Blogs of Professor(Dr.) Pranab Kumar Bhattacharyya MD(calcutta.Univ) Pathology; : The first generation of stars formation at Redshift Z=0 and when did they lit up the dark matter?

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Abstracts

Our home is our own life igalaxy, the "Milky

Way " which consists of trillions and trillions numbers of stars . One of the middle aged, yellow stars is our sun . 400 billions of stars moving with a very complex and orderly grace in our spiral galaxy the Milky Way. In all galaxies there are perhaps as many as many planets as stars i.e 10 11 x 1011 =1022 ,10 billion trillions planets .Some stars are solitary ( though in a binary star formation system) like our sun and most of the stars have their own companions. Systems of stars are commonly seen double, i.e two stars are orbiting one another. Some stars are so close that they touch each other and star staff flow beneath them .Most stars are however separated from one another by vast spacetime. Stars are born and they die too. Some stars went into novas and or in supernovas and are as bright as the entire galaxy that contains them. Some stars end them in blackholes and are invisible even from a few hundred kilometres away . Some stars are in triple star systems, some are in binary star systems. Some stars are blue hot and very young. Some stars are yellow stars. Yellow stars are conventionally middle aged, while red ( red giants ) stars are elderly or dyeing stars. Some stars are in white dwarfs and they are in the final stage of death. Our '' sun " is a second generation star of a binary star formation process, produced by collapse of gases, Interstellar clouds within the framework of spiral pattern, a gaseous cloud which contains material required for nuclear furnaces,appearing inside the star. Stars are formed of giant interstellar mass, molecular clouds, containing trillions and trillions tons of gaseous hydrogen and deuterium ions as they collapse under gravity. Now in the dense clouds containing perhaps ten thousands millions (1010) atoms per cubic centimetre- that represent a much more dense collection of material , rather than gaseous material in stars , how are they converted into bright stars? How the stars were formed in the nebula or in galaxies of the universe? Stars formation is an astronomical puzzle that involves pure poor understanding of how interstellar giant molecular clouds( CDM+HDM) turned into the stars ! stars are formed from protostellar condensation in the star forming regions like Nebulas.

Key words

Age of the universe, Red shift, Hubble constant , cepheids, super cooled stage of universe, voids , COBE,

The age of the universe and Hubble constant -: The universe started at 20 x 1010 (that is 20,000,00 million years) ago but there is still uncertainty about the age of the universe according to the present authors. Determination of hydrogen molecules suggest that H~50km/s~1 MPC OH-2 =20M102 years universe , while age of old galactic clusters NGC is 10M x 102

years and the age of elements obtained from the active isotopes were more than ~10M x102 years . The Friedmann and the Le-Maitre models of the universe tell us that the universe however has a finite age and it must be either expanding or contracting or simulteniously in both expansion and contraction i.e in the Big Bounce( Ref 1) . This observation that the galaxies are in redshift having special features of shifted to red wavelength in an apparent Doppler recession strongly supports the expanding universe model now. Confidence in the Friedmann Le -Maitre model was strengthening further when Edwin Hubble discovered the near relation between redshift and distances in galaxies in 1929. Hubble discovered a cosmological constant and this constant H(0) is popularly is known as Hubble constant, which is usually expressed in terms of kilometres per second per mega per second I.e 50 km/ S/MPC.The Hubble parameter is defined as H(t) =1/R (t) xdR (t)/dt , whereR(t) is the scale factor of the universe. Hubble constant in the current value of that parameter and is defined as H(0)= H(Now ) = velocity/ distance and is estimated by measuring the velocity and distance of extragalactic objects. Hubble is perhaps the most important parameter in cosmology because it not only provides us the physical scale of the universe which affects the observed absolute wise, dynamical mass and luminosity of extragalactic objects but it also provides us with an approximate estimated age of the universe.The Hubble constant has the unit of inverse time. An estimate of the age of the universe, is the hubble time 1/ H0 . This is the approximate age at a nearly empty Universe one, where expansion had not significantly been solved by its mass energy content. A new model of the universe called the Ω=1 model, where Ω is the ratio of the universe's mass energy density to the critical value required for binding. In the Friedmann model, the expansion rate of the universe approach is zero, as time approaches to infinity and the current age of the universe is then (2/3 ) H0-1 then age=1/H0[1-2q0)+1-q0(1-2q0)-3/2σσ=h-1(1/q0-1) where the deceleration parameter q0 is (½) Ω the ratio if you of universe mean mass density to the closer density ( reference Bhattacharya Rupak and Bhattacharya Pranab Kumar unpublished ). The age of the universe when M0 is of 50kmxS-1MPC-2 gives the age of the universe near 20 billion years while an H0 of 10035km S-1MPC-1 in an empty universe corresponds to an age of 13.8 billion years.

