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M–sigma Relation
The M–sigma (or ''M''–''σ'') relation is an empirical correlation between the stellar velocity dispersion ''σ'' of a galaxy bulge and the mass M of the supermassive black hole at its center. The ''M''–''σ'' relation was first presented in 1999 during a conference at the Institut d'astrophysique de Paris in France. The proposed form of the relation, which was called the "Faber–Jackson law for black holes", was : \frac \approx 3.1\left(\frac\right)^4. where M_\odot is the solar mass. Publication of the relation in a refereed journal, by two groups, took place the following year. One of many recent studies, based on the growing sample of published black hole masses in nearby galaxies, givesMcConnell, N. J. et al. (2011) Two ten-billion-solar-mass black holes at the centres of giant elliptical galaxies ''Nature'', 480, 215–218 : \frac \approx 1.9\left(\frac\right)^. Earlier work demonstrated a relationship between galaxy luminosity and black hole mass, which nowaday ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crossing Time
is a Japanese manga series by Yoshimi Sato. It was serialized in Futabasha's ''seinen'' manga magazine ''Monthly Action'' from May 2016 to September 2021 and was collected in eight ''tankōbon'' volumes. An anime television series adaptation by Ekachi Epilka aired from April to June 2018. Plot Our whole life consists of sheer fuss. People all the time somewhere in a hurry, in a hurry, run ... In the dizzy everyday bustle, sometimes we even have no time to take a breath. But there must be a balance in everything. And if we can not stop in time, the city will do it for us. There are traffic lights on which you can slow down and spend a moment in simple waiting. And there are railway crossings, where you will have to stand a little longer, peering into the distance and looking for the silhouette of an approaching train, and also calculate how many cars there are. What thoughts come to their mind when the barrier suddenly blocks them further? For them, every day is a new story, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrophysics
Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline said, Astrophysics "seeks to ascertain the nature of the heavenly bodies, rather than their positions or motions in space–''what'' they are, rather than ''where'' they are." Among the subjects studied are the Sun, other stars, galaxies, extrasolar planets, the interstellar medium and the cosmic microwave background. Emissions from these objects are examined across all parts of the electromagnetic spectrum, and the properties examined include luminosity, density, temperature, and chemical composition. Because astrophysics is a very broad subject, ''astrophysicists'' apply concepts and methods from many disciplines of physics, including classical mechanics, electromagnetism, statistical mechanics, thermodynamics, quantum mechanics, relativity, nuclear and particle physics, and atomic and m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sigma-D Relation
The Sigma-D relation, or Σ-D Relation, is the radio surface brightness to diameter relation of a supernova remnant.Urošević, D. et al. (2009Sigma-D relation for supernova remnants and its dependent on the density of the interstellar medium ''Astronomy and Astrophysics'', 495, 537-546 See also *Cosmic distance ladder *Faber–Jackson relation *M–sigma relation The M–sigma (or ''M''–''σ'') relation is an empirical correlation between the stellar velocity dispersion ''σ'' of a galaxy bulge and the mass M of the supermassive black hole at its center. The ''M''–''σ'' relation was first presented ... References Physical cosmology Astrophysics Equations of astronomy {{astronomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Galaxy Formation And Evolution
The study of galaxy formation and evolution is concerned with the processes that formed a heterogeneous universe from a homogeneous beginning, the formation of the first galaxies, the way galaxies change over time, and the processes that have generated the variety of structures observed in nearby galaxies. Galaxy formation is hypothesized to occur from structure formation theories, as a result of tiny quantum fluctuations in the aftermath of the Big Bang. The simplest model in general agreement with observed phenomena is the Lambda-CDM model—that is, that clustering and merging allows galaxies to accumulate mass, determining both their shape and structure. Commonly observed properties of galaxies Because of the inability to conduct experiments in outer space, the only way to “test” theories and models of galaxy evolution is to compare them with observations. Explanations for how galaxies formed and evolved must be able to predict the observed properties and types of galax ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Faber–Jackson Relation
The Faber–Jackson relation provided the first empirical power-law relation between the luminosity L and the central stellar velocity dispersion \sigma of elliptical galaxy, and was presented by the astronomers Sandra M. Faber and Robert Earl Jackson in 1976. Their relation can be expressed mathematically as: : L \propto \sigma^ \gamma with the index \gamma approximately equal to 4. In 1962, Rudolph Minkowski had discovered and wrote that a "correlation between velocity dispersion and uminosityexists, but it is poor" and that "it seems important to extend the observations to more objects, especially at low and medium absolute magnitudes". This was important because the value of \gamma depends on the range of galaxy luminosities that is fitted, with a value of 2 for low-luminosity elliptical galaxies discovered by a team led by Roger Davies, and a value of 5 reported by Paul L. Schechter for luminous elliptical galaxies.Paul L. Schechter (1980)Mass-to-light ratios fo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daniel Batcheldor
