The magnetic fields observed in the Milky Way and nearby galaxies appear to be in
equipartition with the turbulent, thermal and cosmic ray energy densities, and hence are
expected to be dynamically important. However, the origin of these strong magnetic fields is
still unclear, and most previous attempts to simulate galaxy formation from cosmological
initial conditions have ignored them altogether. Here, we analyse the magnetic fields
predicted by the simulations of the Auriga Project, a set of 30 high-resolution cosmological�…

The ESA Rosetta spacecraft followed comet 67P at a close distance for more than 2 yr. In
addition, it deployed the lander Philae on to the surface of the comet. The (surface)
composition of the comet is of great interest to understand the origin and evolution of
comets. By combining measurements made on the comet itself and in the coma, we probe
the nature of this surface material and compare it to remote sensing observations. We
compare data from the double focusing mass spectrometer (DFMS) of the ROSINA�…

We collect observational evidence that supports the scheme of mass transfer on the nucleus
of comet 67P/Churyumov–Gerasimenko. The obliquity of the rotation axis of 67P causes
strong seasonal variations. During perihelion the southern hemisphere is four times more
active than the north. Northern territories are widely covered by granular material that
indicates back fall originating from the active south. Decimetre sized chunks contain water
ice and their trajectories are influenced by an antisolar force instigated by sublimation�…

We use weak-lensing shear measurements to determine the mean mass of optically
selected galaxy clusters in Dark Energy Survey Science Verification data. In a blinded
analysis, we split the sample of more than 8000 redMaPPer clusters into 15 subsets,
spanning ranges in the richness parameter 5≤ λ≤ 180 and redshift 0.2≤ z≤ 0.8, and fit the
averaged mass density contrast profiles with a model that accounts for seven distinct
sources of systematic uncertainty: shear measurement and photometric redshift errors;�…

We report on the discovery of a new fast radio burst (FRB), FRB 150215, with the Parkes
radio telescope on 2015 February 15. The burst was detected in real time with a dispersion
measure (DM) of 1105.6�0.8 pc cm− 3, a pulse duration of 2.8 ms, and a measured peak
flux density assuming that the burst was at beam centre of 0.7 Jy. The FRB originated at a
Galactic longitude and latitude of 24.66�, 5.28� and 25� away from the Galactic Center. The
burst was found to be 43�5 per cent linearly polarized with a rotation measure (RM) in the�…

As the spin axis of comet 67P/Churyumov–Gerasimenko (67P) is not normal to the orbital
plane, 67P has strong seasonal changes in the illumination conditions on the nucleus'
surface, with a short and intense summer in the Southern hemisphere. We have been
monitoring these seasonal variations in the gas coma with the Rosetta Orbiter Spectrometer
for Ion and Neutral Analysis (ROSINA) instrument suite aboard the ESA's Rosetta spacecraft.
Rosetta followed 67P from its rendezvous in 2014 August, from a distance of almost 3.5 au�…

Abstract The z= 6.6 Lyman α emitter 'CR7'has been claimed to have a Population III (Pop III)
like stellar population, or alternatively, be a candidate direct collapse black hole (DCBH). In
this paper, we investigate the evidence for these exotic scenarios using recently available,
deeper, optical, near-infrared and mid-infrared imaging. We find strong Spitzer/Infrared Array
Camera detections for the main component of CR7 at 3.6 and 4.5 μm, and show that it has a
blue colour ([3.6]−[4.5]=− 1.2�0.3). This colour cannot be reproduced by current Pop III or�…

We present a detailed study of the galaxy cluster thermal Sunyaev–Zel'dovich effect (SZE)
signal Y and pressure profiles using Magneticum Pathfinder hydrodynamical simulations.
With a sample of 50 000 galaxy clusters (M 500c> 1.4� 1014 M⊙) out to z= 2, we find
significant variations in the shape of the pressure profile with mass and redshift and present
a new generalized NFW (Navarro–Frenk–White) model that follows these trends. We show
that the thermal pressure at R 500c accounts for only 80 per cent of the pressure required to�…

The study of dust, the most abundant material in cometary nuclei, is pivotal in understanding
the original materials forming the Solar system. Measuring the coma phase function
provides a tool to investigate the nature of cometary dust. Rosetta/OSIRIS sampled the coma
phase function of comet 67P/Churyumov–Gerasimenko, covering a large phase angle range
in a small amount of time. Twelve series were acquired in the period from 2015 March to
2016 February for this scientific purpose. These data allowed, after stray light removal�…

On 2016 July 03, several instruments onboard ESA's Rosetta spacecraft detected signs of
an outburst event on comet 67P, at a heliocentric distance of 3.32 au from the Sun, outbound
from perihelion. We here report on the inferred properties of the ejected dust and the surface
change at the site of the outburst. The activity coincided with the local sunrise and continued
over a time interval of 14–68 min. It left a 10-m-sized icy patch on the surface. The ejected
material comprised refractory grains of several hundred microns in size, and sub-micron�…