Virgo Cepheids -:

But the cepheid variables are the bright stars whose brightness varies periodically on a time scale between one and hundreds days . The period of cepheid is very tightly correlated with its brightness. So they are excellent indicators of the distance of the expanding universe and also the age of the universe and are figured permanently in the extragalactic distance scale. Cepheid first gave us the idea of other galaxies lying outside our Milky Way. Virgo cepheid or Virgo galaxy clusters are so far away , as far as the most distant previously measured cepheids. They are now measured by the Hubble space telescope. New example of Virgo cepheids H0=87+-7kms-1 MPC-1 ..The galaxy there NGC4571 is in the core of Virgo clusters Galaxy. Again H0~=87+-7kms-1MPC as short value and long value H0= 50 kmxS-1MPC-1 will after the age of the universe for 20 billions years to 11.2+-0.9 billions years and 7.3+- billion years for Ω=0 model and Ω=1 model respectively. The absence of accelerating force for the age of the universe is less than 1/H0 and in standard Big Bang model as 2/3x1/H0 or 7x109 years. In contrast some stars are thought to be 8x109 years old. So here starts the crisis regarding the age of the universe. In the Friedmann universe model Freidmann et al calculated H0~=80 +-17kms-1MPC-1 implying that the age of the universe is 9X109 years. In that case, identifying 20 cepheid variables in M100 is a beautiful spiral galaxy in Virgo. However if we are ready to accept the theory that the age of the universe is estimated from the cosmological model based on the Hubble constant as per this model, the age of the universe will be then 13.7+-2GYR I.e 13.8 billions years .

Big Bang ,Supercooled stage, GUT, Vacuum, cold and hot Dark Matter-:

Though a Big Bang like event happened in the early universe ,the universe spent a period of time in the early phase (1S planck's time) in a super cooled stage (about 400,000 years after the Big Bang ,that the cosmos had cooled sufficiently for protons and electrons to recombine into atoms ). In the super cooled stage its density (3K) was then dominated by large positive constant vacuum energy and false vacuum.The supercooled stage was then followed by the appearance of multiple bubbles inflation. The temperature variations occured in 3K cosmological background imprinted some 10-35 second pre inflationary stage and Grand Unified Theory ( GUT) happened there with generation of trillions and trillions degree of temperature. As per old inflationary theory of the Big Bang, there appeared multiple bubbles of true vacuum and inflation blew up a small causally connected region of the universe that was something much like the observable universe of today. This actually preceded large scale cosmological homogeneity and were reduced to an exponentially small number the present density of any magnetic monopoles, that according to many particle physicists GUTs would have been produced in the pre inflationary phase. In the old inflationary theory the universe must be homogeneous in all its directions and was isotropic. In old inflation theory the super cooled stage was married by the appearance bubbles of the true vacuum, the broken symmetry of ground state . The model of old inflation theory however was later on abundant, because the exponential expansion of any supercooled state always prevented the bubbles from marching and complicated the phase transition. Moreover In true sense, the universe is not totally homogeneous but on a small scale non homogeneous too. It is very much a well known fact that the universe contains a critical density of matter (3K) and infinite space time. The matter was mostly baryonic and Mixed Dark Matter ( MDM) . Through COBE satellite studies we know that the early universe was a mixture of Cold Dark Matter and Hot Dark Matter, which is known all together as Mixed Dark Matter (MDM). Most Redshift surveys had been either shallow ( Z =< 0.03 ), and three dimensional surveys of a few thousands of galaxies covering a large angle or somewhat deeper (Z > 0.05).

