The Origin of C IV Absorption Systems at Redshifts z<1---Discovery of Extended C IV Envelopes Around Galaxies

(Abridged) We report the discovery of extended CIV gaseous envelopes around galaxies of a wide range of luminosity and morphological type. First, we show that CIV absorption systems are strongly clustered around galaxies on velocity scales of v < 250 km/s and impact parameter scales of rho < 100 h^{-1} kpc but not on larger velocity or impact parameter scales. Next, adopting measurements of galaxy properties presented in previous papers, we examine how properties of the CIV absorption systems depend on properties of the galaxies. On the basis of 14 galaxy and absorber pairs and 36 galaxies that do not produce corresponding CIV absorption lines to within sensitive upper limits, we find that: (1) Galaxies of a range of morphological type and luminosity appear to possess extended CIV gaseous envelopes of radius R ~ 100 h^{-1} kpc, with abrupt boundaries between the CIV absorbing and non-absorbing regions. (2) The extent of CIV-absorbing gas around galaxies scales with galaxy B-band luminosity as R \propto L_B^{0.5 +/- 0.1} but does not depend strongly on galaxy surface brightness, redshift, or morphological type. And (3) the covering factor of CIV clouds within ~ 100 h^{-1} kpc of galaxies is nearly unity, but there is a large scatter in the mean number of clouds encountered along the line of sight. The most significant implication of the study is that galaxies of a wide range of luminosity and morphological type are surrounded by chemically enriched gas that extends for at least ~ 100 h^{-1} kpc. We consider various scenarios that may have produced metals at large galactic distance and conclude that accreting satellites are most likely to be responsible for chemically enriched gas at large galactic distances to regular looking galaxies.Comment: 19 pages, 3 figures, to appear in ApJ, July 20 200

C++ programming language for an abstract massively parallel SIMD architecture

The aim of this work is to define and implement an extended C++ language to support the SIMD programming paradigm. The C++ programming language has been extended to express all the potentiality of an abstract SIMD machine consisting of a central Control Processor and a N-dimensional toroidal array of Numeric Processors. Very few extensions have been added to the standard C++ with the goal of minimising the effort for the programmer in learning a new language and to keep very high the performance of the compiled code. The proposed language has been implemented as a porting of the GNU C++ Compiler on a SIMD supercomputer.Comment: 10 page

Protostellar accretion traced with chemistry. High resolution C18O and continuum observations towards deeply embedded protostars in Perseus

Context: Understanding how accretion proceeds is a key question of star formation, with important implications for both the physical and chemical evolution of young stellar objects. In particular, very little is known about the accretion variability in the earliest stages of star formation. Aims: To characterise protostellar accretion histories towards individual sources by utilising sublimation and freeze-out chemistry of CO. Methods: A sample of 24 embedded protostars are observed with the Submillimeter Array (SMA) in context of the large program "Mass Assembly of Stellar Systems and their Evolution with the SMA" (MASSES). The size of the C$^{18}$O emitting region, where CO has sublimated into the gas-phase, is measured towards each source and compared to the expected size of the region given the current luminosity. The SMA observations also include 1.3 mm continuum data, which are used to investigate whether a link can be established between accretion bursts and massive circumstellar disks. Results: Depending on the adopted sublimation temperature of the CO ice, between 20% and 50% of the sources in the sample show extended C$^{18}$O emission indicating that the gas was warm enough in the past that CO sublimated and is currently in the process of refreezing; something which we attribute to a recent accretion burst. Given the fraction of sources with extended C$^{18}$O emission, we estimate an average interval between bursts of 20000-50000 yr, which is consistent with previous estimates. No clear link can be established between the presence of circumstellar disks and accretion bursts, however the three closest known binaries in the sample (projected separations <20 AU) all show evidence of a past accretion burst, indicating that close binary interactions may also play a role in inducing accretion variability.Comment: Accepted for publication in A&A, 21 pages, 13 figure

An acidic region of the 89K murine cytomegalovirus immediate early protein interacts with DNA

