian spectrum of density perturbation appropriate
for an inflationary model lead collapse along one(sheet) and two(filaments) direction before
formation of Haloes. Altogether the large scale filamentary pattern is very
similar in CDM &WDM. This structure of filaments themselves were very
different. The CDM filaments fragmented later into numerous nearly spherical high
density regions(haloes) and WDM filaments fragmented at red shift Z=23.34 when
universe was 140 millions years old. Gas and Dark matter accreted perpendicular
and to filament axis. Dark matter particles falling into filaments performed
damped oscillations as the potential well deepened. Baryons did not under go
orbit but gas compressed to a temperature T~7000K atγ~ 20Pc. Rapid build up of
H2 induced cooling and gas started to dominate the density.
See the following Links also
http://www.sciencenews.org/view/generic/id/48016/description/
http://phys.org/news162651549.html
http://mnras.oxfordjournals.org/content/378/2/449.full.pd
http://www.firstgalaxies.org/the-early-universe
http://www.sciencenews.org/view/generic/id/48016/description/
See the following Links also
http://www.sciencenews.org/view/generic/id/48016/description/
http://phys.org/news162651549.html
http://mnras.oxfordjournals.org/content/378/2/449.full.pd
http://www.firstgalaxies.org/the-early-universe
http://www.sciencenews.org/view/generic/id/48016/description/
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