scholarly journals Physical explanation for the galaxy distribution on the (λR, ε) and (V/σ, ε) diagrams or for the limit on orbital anisotropy

2020 ◽  
Vol 500 (1) ◽  
pp. L27-L31
Author(s):  
Bitao Wang ◽  
Michele Cappellari ◽  
Yingjie Peng
Keyword(s):  
Early Type ◽  
Equilibrium Solutions ◽  
Physical Explanation ◽  
Anisotropic Models ◽  
Galaxy Distribution ◽  
Upper Limit ◽  
The Galaxy ◽  
Radial Anisotropy ◽  
Axisymmetric Equilibrium ◽  
Variable Anisotropy

ABSTRACT In the (λR, ε) and (V/σ, ε) diagrams for characterizing dynamical states, the fast-rotator galaxies (both early type and spirals) are distributed within a well-defined leaf-shaped envelope. This was explained as due to an upper limit to the orbital anisotropy increasing with galaxy intrinsic flattening. However, a physical explanation for this empirical trend was missing. Here, we construct Jeans Anisotropic Models (JAM), with either cylindrically or spherically aligned velocity ellipsoid (two extreme assumptions), and each with either spatially constant or variable anisotropy. We use JAM to build mock samples of axisymmetric galaxies, assuming on average an oblate shape for the velocity ellipsoid (as required to reproduce the rotation of real galaxies), and limiting the radial anisotropy β to the range allowed by physical solutions. We find that all four mock samples naturally predict the observed galaxy distribution on the (λR, ε) and (V/σ, ε) diagrams, without further assumptions. Given the similarity of the results from quite different models, we conclude that the empirical anisotropy upper limit in real galaxies, and the corresponding observed distributions in the (λR, ε) and (V/σ, ε) diagrams, are due to the lack of physical axisymmetric equilibrium solutions at high β anisotropy when the velocity ellipsoid is close to oblate.

scholarly journals Tracing Large-Scale Structure with Galaxy Objective-Prism Spectra

1988 ◽  
Vol 130 ◽  
pp. 525-525
Author(s):  
Q.A. Parker ◽  
H.T. Macgillivray ◽  
S.M. Beard
Keyword(s):  
Large Scale ◽  
Large Scale Structure ◽  
Scale Structure ◽  
Early Type ◽  
Galaxy Distribution ◽  
Large Numbers ◽  
The Galaxy ◽  
Measured Sample ◽  
Objective Prism ◽  
Low Dispersion

A new and promising use of galaxy objective-prism spectra as a means of highlighting features in the large scale galaxy distribution has been recently reported by Parker et al. (1987). The technique relies on the property that galaxies with identifiable 4000Å features in low dispersion objective-prism spectra are mostly ellipticals (Cooke, 1980), and that early type galaxies seem to delineate structure and clumpiness in the galaxy distribution (e.g. Giovanelli and Haynes, 1982). The effect is most striking when large numbers of objective-prism galaxy spectra are considered. Figure 1 gives the X-Y plot for 1539 galaxies with 4000Å features to Bj=18.7 in one UKST field out of a manually measured sample of 2903 galaxy prism spectra. Substantial clumpiness is evident. This technique can trace structure in the galaxy distribution across many UKST fields to depths of 400 h−1Mpc.

Supermassive Black Hole feedback in early type galaxies

2020 ◽  
Vol 15 (S359) ◽  
pp. 119-125
Author(s):  
W. Forman ◽  
C. Jones ◽  
A. Bogdan ◽  
R. Kraft ◽  
E. Churazov ◽  
...  
Keyword(s):  
Dark Matter Halo ◽  
Scaling Relations ◽  
Radio Sources ◽  
Early Type ◽  
X Ray ◽  
Galaxy Groups ◽  
Sufficient Energy ◽  
The Galaxy ◽  
Simple Scaling ◽  
Halo Masses

AbstractOptically luminous early type galaxies host X-ray luminous, hot atmospheres. These hot atmospheres, which we refer to as coronae, undergo the same cooling and feedback processes as are commonly found in their more massive cousins, the gas rich atmospheres of galaxy groups and galaxy clusters. In particular, the hot coronae around galaxies radiatively cool and show cavities in X-ray images that are filled with relativistic plasma originating from jets powered by supermassive black holes (SMBH) at the galaxy centers. We discuss the SMBH feedback using an X-ray survey of early type galaxies carried out using Chandra X-ray Observatory observations. Early type galaxies with coronae very commonly have weak X-ray active nuclei and have associated radio sources. Based on the enthalpy of observed cavities in the coronae, there is sufficient energy to “balance” the observed radiative cooling. There are a very few remarkable examples of optically faint galaxies that are 1) unusually X-ray luminous, 2) have large dark matter halo masses, and 3) have large SMBHs (e.g., NGC4342 and NGC4291). These properties suggest that, in some galaxies, star formation may have been truncated at early times, breaking the simple scaling relations.