The product of the ie 1 gene, the regulatory immediate early protein pp89 of murine cytomegalovirus (MCMV), interacts with core histones, which can mediate the association of pp89 with DNA. We report the capacity of pp89 to interact directly with DNA in the absence of cellular proteins. After separation of proteins by SDS–PAGe, pp89 bound ds- and ssDNA, with a preference for ssDNA. Binding to specific DNA sequences in the MCMV genome was not detected. The DNA-binding region of pp89 was located to amino acids 438 to 534 by analysis of deletion mutants expressed as -galactosidase or TrpE fusion proteins. This region is identical to the highly acidic C-terminal region spanning amino acids 424 to 532. The human cytomegalovirus IE1 protein, which contains a similar extended C-terminal acidic region, does not react with DNA under the same experimental conditions

Extended [C I] and ^{13}CO(5-4) Emission in M17SW

We mapped a 13 by 22 pc region in emission from 492 GHz [C I] and, for the first time, 551 GHz ^{13}CO(5-4) in the giant molecular cloud M17SW, using the Submillimeter Wave Astronomy Satellite. The morphologies of the [C I] and ^{13}CO emission are strikingly similar. The extent and intensity of the [C I] and ^{13}CO(5-4) emission is explained as arising from photodissociation regions on the surfaces of embedded molecular clumps. Modeling of the ^{13}CO(5-4) emission in comparison to ^{13}CO(1-0) indicates a temperature gradient across the cloud, peaking to at least 63 K near the M17 ionization front and decreasing to at least 20 K at the western edge of the cloud. We see no correlation between gas density and column density. The beam-averaged column density of C I in the core is 1x10^{18} cm^-2, and the mean column density ratio N(C I)/N(CO) is about 0.4. The variations of N(C I)/N(CO) with position in M17SW indicate a similar clump size distribution throughout the cloud.Comment: 5 pages, 3 Postscript figures, uses aastex.cls, emulateapj5.sty (included), and apjfonts.sty (included

Interference Potential of FSS and BWA on the Extended C-Band

The Indonesian government has allocated the 3.3-3.4 GHz band, which is adjacent to the extended C-band 3.4-3.7 GHz, for Broadband Wireless Access (BWA) services. The country has been using the extended C-band for Fixed Satellite Service (FSS). This research shows the interference potential between the two systems if an adjacent band is allocated for them. Using a clutter loss of 10 dB and site shielding of 40 dB, a BWA network consisting of 57 base-stations will potentially intefere an FSS with probability 56.16% if the protection distance used is 1.55 km. The interference potential will decrease to 0% if the protection distance is increased to 3 km. With a BWA network consisting of 20 base-stations, the interference probability is 10.72% and 0% for a protection distance of 1.55 km and 2 km, respectively.  With this interference potential it is urgent that Indonesia enforces interference mitigation techniques to protect FSS from disruptive interference

ALMA Detection of Extended [C II] Emission in Himiko at z = 6.6

Himiko is one of the most luminous Ly{\alpha} emitters at z = 6.595. It has three star forming clumps detected in the rest-frame UV, with a total SFR = 20 M$_\odot$/yr. We report the ALMA detection of the [CII]158$\mu$m line emission in this galaxy with a significance of 9$\sigma$. The total [CII] luminosity (L[CII]= (1.2$\pm$0.2)$\times$10$^{8}$ L$_{\odot}$) is fully consistent with the local L[CII]-SFR relation. The ALMA high-angular resolution reveals that the [CII] emission is made of two distinct components. The brightest [CII] clump is extended over 4 kpc and is located on the peak of the Ly{\alpha} nebula, which is spatially offset by 1 kpc relative to the brightest UV clump. The second [CII] component is spatially unresolved (size $<$2 kpc) and coincident with one of the three UV clumps. While the latter component is consitent with the local L[CII]-SFR relation, the other components are scattered above and below the local relation. We shortly discuss the possible origin of the [CII] components and their relation with the star forming clumps traced by the UV emission