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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A new observable of the large-scale structure: the position-dependent two-point correlation function

June 01, 2015
Observations of the large-scale structure, such as galaxy surveys, are one of the most important tools to study our universe. In particular, how the growth of structure is affected by the large-scale environment can be used to test our understanding of gravity, as well as the physics of inflation. A research group at MPA has recently developed a new technique to extract this signal more efficiently from real observations. Specifically, we divide a galaxy survey into sub-volumes, quantify the structure and the environment in each sub-volume, and measure the correlation between these two quantities. This technique thus opens a new avenue to critically test fundamental physics from real observations. [more]
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Understanding X-ray emission from galaxies and galaxy clusters

May 01, 2015
By combining data for more than 250,000 individual objects, an MPA-based team has for the first time been able to measure X-ray emission in a uniform manner for objects with masses ranging from that of the Milky Way up to that of rich galaxy clusters. The results are surprisingly simple and give insight into how ordinary matter is distributed in today's universe, and how this distribution has been affected by energy input from galactic nuclei. [more]
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Computer simulation confirms supernova mechanism in three dimensions

April 01, 2015
Massive stars explode as supernovae at the end of their lives, but how exactly does the explosion begin and what is the role of different physical processes? For the first time, scientists at the Max Planck Institute for Astrophysics have been able to simulate such a stellar explosion in all three dimensions with detailed physical input. The results show that the energetic neutrinos radiated by the newly formed neutron star indeed trigger the explosion by heating the stellar matter. Turbulent flows support this process and lead to an even more energetic explosion. [more]
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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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