Otto H. Bauer

Bio: Otto H. Bauer is an academic researcher from Max Planck Society. The author has contributed to research in topics: Spectrometer & Solar wind. The author has an hindex of 26, co-authored 67 publications receiving 4288 citations.

The Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory

Abstract: The Photodetector Array Camera and Spectrometer (PACS) is one of the three science instruments on ESA's far infrared and submil- limetre observatory. It employs two Ge:Ga photoconductor arrays (stressed and unstressed) with 16 × 25 pixels, each, and two filled silicon bolometer arrays with 16 × 32 and 32 × 64 pixels, respectively, to perform integral-field spectroscopy and imaging photom- etry in the 60−210 μm wavelength regime. In photometry mode, it simultaneously images two bands, 60−85 μ mo r 85−125 μ ma nd 125−210 μm, over a field of view of ∼1.75 � × 3.5 � , with close to Nyquist beam sampling in each band. In spectroscopy mode, it images afi eld of 47 �� × 47 �� , resolved into 5 × 5 pixels, with an instantaneous spectral coverage of ∼ 1500 km s −1 and a spectral resolution of ∼175 km s −1 . We summarise the design of the instrument, describe observing modes, calibration, and data analysis methods, and present our current assessment of the in-orbit performance of the instrument based on the performance verification tests. PACS is fully operational, and the achieved performance is close to or better than the pre-launch predictions.

Dissecting the cosmic infra-red background with Herschel/PEP

Abstract: The constituents of the cosmic IR background (CIB) are studied at its peak wavelengths (100 and 160 μ m) by exploiting Herschel /PACS observations of the GOODS-N, Lockman Hole, and COSMOS fields in the PACS evolutionary probe (PEP) guaranteed-time survey. The GOODS-N data reach 3σ depths of ~3.0 mJy at 100 μ m and ~5.7 mJy at 160 μ m. At these levels, source densities are 40 and 18 beams/source, respectively, thus hitting the confusion limit at 160 μ m. Differential number counts extend from a few mJy up to 100-200 mJy, and are approximated as a double power law, with the break lying between 5 and 10 mJy. The available ancillary information allows us to split number counts into redshift bins. At z ≤ 0.5 we isolate a class of luminous sources (L IR ~ 1011 ), whose SEDs resemble late-spiral galaxies, peaking at ~130 μ m restframe and significantly colder than what is expected on the basis of pre-Herschel models. By integrating number counts over the whole covered flux range, we obtain a surface brightness of 6.36± 1.67 and 6.58± 1.62 [ nW m-2 sr-1 ] at 100 and 160 μ m, resolving ~45% and ~52% of the CIB, respectively. When stacking 24 μ m sources, the inferred CIB lies within 1.1σ and 0.5σ from direct measurements in the two bands, and fractions increase to 50% and 75%. Most of this resolved CIB fraction was radiated at z ≤ 1.0, with 160 μ m sources found at higher redshift than 100 μ m ones.

The Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory

Abstract: The Photodetector Array Camera and Spectrometer (PACS) is one of the three science instruments on ESA's far infrared and submillimetre observatory. It employs two Ge:Ga photoconductor arrays (stressed and unstressed) with 16x25 pixels, each, and two filled silicon bolometer arrays with 16x32 and 32x64 pixels, respectively, to perform integral-field spectroscopy and imaging photometry in the 60-210\mu\ m wavelength regime. In photometry mode, it simultaneously images two bands, 60-85\mu\ m or 85-125\mu\m and 125-210\mu\ m, over a field of view of ~1.75'x3.5', with close to Nyquist beam sampling in each band. In spectroscopy mode, it images a field of 47"x47", resolved into 5x5 pixels, with an instantaneous spectral coverage of ~1500km/s and a spectral resolution of ~175km/s. We summarise the design of the instrument, describe observing modes, calibration, and data analysis methods, and present our current assessment of the in-orbit performance of the instrument based on the Performance Verification tests. PACS is fully operational, and the achieved performance is close to or better than the pre-launch predictions.

