Academia.edu no longer supports Internet Explorer.
To browse Academia.edu and the wider internet faster and more securely, please take a few seconds to upgrade your browser.
1999, arXiv (Cornell University)
…
12 pages
1 file
Elliptical and bulge galaxies share a tight correlation of velocity distribution to both luminosity and black hole mass. There are similar orbital speeds for all galaxies of a given luminosity including dark matter (DM) at large radii. The halo surface density of DM is constant for almost all types of galaxies and ranges 14 mag. down to dwarf spherical galaxies. There are supermassive black holes or giant, pure disk galaxies at high redshift inexplicable with hierarchical clustering or collapse dynamics. These and a myriad of other galaxy formation problems are explainable by an initial shell which caused the Planck cosmic microwave background radiation. A reduction in the energydensity of primordial galactic black holes is necessary to explain dark energy.
arXiv: Astrophysics, 1999
Eliptical and bulge galaxies share a tight correlation of velocity distribution to both luminosity and black hole mass. There are similar orbital speeds for all galaxies of a given luminosity including dark matter (DM) at large radii. The halo surface density of DM is constant for almost all types of galaxies and ranges 14 mag. down to dwarf spherical galaxies. There are supermassive black holes or giant, pure disk galaxies at high redshift inexplicable with hierarchical clustering or collapse dynamics. These and a myriad of other galaxy formation problems are explainable by an initial shell which caused the Planck cosmic microwave background radiation. A reduction in the energy-density of primordial galactic black holes is necessary to explain dark energy.
Nature, 2009
Virtually all massive galaxies, including our own, host central black holes ranging in mass from millions to billions of solar masses. The growth of these black holes releases vast amounts of energy that powers quasars and other weaker active galactic nuclei. A tiny fraction of this energy, if absorbed by the host galaxy, could halt star formation by heating and ejecting ambient gas. A central question in galaxy evolution is the degree to which this process has caused the decline of star formation in large elliptical galaxies, which typically have little cold gas and few young stars, unlike spiral galaxies.
The Astrophysical Journal, 2001
The influence of a dark component on the first epoch of galaxy formation is analysed by using the ages of the three oldest high-redshift galaxies known in the literature. Our results, based on a spatially flat accelerated Universe driven by a "quintessence" component (p x = ωρ x), show that if the inferred ages of these objects are correct the first formation era is pushed back to extremely high redshifts. For the present best-fit quintessence model (Ω x = 0.7, ω < −0.6), we find a lower bound of z f ≥ 7.7, whereas in the extreme case of ΛCDM model (ω = −1) the limit is slightly smaller (z f ≥ 5.8). The case for open cold dark matter models (OCDM) has also been discussed. For Ω m 0.3, the formation redshift is restricted by z f ≥ 18. As a general result, if Ω m ≥ 0.37, these galaxies are not formed in FRW cosmologies with no dark energy since for all these cases z f → ∞.
Physical Review D, 2014
The self-gravitating gas in the Newtonian limit is studied in the presence of dark energy with a linear and constant equation of state. Entropy extremization associates to the isothermal Boltzmann distribution an effective density that includes 'dark energy particles', which either strengthen or weaken mutual gravitational attraction, in case of quintessence or phantom dark energy, respectively, that satisfy a linear equation of state. Stability is studied for microcanonical (fixed energy) and canonical (fixed temperature) ensembles. Compared to the previously studied cosmological constant case, in the present work it is found that quintessence increases, while phantom dark energy decreases the instability domain under gravitational collapse. Thus, structures are more easily formed in a quintessence rather than in a phantom dominated Universe. Assuming that galaxy clusters are spherical, nearly isothermal and in hydrostatic equilibrium we find that dark energy with a linear and constant equation of state, for fixed radius, mass and temperature, steepens their total density profile! In case of a cosmological constant, this effect accounts for a 1.5% increase in the density contrast, that is the center to edge density ratio of the cluster. We also propose a method to constrain phantom dark energy.