Daniel Batcheldor is an Anglo-American astrophysicist, a former professor at Florida Institute of Technology and Head of the Department of Aerospace, Physics and Space Sciences, and Director of the Jacobus Kapteyn Telescope. Early life and education In 2000, Batcheldor served as a student support astronomer at the Isaac Newton Group of Telescopes with responsibilities for the Jacobus Kapteyn Telescope. He received a bachelor's degree in astronomy from the University of Hertfordshire in 2001, and in 2004 he completed his Ph.D. at the same institution. Career In 2010, Batcheldor moved to a faculty position at Florida Institute of Technology and became the Director of the Olin Observatory. In 2014, he became Head of the Department of Physics and Space Sciences at Florida Institute of Technology, until his departure in July 2020. Contributions Astrophysics Batcheldor's work includes the quantification of selection effects in the ''M''–''σ'' relation.,Batcheldor, D. (2010)The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intermediate-mass Black Hole
An intermediate-mass black hole (IMBH) is a class of black hole with mass in the range 102–105 solar masses: significantly more than stellar black holes but less than the 105–109 solar mass supermassive black holes. Several IMBH candidate objects have been discovered in our galaxy and others nearby, based on indirect gas cloud velocity and accretion disk spectra observations of various evidentiary strength. Observational evidence The gravitational wave signal GW190521, which occurred on 21 May 2019 at 03:02:29 UTC, and was published on 2 September 2020, resulted from the merger of two black holes, weighing 85 and 65 solar masses, with the resulting black hole weighing 142 solar masses, and 8 solar masses being radiated away as gravitational waves. Before that, the strongest evidence for IMBHs comes from a few low-luminosity active galactic nuclei. Due to their activity, these galaxies almost certainly contain accreting black holes, and in some cases the black hole masses c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sphere Of Influence (black Hole)
The sphere of influence is a region around a supermassive black hole in which the gravitational potential of the black hole dominates the gravitational potential of the host galaxy. The radius of the sphere of influence is called the "(gravitational) influence radius". There are two definitions in common use for the radius of the sphere of influence. The first is given by r_h = \frac where MBH is the mass of the black hole, ''σ'' is the stellar velocity dispersion of the host bulge, and ''G'' is the gravitational constant. The second definition is the radius at which the enclosed mass in stars equals twice MBH, i.e. M_\star(r [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quasar
A quasar is an extremely Luminosity, luminous active galactic nucleus (AGN). It is pronounced , and sometimes known as a quasi-stellar object, abbreviated QSO. This emission from a galaxy nucleus is powered by a supermassive black hole with a mass ranging from millions to tens of billions of solar masses, surrounded by a gaseous accretion disc. Gas in the disc falling towards the black hole heats up because of friction and releases energy in the form of electromagnetic radiation. The radiant energy of quasars is enormous; the most powerful quasars have luminosity, luminosities thousands of times greater than that of a galaxy such as the Milky Way. Usually, quasars are categorized as a subclass of the more general category of AGN. The redshifts of quasars are of Expansion of the universe, cosmological origin. The term originated as a Contraction (grammar), contraction of "quasi-stellar ''[star-like]'' radio source"—because quasars were first identified during the 1950s as sour ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sołtan Argument
The Sołtan argument is an astrophysical theory outlined in 1982 by Polish astronomer . It maintains that if quasars were powered by accretion onto a supermassive black hole, then such supermassive black holes must exist in our local universe as "dead" quasars. History As early as 1969, Donald Lynden-Bell wrote a paper suggesting that "dead quasars" were found at the center of the Milky Way and nearby galaxies by arguing that given the quasar-number counts, luminosities, distances, and the efficiency of accretion into a "Schwarzschild throat" through the last stable circular orbit (note that the term ''black hole'' had been coined only two years earlier and was still gaining popular usage), roughly 1010 quasars existed in the observable universe. This number density of "dead quasars" was attributed by Lynden-Bell to high mass-to-light ratio objects found at the center of galaxies. This is essentially the Sołtan argument, though the direct connection between black hole masses and q ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Galactic Nuclei
An active galactic nucleus (AGN) is a compact region at the center of a galaxy that has a much-higher-than-normal luminosity over at least some portion of the electromagnetic spectrum with characteristics indicating that the luminosity is not produced by stars. Such excess non-stellar emission has been observed in the radio, microwave, infrared, optical, ultra-violet, X-ray and gamma ray wavebands. A galaxy hosting an AGN is called an "active galaxy". The non-stellar radiation from an AGN is theorized to result from the accretion of matter by a supermassive black hole at the center of its host galaxy. Active galactic nuclei are the most luminous persistent sources of electromagnetic radiation in the universe, and as such can be used as a means of discovering distant objects; their evolution as a function of cosmic time also puts constraints on models of the cosmos. The observed characteristics of an AGN depend on several properties such as the mass of the central black hole, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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