scholarly journals Central Black Holes and Dark Halos in Elliptical Galaxies

1995 ◽  
Vol 164 ◽  
pp. 215-225
Author(s):  
P.T. De Zeeuw

Studies of the mass–to–light ratio M/L as a function of radius in a galaxy usually focus on: a) the existence of dark matter in and around galaxies, and b) the presence of massive black holes in their nuclei. Here we concentrate on elliptical galaxies, and summarize some recent work in both areas. We refer to more extensive reviews for earlier developments (Schwarzschild, 1954; Trimble, 1987; Ashman, 1992; Kormendy, 1993). A third area of interest is the behavior of the stellar populations as a function of radius, and its effect on M/L (e.g., Peletier, 1989). We will not discuss this here.

1997 ◽  
Vol 163 ◽  
pp. 620-625 ◽  
Author(s):  
H. Ford ◽  
Z. Tsvetanov ◽  
L. Ferrarese ◽  
G. Kriss ◽  
W. Jaffe ◽  
...  

AbstractHST images have led to the discovery that small (r ~ 1″ r ~ 100 – 200 pc), well-defined, gaseous disks are common in the nuclei of elliptical galaxies. Measurements of rotational velocities in the disks provide a means to measure the central mass and search for massive black holes in the parent galaxies. The minor axes of these disks are closely aligned with the directions of the large–scale radio jets, suggesting that it is angular momentum of the disk rather than that of the black hole that determines the direction of the radio jets. Because the disks are directly observable, we can study the disks themselves, and investigate important questions which cannot be directly addressed with observations of the smaller and unresolved central accretion disks. In this paper we summarize what has been learned to date in this rapidly unfolding new field.


2009 ◽  
Vol 5 (H15) ◽  
pp. 269-270
Author(s):  
Dong-Woo Kim ◽  
Silvia Pellegrini

The physical properties of the hot interstellar matter in elliptical galaxies are directly related with the formation and evolution of elliptical galaxies via star formation episodes, environmental effects such as stripping, infall, and mergers, and growth of super-massive black holes. The recent successful Chandra and XMM-Newton X-ray space missions have provided a large amount of high spatial/spectral resolution observational data on the hot ISM in elliptical galaxies. At the same time, theoretical studies with numerical simulations and analytical modeling of the dynamical and chemical evolution of elliptical galaxies have made a significant progress and start to predict various observable quantities.


2015 ◽  
Vol 815 (1) ◽  
pp. 21 ◽  
Author(s):  
Mirko Krumpe ◽  
Takamitsu Miyaji ◽  
Bernd Husemann ◽  
Nikos Fanidakis ◽  
Alison L. Coil ◽  
...  

2003 ◽  
Vol 209 ◽  
pp. 635-636
Author(s):  
Eric Peng ◽  
Holland Ford ◽  
Kenneth Freeman

Extragalactic planetary nebulae (PNe) and globular clusters (GCs) are complementary tools for obtaining kinematic information on stellar populations in the outer halos elliptical galaxies. NGC 5128, as the nearest large elliptical (D ~ 3.5 Mpc), is an excellent galaxy for halo studies. We have now identified a total of 1140 PNe, and possess radial velocities for 736 PNe at distances out to 80 and 50 kpc along the photometric axes. There is clear evidence for kinematic axis twisting (triaxiality) in the PNe velocity field. The mass of NGC 5128 continues to rise out to 80 kpc, where M(< 80 kpc) ~ 6.4 x 1011M⊙ with M80/LB ~ 20. We also conducted a new survey for GCs out to 50 and 30 kpc, and now have radial velocities for 188 GCs (125 new). Both the red and blue GC systems exhibit rotation. The red (metal-rich) GCs share a misaligned kinematic axis with the PNe. The success of this survey bodes well for future galaxy halo studies.


Author(s):  
Martin G. Haehnelt

Massive black holes appear to be an essential ingredient of massive galactic bulges but little is known yet to what extent massive black holes reside in dwarf galaxies and globular clusters. Massive black holes most likely grow by a mixture of merging and accretion of gas in their hierarchically merging host galaxies. While the hierarchical merging of dark matter structures extends to sub-galactic scales and very high redshift, it is uncertain if the same is true for the build–up of massive black holes. I discuss here some of the relevant problems and open questions.


2011 ◽  
Vol 20 (10) ◽  
pp. 1937-1940
Author(s):  
PASCAL CHARDONNET ◽  
ANNA CHIAPPINELLI

The center of our Galaxy provides a uniquely accessible laboratory. It is a rich environment of extreme density, velocity and tidal fields of stars. It is the closest example of a galactic nucleus and could give the opportunity to understand the role that massive black-holes play in the formation and evolution of galaxies. It could be used to test the effects of relativity and dark matter in the Galactic Center. If the central object is a black-hole such observation would be a milstone: the first direct proof that an event horizon, and therefore a black-hole exists. The next decade will be decisive in new discoveries.


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