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Monday, 30 January 2012

The cosmic Web, the seed of galaxies- are also made of Warm Intergalactic Medium(WHIM) and Dark energy?


Authors_:
 *** Mr Rupak Bhattacharya
-. Bsc(cal), Msc(JU), 7/51 Purbapalli, Sodepur, Dist 24 Parganas(north), Kol-110,West Bengal, India *Professor Pranab kumar Bhattacharya- MD(cal); FIC Path(Ind),  Professor and Head of department of  Pathology,  Calcutta School of Tropical Medicine, C.R avenue; Kolkata-73, West Bengal, India Ex professor and HOD Pathology RIO Ex Professor of IPGMER Kol-73 W.B, India *Miss Upasana Bhattacharya- Student, Mahamayatala, Garia, kol-86, only daughter of Prof.PK Bhattacharya ***Mr.Ritwik Bhattacharya B.com(cal), ***Mr
Soumyak Bhattacharya MBA  Student of residence7/51 Purbapalli, Sodepur, Dist 24 parganas(north) ,Kolkata-110,WestBengal, India , *** Miss Rupsa Bhattacharya **** Mrs. Dalia Mukherjee BA(hons) Cal, Swamiji Road, South Habra, 24 Parganas(north) West Bengal, India**** Miss Oindrila Mukherjee-Student ,**** Mr. Debasis Mukherjee Bsc(cal) of Residence Swamiji Road, South Habra, 24 Parganas(north), West Bengal, India   Runa Mitra  MA  BK MItra Palliative care center Barrackplore  24 Parganas(north), West Bengal, India           


 We all today know that our universe is made of voids, filaments, knots and sheets known as cosmic webs. Each point in space may be classified in one of four possible cosmic web types: voids, sheets, filaments and knots. Voids co-exist with a net of interconnected filaments. The entire observable universe is tangled in a web like structure, the frame work, on which the universe was once built up. We all today know it also that universe consisted of mysterious Dark energy (70%), Dark matter(25%) and that make up now 95% of the matter in the universe and which revel it self as gravity. Enormous filaments and blobs of dark matter in early universe condensed as universe condensed. Within the cosmic webs, all galaxies, stars, planets were created. The universe consists of billons and billions numbers of galaxies, some are larger, some smaller, some spiral disc shaped, like our Milky way, some non spiral, elliptical, some  dwarf galaxies, some dark galaxies  some as say ferst. More than 700,000 galaxies, whose observed Doppler colors indicate a significant red shift and are therefore presumed to be at large cosmological distances. Galaxies are however not dotted randomly through out universe but are generally either concentrated in groups or in clusters, which are connected again by multitude of filaments. These filamentary distributions of galaxies can be explained by vast quantities of dark matter enveloping galaxies and filamentary cold gas  flowing within them ,responsible for star formation  within them and the dark matter ISM is the dominant mass in the universe.
The most current theory of structures formation in the observable universe aims to explain, the structures are mostly homogeneous but slightly inhomogeneous too, Universe that we observe around us, 13.7 Gyr after the Big bang, as the outcome of the growth of the primordial density fluctuations of  quark gluon plasma that are observed as the temperature variations in the CMB. The formation of galaxies were possibly the most prominent visual aspect of the formation of cosmic structures that were shaped by the interplay next between the pull of the gravity and the expansion of space under influence of Dark energy.  Baryonic gas condensed in the gravitational wells that had already been established by the gravitational contraction of dark matter density perturbations. This condensation was followed by the formation of stars as filamentary cold gas  flowed within them ,responsible for star formation  within  galaxies and thus the emission of photons. All  galactic structures [galaxies over  passing time , clumped itself in a filamentary network]  through the gravitational instability, eventually formed a cosmic net work of voids, filaments, knots and sheets, because gravity was purely then attractive force, and regions of slightly higher density in the early universe accreted matter from their surroundings and grew more over dense, with time. In the cosmic web hypothesis, spherical structures appeared  probably first within filaments, growing in between them, followed by the great  walls [planar  structures] connecting the filaments of cosmic Web. These filaments were spreded millions of light years long and did constitute the skeleton of the early Universe: Galaxies gathered around them, and immense galaxy clusters were formed at their intersections, lurking like giant spiders waiting for more matter to accreted. Scientists and physicists are today struggling to determine how they swirl into existence. Although massive filamentary structures have been often observed at relatively small distances from us. The filament is located about 6.7 billion light-years away from us and extends over at least 60 million light-years even. As our  early universe evolved, the cosmic web gradually  sharpened more & more, under dense regions known as voids, empty material known as filaments and these materials subsequently flowed into over dense knots.[ In the cosmic web, under dense, almost empty regions of the universe, the voids, are delimited by  great wall-like sheets and very elongated filaments of matter, which sporadically intersected each other, gave rise to very high-density regions, the clusters. Galaxies, including the most massive ones, are found in large concentrations at such ’nodes’ of the web, the clusters; less massive galaxies are prominent in filaments; only very few galaxies inhabit the voids. Large scale structures in the distribution of galaxies were thought to have evolved through gravitational instabilities from small density fluctuations in the (largely homogeneous) early Universe. These structure of galaxies consisted of rich and poor clusters, were connected by filaments and sheets, with regions largely devoid of galaxies (voids) in between. Numerical simulations of the growth of initial density fluctuations through a nonlinear regime, motivated by the likely physics of the early Universe, also show a network of filaments and voids, but the origin of this picture of filaments as the dominant structure was not well understood. J. Richard Bond, Lev Kofman & Dmitry Pogosyan[1] showed in 1996 that the 'web' of filaments that defined the final state in these simulations was present  also in the initial density fluctuations; the pattern of the web was defined largely by the rare density peaks in the initial fluctuations, with the subsequent nonlinear evolution of the structure bringing the filamentary network into sharper relief. Applying these results to the observed galaxy distribution, they suggested that 'superclusters' were filamentary cluster–cluster bridges, and we predict that the most pronounced filaments will be found between clusters of galaxies that are aligned with each other and close together.
[ All sky high resolution map of the microwave light emitted only380’000 years after the big bang and detected by the WMAP satellite. Colours correspond to temperature variations with amplitude of 105 around the2.7K black body spectrum. (Image courtesy of the NASA / WMAP Science Team]


