High-resolution X-ray spectroscopy and modeling of the absorbing and emitting outflow in NGC 3783

The high-resolution X-ray spectrum of NGC 3783 shows several dozen absorpti on lines and a few emission lines from the H-like and He-like ions of O, Ne , Mg, Si, and S, as well as from Fe XVII-Fe XXIII L-shell transitions. We h ave reanalyzed the Chandra HETGS spectrum using better flux and wavelength calibrations, along with more robust methods. Combining several lines from each element, we clearly demonstrate the existence of the absorption lines and determine that they are blueshifted relative to the systemic velocity b y -610 +/- 130 km s(-1). We find the Ne absorption lines in the High-Energy Grating spectrum to be resolved with FWHM = 840(-360)(+490) km s(-1): no o ther lines are resolved. The emission lines are consistent with being at th e systemic velocity. We have used regions in the spectrum where no lines ar e expected to determine the X-ray continuum, and we model the absorption an d emission lines using photoionized-plasma calculations. The model consists of two absorption components, with different covering factors, which have an order-of-magnitude difference in their ionization parameters. The two co mponents are spherically outflowing from the active galactic nucleus, and t hus contribute to both the absorption and the emission via P Cygni profiles . The model also clearly requires O VII and O VIII absorption edges. The lo w-ionization component of our model can plausibly produce UV absorption lin es with equivalent widths consistent with those observed from NGC 3783. How ever, we note that this result is highly sensitive to the unobservable UV t o X-ray continuum, and the available UV and X-ray observations cannot firml y establish the relationship between the UV and X-ray absorbers. We find go od agreement between the Chandra spectrum and simultaneous ASCA and RXTE ob servations. The 1 keV deficit previously found when modeling ASCA data prob ably arises from iron L-shell absorption lines not included in previous mod els. We also set an upper limit on the FWHM of the narrow Fe K alpha emissi on line of 3250 km s(-1). This is consistent with this line originating out side the broad-line region, possibly from a torus.