The luminous X-ray hotspot in 4C 74.26: synchrotron or inverse-Compton emission?

We report the discovery of an X-ray counterpart to the southern radio hotspot of the largest-known radio quasar 4C 74.26 (whose redshift is z=0.104). Both XMM-Newton and Chandra images reveal the same significant (10arcsec, i.e. 19kpc) offset between the X-ray hotspot and the radio hotspot imaged with MERLIN. The peak of the X-ray emission may be due to synchrotron or inverse-Compton emission. If synchrotron emission, the hotspot represents the site of particle acceleration and the offset arises from either the jet exhibiting Scheuer's `dentist's drill' effect or a fast spine having less momentum than the sheath surrounding it, which creates the radio hotspot. If the emission arises from the inverse-Compton process, it must be inverse-Compton scattering of the CMB in a decelerating relativistic flow, implying that the jet is relativistic (Gamma >= 2) out to a distance of at least 800kpc. Our analysis, including optical data from the Liverpool Telescope, rules out a background AGN for the X-ray emission and confirms its nature as a hotspot, making it the most X-ray luminous hotspot yet detected.Comment: 9 pages, 9 figures, definitive version published by MNRA

Movements Into and Out of Child Poverty in New Zealand: Results from the Linked Income Supplement

This paper considers the dynamics of child income poverty in New Zealand. Annual movements into and out of poverty by children’s households in New Zealand over the 1997/98, 1998/99, and 1999/2000 periods are analysed. The annual Income Supplement to the Household Labour Force Survey allows tracking of dwellings and people in two consecutive June quarterly weeks, and thus allows observation of changes in equivalised household disposable income over a June year. This project is the first to use the Linked Income Survey for analysis of income dynamics and is part of the Ministry of Social Policy’s ongoing research on family dynamics.New Zealand adult and child poverty transitions are compared. Child poverty transitions in New Zealand are compared and contrasted to those of five other countries—Britain, Germany, Hungary, Russia and Spain—where a similar current income measure of poverty is available. The frequency of poverty “trigger events” in New Zealand and their impact on the chances of children exiting and entering poverty are compared to similar data for Britain and West Germany.child poverty, household income, income mobility

Movements Into and Out of Child Poverty in New Zealand: Results from the Linked Income Supplement

This paper considers the dynamics of child income poverty in New Zealand. Annual movements into and out of poverty by children's households in New Zealand over the 1997/98, 1998/99, and 1999/2000 periods are analysed. The annual Income Supplement to the Household Labour Force Survey allows tracking of dwellings and people in two consecutive June quarterly weeks, and thus allows observation of changes in equivalised household disposable income over a June year. This project is the first to use the Linked Income Survey for analysis of income dynamics and is part of the Ministry of Social Policy's ongoing research on family dynamics. New Zealand adult and child poverty transitions are compared. Child poverty transitions in New Zealand are compared and contrasted to those of five other countries-Britain, Germany, Hungary, Russia and Spain-where a similar current income measure of poverty is available. The frequency of poverty "trigger events" in New Zealand and their impact on the chances of children exiting and entering poverty are compared to similar data for Britain and West Germany.Child poverty, household income, income mobility

Fe K\alpha emission from photoionized slabs: the impact of the iron abundance

Iron K\alpha emission from photoionized and optically thick material is observed in a variety of astrophysical environments including X-ray binaries, active galactic nuclei, and possibly gamma-ray bursts. This paper presents calculations showing how the equivalent width (EW) of the Fe K line depends on the iron abundance of the illuminated gas and its ionization state -- two variables subject to significant cosmic scatter. Reflection spectra from a constant density slab which is illuminated with a power-law spectrum with photon-index \Gamma are computed using the code of Ross & Fabian. When the Fe K EW is measured from the reflection spectra alone, we find that it can reach values greater than 6 keV if the Fe abundance is about 10 times solar and the illuminated gas is neutral. EWs of about 1 keV are obtained when the gas is ionized. In contrast, when the EW is measured from the incident+reflected spectrum, the largest EWs are ~800 keV and are found when the gas is ionized. When \Gamma is increased, the Fe K line generally weakens, but significant emission can persist to larger ionization parameters. The iron abundance has its greatest impact on the EW when it is less than 5 times solar. When the abundance is further increased, the line strengthens only marginally. Therefore, we conclude that Fe K lines with EWs much greater than 800 eV are unlikely to be produced by gas with a supersolar Fe abundance. These results should be useful in interpreting Fe K emission whenever it arises from optically thick fluorescence.Comment: 5 pages, 5 figures, accepted by MNRAS Letter

An XMM-Newton observation of Ton S180: Constraints on the continuum emission in ultrasoft Seyfert galaxies

We present an XMM-Newton observation of the bright, narrow-line, ultrasoft Seyfert 1 galaxy Ton S180. The 0.3-10 keV X-ray spectrum is steep and curved, showing a steep slope above 2.5 keV (Gamma ~ 2.3) and a smooth, featureless excess of emission at lower energies. The spectrum can be adequately parameterised using a simple double power-law model. The source is strongly variable over the course of the observation but shows only weak spectral variability, with the fractional variability amplitude remaining approximately constant over more than a decade in energy. The curved continuum shape and weak spectral variability are discussed in terms of various physical models for the soft X-ray excess emission, including reflection off the surface of an ionised accretion disc, inverse-Compton scattering of soft disc photons by thermal electrons, and Comptonisation by electrons with a hybrid thermal/non-thermal distribution. We emphasise the possibility that the strong soft excess may be produced by dissipation of accretion energy in the hot, upper atmosphere of the putative accretion disc.Comment: 9 pages, accepted for publication in MNRA

Relativistic ionized accretion disc models of MCG--6-30-15

We present results from fitting ionized accretion disc models to three long ASCA observations of the Seyfert 1 galaxy MCG--6-30-15. All three datasets can be fit by a model consisting of ionized reflection from the inner region of the accretion disc (with twice solar Fe abundance) and a separate diskline component from farther out on the the disc. The diskline is required to fit the height of the observed Fe K line profile. However, we show that a much simpler model of reflection from a very weakly ionized constant density disc also fits the data. In this case only a single cold Fe K line at 6.4 keV is required to fit the observed line. The ionized disc models predict that O VIII K, C VI K, Fe XVII L, and Fe XVIII L lines will appear in the soft X-ray region of the reflection spectrum, but are greatly blurred due to Compton scattering. The equivalent width (EW) of O VIII K is estimated to be about 10 eV and seems to be as strong as the blend of the Fe L lines. This result creates difficulty for the claim of a strong relativistic O VIII line in the XMM-Newton grating spectrum of MCG--6-30-15, although we can not strictly rule it out since MCG--6-30-15 was in an anomalously low state during that observation. We find that increasing the O abundance or breaking the continuum below 2 keV will not significantly strengthen the line. The second Fe K line component in the ionized disc model may arise from neutral reflection from a flared disc, or from a second illumination event. The data cannot distinguish between the two cases, and we conclude that single zone ionized disc models have difficulty fitting these hard X-ray data of MCG--6-30-15.Comment: 6 pp., accepted by MNRAS Letter