 Cosmic web  even in dwarf  and local group galaxies-: The near by filaments of the cosmic web connected also our local group of galaxies to large scale cosmic web and computer simulation model reveal that these filaments should channel a steady rain of pristine dwarf galaxies which are  too composed of dark matter into the local environment. Because filaments fall into them, also in firm large distances and accrete over a large fraction of the age of universe. These dwarf galaxies that are in process of arriving today can be expected to exhibit very large speed gas is also conveyed into galaxies along the filaments but because of presence  of gravitational forces this is rapidly slowed down, first shock heating and then condensing into clouds that fall into the center of gravitational well and contribute to build up gaseous disk component of galaxies. Cloud of active hydrogen known as high velocity cloud surround so our milky way and andromeda galaxies . Hence both large galaxies within local group appear to be continuously accreting gas fed to them from the cosmic web

The COBE (Cosmic Background Explorer Study) could detect small anisotropy, subsequently mapped in sharp detailed by WMAP (Wilkinson Microwave Anisotropy Probe) imprinted on the cosmic Microwave Back Ground (CMB) when universe was 3, 80,000 years old. COBE study fueled the model of growth structure universe and mini scale fluctuations in very early universe. The fact, very little is known about the energy and Mass of the Universe, within the frame work of Standard cosmological model. 95% of the universe ( Ω the mass density of the universe divided by the Critical density for closed universe) is corporated primarily of Dark energy (72%) and Dark Matter(23%) and only 5% is the detectable matter As baryons [most of which is hydrogen and helium], - the protons, atomic nuclei that constitute of ordinary matter, galaxies, Stars, planets, Planetismals, all comets, all planets, all living and dead trees, all animals and ourselves and all the materials we see,  The remaining 95% matter is mysterious in nature. The dark energy is assumed to be uniform, but the normal and dark matter are not.. The balance between dark matter and dark energy determines both how the universe expands and how regions of unusually high or low matter density evolved with time.  We can, should detect and measure it in physical state.  From studies of Quasars we know that clouds of baryons were present in the early universe about 4 billions years ago(red shift Z≈ 2) in the form of Photo Ionized diffuse high speed intergalactic gas as told just in previous paragraph and that accounted 3/4th of total baryonic mass in the universe. When nucleon synthesis happened with observed light elements at Z>2,Ωb>3.5%, 75% estimated baryons mass were involved. These clouds of Photo ionized intergalactic gas became more and more sparse as time moved towards present and structures like galaxies, galaxy groups, galaxy clusters started to be assembled, only a small fraction of the baryons that were present in Intergalactic medium(ISM) at red shift Z>2 are found in stars, cold or warm ISM hot inter cluster gas and residual photo ionized inter galactic medium and it is estimated that 50% of baryon mass is still missing. Most of the baryons in the local universe are also missing in that they are not in galaxies or in the previously detected gaseous phases.  RUpak Bhattacharya and Pranab Bhattacharya suggested that these missing baryons are so predicted may be in a moderately hot phase, 1E5 to 1E7 K, largely in the form of giant cosmic filaments that connect the denser virialized clusters and groups of galaxies. These filaments can be detected through absorption lines they produce in the spectra of background AGNs. Models show that the highest covering fraction of such filaments occurs in super clusters and the archive has two AGNs projected behind superclusters, both of which show absorption systems (in LyalphaLybetaOVI) at the super cluster red shift.