Black holesÐan extreme consequence of the mathematics of General RelativityÐhave long been suspected of being the main energy source for quasars, which emit more energy than any other objects in the Universe. Recent evidence indicates that supermassive black holes reside at the centres of most galaxies, where they are probably the remnants of quasars that have been starved of fuel. As our knowledge of the demographics of supermassive black holes improves, we see clues that they participated in the formation of galaxies, and strongly in¯uenced the evolution towards the present-day structure of their surrounding hosts. Black holes are a prediction of Einstein's theory of gravity, fore-shadowed by the work of Michell and later Laplace in the late eighteenth century. K. Schwarzschild discovered the simplest kind of black hole in the ®rst solution of Einstein's equations of General Relativity, and Oppenheimer was among the ®rst to consider the possibility that black holes might actually form in nature. The subject gained life in the 1960s and 1970s, when supermassive black holes were implicated as the powerhouses for quasars, and stellar-mass black holes were touted as the engines for many galactic X-ray sources. In the past decade, we have progressed from seeking supermassive black holes in only the most energetic astrophysical contexts, to suspecting that they might be routinely present at the centres of galaxies 1±3. The de®ning property of a black hole is its event horizon, the boundary of the region surrounding the black hole from which no matter or photons can escape. Because the horizon itself is invisible, we must often settle for evidence of mass without light. All dynamical techniques for ®nding supermassive black holes at the centres of galaxies rely on a determination of mass enclosed within a radius r from the velocity v of test particles. In newtonian physics, this mass is M r av 2 r=G. Determining a requires a detailed dynamical analysis, but it is often of order 1. In cases where there is extra mass above that associated with starlight, we refer to the object as a `massive dark object' (MDO). In most of the cases discussed in this paper, it is likely that the MDO is a supermassive black hole (MBH), but in only a few cases have plausible alternatives to a black hole been ruled out. These are important because they establish the reality of MBHs and justify the interpretation of less compelling objects as MBHs. Black holes as energy sources of quasars Black holes are thought to exist in two mass ranges. Small ones of ,10M (are the evolutionary end points of some massive stars. This paper discusses the much more massive black holes that might power quasars and their weaker kin, active galactic nuclei (AGN). Quasars produce luminosities of L,10 46 erg s-1 (,10 12 L (). Where they power double-lobed radio sources, the minimum energy stored in the lobes is E,10 60 ±10 64 erg. The mass equivalent of this energy is M E=c 2 ,10 6 ±10 10 M (, and the horizon scale associated with that mass is R S GM=c 2 ,10 11 ±10 15 cm. Although most quasars do not vary much at visual wavelengths, a few objects change their luminosity in minutes at high energies 4,5. Because an object cannot causally vary faster than the light-travel time t across it, such objects must be smaller than R,ct,10 13 cm. Although relativistic corrections can alter this limit somewhat in either direction via Doppler boosting or gravitational redshift, there is no escaping the conclusion that many quasars are prodigiously luminous yet tiny, outshining a galaxy in a volume smaller than the Solar System. The small size, together with the enormous energy output of quasars, mandates black-hole accretion as the energy source. Most investigators believe that quasars and AGNs are MBHs accreting mass from their environment, nearly always at the centre of a galaxy 6±8. Black holes of mass .10 7 M (must normally lie at the centre because dynamical friction drags them to the bottom of the potential well. This location is now clearly established for low-redshift (z (0:3) quasars 9. The connection between MBHs and quasars was ®rst made by Zeldovich 10 and Salpeter 11. Lynden-Bell 12 sharpened the argument by computing the ratio of gravitational energy to nuclear energy: E g E n , e g GM 2 =R e n Mc 2 , e