arXiv subjects

J. J. Bock

Publications and source records attributed to J. J. Bock.

294 records · Page 17Linked to original sources

arXiv1999

BOOMERanG: a scanning telescope for 10 arcminutes resolution CMB maps

The BOOMERanG experiment is a stratospheric balloon telescope intended to measure the Cosmic Microwave Background anisotropy at angular scales between a few degrees and ten arcminutes. The experiment features a wide focal plane with 16 detectors in the frequency bands centered at 90, 150, 220, 400 GHz, with FWHM ranging between 18 and 10 arcmin. It will be flown on a long duration (7-14 days) flight circumnavigating Antarctica at the end of 1998. The instrument was flown with a reduced focal plane (6 detectors, 90 and 150 GHz bands, 25 to 15 arcmin FWHM) on a qualification flight from Texas, in August 1997. A wide (~300 sq. deg, i.e. about 5000 independent beams at 150 GHz) sky area was mapped in the constellations of Capricornus, Aquarius, Cetus, with very low foreground contamination. The instrument was calibrated using the CMB dipole and observations of Jupiter. The LDB version of the instrument has been qualified and shipped to Antarctica.

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arXiv1999

A measurement of Omega from the North American test flight of BOOMERANG

We use the angular power spectrum of the Cosmic Microwave Background, measured during the North American test flight of the BOOMERANG experiment, to constrain the geometry of the universe. Within the class of Cold Dark Matter models, we find that the overall fractional energy density of the universe, Omega, is constrained to be 0.85 < Omega < 1.25 at the 68% confidence level. Combined with the COBE measurement and the high redshift supernovae data we obtain new constraints on the fractional matter density and the cosmological constant.

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arXiv1999

Mapping the CMB Sky: The BOOMERANG experiment

We describe the BOOMERanG experiment, a stratospheric balloon telescope intended to measure the Cosmic Microwave Background anisotropy at angular scales between a few degrees and ten arcminutes. The experiment has been optimized for a long duration (7 to 14 days) flight circumnavigating Antarctica at the end of 1998. A test flight was performed on Aug.30, 1997 in Texas. The level of performance achieved in the test flight was satisfactory and compatible with the requirements for the long duration flight.

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arXiv1999

Measurement of a Peak in the Cosmic Microwave Background Power Spectrum from the North American test flight of BOOMERANG

We describe a measurement of the angular power spectrum of anisotropies in the Cosmic Microwave Background (CMB) from 0.3 degrees to ~10 degrees from the North American test flight of the BOOMERANG experiment. BOOMERANG is a balloon-borne telescope with a bolometric receiver designed to map CMB anisotropies on a Long Duration Balloon flight. During a 6-hour test flight of a prototype system in 1997, we mapped > 200 square degrees at high galactic latitudes in two bands centered at 90 and 150 GHz with a resolution of 26 and 16.6 arcmin FWHM respectively. Analysis of the maps gives a power spectrum with a peak at angular scales of ~1 degree with an amplitude ~70 uK.

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arXiv1998

First measurement of the submillimetre Sunyaev-Zel'dovich effect

We report the first detection of the Sunyaev-Zel'dovich increment on the cosmic microwave background (CMB) at submillimetre wavelengths in the direction of a cluster of galaxies.It was achieved towards the rich cluster Abell 2163, using the PRONAOS 2-metre stratospheric telescope. Together with data from the SuZIE, Diabolo, and ISO-PHT experiments, these measurements, for the first time, give a complete picture of the far-infrared to millimetre spectral energy distribution of the diffuse emission toward a cluster of galaxies. It clearly shows the positive and negative parts of the S.Z. effect and also a positive signal at short wavelengths that can be attributed to foreground dust in our galaxy.

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arXiv1998

High Resolution Mid-Infrared Imaging of the Nucleus of NGC 1068

We have obtained mid-infrared images of the nucleus of NGC 1068 from the Hale 5 m telescope at Mt. Palomar with diffraction-limited resolution and high sensitivity at 8.8, 10.3, and 12.5 microns. Deconvolved images show that the infrared emission extends north to south in the inner 2", consisting of a central peak, a component extending 1" north of the central source, a component extending 1" south of the central source, and several smaller structures located 1" to the northeast. The central peak is extended 0.4" N-S and unresolved (<= 0.2") E-W. We find that 50 +/- 5% of the flux emerges from the central 0.4" and that a single unresolved point source can account for only 27 +/- 5% of the total flux. However, if the central peak arises from optically thick emission, we estimate that the emitting region has a projected area >= 2 pc^2, and may thus contain a compact source such as a parsec-scale torus. We observe a correspondence between the northern extension and the northeastern sources appearing on the mid-infrared images and the [OIII] clouds A-C & E. We interpret the faint optical counterpart to the mid-infrared southern extension as being due to partial obscuration by the intervening disk of the host galaxy. The N-S extension of the mid-infrared emission coincides with one wall of the conical narrow line region and aligns with the N-S orientation of the radio jet close to the nucleus. We interpret the infrared emission as arising from optically thick dust lining the walls of the low density cavity formed by the radio jet and heated by radiation from the central source.

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