How first generation galaxy and stars formed at redshift zero-:

So arguments still persist about the mechanism by which first galaxies and first generation stars were formed in the early universe. The essence of the problem is that while galaxies were on average, were uniformly distributed throughout the volume of the universe as it should be in the inflationary "Big Bang model " the observed distribution of both optically visible and radio galaxies on the sky were not at all uniform. But they were very patchy . Does this clumsiness represent that distribution of matter at some primaeval stage in the evolution of the universe or there has been some time of gravitational process? . Jerhimia Ostriker and Lennox Cowie ( Ref no 2 ) had suggested that the present distribution of galaxies is in the relic of a dynamic process, in which outward propagating shock waves created an earlier generation of galaxies. Created galaxies at some place were of high density on the shock front. But the problem of their theory to present authors are that the empirical rule which says the chance finding of a second galaxy within same value unit at a distance of "S" is proportional to an inverse power of "S" which simply means that there is a greater chance that galaxies will be close together than it is far apart. Secondly the distribution of galaxies in the universe may have a fractional three – dimensional structures. The most spectacular of large voids in three dimensions of galaxies is BOTES VOID - a region at least 50 MPS in diameter that contains no luminous galaxies. A survey of large scale galaxy distributions reveals that the" Large voids were not the exceptions, but the rules. The survey was the systematic collection of red shifts of all galaxies of apparent magnitude brightness than 15.5 in a region measuring 6 degrees by 12 degrees in the sky. The Red shifts via the'' Hubble laws `` provide us a three dimensional map of galaxy distributions in a limited volume of the universe. Inspection of the map of the galaxy revealed a striking results - large apparently empty ,quase spherical voids dominated space time and galaxies are crammed into the thin sheet and ridges in between hole ( ref no 3 Joseph Sick ) and Joseph Sick discussed in his article, that galaxies were distributed in a thin slice of universe to 150 MPC. The redshift measurement of galaxies however revealed a foamy and clustered distribution of galaxies in the early universe. Most of them were lying on a sheet , surrounding large almost empty holes up to 50 MPC. According to Ostriker and Cowie, an explosion initiated by many supernovas in a newly formed galaxy drove a blast wave, which propagated outward shock waves and swept away a spherical shell of ambient gas . A hole was thus evacuated and an unstable compressed shell fragmented to form many more galaxies. These in turn developed blast waves and a series of bubbles developed that filled most of the spaces with galaxies ( reference no 4 Jehemia Ostriker and Lennox Cowie ) and published independently by Satron Takeuchi ( reference no 5 ).

But problems of this hypothesis to present authors are *1) possibility of the mechanism itself-: supernovas exploded and cleared out holes that are tens or in rare cases hundreds of processors? and **2) Did this phenomenon really work out on the scale of MPC?*** 3) Billions of supernovas were presumed to be exploded coherently over the crossing time of galaxy of about 109 years to yield a vast explosions**** 4 ) Next is the missing ingredient which is gravity. Density fluctuations were present at the beginning of the time in the earliest instant of the "Big Bang gospel " and gravity amplified the fluctuations into a large-scale structure of the universe. Most cosmologists believe today that galaxies originated in this manner ,rather than explosive amplification of primordial seeds which themselves must be attributed into initial conditions.

A "giant hole" in the universe had been discovered by astronomers from Minnesota in 2009 January. Investigating an area of the sky known as the WMAF cold spot, Lawrence Rudnick and his colleagues found a void empty of stars gas and even dark matter. As AF's widely circulated report notes, the hole is big : an" expense of nearly 6 billions trillions 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 structures first formed ( reference no 6 Daniel Cressey) .

