Dynamical Blueprints for Galaxies

By L. Widrow, Brent Pym, John Dubinski. 2008

183 citations recorded by the source corpus.

We present an axisymmetric, equilibrium model for late-type galaxies which consists of an exponential disk, a Sérsic bulge, and a cuspy dark halo. The model is specified by a phase-space distribution function which, in turn, depends on the integrals of motion. Bayesian statistics and the Markov chain Monte Carlo method are used to tailor the model to satisfy observational data and theoretical constraints. By way of example, we construct a chain of 105 models for the Milky Way designed to fit a wide range of photometric and kinematic observations. From this chain, we calculate the probability distribution function of important Galactic parameters such as the Sérsic index of the bulge, the disk scale length, and the disk, bulge, and halo masses. We also calculate the probability distribution function of the local dark matter velocity dispersion and density, two quantities of paramount significance for terrestrial dark matter detection experiments. Although the Milky Way models in our chain all satisfy the prescribed observational constraints, they vary considerably in key structural parameters and therefore respond differently to nonaxisymmetric perturbations. We simulate the evolution of 25 models which have different Toomre Q and Goldreich-Tremaine X parameters. Virtually all of these models form a bar, although some more quickly than others. The bar pattern speeds are ~40-50 km s−1 kpc−1 at the time when they form and then decrease, presumably due to coupling of the bar with the halo. Since the Galactic bar has a pattern speed ~50 km s−1 kpc−1, we conclude that it must have formed recently.

Subfields: Astronomy and Astrophysics, Instrumentation, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/21504b8f2d17c373c8c83351c81ac1eda1e4ba28

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Citations in the corpus

ON THE SHOULDERS OF GIANTS: PROPERTIES OF THE STELLAR HALO AND THE MILKY WAY MASS DISTRIBUTION (2014, methodology): “Here we use the terminal velocity curves from Malhotra (1994, 1995), as done e.g. in Dehnen & Binney (1998); Widrow et al. (2008); McMillan (2011).”
IMPROVED ESTIMATES OF THE MILKY WAY’S STELLAR MASS AND STAR FORMATION RATE FROM HIERARCHICAL BAYESIAN META-ANALYSIS (2014, result): “We have also tested the impact that the Bissantz & Gerhard (2002) and Widrow et al. (2008) MB⋆ estimates make on our final results, as these two measurements are more strongly peaked than the other estimates and are centered at similar bulge mass values (see Figure 7).”
emcee: The MCMC Hammer (2012, methodology): “As a result, many heuristic methods have been developed to attempt to determine the optimal parameters in a data-driven way (for example, Gregory 2005; Dunkley et al. 2005; Widrow et al. 2008).”
THE END OF THE MACHO ERA, REVISITED: NEW LIMITS ON MACHO MASSES FROM HALO WIDE BINARIES (2014, background): “It also grees with the value obtained by Widrow et al. (2008).”
Phantom: A Smoothed Particle Hydrodynamics and Magnetohydrodynamics Code for Astrophysics (2017, methodology): “To create a Milky Way-like galaxy, we used GalactICs (Kuijken & Dubinski, 1995b; Widrow & Dubinski, 2005; Widrow et al., 2008) to first create a galaxy con- sisting of a stellar bulge, stellar disc and a dark matter halo.”
CONSTRAINING THE MILKY WAY POTENTIAL WITH A SIX-DIMENSIONAL PHASE-SPACE MAP OF THE GD-1 STELLAR STREAM (2009, background): “We suggest that any attempt to fit the Galactic potential(such as Widrow et al. 2008) now should not ignore the dataset on GD-1 and should incorporate it into their fits.”
Galaxy Masses: A Review (2013, methodology): “Modulo model uncertainties as detailed in the following sections, convergence to the right M∗/L value may be achieved (as shown by Zibetti et al. (2009) or by Maraston et al.”
A novel determination of the local dark matter density (2009, unknown): “We overcome here this difficulty implementing instead a Bayesian approach to the parameter estimation (see also [16]), analogously to what is commonly done to estimate cosmological parameters, and also to some recent studies of supersymmetric models in a dark matter contest, see, e.”
Mass models of the Milky Way (2011, result): “This is significantly larger than most of the values found by DB98, and comparable to the bulge masses found by Widrow et al. (2008).”