Question to Be solved yet
 The question  still to be solved as per authors, is how the large-scale cosmic environment of a CDM universe affected the internal properties of dark matter haloes and of the baryonic galaxies, they hosted during their formation and the subsequent billion years of cosmic evolution?.
Unlike the ‘‘baryonic’ matter (neglecting the real fact that there are also leptons that, however, contributed very negligible mass of universe), dark matter does not interact appreciably in any other way than through gravity —the weakest but only real long-range force among the four fundamental forces that govern the laws of universe. The best candidates for dark matter is probably  till date so far  is Cold Dark Matter(CDM), a kind of dark matter that has non-relativistic energies already at very early times and thus led to a bottom-up theory of galaxy structures formation in the early universe in COBE. Dark energy is on the other hand required to explain the observed accelerated expansion of space time (or in other way, equivalently, the weakening of gravity on very large scales and responsible for the expansion of the universe). Baryonic matter thus appeared to be a subdominant component that, while making up all the visible objects in the Universe, is not the most important ingredient in the attempt to understand the structure of the Universe.

[The highly inhomogeneous universe in 13.7 Gyr, all sky distribution of infrared sources (mostly galaxies) from the Two Micron All Sky Survey (2MASS) in the nearby Universe. The filamentary nature of the cosmic web is clearly visible. (Atlas Image courtesy of 2MASS/UMass/IPAC-Caltech/NASA/NSF).]


 N body Simulations study of Cosmic Web
 This cosmic web is the large-scale environment, in which galaxies formed and evolved and its existence had been established in large red shift surveys(z ≈ 2)of many hundred thousand galaxies over the last decades. Since dark matter interacts only gravitationally, it is thus relatively easy to model and computationally affordable. For many years, the numerical study of cosmic structures formation had therefore been focused on the realm of N-body simulations[Simulations that use a particle discretisation of the phase-space are known as N-body simulations. In these simulations, the phase-space density f(x, p, t) is discretized with massive particles and evolved according to the collision less limit of the Boltzmann equation, Thus, in the N-body method, the initial phase space is sampled with particles representing a small sub volume of the full 6-dimensional phase space. Each one of these particles is then evolved in a self-consistent way, fulfilling Liouville’s theorem (cf. e.g. Hockney & Eastwood, 1981). The numerical evolution thus requires two steps: (1) a gravity solver, to compute the particle accelerations, and (2) a time integrator, to update particle positions and momentum.]i.e. the Vlasov equation, under self-gravity]: which have had a huge success in showing that the spatial distribution of gravitationally collapsed structures — the dark matter haloes — is highly compatible with the observed distribution of galaxies. Dark matter haloes are connected to each other by large-scale filamentary structures. Cold gas flowing within this ‘cosmic web’ is believed to be an important source of fuel for galaxy and star formation at high red shift.  These simulations are still giving important insights into the detailed aspects of spatial clustering, mass distribution and even internal properties of galaxies through additional semi-analytic models that attempt to relate the properties of galaxies to those of the dark matter haloes in which they are embedded. The physics of baryonic matter is in contrast very complex and computationally expensive. However, it is baryonic galaxies that we see and use to constrain our cosmological theories to reproduce the one Universe in which we live. Including baryonic matter in our simulations of the universe is a challenging necessity to bring our understanding of structure formation to the next level. Only rather recently, the huge growth in available computer power has opened the spectacular possibility to study the condensation of the baryonic gas component into galaxies in cosmological simulations. Gas is able to radioactively cool and thus settles in the centers of the dark matter haloes. ’Sub-grid’ models capture the collapse of gas clumps below the resolution limit, making it possible to simulate the formation of stars. The simulated disk galaxies thus consist of a dark matter halo filled with hot gas, a cold gaseous disk and a stellar disk. The quest has indeed started to use such hydrodynamic cosmological simulations to further our detailed understanding of the formation and evolution of galaxies and structure in the universe.
From the point of view of cosmology, the vacuum or voids appears to have an energy density, which may be called “dark energy” or the “cosmological constant” From a particle physics viewpoint, the vacuum is also permeated by a “Higgs Field” - named after physicist Peter Higgs,

