A Practical Theorem on Gravitational Wave Backgrounds

There is an extremely simple relationship between the spectrum of the gravitational wave background produced by a cosmological distribution of discrete gravitational wave sources, the total time-integrated energy spectrum of an individual source, and the present-day comoving number density of remnants. Stated in this way, the background is entirely independent of the cosmology, and only weakly dependent on the evolutionary history of the sources. This relationship allows one easily to compute the amplitude and spectrum of cosmic gravitational wave backgrounds from a broad range of astrophysical sources, and to evaluate the uncertainties therein.Comment: 7 pages, no figures, uses mn2e.cls; submitted to MNRA

Preliminary evaluation of the Environmental Research Institute of Michigan crop calendar shift algorithm for estimation of spring wheat development stage

An algorithm for estimating spectral crop calendar shifts of spring small grains was applied to 1978 spring wheat fields. The algorithm provides estimates of the date of peak spectral response by maximizing the cross correlation between a reference profile and the observed multitemporal pattern of Kauth-Thomas greenness for a field. A methodology was developed for estimation of crop development stage from the date of peak spectral response. Evaluation studies showed that the algorithm provided stable estimates with no geographical bias. Crop development stage estimates had a root mean square error near 10 days. The algorithm was recommended for comparative testing against other models which are candidates for use in AgRISTARS experiments

Large Area Crop Inventory Experiment (LACIE). Experiment plan for evaluation of LANDSAT agronomic variables using wheat intensive test sites

There are no author-identified significant results in this report

Feasibility of estimation of surface air temperature from meteorological satellite data test plan

A conceptual system designed to estimate daily surface air temperatures utilizing radiometric data obtained from polar orbiting meteorological satellites is discussed in this memorandum. The Surface Air Temperature Estimation System is an outgrowth of previous developmental and operational systems. The system represents an effort to integrate both satellite and surface meteorological observations into an operational framework which would be usable worldwide

Dynamics and Interactions of Binaries and Neutron Stars in Globular Clusters

We model the dynamics of test binaries in isotropic, multi-mass models of galactic globular clusters. The evolution of binary orbits through the cluster potentials is modeled, including second order diffusion terms, and probabilities for close encounters with field stars are calculated. We carry out Monte Carlo simulations of the effects of the binary--single star encounters on the binary population and distribution in the cluster, and estimate the collision rate for different stellar populations in globular clusters with different structural parameters. Assuming a Salpeter IMF, for low concentration clusters the core encounter rate is dominated by turnoff mass main--sequence stars and medium mass white dwarfs. For high concentration, high density clusters the encounter probabilities are increasingly dominated by neutron stars and heavy white dwarfs. Hence we predict a smaller ratio of blue stragglers and cataclysmic variables to pulsars in high concentration clusters. The total number of millisecond pulsars, and the ratio of single to binary pulsars, is broadly consistent with the observed population, suggesting the binary--single star encounters contribute significantly to the pulsar formation rate in globular clusters, for the whole range of globular cluster types. The number of millisecond pulsars and the ratio of pulsars in different globular clusters is best explained by a total binary fraction comparable to that of the galaxy, and a modest number of primordial neutron stars in the globular clusters.Comment: 59 pages, uuencoded compressed postscript, including 18 figures. Astrophysical Journal Supplements, in pres

Stellar Forensics II: Millisecond Pulsar Binaries

We use the grid of models described in paper~I to analyse those millisecond pulsar binaries whose secondaries have been studied optically. In particular, we find cooling ages for these binary systems that range from $< 1 \rm Gyr$ to $\sim \rm 15 Gyr$. Comparison of cooling ages and characteristic spin down ages allows us to constrain the initial spin periods and spin-up histories for individual systems, showing that at least some millisecond pulsars had sub-Eddington accretion rates and long magnetic field decay times.Comment: Latex, 14 pages, and 15 postscript figures. Accepted by Monthly Notice

La Freccia Rossa: An IR-dark cloud hosting the Milky Way intermediate-mass black hole candidate

The dynamics of the high-velocity compact molecular cloud CO-0.40-0.22 have been interpreted as evidence for a $\sim10^{5}M_{\odot}$ black hole within 60 pc of Sgr A*. Recently, Oka et al. have identified a compact millimetre-continuum source, CO-0.40-0.22*, with this candidate black hole. Here we present a collation of radio and infrared data at this location. ATCA constraints on the radio spectrum, and the detection of a mid-infrared counterpart, are in tension with an Sgr A*-like model for CO-0.40-0.22* despite the comparable bolometric to Eddington luminosity ratios under the IMBH interpretation. A protostellar-disk scenario is, however, tenable. CO-0.40-0.22(*) is associated with an arrowhead-shaped infrared-dark cloud (which we call the Freccia Rossa). Radio-continuum observations reveal a candidate HII region associated with the system. If the $V_{\rm LSR}\approx70$ km s$^{-1}$ systemic velocity of CO-0.40-0.22 is common to the entire Freccia Rossa system, we hypothesise that it is the remnant of a high-velocity cloud that has plunged into the Milky Way from the Galactic halo.Comment: 6 pages, 3 figures, submitted to MNRAS Letter

The Pulsar Kick Velocity Distribution

We analyse the sample of pulsar proper motions, taking detailed account of the selection effects of the original surveys. We treat censored data using survival statistics. From a comparison of our results with Monte Carlo simulations, we find that the mean birth speed of a pulsar is 250-300 km/s, rather than the 450 km/s foundby Lyne & Lorimer (1994). The resultant distribution is consistent with a maxwellian with dispersion $\sigma_v = 190 km/s$. Despite the large birth velocities, we find that the pulsars with long characteristic ages show the asymmetric drift, indicating that they are dynamically old. These pulsars may result from the low velocity tail of the younger population, although modified by their origin in binaries and by evolution in the galactic potential.Comment: Latex, 10 pages, and 11 postscript figures. Accepted by Monthly Notice