2,914 research outputs found
J06587-5558 -- A Very Unusual Polarised Radio Source
We have found a peculiar radio source in the field of one of the hottest
known clusters of galaxies 1E0657-56. It is slightly extended, highly polarised
(54% at 8.8GHz) and has a very steep spectrum, with alpha ~ -1 at 1.3 GHz,
steepening to ~ -1.5 at 8.8GHz (S \propto nu^alpha). No extragalactic sources
are known with such high integrated polarisation, and sources with spectra as
steep as this are rare. In this paper, we report the unusual properties of the
source J06587-5558 and speculate on its origin and optical identification.Comment: 5 pages, 6 figures, accepted by MNRAS letter
Development of dispersion strengthened chromium alloys Summary report
Dispersion strengthened chromium alloys with minimal quantities of interstitial impuritie
Obtaining Highway Engineering Services from Professional Engineers in Private Practice
Current state highway department procedures for obtaining private professional engineering services are reviewed and summarized as part of a study of the consulting engineering contracting policy and procedures of the Kentucky Department of Highways. The current bases used by state highway departments for establishment of fees for the professional services of Engineering Consultants, Attorneys, Right-of-Way Appraisers, Right-of-Way Buyers, and Architects are summarized, by state, in Table 1. In general, the consulting engineering contracting practices followed in Kentucky were found to be a combination of the most desirable points of procedure represented in the replies received from other state highway departments and recommended by the Bureau of Public Roads and the professional societies. The recommendations include a Statement of Consulting Engineering Contracting Policy and Procedures which, except for noted revisions, is a restatement of Kentucky Department of Highways Official Order No. 73646, Consulting Engineering Contract Procedures, dated March 2, 1965
Do Quasars Lens Quasars?
If the unexpectedly high frequency of quasar pairs with very different
component redshifts is due to the lensing of a population of background quasars
by the foreground quasar, typical lens masses must be \sim10^{12}M_{\sun} and
the sum of all such quasar lenses would have to contain times the
closure density of the Universe. It then seems plausible that a very high
fraction of all \sim10^{12} M_{\sun} gravitational lenses with redshifts
contain quasars. Here I propose that these systems have evolved to
form the present population of massive galaxies with M and M
>5\times10^{11} M_{\sun}.Comment: 6 pages, aas style, ams symbols, ApJL (accepted
Paul Grady and his contributions to accounting and auditing
Paul Franklin Grady (1900-1984) was one of those leaders whose contributions to accounting will remain the subject of intensive study for future guidance. The purpose of this paper is to examine Paul Grady\u27s significant contributions to accounting and auditing and to take the reader into Grady\u27s mind as he was writing his most influential works. Grady strongly believed that in order for accounting to gain respect in society, it must be based on solid principles. His works showed this conviction
Cosmic 21-cm Delensing of Microwave Background Polarization and the Minimum Detectable Energy Scale of Inflation
The curl (B) modes of cosmic microwave background (CMB) polarization
anisotropies are a unique probe of the primordial background of inflationary
gravitational waves (IGWs). Unfortunately, the B-mode polarization anisotropies
generated by gravitational waves at recombination are confused with those
generated by the mixing of gradient-mode (E-mode) and B-mode polarization
anisotropies as CMB photons propagate through the Universe and are
gravitationally lensed. We describe here a method for delensing CMB
polarization anisotropies using observations of anisotropies in the cosmic
21-cm radiation emitted or absorbed by neutral hydrogen atoms at redshifts 10
to 200. While the detection of cosmic 21-cm anisotropies at high resolution is
challenging, a combined study with a relatively low-resolution (but
high-sensitivity) CMB polarization experiment could probe inflationary energy
scales well below the Grand Unified Theory (GUT) scale of 10^{16} GeV --
constraining models with energy scales below 10^{15} GeV (the detectable limit
derived from CMB observations alone). The ultimate theoretical limit to the
detectable inflationary energy scale via this method may be as low as 3 \times
10^{14} GeV.Comment: 4 pages, 2 figures, submitted to Phys. Rev. Let
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