ar X iv : a st ro - p h / 02 06 19 9 v 1 1 2 Ju n 20 02 An Upper Limit to The Age of the Galactic

ar X iv : a st ro - p h / 02 06 48 5 v 1 2 7 Ju n 20 02 Noise and the strong signal limit in radio astronomical measurement

Received ; accepted – 2 – ABSTRACT The random error of radioastronomical measurements is usually computed in the weak-signal limit, which assumes that the system temperature is sensibly the same on and off source, or with and without a spectral line. This assumption is often very poor. We give examples of common situations in which it is important to distinguish the system noise in signal-beari...

ar X iv : a st ro - p h / 02 06 16 6 v 1 1 1 Ju n 20 02 How fast could a proto - pulsar rotate ?

According to two estimated relations between the initial period and the dynamo-generated magnetic dipole field of pulsars, we calculate the statistical distributions of pulsar initial periods. It is found that proto-pulsars are very likely to have rotation periods between 20 and 30 ms, and that most of the pulsars rotate initially at a period < 60 ms.

ar X iv : a st ro - p h / 99 02 06 2 v 1 4 F eb 1 99 9 SOURCES OF RELATIVISTIC JETS IN THE GALAXY

ar X iv : a st ro - p h / 02 06 49 6 v 1 2 7 Ju n 20 02 To appear in ApJL Rethinking Lensing and Λ

Strong gravitational lensing has traditionally been one of the few phenomena said to oppose a large cosmological constant; many analyses of lens statistics have given upper limits on ΩΛ that are marginally inconsistent with the concordance cosmology. Those conclusions were based on models where the predicted number counts of galaxies at moderate redshifts (z ∼ 0.5–1) increased significantly wit...

ar X iv : a st ro - p h / 02 06 29 8 v 1 1 8 Ju n 20 02 KUNS - 1791 astro - ph / 0206298 Tracking K - essence

We derive a condition for converging a common evolutionary track (“tracking condition”) for k-essence (a scalar field dark energy with non-canonical kinetic terms). For the Lagrangian density V (φ)W (X) with X = φ̇/2, we find tracker solutions with wφ < wB exist if Γ ≡ V V/(V ) > 3/2. Here wφ(wB) is the equation-of-state of the scalar field (background radiation/matter). Our condition may be use...