Galactic Disks of spiral galaxies consist of Dark matter, COBE study

Our galaxy ,the Milky Way, also contains 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 are neutral, it does not couple directly to the electromagnetic field and hence annihilation straight into two monochromatic photons ( or a Photon and a Z boson) are typically strongly suppressed, (y)Gamma rays can be a significant by product of Dark matter annihilation ) since they can rises either from the decay of neutral pions produced in the hydronization of the annihilation products or through Internal bremsstrahlung associated into charged particles,with annihilation into charged particles, interactions of energetic leptons. In the Massimiliano Lattazi and Joseph Silk model of 2009 ( Ref no 7) the annihilation results in two neutral Z Bosons or a pair of W+ and W- Bosons, and the dominant source of y ( Gamma) rays is pion decay . From =~4.5TeV, every annihilation results in 26 photons with energy between 200 and 300 Gev. Physicists today believe that dark matter makes 22% of the mass of the universe ( compared with 4%of normal matter and 74% comprising the supermassive ,"Dark energy" ) . But, despite its pervasive influences, even today no one is sure of what the dark matter consists of. It was thought that matter forms in roughly spherical lumps called halols, one of which envelopes the MilkyWay 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 suggests 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 galaxy's disk and were then torn apart, creating a dicks of matter within the galaxy. The presence of unseen haloes of dark matter had long been inferred from the high rotation speed of gas and stars in the outer part of spiral galaxies. The volume of density of these dark matter decreases less quickly from the galaxy centre than does heat luminous mass such as that in stars meaning that that matter dominates the mass from the centre of galaxies .A spiral galaxy is composed of thin disk of young stars called population T stars whose local surface brightness falls below exponentially with cylindrical distances from galactic centres and with height above galactic plane.

Biassing hypothesis , Density fluctuations, COBE-:

The concept of biassing the formation of large scale structure of universe was first introduced by Nick Kesar in journal of astrophysics ( Reference no 8 Peacock JA , Heavens AF Monday And Reference no 9 Barden J Bond jr, kaiser Nick Essalay ). Galaxies were presumed only to form in the rare peaks of initial Gaussian distribution of density fluctuations. The average Density of the universe is roughly 10-31gcm-3 which is less than the critical density (K) of the present universe 9×10-27 kg m-3. ( The matter of which universe is made of 42.3% is CDM matter and 73% is Dark energy). Density fluctuations peaks that occurred in potential large scale structure acquired with a slight boost that enabled galaxies to form. The biassing hypothesis enhanced the large scale structure that developed as gravitational forces amplified the initial fluctuations. Biasing hypothesis enabled stimulation of a universe containing" Cold Dark Matter '' at the critical density, with observational determination of density perturbation of the universe. Density fluctuation was present at the beginning of time, in the earliest instances of the Big Bang and gravity amplified the fluctuations into the large scale structure of the universe. The voids were not really voids but contained matter that had somehow failed to become luminous. Dark matter was more uniformly distributed than luminous matter and does not respond to most astronomical tests. The universe is now populated with a non luminous component of matter ( Dark matter ) made of weakly interacting massive particles which cluster in galactic scale and are designated ….. The Dark matter was weakly interacting and was clustered in all scales( and hence labelled as cold ). It selectively formed galaxies at an early epoch in the rare density peaks. The cosmic background explorer study announced on 18th November 1990 that COBE had used its helium cooled detectors to make stunningly accurate measurements of the Big Bang afterglow. The COBE study was based on microwave background radiation that bathed every object of the universe with a cool wash of photon 2.7K .COBE study conferred that the Big Bang was a remarkably smooth and homogeneous event. The COBE study consistently pegged its temperature at about 2.7 K what was predicted by the standard model which holds that radiation was emitted by cosmic fireball just a few hundred after the big bang moment itself and cooling of ever since then. George Smoot ( 2006 Nobel laureate in physics) and his colleagues of Barkley University used differential microwaves radiometer to look for anisotropic variations in the brightness of radiation from point to point in the sky

