Lynx Mission Concept Status

Lynx is a concept under study for prioritization in the 2020 Astrophysics Decadal Survey. Providing orders of magnitude increase in sensitivity over Chandra, Lynx will examine the first black holes and their galaxies, map the large-scale structure and galactic halos, and shed new light on the environments of young stars and their planetary systems. In order to meet the Lynx science goals, the telescope consists of a high-angular resolution optical assembly complemented by an instrument suite that may include a High Definition X-ray Imager, X-ray Microcalorimeter and an X-ray Grating Spectrometer. The telescope is integrated onto the spacecraft to form a comprehensive observatory concept. Progress on the formulation of the Lynx telescope and observatory configuration is reported in this paper

The relation between optical extinction and hydrogen column density in the Galaxy

A linear relation between the hydrogen column density (N-H) and optical extinction (A(V)) in the Galaxy has long been observed. A number of studies found differing results in the slope of this relation. Here, we utilize the data on 22 supernova remnants that have been observed with the latest generation X-ray observatories and for which optical extinction and/or reddening measurements have been performed and find N-H (cm-2) = (2.21 +/- 0.09) x 1021 A(V) (mag). We compare our result with the previous studies and assess any systematic uncertainties that may affect these results

Physical properties of the AXP 4U 0142+61 from X-ray spectral analysis

We analyze archival Chandra and XMM-Newton data of 4U 0142+61 within the context of the surface thermal emission and magnetospheric scattering model. We show that the 4U 0142+61 spectrum can be fit very well with this physical model that contains only four parameters. The system parameters can be tightly constrained from the fits, yielding a surface magnetic field strength of B (4.75 +/- 0.02) x 10(14) G, a surface temperature of kT 0.309 +/- 0.001 keV, and a scattering optical depth of a few in the magnetosphere. These values do not vary between observations due to the stability of the source within the window of the observations. The detailed fits yield chi(2) values that are statistically much better than the traditionally employed blackbody+power-law and two blackbody fits. The spectroscopically measured surface magnetic field strength is higher than, but within, the theoretical uncertainties of the value inferred from the dipole spin-down formula