Search Publications
LOFAR observations of decameter carbon radio recombination lines towards Cassiopeia A
van Weeren, R. J.; Tielens, A. G. G. M.; Röttgering, H. J. A. +6 more
We present a study of carbon radio recombination lines towards Cassiopeia A using low frequency array (LOFAR) observations in the frequency range 10-33 MHz. Individual carbon α lines are detected in absorption against the continuum at frequencies as low as 16 MHz. Stacking several Cα lines we obtain detections in the 11-16 MHz range. These are the…
Constraints on AGN feedback from its Sunyaev-Zel'dovich imprint on the cosmic background radiation
Sijacki, Debora; Efstathiou, George; Puchwein, Ewald +2 more
We derive constraints on feedback by active galactic nuclei (AGN) by setting limits on their thermal Sunyaev-Zel'dovich (SZ) imprint on the cosmic microwave background. The amplitude of any SZ signature is small and degenerate with the poorly known sub-mm spectral energy distribution of the AGN host galaxy and other unresolved dusty sources along …
Discovery of a glitch in the accretion-powered pulsar SXP 1062
Serim, M. M.; Şahiner, Ş.; ćerri-Serim, D. +2 more
We present timing analysis of the accretion-powered pulsar SXP 1062, based on the observations of Swift, XMM-Newton and Chandra satellites covering a time span of about 2 yr. We obtain a phase coherent timing solution that shows that SXP 1062 has been steadily spinning down with a rate -4.29(7) × 10-14 Hz s-1 leading to a sur…
Long-term survival of surface water ice on comet 67P
Jorda, L.; Lamy, P. L.; Lara, L. M. +53 more
Numerous water-ice-rich deposits surviving more than several months on comet 67P/Churyumov-Gerasimenko were observed during the Rosetta mission. We announce the first-time detection of water-ice features surviving up to 2 yr since their first observation via OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) NAC (narrow angle came…
Obscured active galactic nuclei triggered in compact star-forming galaxies
Juneau, Stéphanie; Capak, Peter; McCracken, H. J. +10 more
We present a structural study of 182 obscured active galactic nuclei (AGNs) at z ≤ 1.5, selected in the Cosmic Evolution Survey field from their extreme infrared to X-ray luminosity ratio and their negligible emission at optical wavelengths. We fit optical to far-infrared spectral energy distributions and analyse deep Hubble Space Telescope imagin…
The puzzling orbital period evolution of the LMXB AX J1745.6-2901
Stella, L.; Nandra, K.; Ponti, G. +2 more
The orbital period evolution of X-ray binaries provides fundamental clues to understanding mechanisms of angular momentum transfer and loss in these systems. We present an X-ray eclipse timing analysis of the transient low-mass X-ray binary AX J1745.6-2901. This system shows full eclipses and thus is one of the few objects of this class for which …
Lower hybrid waves at comet 67P/Churyumov-Gerasimenko
André, M.; Karlsson, T.; Henri, P. +9 more
We investigate the generation of waves in the lower hybrid frequency range by density gradients in the near plasma environment of comet 67P/Churyumov-Gerasimenko. When the plasma is dominated by water ions from the comet, a situation with magnetized electrons and unmagnetized ions is favourable for the generation of lower hybrid waves. These waves…
Revisiting the extremely fast disc wind in a gravitationally lensed quasar APM 08279+5255
Done, Chris; Takahashi, Tadayuki; Hagino, Kouichi +2 more
The gravitationally lensed quasar APM 08279+5255 has the fastest claimed wind from any active galactic nucleus, with velocities of 0.6-0.7c, requiring magnetic acceleration as special relativistic effects limit all radiatively driven winds to v < 0.3-0.5c. However, this extreme velocity derives from interpreting both the narrow and broad absorp…
A close encounter of the massive kind
Maíz Apellániz, J.; Sana, H.; Barbá, R. H. +2 more
We have used (I) Hubble Space Telescope Advanced Camera for Surveys imaging and Space Telescope Imaging Spectrograph spectroscopy, (II) ground-based Precision Integrated-Optics Near-infrared Imaging ExpeRiment/Very Large Telescope long-baseline interferometry, and (III) ground-based spectroscopy from different instruments to study the orbit of the…
Outbursts of the intermediate-mass black hole HLX-1: a wind-instability scenario
Soria, Roberto; Wu, Kinwah; Zampieri, Luca +5 more
We model the intermediate-mass black hole HLX-1, using the Hubble Space Telescope, XMM-Newton and Swift. We quantify the relative contributions of a bluer component, function of X-ray irradiation, and a redder component, constant and likely coming from an old stellar population. We estimate a black hole mass {≈ } (2^{+2}_{-1}) × 10^4 M_{⊙}, a spin…