They presumably correspond to the density variation in the cosmic plasma shortly after the big bang and these variations are in turn presumably the clumps of matter that contracted by gravity to form the galaxies . The problem was that anisotropic if they existed at all,were so weak that it was hard to see now that how they had contracted into much of galaxies Any clump that was going to form a galaxy needs to be heavy enough to fight the cosmic expansion which tends to pull the material apart almost as fast as gravity can pull it together. COBE showed no anisotropy at all to an accuracy of one part in 104 to 105 and it was dark matter. The dark matter consisted of some kind of massive but weakly interacting elementary particles produced in the Big Bang. The cosmic background explorer satellite study was undertaken by the leadership of George Smoot and he considered the Big Bang seriously. Microwave background study also provided that Big Bang COBE study had spotted millionth of a degree variations in the temperature of microwave left over from Big Bang traces of the early universe . Images of Big Bang,provide the earliest snapshots of the cosmos from when it was only about 4000,0000 years old only. The model of MDM of the universe is consistent with homogeneous inflation theory and large scale density fluctuations and galaxy distribution that happened in the early universe. It was Merry Gelman who first described the nature of the earliest particles in the universe. According to him it was quarks particles in Quantum theory. Actually speaking, the quest for the early universe had provided the particle physicists with development of an unrivalled accelerator of high energy particles in the Geneva LHC. The Grand unified theory ( GUT) based on gauge symmetry says that protons (the nucleon) should decay with half life of at most 1031 years. But while isolating the rarest events due to spontaneous decaying of protons ,extensive shielding from atmospheric muons produced by cosmic rays showers were also regarded and primary results once were supported at Geneva, Switzerland , at LHC . This experiment was carried out provided in the deep underground Kolar Goldfield,kamoka. This experiment provided us with the most sensitive limit so far that the half life of protons is 1.5x1032 years. This half life of protons is close to the age of the elements obtained from radioactive isotopes ~10x1032 years. This experiments had great implications to astrophysicists in that 1) possible explanation of ratio of proton to photon in the Universe.Since the photons now seen in 3K background radiation, are the remnants of equal numbers of particles and antiparticles created during thermal equilibrium of first instances of the universe. These particles were Merry Gelman's quark particles and its anti-particles were anti quarks . Today's observed protons ( matter) represent an excess of matter after antimatter . This is the asymmetry in the universe. This asymmetry probably had arisen naturally after 10-35 second of initial Big Bang.However Madsen and Mark Tailor gave the concept of another particle in the primordial universe (Reference no 10=Gerard Jungmank) .The name of their particles is neutrinos.There are broadly three types of species of neutrinos 1) Electron neutrinos 2) Muon neutrinos 3) tat neutrinos ,when professor Peter Higgs( Nobel laureate in physics) gave concept of another near zero mass ( but not exactly zero mass particle ) in primordial universe the particles named after him "The Higgs particles '' which is concluded and recognized particles that gave mass to all particles in the universe and Higgs particles are many but not a single particle . To start the universe ie before the nucleosynthesis there must be some particles with zero rest mass , which may be either neutrinos or may be one of Higgs particles or some others particles (not yet discovered in accelerator ) like Rupak particles ( r particles) or spinors or gravitons that gave dark energy which constitute 73% of the mass of universe. According to Maiden and Tailor the dark matter of which the universe consisted of were the neutrinos and not the quarks .Neutrinos are constantly born during the process of nuclear fusions within every star in the galaxy like it is produced in every second in our sun. In fusion, protons (the nucleus from the simplest element, hydrogen) fuse together to form a heavier element, helium. This fusion process releases neutrinos and energy that will eventually reach our Earth as light and heat. The sun is the source of most of the neutrinos that are passing through any body though any things through any planets at any moment. About 100 billion solar neutrinos pass through your thumbnail in every second .All of the neutrinos produced in the sun are electron neutrinos. An interesting thing happened when scientists started looking for those electron neutrinos in the 1960s. They started an experiment led by Ray Davis Jr. His experiment used 100,000 gallons of dry perchloroethylene to search for neutrinos. It was housed a mile underground in the caverns of the Homestake Gold Mine in South Dakota, which was then an active mine and is now used for science experiments, including further neutrino research in the Deep Underground Neutrino Experiment. Davis’s scientific partner, John Bahcall, had predicted how many neutrinos should arrive from the sun and transform one of the chlorine atoms in the detector into an argon atom. But only one third of the neutrinos seemed to arrive. Researchers weren’t sure if the problem was in Davis’s experiment, Bahcall’s calculations and the current model of the sun, or their picture of neutrinos. Some scientists, including Bruno Pontecorvo, proposed that the neutrino experiment model itself was the error, but many were sceptical. In 1989, the Kamiokande experiment in Japan added to the confusion. The pure water detector found more neutrinos than Davis’s experiment, about half of the predicted number. But there was still the question of all those missing neutrinos. The GALLEX experiment in Italy and SAGE experiment in Russia also found that expected low-energy neutrinos were missing. As measurements of the sun improved and the solar model was validated, researchers looked more and more to new physics beyond the Standard Model to explain the neutrino deficit. The breakthrough came with data from two newer experiments. Super-Kamiokande, an improved version of the Kamiokande experiment, began observations in 1996, and the Sudbury Neutrino Observatory in Canada joined in 1999. Leaders of these two projects would go on to receive the 2015 Nobel Prize in physics for discovering the solution to the solar neutrino problem: neutrino oscillations. Roughly two-thirds of the electron neutrinos coming from the sun were changing their flavour as they travelled, arriving as muon or tau neutrinos. Evidence that neutrinos changed type also proved that they have mass, a shocking discovery. Only about one third to one half of the predicted number of neutrinos actually showed up in detectors. This became known as the solar neutrino problem, and it took nearly four decades to solve it.