The Electron Drift Instrument on Cluster: overview of first results

Abstract: . EDI measures the drift velocity of artificially injected electron beams. From this drift velocity, the perpendicular electric field and the local magnetic field gradients can be deduced when employing different electron energies. The technique requires the injection of two electron beams at right angles to the magnetic field and the search for those directions within the plane that return the beams to their associated detectors after one or more gyrations. The drift velocity is then derived from the directions of the two beams and/or from the difference in their times-of-flight, measured via amplitude-modulation and coding of the emitted electron beams and correlation with the signal from the returning electrons. After careful adjustment of the control parameters, the beam recognition algorithms, and the onboard magnetometer calibrations during the commissioning phase, EDI is providing excellent data over a wide range of conditions. In this paper, we present first results in a variety of regions ranging from the polar cap, across the magnetopause, and well into the magnetosheath. Key words. Electron drift velocity (electric fields; plasma convection; instruments and techniques)

Dissecting the cosmic infra-red background with Herschel/PEP

Abstract: The constituents of the cosmic IR background (CIB) are studied at its peak wavelengths (100 and 160 um) by exploiting Herschel/PACS observations of the GOODS-N, Lockman Hole, and COSMOS fields in the PACS Evolutionary Probe (PEP) guaranteed-time survey. The GOODS-N data reach 3 sigma depths of ~3.0 mJy at 100 um and ~5.7 mJy at 160 um. At these levels, source densities are 40 and 18 beams/source, respectively, thus hitting the confusion limit at 160 um. Differential number counts extend from a few mJy up to 100-200 mJy, and are approximated as a double power law, with the break lying between 5 and 10 mJy. The available ancillary information allows us to split number counts into redshift bins. At z<=0.5 we isolate a class of luminous sources (L(IR)~1e11 Lsun), whose SEDs resemble late-spiral galaxies, peaking at ~130 um restframe and significantly colder than what is expected on the basis of pre-Herschel models. By integrating number counts over the whole covered flux range, we obtain a surface brightness of 6.36 +/- 1.67 and 6.58 +/-1.62 [nW m^-2 sr^-1] at 100 and 160 um, resolving ~45% and ~52% of the CIB, respectively. When stacking 24 um sources, the inferred CIB lies within 1.1 sigma and 0.5 sigma from direct measurements in the two bands, and fractions increase to 50% and 75%.Most of this resolved CIB fraction was radiated at z<=1.0, with 160 um sources found at higher redshift than 100 um ones.

Herschel Space Observatory - An ESA facility for far-infrared and submillimetre astronomy

Abstract: Herschel was launched on 14 May 2009, and is now an operational ESA space observatory o ering unprecedented observational capabilities in the far-infrared and submillimetre spectral range 55 671 m. Herschel carries a 3.5 metre diameter passively cooled Cassegrain telescope, which is the largest of its kind and utilises a novel silicon carbide technology. The science payload comprises three instruments: two direct detection cameras/medium resolution spectrometers, PACS and SPIRE, and a very high-resolution heterodyne spectrometer, HIFI, whose focal plane units are housed inside a superfluid helium cryostat. Herschel is an observatory facility operated in partnership among ESA, the instrument consortia, and NASA. The mission lifetime is determined by the cryostat hold time. Nominally approximately 20,000 hours will be available for astronomy, 32% is guaranteed time and the remainder is open to the worldwide general astronomical community through a standard competitive proposal procedure.

The Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory

Abstract: The Photodetector Array Camera and Spectrometer (PACS) is one of the three science instruments on ESA's far infrared and submil- limetre observatory. It employs two Ge:Ga photoconductor arrays (stressed and unstressed) with 16 × 25 pixels, each, and two filled silicon bolometer arrays with 16 × 32 and 32 × 64 pixels, respectively, to perform integral-field spectroscopy and imaging photom- etry in the 60−210 μm wavelength regime. In photometry mode, it simultaneously images two bands, 60−85 μ mo r 85−125 μ ma nd 125−210 μm, over a field of view of ∼1.75 � × 3.5 � , with close to Nyquist beam sampling in each band. In spectroscopy mode, it images afi eld of 47 �� × 47 �� , resolved into 5 × 5 pixels, with an instantaneous spectral coverage of ∼ 1500 km s −1 and a spectral resolution of ∼175 km s −1 . We summarise the design of the instrument, describe observing modes, calibration, and data analysis methods, and present our current assessment of the in-orbit performance of the instrument based on the performance verification tests. PACS is fully operational, and the achieved performance is close to or better than the pre-launch predictions.

Star Formation in the Milky Way and Nearby Galaxies

Abstract: We review progress over the past decade in observations of large-scale star formation, with a focus on the interface between extragalactic and Galactic studies. Methods of measuring gas contents and star-formation rates are discussed, and updated prescriptions for calculating star-formation rates are provided. We review relations between star formation and gas on scales ranging from entire galaxies to individual molecular clouds.

The Herschel-SPIRE instrument and its in-flight performance

Abstract: The Spectral and Photometric Imaging REceiver (SPIRE), is the Herschel Space Observatory`s submillimetre camera and spectrometer It contains a three-band imaging photometer operating at 250, 350 and 500 mu m, and an imaging Fourier-transform spectrometer (FTS) which covers simultaneously its whole operating range of 194-671 mu m (447-1550 GHz) The SPIRE detectors are arrays of feedhorn-coupled bolometers cooled to 03 K The photometer has a field of view of 4' x 8', observed simultaneously in the three spectral bands Its main operating mode is scan-mapping, whereby the field of view is scanned across the sky to achieve full spatial sampling and to cover large areas if desired The spectrometer has an approximately circular field of view with a diameter of 26' The spectral resolution can be adjusted between 12 and 25 GHz by changing the stroke length of the FTS scan mirror Its main operating mode involves a fixed telescope pointing with multiple scans of the FTS mirror to acquire spectral data For extended source measurements, multiple position offsets are implemented by means of an internal beam steering mirror to achieve the desired spatial sampling and by rastering of the telescope pointing to map areas larger than the field of view The SPIRE instrument consists of a cold focal plane unit located inside the Herschel cryostat and warm electronics units, located on the spacecraft Service Module, for instrument control and data handling Science data are transmitted to Earth with no on-board data compression, and processed by automatic pipelines to produce calibrated science products The in-flight performance of the instrument matches or exceeds predictions based on pre-launch testing and modelling: the photometer sensitivity is comparable to or slightly better than estimated pre-launch, and the spectrometer sensitivity is also better by a factor of 15-2

From filamentary clouds to prestellar cores to the stellar IMF: Initial highlights from the Herschel Gould Belt survey

Abstract: We summarize the first results from the Gould Belt survey, obtained toward the Aquila Rift and Polaris Flare regions during the 'science demonstration phase' of Herschel. Our 70-500 micron images taken in parallel mode with the SPIRE and PACS cameras reveal a wealth of filamentary structure, as well as numerous dense cores embedded in the filaments. Between ~ 350 and 500 prestellar cores and ~ 45-60 Class 0 protostars can be identified in the Aquila field, while ~ unbound starless cores and no protostars are observed in the Polaris field. The prestellar core mass function (CMF) derived for the Aquila region bears a strong resemblance to the stellar initial mass function (IMF), already confirming the close connection between the CMF and the IMF with much better statistics than earlier studies. Comparing and contrasting our Herschel results in Aquila and Polaris, we propose an observationally-driven scenario for core formation according to which complex networks of long, thin filaments form first within molecular clouds, and then the densest filaments fragment into a number of prestellar cores via gravitational instability.