MeerKAT

Abstract:

We report on a timing programme of 74 young pulsars that have been observed by the Parkes 64-m radio telescope over the past decade. Using modern Bayesian timing techniques, we have measured the properties of 124 glitches in 52 of these pulsars, of which 74 are new. We demonstrate that the glitch sample is complete to fractional increases in spin frequency greater than Delta \nu 90{{\ \rm per\ cent}} \mathrm{ g}}/\nu \approx 8.1 \times 10 -9}$. We measure values of the braking index, n, in 33 pulsars. In most of these pulsars, their rotational evolution is dominated by episodes of spin-down with n > 10, punctuated by step changes in the spin-down rate at the time of a large glitch. The step changes are such that, averaged over the glitches, the long-term n is small. We find a near one-to-one relationship between the interglitch value of n and the change in spin-down of the previous glitch divided by the interglitch time interval. We discuss the results in the context of a range of physical models.

Abstract:

We present Lyα and ultraviolet (UV)-continuum luminosity functions (LFs) of galaxies and active galactic nuclei (AGNs) at z = 2.0-3.5 determined by the untargeted optical spectroscopic survey of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). We combine deep Subaru imaging with HETDEX spectra resulting in 11.4 deg2 of fiber spectra sky coverage, obtaining 18,320 galaxies spectroscopically identified with Lyα emission, 2126 of which host type 1 AGNs showing broad (FWHM > 1000 km s-1) Lyα emission lines. We derive the Lyα (UV) LF over 2 orders of magnitude covering bright galaxies and AGNs in (-27 < MUV < -20) by the 1/Vmax estimator. Our results reveal that the bright-end hump of the Lyα LF is composed of type 1 AGNs. In conjunction with previous spectroscopic results at the faint end, we measure a slope of the best-fit Schechter function to be αSch=-1.70-0.14+0.13, which indicates that αSch steepens from z = 2-3 toward high redshift. Our UV LF agrees well with previous AGN UV LFs and extends to faint-AGN and bright-galaxy regimes. The number fraction of Lyα-emitting objects (XLAE) increases from MUV∗ ∼ -21 to bright magnitude due to the contribution of type 1 AGNs, while previous studies claim that XLyα decreases from faint magnitudes to MUV∗, suggesting a valley in the XLyα-magnitude relation at MUV∗. Comparing our UV LF of type 1 AGNs at z = 2-3 with those at z = 0, we find that the number density of faint (MUV > -21) type 1 AGNs increases from z ∼ 2 to 0, as opposed to the evolution of bright (MUV < -21) type 1 AGNs, suggesting AGN downsizing in the rest-frame UV luminosity.