How did the cosmic Dark age end and when did the first star light up in a few hundred millions years ,after the Big Bang?

According to the standard model of the Big Bang, stars formation in the early universe was very different from the present now. Stars today form in the giant clouds of molecular gas and dust embedded in the disks of large galaxies like our Milky Way or in the dust of nebulas . In the Milky Ways some of these regions are corona Australis clouds, Taras molecular clouds, Orion nebula , Vela ,molecular ridge, Cygnus x, NGC 6334 and 6357, Eagle Nebula, carina nebula,W40, Rcw 36, w43,W49, M17 molecular clouds and extragalactic 30 Doradus regions .

Whereas the first star evolved inside the Mini Hole that aggregated of primordial gas and dark matter with a total mass of millions of our suns. The very first stars might have appeared when the Universe was only 100 million years old, or less than 1 percent of its current age . All the stars in the universe, we can observe now, can be classified as either Population I or Population II, stars depending on their age and composition in it . Population I stars are younger stars and they contain more heavy elements, while Population II stars are older stars with fewer heavy elements. All of the very first stars that appeared first in the universe to light up the universe from darkness are described as Population III stars and these stars are older still, their existence coinciding with cosmic distances that put them well out of sight of even with help of our best technologies so far. For them now, we can only theorise what they might have looked like. Theoretical physicists think those most earliest stars were super hot, brightest, and massive, may be hundreds of times the mass of our Sun, that we told .Without any clue or history of powerful cosmic in the beginning events of formation of first stars to generate elements heavier than lithium, Population III stars would consist entirely of the simplest of gases. Back then, the only materials available in the Universe were hydrogen, helium, and a little lithium, found in primordial gas left over from the Big Bang. Only once the first stars themselves collapsed in heated violence ,could heavier elements emerge?.Those first stars likely concluded their lives with pair-instability supernovae, -a theoretical type of super-supernova only possible in such massive stars. Unlike other supernovae, this would leave behind no stellar remnants, like a neutron star or a black hole, instead blasting everything outward in an ever-expanding cloud. That blast might have seeded ancient interstellar space with the heavy elements needed for the formation of rocky worlds like our own planet — thus enabling life as we know it — so the net effect is positive . For astronomers on the earth now hoping to learn about Population III stars, however, the light from those ancient mega-explosions has faded into the distance, leaving little more than a diffuse cloud containing a complex mixture of elements. Given time, that mixture of material could itself collapse into something new star . Using near-infrared spectrography data from one of the most distant-known quasars — a type of active galactic nucleus, or the extremely luminous centre of a young galaxy.This quasar's light had been travelling through space for 13.1 billion years before it reaches the Earth, the researchers noted, which means we're seeing the quasar as it looked when the Universe was only 700 million years old. A spectrograph is an instrument that captures and splits incoming light, in this case from a celestial object, into its component wavelengths. This can reveal which elements are present in a far away object, although gleaning that information isn't always easy.The brightness of lines in astronomical spectra can hinge on factors other than the abundance of an element, which may complicate one's efforts to identify specific elements.Analysing the composition of clouds around most distant quasars revealed a strangely low ratio of magnesium to iron in the clouds, which had 10 times more iron than magnesium compared with our Sun. That was a clue, the researchers say, suggesting this was material from the cataclysmic explosion of a first-generation star.It was obvious to us authors then that the supernova candidate for this would be a pair-instability supernova of a Population III star, in which the entire star explodes without leaving any remnant behind,So the first stars that lit up the universe were in most distant quasars