g e n R S R ,100e g 1 where R S is the Schwarzschild radius of a black hole of mass M, R is the size of the quasar, and e g and e n are gravitational and nuclear energy conversion ef®ciencies; the last equality follows from the typical astrophysical thermonuclear ef®ciency of ,1% and the size scale from variability noted above. Because quasars were populous in the youthful Universe, but have mostly died out, the Universe should be populated with relic black holes whose average mass density r u matches or exceeds the mass-equivalent of the energy density u emitted by them 13. The integrated co-moving energy density in quasar light (as emitted) is: u # ` 0 # ` 0 L©L j zdL dt dz dz 1:3 3 10 2 15 erg cm 2 3 2 where © is the co-moving density of quasars of luminosity L, and t is cosmic time. The corresponding present-day mass density for a radiative ef®ciency e is r u u=ec 2 2 3 10 5 0:1=eM (Mpc-3. This density can be compared with the luminous density in galaxies, j 1:1 3 10 8 L (Mpc-3 (ref. 14), to obtain the ratio of the mass in relic MBHs to the light of galaxies: ¨ r u j 1:8 3 10 2 3 0:1 e M (L (: 3 Dynamical evidence for massive black holes First steps. The ®rst dynamical evidence for black holes in galactic centres was the measurement 15 of a rising central velocity dispersion , reaching ,400 km s-1 , in the giant elliptical galaxy M87. This object is a prime site to prospect for an MBH by virtue of its AGN featuresÐnon-thermal radio emission, broad nuclear emission lines, and a `jet' of collimated relativistic particles being ejected from the nucleus. Isotropic models of the stellar kinematics, when reviews A14
Connection to three outstanding problems in 21 st Physics: • The identity of the dark matter • The nature of the dark energy • Origin of cosmic structure Goal: understand origin and evolution of cosmic structures
Astronomy Reports, 2008
Model of supermassive black holes formation inside the clusters of primordial black holes is developed. Namely, it is supposed, that some mass fraction of the universe ∼ 10 −3 is composed of the compact clusters of primordial (relic) black holes, produced during phase transitions in the early universe. These clusters are the centers of dark matter condensation. We model the formation of protogalaxies with masses about 2 10 8 M⊙ at the redshift z = 15. These induced protogalaxies contain central black holes with mass ∼ 10 5 M⊙ and look like dwarf spheroidal galaxies with central density spike. The subsequent merging of induced protogalaxies and ordinary dark matter haloes corresponds to the standard hierarchical clustering scenario of large-scale structure formation. The coalescence of primordial black holes results in formation of supermassive black holes in the galactic centers. As a result, the observed correlation between the masses of central black holes and velocity dispersion in the galactic bulges is reproduced. * Electronic address: dokuchaev@lngs.infn.it † Electronic address: erosh@inr.npd.ac.ru ‡ Electronic address: sergeirubin@list.ru
Monthly Notices of the Royal Astronomical Society, 2014
We investigate the black hole (BH) scaling relation in galaxies using a model in which the galaxy halo and central BH are a self-gravitating sphere of dark matter (DM) with an isotropic, adiabatic equation of state. The equipotential where the escape velocity approaches the speed of light defines the horizon of the BH. We find that the BH mass (m•) depends on the DM entropy, when the effective thermal degrees of freedom (F) are specified. Relations between BH and galaxy properties arise naturally, with the BH mass and DM velocity dispersion following m• ∝ σF/2 (for global mean density set by external cosmogony). Imposing observationally derived constraints on F provides insight into the microphysics of DM. Given that DM velocities and stellar velocities are comparable, the empirical correlation between m• and stellar velocity dispersions σ⋆ implies that 7 ≲ F < 10. A link between m• and globular cluster properties also arises because the halo potential binds the globular cluster swarm at large radii. Interestingly, for F > 6 the dense dark envelope surrounding the BH approaches the mean density of the BH itself, while the outer halo can show a nearly uniform kpc-scale core resembling those observed in galaxies.
