We present the details and early results from a deep near-infrared survey utilizing the NICMOS instrument on the Hubble Space Telescope centred around massive M * > 10 11 M galaxies at 1.7 < z < 2.9 found within the Great Observatories Origins Deep Survey (GOODS) fields North and South. The GOODS NICMOS Survey (GNS) was designed to obtain deep F160W (H-band) imaging of 80 of these massive galaxies and other colour-selected objects such as Lyman-break dropouts, BzK objects, distant red galaxies (DRGs), extremely red objects (EROs), Spitzer-selected EROs, BX/BM galaxies, as well as flux-selected submillimetre galaxies. We present in this paper details of the observations, our sample selection, as well as a description of the properties of the massive galaxies found within our survey fields. This includes photometric redshifts, rest-frame colours and stellar masses. We furthermore provide an analysis of the selection methods for finding massive galaxies at high redshifts, including colour-selection methods and how galaxy populations selected through these colour methods overlap. We find that a single colour selection method cannot locate all of the massive galaxies,
Abstract.We have conducted a search for "dust chimneys" in a sample of 10 highly-inclined spiral galaxies (i = 86 − 90• ) which we had previously observed in the Hα emission line (Rand 1996). We have procured B-band CCD images for this purpose and employed unsharp-masking techniques to accentuate the structure of the dust lane. A scattering+absorption radiation transfer model enabled us to separate 5 galaxies from the sample which are sufficiently inclined (i > 87• ) for us to reliably identify and quantify dust clouds residing at over 2 scale-heights above the disk. Three of these galaxies possess numerous curvi-linear chimney structures stretching up to 2 kpc from the midplane and the fraction of total galactic dust contained in such structures is of order 1%. Optical extinction offers a lower limit to the amount of dust contained in the extraplanar layer but, by examining the transparent submm thermal emission from NGC 891, we fix an upper limit of 5%. Our results are consistent with a similar recent study by Howk & Savage (1999) which indicates that about half of quiescent spiral disks possess detectable dust chimneys.We have compared our optical images with the corresponding Hα emission-line radiation. We do not find a detailed spatial correspondance between dust chimneys and either sites of recent star-formation or the extraplanar diffuse ionized gas. This is somewhat surprising given that FIR-bright galaxies, such as M 82, are known to entrain dust at the working surface of the starburst-driven outflow (traced in Hα). It is possible a global correlation exists, with disks experiencing overall higher rates of starformation also possessing the greatest number of chimneys. This may indicate a timescale difference between the two phenomena with the Hα phase lasting ∼ 10 6 yr but chimneys requiring ∼ 10 7 yr to form. Additionally, we have investigated the edge-on disk NGC 55 which, being ten times closer than galaxies in Send offprint requests to: P.B. Alton, e-mail: paul.alton@astro.cf.ac.uk our main sample, allows us to examine in greater spatial detail the relationship between chimneys and recent starformation. Our discussion touches upon high latitude dust and supershells observed in the Milky Way. We rule out quiescent disks as prolific sources of intergalactic grains and metals but note that the rate at which dust is expelled from the main dust layer is comparable to the rate at which it is produced by disk stars (suggesting that it may be an important regulatory process).
We present an interferometric technique for the reconstruction of ultra-wide band impulsive signals from point sources. This highly sensitive method was developed for the search for ultrahigh energy neutrinos with the ANITA experiment but is fully generalizable to any antenna array detecting radio impulsive events. Applications of the interferometric method include event reconstruction, thermal noise and anthropogenic background rejection, and solar imaging for calibrations. We illustrate this technique with applications from the analysis of the ANITA-I and ANITA-II data in the 200-1200 MHz band.
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