Research Highlights

On this page you can find a monthly updated list of short articles highlighting current MPA research topics.

Current Research Highlights

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Measuring gas velocities in galaxy clusters with X-ray images

March 01, 2015
X-ray observations provide us with detailed information on the density and temperature of the hot gas inside galaxy clusters. The other major gas characteristic that still needs to be measured is the gas velocity. While current generation X-ray observatories lack the required energy resolution to measure velocities directly, future observatories such as ASTRO-H and ATHENA will address this limitation. An international team including MPA scientists has shown that the power spectrum of the velocity field can inferred indirectly from existing X-ray images of relaxed clusters. Numerical simulations confirm this simple theoretical idea, opening a way of probing gas velocities using already existing X-ray data. [more]
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Galactic anatomy with gamma rays

February 01, 2015
The anatomy of the Milky Way as seen in gamma light is full of mysteries. For example, there are gigantic bubbles of unknown origin above and below the center of the Milky Way that emit a lot of this high-energy radiation. A new method for imaging, developed at the Max Planck Institute for Astrophysics, now divided the Galactic gamma-radiation into three fundamental components: radiation from point sources, radiation from reactions of energetic protons with dense cold gas clouds, and radiation from electrons scattering light in the thin, hot, Galactic gas. The anatomic insights gained unravel some Galactic mysteries. Thus, it appears that the gamma-ray bubbles are simply outflows of ordinary, hot gas from the central region of the Milky Way. [more]
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Starburst cycles in galaxies

January 01, 2015
While it is well known that galaxies reside in halos of dark matter, there has been disagreement about the detailed distribution of dark matter between cosmological simulations and observations: the so-called "cuspy halo problem". Astrophysicists at the MPA have now used spectral features in a number of SDSS galaxies to show that strong starbursts occur frequently enough in low mass galaxies flatten the inner mass profiles of these systems, explaining why the theoretically predicted "cusps" are not observed. [more]
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A new standard ruler: Measuring angular diameter distances using time-delay strong lenses

December 01, 2014
Since the discovery of the expansion of the universe in 1929, measuring cosmological distances has played a fundamental role in testing the cosmological models. Scientists at MPA now propose a crucially improved ruler method in addition to the well-known standard candle and standard ruler methods, which use the known luminosity or the known size of an object, respectively. For their method, they use a strong gravitational lens system with a time-varying source (e.g. a quasar) to measure the angular diameter distance to the lens. This method opens a new avenue to chart our universe and to understand the origin of the acceleration of the universe. [more]
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Stars influence the central distribution of dark matter in galaxy clusters

November 01, 2014
Dark matter is at the centre of our understanding of the physics of the early Universe, of cosmic large-scale structure and of galaxy formation. In its simplest form, "cold dark matter" consists of non-relativistic weakly interacting particles of a kind not included in the standard model of particle physics. On astrophysical scales the dark matter only interacts with baryons (ordinary matter) through the force of gravity. Because of the simple physics this entails, its dynamics and clustering can be followed through N-body simulations. Recently, scientists at the MPA have performed cosmological N-body simulations showing that the mergers of galaxies (containing both stars and dark matter) at the centre of galaxy clusters can alter the central distribution of dark matter in a way that alleviates recent discrepancies found between observations and simulations. [more]
 
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