Вопросы ономастики / Voprosy onomastiki, 2023
В работах А. К. Матвеева, О. В. Смирнова и др. надежно обоснована старая гипотеза о родстве мерянских языков (сегодня представляется возможным говорить о целой группе языков или диалектов, реконструируемых на базе субстратной топонимии Центральной России: ростовском мерянском, костромском мерянском и муромском, или «нижнеклязьминском») с марийским. В статье рассматривается дискуссия, ведущаяся в данной области; отмечается, что современная реконструкция прамарийского вокализма, базирующаяся, в частности, на учете истории марийско-тюркских контактов, безусловно, подкрепляет эту гипотезу. Авторы предлагают вариант схемы родословного древа финно-пермских языков с включением марийско-мерянской группы и других реконструированных по данным субстратной топонимии мертвых финно-пермских языков. Однако, поскольку результаты анализа субстратного топонимического материала, на которых базируется реконструкция мерянских языков, всегда по природе своей остаются в известной мере дискуссионными, авторы предлагают обратиться к анализу этнонимии. В статье рассматривается давно (М. А. Кастрен) отмеченное сходство этнонимов мари и меря, а также мурома, исходя из того, что во всех случаях отражены самоназвания. С привлечением данных по историческому вокализму марийского и тех особенностей вокализма мерянского и муромского языков, которые можно извлечь из топонимического материала, реконструируются праформы мар. *märə, мер. *märə, муром. *mürə, возводимые к общей мар.-мер. *märə, которую, как это уже принято в финно-угроведении, предлагается возводить к какому-то рефлексу арийского *marya- ‘юноша, молодой воин, член молодежного воинского союза’ (авторы намерены рассмотреть проблемы арийского источника данного этнонима в отдельной статье). Реконструкция общего для марийцев, мери и муромы этнонима *märə служит сильнейшим аргументом не только в пользу близости языков марийско-мерянской группы, но и указывает на тесные этнические связи носителей этих языков и их общее происхождение. The old hypothesis on the relatedness of Merya languages (today we can speak about a group of languages or dialects reconstructed on the basis of substrate toponymy of Central Russia: Merya of Rostov, Merya of Kostroma, and Merya of Murom also known as “Lower Klyazma” Merya) with the Mari (Cheremis) language has been reliably proven in the works of A. K. Matveyev, O. V. Smirnov and others. The authors contribute to the ongoing discussion in this area and argue that the new reconstruction of Proto-Mari vocalism based on the history of Mari-Turkic contacts undoubtedly supports this hypothesis. The article suggests a version of the Stammbaum of Finno-Permian languages, including the Mari-Merya group and some other extinct Finno-Permian languages, reconstructed on the basis of substrate toponymic data. However, since the results of the analysis of substrate toponymy are inevitably debatable to a certain extent, the authors propose to turn to the analysis of ethnonymy. The long-noted (by M. A. Castrén) similarity of the ethnonyms Mari, Merya, and Muroma is considered, suggesting them to be self-names of the respective ethnic groups. The reconstruction of the Mari historical vocalism (as well as features of the vocalism of the Merya and Muromian languages that can be extracted from toponymic materials) delivers the proto-forms Mari *märə, Merya *märə, Muromian *mürə, all going back to the ancestral *märə. The latter protoform should be explained (as it is now common in the Finno-Ugric studies) as some reflex of Aryan *marya- ‘young man, warrior, member of youth war community’ (the authors are going to devote a special article to the problem of the Aryan source of this ethnonym). The reconstruction of the common Mari–Meryan–Muromian auto-ethnonym *märə is not only a strong argument for the relatedness of these languages, but also indicates close relations between the respective ethnic groups and their common origin.
El Universal, 2024
Practice Periodical on Structural Design and Construction, 2012
Journal of Documentation, 2022
Bruniana & Campanelliana, 2022
British Journal of General Practice, 2011
Coupled Electro-Thermal Transients Simulation of Gas-Insulated Transmission Lines Using FDTD and VEM Modeling, 2017
Aprendizajes para iniciativas público-privadas de transformación digital, 2023
A Narrative Review and Feasibility Study of a Quantitative Decision-Making Tree for a High-Performance Centre: A Collaborative Approach, 2024
Frontiers: The Interdisciplinary Journal of Study Abroad
Revista Brasileira De Agroecologia, 2007
TalTech Journal of European Studies, 2021
International journal of nursing studies, 2012
Otolaryngology - Head and Neck Surgery, 2003
Rendiconti Lincei - Matematica e Applicazioni, 2021
Policy Research Working Papers, 2004
Neural Networks in Business Forecasting
European Respiratory Journal, 2013
Air Quality, Atmosphere & Health, 2020
verve. revista semestral autogestionária do Nu-Sol., 2004