Christian Henkel

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This article presents results of VLBI observations of regions of H 2 O maser activity in the Local Group galaxies M33 and IC 10. Since all position measurements were made relative to extragalactic background sources, the proper motions of the two galaxies could be measured. For M33, this provides this galaxy's three dimensional velocity, showing that this(More)
(Affiliations are available in the online edition) ABSTRACT We present a full high resolution SPIRE FTS spectrum of the nearby ultraluminous infrared galaxy Mrk 231. In total 25 lines are detected, including CO J = 5−4 through J = 13−12, 7 rotational lines of H 2 O, 3 of OH + and one line each of H 2 O + , CH + , and HF. We find that the excitation of the(More)
We measured the angular rotation and proper motion of the Triangulum Galaxy (M33) with the Very Long Baseline Array by observing two H2O masers on opposite sides of the galaxy. By comparing the angular rotation rate with the inclination and rotation speed, we obtained a distance of 730 +/- 168 kiloparsecs. This distance is consistent with the most recent(More)
We report the detection of high excitation CO emission from the most distant quasar currently known, SDSS J114816.64+525150.3 (hereafter J1148+5251), at a redshift z = 6.419. The CO (J =6→5) and (J =7→6) lines were detected using the IRAM Plateau de Bure interferometer, showing a width of ≈ 280 km s −1. An upper flux limit for the CO (J =1→0) line was(More)
Active galactic nuclei are thought to be powered by gas falling into a massive black hole; the different types of active galaxy may arise because we view them through a thick torus of molecular gas at varying angles of inclination. One way to determine whether the black hole is surrounded by a torus, which would obscure the accretion disk around the black(More)
The standard model of physics is built on the fundamental constants of nature, but it does not provide an explanation for their values, nor require their constancy over space and time. Here we set a limit on a possible cosmological variation of the proton-to-electron mass ratio μ by comparing transitions in methanol observed in the early universe with those(More)
The Standard Model of particle physics assumes that the so-called fundamental constants are universal and unchanging. Absorption lines arising in molecular clouds along quasar sightlines offer a precise test for variations in the proton-to-electron mass ratio, mu, over cosmological time and distance scales. The inversion transitions of ammonia are(More)
We analyze the spatial coherence of the electromagnetic field emitted by a half-space at temperature T close to the interface. An asymptotic analysis allows to identify three different contributions to the cross-spectral density tensor in the near-field regime. It is shown that the coherence length can be either much larger or much shorter than the(More)
We report Karl G. Jansky Very Large Array (VLA) absorption spectroscopy in four methanol (CH 3 OH) lines in the z = 0.885 82 gravitational lens towards PKS1830−211. Three of the four lines have very different sensitivity coefficients K μ to changes in the proton–electron mass ratio μ; a comparison between the line redshifts thus allows us to test for(More)