These first stars are quasars, a population III stars. Since then, the rapid expansion of space has stretched their light into oblivion, leaving us to seek clues about their existence in cosmic sources closer to home . Another difference arises for the initial absence of elements of lithium in enough quantity, other than hydrogen and helium that were synthesised in the Big Bang. Gas clouds today are efficiently via radiation emitted by atoms , molecules,or dust grains that contain heavy elements. Because the primordial gas lacked those contain it remained comparatively hot. For gravity to overcome the higher thermal pressure, the mass of all first stars must have been larger as well . The emergence of the first stars in quasars fundamentally changed the early universe at the end of the cosmic dark age. Owing to high masses these stars were copious. They also produced many ultraviolet photons that were energetic enough to ionise hydrogen, the most abundant elements in the universe. Thus began the extension process re- re-ionisation which transformed the universe from the completely cooled and dark material state into fully ionised medium. Observation of CMB due to scattering of CMB photons of free electrons, phase constraints, in the onset of re ionisation . How the first stars were formed and how they affected the evolution of the cosmos assumes that dark matter is made of WIMP - yet undetected because they interact with normal matter only via gravity with weak nuclear interactions (Unlike normal matter, dark matter does not interact with the electromagnetic force. This means it does not absorb, reflect or emit light, making it extremely hard to spot. In fact, researchers have been able to infer the existence of dark matter only from the gravitational effect it seems to have on visible matter. Dark matter seems to outweigh visible matter roughly six to one, making up about 27% of the universe..)

A possible may be non baryonic dark matter is a WIMP candidate is the neutrinos particles,the lightest superpartner in mass supersymmetry theory but not the zero rest mass particles. Super symmetry postulated that for every known particle there must be a super partner thus effectively doubling the mass of the elementary particles .Most of the super particles that were produced after the Big Bang ( including sub quark 2 Rupak Particles ) were unstable and decayed . The neutrinos are expected to be rather massive having roughly the mass of hundreds of protons so they are a part of the cosmos.

There are three prominent hypotheses on non baryonic dark matter, called Hot Dark Matter (HDM), Warm Dark Matter (WDM), and Cold Dark Matter (CDM) and Mixed Dark matter ( MDM) ; some combination of these is also possible in MDM . The most widely discussed models for non baryonic dark matter are based on the Cold Dark Matter hypothesis, and the corresponding particle is most commonly assumed to be a neutralino. Hot dark matter might consist of (massive) neutrinos. Cold dark matter leads to a "bottom-up" formation of structure in the universe while hot dark matter results in a "top-down" formation scenario.

Most of the matter in the universe did not interact then with light except gravitationally .These dark matters 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 scale. Dark matter has yet to be detected in the human laboratories.However there might exist some variable dark matter candidates from particle physics that were not cold and they may be termed as Warm Dark matter ( WDM) as per these authors. Warm dark matter particles had intensive thermal velocities and there motion quenched the growth of structure bellow a "Free streaming scale"(The distances over which a typical WDM particles travel),which depends on the nature of the particle, because small and dark haloes do not form better than free streaming scale. The dark matter haloes that formed the first quasars in a WDM model had far less substructures and we're less concentrated as compared to the cold dark matter( CDM) counterparts।

The first generation stars in the universe formed when the primordial gas compressed by falling into these small Dark matter potential walls. Large scale partners in the spectrum of density perturbation causes progenitors of present day clusters of galaxies to be among the first objects to condense out of initially almost smooth mass distribution