Since 2010 , many important  studies across the world,  showed that the main constituents of the universe , across 90 percent of its history, from the formation and evolution of structures such as galaxies, clusters of galaxies, and the "cosmic web” of intergalactic matter, to the stars, gas, dust, super massive black holes, and dark matter of which they are composed. These elements are coupled in a complicated evolutionary progression as matter accreted into galaxies, stars form and evolve, black holes grew, supernovae and active galactic nuclei expelled matter and energy into the intergalactic medium (IGM), and galaxies collide and merge. There  remained four questions  to be solved yet ,form the focus for research in the coming decade. The questions are: (1) How do cosmic structures form and evolve? (2) How do baryons cycle in and out of galaxies, and what do they do while they are there? (3) How do black holes grow, radiate, and influence their surroundings? (4) What were the first objects to light up the universe and when did they do it?
 

Simulations based on the standard cosmological model, as shown here, indicate that on very large distance scales, galaxies should be uniformly distributed. But observations show a clumpier distribution than expected. (The length bar represents about 2.3 billion light years. Credit: Courtesy of Volker Springel/Max-Planck-Institute for Astrophysics, Garching, Germany
In the modern hierarchical theories of galaxies structure formation,  It is considered that rich clusters of galaxies formed at the vertices of a web like distribution of matter, with filaments emanating from them to large distances and with smaller objects forming and draining in along these filaments. The amount of mass contained in structures near the clusters can be comparable to the collapsed mass of the cluster itself. As the lensing kernel is quite broad along the line of sight around cluster lenses with typical red shifts zl=0.5, structures many mega parsecs away from the cluster are essentially at the same location as the cluster itself, when considering their effect on the cluster's weak lensing signal.  When  large-scale numerical simulations of structure formation in a Λ-dominated cold dark matter model  was used to quantify the effect that large-scale structure near clusters has upon the cluster masses deduced from weak lensing analysis. A correction for the scatter in possible observed lensing masses should be included when interpreting mass functions from weak lensing surveys

