12 research outputs found
The role of baryons in self-interacting dark matter mergers
Mergers of galaxy clusters are promising probes of dark matter (DM) physics.
For example, an offset between the DM component and the galaxy distribution can
constrain DM self-interactions. We investigate the role of the intracluster
medium (ICM) and its influence on DM-galaxy offsets in self-interacting dark
matter (SIDM) models. To this end, we employ Smoothed Particle Hydrodynamics +
N-body simulations to study idealised setups of equal- and unequal-mass mergers
with head-on collisions. Our simulations show that the ICM hardly affects the
offsets arising shortly after the first pericentre passage compared to DM-only
(DMO) simulations. But later on, e.g. at the first apocentre, the offsets can
be amplified by the presence of the ICM. Furthermore, we find that
cross-sections small enough not to be excluded by measurements of the core
sizes of relaxed galaxy clusters have a chance to produce observable offsets.
We found that different DM models affect the DM distribution and also the
galaxy and and ICM distribution, including its temperature. Potentially, the
position of the shock fronts, combined with the brightest cluster galaxies
(BCGs), provides further clues to the properties of DM. Overall our results
demonstrate that mergers of galaxy clusters at stages about the first apocentre
passage could be more interesting in terms of DM physics than those shortly
after the first pericentre passage. This may motivate further studies of
mergers at later evolutionary stages.Comment: 14 pages, 10 figures + appendices, submitted to MNRA
Cognitive Function Is Impaired in Patients with Recently Diagnosed Type 2 Diabetes, but Not Type 1 Diabetes
Objective. To test whether cognitive function is impaired in early states of diabetes and to identify possible risk factors for cognitive impairment. Methods. A cross-sectional analysis within the German Diabetes Study included patients with type 1 or type 2 diabetes within the first year after diagnosis or five years after study inclusion and metabolically healthy individuals. Participants underwent comprehensive metabolic phenotyping and testing of different domains of cognitive function. Linear regression models were used to compare cognition test outcomes and to test associations between cognitive function and possible influencing factors within the groups. Results. In participants with recently diagnosed diabetes, verbal memory was poorer in patients with type 2 diabetes (P=0.029), but not in type 1 diabetes (P=0.156), when compared to healthy individuals. Five years after diagnosis, type 2 diabetes patients also showed lower verbal memory than those with type 1 diabetes (P=0.012). In addition to crystallized intelligence, a higher body mass index among individuals with recently diagnosed type 2 diabetes and male sex among individuals with recently diagnosed type 1 diabetes were associated with impaired verbal memory (all P<0.05). Conclusion. Verbal memory is impaired in individuals with recently diagnosed type 2 diabetes and likely associated with higher body mass. This trial is registered with the trial registration number NCT01055093
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The Hot and Energetic Universe: A White Paper presenting the science theme motivating the Athena+ mission
The Hot and Energetic Universe: A White Paper presenting the science theme motivating the Athena+ mission
This White Paper, submitted to the recent ESA call for science themes to define its future large missions, advocates the need for a transformational leap in our understanding of two key questions in astrophysics: 1) How does ordinary matter assemble into the large scale structures that we see today? 2) How do black holes grow and shape the Universe? Hot gas in clusters, groups and the intergalactic medium dominates the baryonic content of the local Universe. To understand the astrophysical processes responsible for the formation and assembly of these large structures, it is necessary to measure their physical properties and evolution. This requires spatially resolved X-ray spectroscopy with a factor 10 increase in both telescope throughput and spatial resolving power compared to currently planned facilities. Feedback from supermassive black holes is an essential ingredient in this process and in most galaxy evolution models, but it is not well understood. X-ray observations can uniquely reveal the mechanisms launching winds close to black holes and determine the coupling of the energy and matter flows on larger scales. Due to the effects of feedback, a complete understanding of galaxy evolution requires knowledge of the obscured growth of supermassive black holes through cosmic time, out to the redshifts where the first galaxies form. X-ray emission is the most reliable way to reveal accreting black holes, but deep survey speed must improve by a factor ~100 over current facilities to perform a full census into the early Universe. The Advanced Telescope for High Energy Astrophysics (Athena+) mission provides the necessary performance (e.g. angular resolution, spectral resolution, survey grasp) to address these questions and revolutionize our understanding of the Hot and Energetic Universe. These capabilities will also provide a powerful observatory to be used in all areas of astrophysics
The Hot and Energetic Universe: A White Paper presenting the science theme motivating the Athena+ mission
This White Paper, submitted to the recent ESA call for science themes to
define its future large missions, advocates the need for a transformational
leap in our understanding of two key questions in astrophysics: 1) How does
ordinary matter assemble into the large scale structures that we see today? 2)
How do black holes grow and shape the Universe? Hot gas in clusters, groups and
the intergalactic medium dominates the baryonic content of the local Universe.
To understand the astrophysical processes responsible for the formation and
assembly of these large structures, it is necessary to measure their physical
properties and evolution. This requires spatially resolved X-ray spectroscopy
with a factor 10 increase in both telescope throughput and spatial resolving
power compared to currently planned facilities. Feedback from supermassive
black holes is an essential ingredient in this process and in most galaxy
evolution models, but it is not well understood. X-ray observations can
uniquely reveal the mechanisms launching winds close to black holes and
determine the coupling of the energy and matter flows on larger scales. Due to
the effects of feedback, a complete understanding of galaxy evolution requires
knowledge of the obscured growth of supermassive black holes through cosmic
time, out to the redshifts where the first galaxies form. X-ray emission is the
most reliable way to reveal accreting black holes, but deep survey speed must
improve by a factor ~100 over current facilities to perform a full census into
the early Universe. The Advanced Telescope for High Energy Astrophysics
(Athena+) mission provides the necessary performance (e.g. angular resolution,
spectral resolution, survey grasp) to address these questions and revolutionize
our understanding of the Hot and Energetic Universe. These capabilities will
also provide a powerful observatory to be used in all areas of astrophysics