Evidence for a high accretion rate as the defining parameter of Narrow-Line Seyfert 1 galaxies

X-ray spectral features which are unusually strong in many Narrow-Line Seyfert galaxies are found to be consistent with reflection from strongly ionized matter, providing further evidence of a high accretion rate in these objects and offering a unique signature of that key parameter in future observations.Comment: Contributed talk presented at the Joint MPE,AIP,ESO workshop on NLS1s, Bad Honnef, Dec. 1999, to appear in New Astronomy Reviews; also available at http://wave.xray.mpe.mpg.de/conferences/nls1-worksho

X-ray reflection in the nearby Seyfert 2 galaxy NGC 1068

We use the full broad-band XMM-Newton EPIC data to examine the X-ray spectrum of the nearby Seyfert 2 galaxy NGC 1068, previously shown to be complex with the X-ray continuum being a sum of components reflected/scattered from cold (neutral) and warm (ionised) matter, together with associated emission line spectra. We quantify the neutral and ionised reflectors in terms of the luminosity of the hidden nucleus. Both are relatively weak, a result we interpret on the Unified Seyfert Model by a near side-on view to the putative torus, reducing the visibility of the illuminated inner surface of the torus (the cold reflector), and part of the ionised outflow. A high inclination in NGC 1068 also provides a natural explanation for the large (Compton-thick) absorbing column in the line-of-sight to the nucleus. The emission line fluxes are consistent with the strength of the neutral and ionised continuum components, supporting the robustness of the spectral model.Comment: 8 pages. 7 figures. Accepted for publication in MNRA

An extended XMM-Newton observation of the Seyfert galaxy NGC 4051. I. Evidence for a shocked outflow

An extended XMM-Newton observation of the Seyfert 1 galaxy NGC 4051 has revealed a rich absorption line spectrum indicating the presence of a photoionized outflow with a wide range of velocities and ionization parameter. At low continuum fluxes an emission line spectrum is well defined with both narrow and broad components of several abundant metal ions. The absorption line velocity structure and a broad correlation of velocity and ionization parameter are consistent with an outflow scenario where a highly ionized, high velocity wind, perhaps launched during intermittent super-Eddington accretion, runs into the interstellar medium or previous ejecta, losing much of its kinetic energy in the resultant strong shock. We explore the possibility that a quasi-constant soft X-ray emission component may be evidence of this post-shock cooling. This revised view of AGN outflows is consistent with multiple minor Eddington accretion episodes creating a momentum-driven feedback linking black hole and host galaxy growth.Comment: accepted for publication in Monthly Notices of the Royal Astronomical Societ

An extended XMM-Newton observation of the Seyfert galaxy NGC 4051. II. Soft X-ray emission from a limb-brightened shell of post-shock gas

An extended XMM-Newton observation of the Seyfert I galaxy NGC 4051 in 2009 revealed a complex absorption spectrum, with a wide range of outflow velocities and ionisation states.The main velocity and ionisation structure was interpreted in Paper I in terms of a decelerating, recombining flow resulting from the shocking of a still higher velocity wind colliding with the ISM or slower moving ejecta. The high sensitivity of the XMM-Newton observation also revealed a number of broad emission lines, all showing evidence of self-absorption near the line cores. The line profiles are found here to be consistent with emission from a limb-brightened shell of post-shock gas building up ahead of the contact discontinuity. While the broad emission lines remain quasi-constant as the continuum flux changes by an order of magnitude, recombination continua of several H- and He-like ions are found to vary in response to the continuum, providing an important key to scaling the ionised flow.Comment: Accepted for publication in MNRA

Black Hole Winds

We show that black holes accreting at or above the Eddington rate probably produce winds which are optically thick in the continuum, whether in quasars or X-ray binaries. The photospheric radius and outflow speed are proportional to \mo^2 and \mo^-1 respectively, where \mo is the mass outflow rate. The outflow momentum rate is always of order L_Edd/c. Blackbody emission from these winds may provide the big blue bump in some quasars and AGN, as well as ultrasoft X-ray components in ULXs.Comment: 3 pages, no figures; MNRAS, in press (with minor corrections applied

S-193 scatterometer backscattering cross section precision/accuracy for Skylab 2 and 3 missions

Procedures for measuring the precision and accuracy with which the S-193 scatterometer measured the background cross section of ground scenes are described. Homogeneous ground sites were selected, and data from Skylab missions were analyzed. The precision was expressed as the standard deviation of the scatterometer-acquired backscattering cross section. In special cases, inference of the precision of measurement was made by considering the total range from the maximum to minimum of the backscatter measurements within a data segment, rather than the standard deviation. For Skylab 2 and 3 missions a precision better than 1.5 dB is indicated. This procedure indicates an accuracy of better than 3 dB for the Skylab 2 and 3 missions. The estimates of precision and accuracy given in this report are for backscattering cross sections from -28 to 18 dB. Outside this range the precision and accuracy decrease significantly

S193 radiometer brightness temperature precision/accuracy for SL2 and SL3

The precision and accuracy with which the S193 radiometer measured the brightness temperature of ground scenes is investigated. Estimates were derived from data collected during Skylab missions. Homogeneous ground sites were selected and S193 radiometer brightness temperature data analyzed. The precision was expressed as the standard deviation of the radiometer acquired brightness temperature. Precision was determined to be 2.40 K or better depending on mode and target temperature