 It was in fact Jerome Drexler, an applied armature physicist who hypothesized and discovered  the  relativistic-baryon dark matter in early part of 2002 and  the dark matters  was considered to be engaged in galaxy formation.  But Drexler’s hypothesis of relativistic dark baryons, would imply that the Dark matter  cannot clump on galaxy scales since they are relativistic.  The alternate hypothesis might  be that Relativistic-baryons entered the universe at the time of the Big bang as a radial outward dispersion of very high energy relativistic charged particles, having low entropy. Because of their very low entropy, the big bang could satisfy the Second Law of Thermodynamics. The initial very high energies of the big-bang relativistic baryons would correspond to the estimated initial temperatures in the current big bang theories. Actually, relativistic-baryon dark matter forms into long large filaments that can create galaxy clusters, galaxies, and stars, but only after those dark matter filaments collide with other similar long large dark matter filaments(http://www.nature.com/nature/journal/v435/n7042/fig_tab/435572a_F1.html what drexler recenly told[2] New Releases from website from NASA/Harvard, entitled “Motions in nearby galaxy cluster reveal presence of hidden superstructure,” regarding Chandra x-ray images of the Fornax cluster makes the significant statement: “Astronomers think that most of the matter in the universe is concentrated in long large filaments of dark matter [now called the “cosmic web”] and galaxy clusters are formed where these filaments intersect[/collide].” [2] http://www.nasa.gov/centers/marshall/news/news/releases/2004/04-231.html) according to the 2004 NASA/Harvard/Columbia University team, relativistic-baryon dark matter does not form galaxy clusters or galaxies until after the dark matter filaments intersect/collide. These collisions slow the relativistic protons and helium nuclei and also create pions and muons, which decay into electrons. The created electrons then transform the slowed protons and helium nuclei into hydrogen and helium atoms, the basic ingredients of galaxies and stars. Thus, these remnants of the dark-matter-filament collisions are ideal for forming galaxies, galaxy clusters, and stars.
 Warm matter In formation of galaxies and cosmic Web?
The most accepted model of cosmology structure formation is so till date CDM model including the dark energy,  or from that particle universe evolved as baryons in diffuse intergalactic medium accelerated towards the site of formation of such structures under influence of gravity and shocks and that heats  trillions of Kelvin temperature.   The question then remains What is  hat Dark energy? If from dark matter, What is dark matter? It is distinct from  Dark energy? How that matter organized and how is cosmic web organized? How galaxies formed in it? Are the dark energy the zero mass particles in Higgs fields and photon that was emitted later with formation of stars is condensation of zero mass (mass less particles), Rupak Bhattacharya and Professor  Pranab kumar Bhattacharya suggested? Are they missing baryons? Is it possible that the missing baryons may be concentrated into those filamentary cosmic web structures and they are hot intergalactic medium(WHIM)?The distribution of baryons beyond galaxies  thus may be described. The majority of the baryons, which represent 4% of the cosmic mass and energy budget, lie far from individual galaxies in the diffuse intergalactic medium (IGM). Many of these baryons may be in a warm phase that can be probed by quasar absorption in the Lyman-α line of hydrogen. The mature field of quasar spectroscopy can diagnose the location, physical state, metallicity, and general geometry of this gas, which is called the “cosmic web.” The remainder of the gas is kept very hot by in fall and shocks and is mostly in higher density regions such as filaments, groups and clusters. The hot gas is only detectable via X-rays and the absorption of highly ionized species of heavy elements. The baryons in low density regions of space are excellent tracers of underlying dark matter. The evolution of the cosmic web indicates where to look for the baryons in collapsed objects but the overall inefficiency of galaxy formation has conspired to keep most baryons dark

Scientists think dark energy is a form of repulsive gravity that now dominates the universe, although they have no clear picture of what it actually is. Understanding the nature of dark energy is one of the biggest problems in science. Possibilities include the cosmological constant, which is equivalent to the energy of empty space. Other possibilities include a modification in general relativity on the largest scales, or a more general physical field. Vikhlinin and his colleagues used Chandra to observe the hot gas in dozens of galaxy clusters, which are the largest collapsed objects in the universe. Some of these clusters are relatively close and others are more than halfway across the universe. increase in mass of the galaxy clusters over time aligns with a universe dominated by dark energy The study strengthens the evidence that dark energy is the cosmological constant. Although it is the leading candidate to explain dark energy, theoretical work suggests it should be about 10 raised to the power of 120 times larger than observed. Therefore, alternatives to general relativity, such as theories involving hidden dimensions, are being explored. These results have consequences for predicting the ultimate fate of the universe. If dark energy is explained by the cosmological constant, the expansion of the universe will continue to accelerate, and the Milky Way and its neighbor galaxy, Andromeda, never will merge with the Virgo cluster. In that case, about a hundred billion years from now, all other galaxies ultimately would disappear from the Milky Way's view and, eventually, the local superclusters of galaxies also would disintegrate.

Reference
1] J. Richard Bond*, Lev Kofman & Dmitry Pogosyan How filaments of galaxies are woven into the cosmic web Nature 380, 603 - 606 (18 April 1996); doi:10.1038/380603a0; 1996
2] Jerome Drexler”Relativistic-Baryon Dark Matter Utilizes Cosmic Web Collisions to Create Hydrogen and Helium Atoms Discovering Dark matter Cosmology” in website Jerome Drexler Discovering Dark matter cosmology
(http://www.nature.com/nature/journal/v435/n7042/fig_tab/435572a_F1.html at Nature News
http://www.bautforum.com/showthread.php/117579-The-cosmic-Web-the-seed-of-galaxies-are-made-of-Warm-Intergalactic-Medium(WHIM)-an  -discussion at BAD Astronomy and Universe today forum



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 This Paper was sent to following journals  and Comments of Editors are enclosed
 1] Journal of Theoretical Physics