Liang Gao and Tom Theuns [ Reference no 11 Liang Gao] did studied the early star formation in the redshift z=0 and they concluded that pristine gas heated and falls into dark matter potential well (halos)cooled radiatively because of formation of molecular hydrogen and became self gravitating . They told another important particles called Gravitinos a popular WDM candidate with mass M 0<6×10−32 eV/c2 and spin 2 a free streaming particle of fewv+- EVs of kelopersec and first star at Redshift z~200 and the growth structure re stimulation in the led to a pattern of filaments and sheets which is familiar from the local large scale distribution of galaxies. The assumed Gaussian spectrum of density perturbation appropriate for an inflationary model led to collapse along one( sheet ) and two ( filaments) direction before formation of haloes. Altogether the large scale filamentary pattern is very similar in CDM and WDM. These structures of filaments themselves were very different. The CDM filaments fragmented later into numerous nearly spherical high density regions ( haloes) and WDM filaments fragmented at redshift z=23.34, when universe was 140 millions years old .Gas and dark matter accredited perpendicular to filament axis. Dark matter particles falling into filaments performed damped oscillation as the potential well deepened. Baryons did not undergo orbit but gas compressed to a temperature T~70000k at ty 20PC. Rapid build up of HE induced cooling and gas started to dominate the density in population III stars.

Conclusion

So the first stars in the universe were formed in quasars , when primordial chemically pristine gas heated up in the form of WDM as it fell into dark-matter potential wells, cooled radiatively because of the formation of molecular hydrogen, and became self-gravitating. Using supercomputer simulations, it was found by us that the first stars' properties also depended critically on the currently unknown nature of the dark matter. If the dark-matter particles have intrinsic velocities that wipe out small-scale structure, then the first stars formed in filaments with lengths on the order of the free-streaming scale, which can be ∼1020 metres (∼3 kiloparsecs, corresponding to a baryonic mass of ∼107 solar masses) for realistic “warm dark matter” candidates. Fragmentation of the filaments forms stars with a range of masses, which may explain the observed peculiar element abundance pattern of extremely metal-poor stars, whereas coalescence of fragments and stars during the filament's ultimate collapsed may seed the supermassive black holes that lurk in the centres of most massive galaxies.

References

Rupak Bhattacharya, Pranab Kumar Bhattacharya, Upasana Bhattacharya, Ritwik Bhattacharya, Aiyshi Mukherjee, Rupsha Bhattacharya, Debasish Mukherjee, Dalia Mukherjee, Hindol Banerjee "What if the "Big Bang" was not the Beginning Point of our Observable Universe?"Research & Reviews: Journal of Space Science & Technology (RRJoSST) vol 10; no 3; page 1-7 ; 2021

https://sciencejournals.stmjournals.in/index.php/RRJoSST/article/view/3335

Jerhimia Ostriker and Lennox Cowie in the journal Astrophysics volume 243 page 127 ,1981

Joseph Sick Nature vol 320 page 12, 1986

Jehemia Ostriker and Lennox Cowie Astrophysics journal letter vol 243,p127,1981

5) Satron Takeuchi, Astronomical society of Japan vol 33 P 211,1981

6) Daniel Cressey " plenty of nothing August 24,2007 The Great Beyond Nature.com http:/blogs.nature.com/cgi-bin/mt-tb.cgi/3329

7) Massimillano Lattazi and Joseph Silk "Can the WIMP annihilation boost factor be boosted by the Sommerfeld enhancement" arXiv:0812.0360 (astro-ph))

8) Peacock JA and Heavens AF Monday Nottingham Royal Astronomical society Vol 217 P 505 1965

9 ) Barden J Bond jr, kaiser Nick Essalay journal of astrophysics

10)Gerard Jungman at "Neutrinos From Particle Decay in the Sun and Earth" Phys.Rev.D51:328-340,1995

11) Liang Gao , Tom thens Lighting the Universe with Filaments SCIENCE 14 Sep 2007 Vol 317, Issue 5844 pp. 1527-1530DOI:10.1126/science.1146676

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Sunday, 11 December 2022

The first generation of stars formation at Redshift Z=0 and when did they lit up the dark matter?

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