Astronomical instrumentation

Abstract:

In 1969, Donald Lynden-Bell became the first astrophysicist to suggest that supermassive black holes in the cores of galaxies might generate the profuse energy put out by quasars — the astonishingly luminous distant bodies identified by astronomer Maarten Schmidt earlier that decade. Lynden-Bell proposed that quasars are powered by the release of gravitational energy as material falls into the deep potential well of the black hole, a process that is much more efficient than thermonuclear fusion

Abstract:

We present detailed simulations of integral field spectroscopic observations of a supernova in a host galaxy at z ∼ 3, as observed by the HARMONI spectrograph on the Extremely Large Telescope, asssisted by laser tomographic adaptive optics. The goal of the simulations, using the HSIM simulation tool, is to determine whether HARMONI can discern the supernova Type from spectral features in the supernova spectrum. We find that in a 3 hour observation, covering the near-infrared H and K bands, at a spectral resolving power of ∼3000, and using the 20×20 mas spaxel scale, we can classify supernova Type Ia and their redshift robustly up to 80 days past maximum light (20 days in the supernova rest frame). We show that HARMONI will provide spectra at z ∼ 3 that are of comparable (or better) quality to the best spectra we can currently obtain at z ∼ 1, thus allowing studies of cosmic expansion rates to be pushed to substantially higher redshifts.

Abstract:

We present a polarisation map of the warm dust emission from the minispiral in the central parsec of the Galactic centre. The observations were made at a wavelength of 12.5 μm with CanariCam mounted on the 10.4-m Gran Telescopio Canarias. The magnetic field traced by the polarised emission from aligned dust grains is consistent with previous observations, but the increased resolution of the present data reveals considerably more information on the detailed structure of the B field and its correspondence with the filamentary emission seen in both mid-infrared continuum emission and free-free emission at cm wavelengths. The magnetic field appears to be compressed and pushed by the outflows from luminous stars in the Northern Arm, but it is not disordered by them. We identify some magnetically coherent filaments that cross the Northern Arm at a Position Angle of ∼45o, and which may trace orbits inclined to the primary orientation of the Northern Arm and circumnuclear disk. In the East-West bar, the magnetic fields implied by the polarization in the lower intensity regions lie predominantly along the bar at a Position Angle of 130 − 140o. In contrast to the Northern Arm, the brighter regions of the bar tend to have lower degrees of polarization with a greater divergence in position angle compared to the local diffuse emission. It appears that the diffuse emission in the East-West bar traces the underlying field and that the bright compact sources are unrelated objects presumably projected onto the bar and with different field orientations.