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Phelps S.,Technion - Israel Institute of Technology | Nusser A.,Asher Space Science Institute | Desjacques V.,University of Geneva
Astrophysical Journal | Year: 2013

We constrain the most likely range of masses for the Milky Way (MW) and M31 using an application of the numerical action method (NAM) that optimizes the fit to observed parameters over a large ensemble of NAM-generated solutions. Our 95% confidence level mass ranges, 1.5-4.5 × 1012 M for MW and 1.5-5.5 × 1012 M for M31, are consistent with the upper range of estimates from other methods and suggests that a larger proportion of the total mass becomes detectable when the peculiar motions of many nearby satellites are taken into account in the dynamical analysis. We test the method against simulated Local Group catalogs extracted from the Millennium Run to confirm that mass predictions are consistent with actual galaxy halo masses. © 2013. The American Astronomical Society. All rights reserved.. Source


Silk J.,University of Oxford | Silk J.,CNRS Paris Institute of Astrophysics | Nusser A.,Asher Space Science Institute
Astrophysical Journal | Year: 2010

Force balance considerations put a limit on the rate of active galactic nucleus radiation momentum output, L/c, capable of driving galactic superwinds and reproducing the observedMBH-σ relation between black hole mass and spheroid velocity dispersion. We show that black holes cannot supply enough momentum in radiation to drive the gas out by pressure alone. Energy-driven winds give a MBH-σ scaling favored by a recent analysis but also fall short energetically once cooling is incorporated.We propose that outflow triggering of star formation by enhancing the intercloud medium turbulent pressure and squeezing clouds can supply the necessary boost and suggest possible tests of this hypothesis. Our hypothesis simultaneously can account for the observed halo baryon fraction. © 2010 The American Astronomical Society. Source

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