An Upper Limit on the Coalescence Rate of Double Neutron‐Star Binaries in the Galaxy

2000 ◽  
Vol 530 (2) ◽  
pp. 890-895 ◽  
Author(s):  
Vassiliki Kalogera ◽  
Duncan R. Lorimer
Keyword(s):  
Neutron Star ◽  
Upper Limit ◽  
Coalescence Rate ◽  
The Galaxy

scholarly journals Analysis of the Galaxy Distribution using Multiscale Methods

2002 ◽  
Author(s):  
Philippe Querre ◽  
Jean-Luc Starck ◽  
Vicent J. Martinez
Keyword(s):  
Multiscale Methods ◽  
Galaxy Distribution ◽  
The Galaxy

scholarly journals The properties of early-type stars in the Magellanic Clouds

2008 ◽  
Vol 4 (S256) ◽  
pp. 325-336
Author(s):  
Christopher J. Evans
Keyword(s):  
Physical Properties ◽  
Mass Loss ◽  
Temperature Scale ◽  
Massive Stars ◽  
Magellanic Clouds ◽  
Early Type ◽  
The Past ◽  
The Galaxy ◽  
Stellar Temperature ◽  
Early Type Stars

AbstractThe past decade has witnessed impressive progress in our understanding of the physical properties of massive stars in the Magellanic Clouds, and how they compare to their cousins in the Galaxy. I summarise new results in this field, including evidence for reduced mass-loss rates and faster stellar rotational velocities in the Clouds, and their present-day compositions. I also discuss the stellar temperature scale, emphasizing its dependence on metallicity across the entire upper-part of the Hertzsprung-Russell diagram.

scholarly journals Probing gaseous halos of galaxies with radio jets

2019 ◽  
Vol 627 ◽  
pp. A113 ◽  
Author(s):  
Martin G. H. Krause ◽  
Martin J. Hardcastle ◽  
Stanislav S. Shabala
Keyword(s):  
Low Frequency ◽  
Mass Range ◽  
Mass Scale ◽  
Radio Luminosity ◽  
Marked Rise ◽  
Radio Jets ◽  
Upper Limit ◽  
The Galaxy ◽  
Galaxy Masses ◽  
Halo Gas

Context. Gaseous halos play a key role in understanding inflow, feedback, and the overall baryon budget in galaxies. Literature models predict transitions of the state of the gaseous halo between cold and hot accretion, winds, fountains, and hydrostatic halos at certain galaxy masses. Since luminosities of radio AGN are sensitive to halo densities, any significant transition would be expected to show up in the radio luminosities of large samples of galaxies. The LOw Frequency ARray (LOFAR) Two-Metre Sky Survey (LoTSS) has identified a galaxy stellar mass scale, 1011 M⊙, above which the radio luminosities increase disproportionately. Aims. We investigate if radio luminosities of galaxies, especially the marked rise at galaxy masses around 1011 M⊙, can be explained with standard assumptions regarding jet powers, scaling between black hole mass and galaxy mass, and gaseous halos. Methods. Based on observational data and theoretical constraints, we developed models for the radio luminosity of radio AGN in halos under infall, galactic wind, and hydrostatic conditions. We compared these models to LoTSS data for a large sample of galaxies in the mass range between 108.5 M⊙ and 1012 M⊙. Results. Under the assumption that the same characteristic upper limit to jet powers known from high galaxy masses holds at all masses, we find the maximum radio luminosities for the hydrostatic gas halos to lie close to the upper envelope of the distribution of the LOFAR data. The marked rise in radio luminosity at 1011 M⊙ is matched in our model and is related to a significant change in halo gas density around this galaxy mass, which is a consequence of lower cooling rates at a higher virial temperature. Wind and infall models overpredict the radio luminosities for small galaxy masses and have no particular steepening of the run of the radio luminosities predicted at any galaxy mass. Conclusions. Radio AGN could have the same characteristic Eddington-scaled upper limit to jet powers in galaxies of all masses in the sample if the galaxies have hydrostatic gas halos in phases when radio AGN are active. We find no evidence of a change of the type of galaxy halo with the galaxy mass. Galactic winds and quasi-spherical cosmological inflow phases cannot frequently occur at the same time as powerful jet episodes unless the jet properties in these phases are significantly different from what we assumed in our model.

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