Chandra and XMM-Newton view of the Warm Absorbing Gas in Mrk 290
  We present a detailed analysis of the Chandra HETGS and XMM-Newton high
resolution spectra of the bright Seyfert 1 galaxy, Mrk 290. The Chandra spectra
reveal complex absorption features that can be best described by a combination
of three ionized absorbers. The outflow velocities of these warm absorbers are
about 450 km/s, consistent with the three absorption components found in a
previous far UV study. The ionizing continuum of Mrk 290 fluctuated by a factor
of 1.4 during Chandra observations on a time scale of 17 days. Thus, we put a
lower limit on the distance from the ionizing source of 0.9 pc for the medium
ionized absorber and an upper limit on distance of 2.5 pc for the lowest
ionized absorber. The three ionization components lie on the stable branch of
the thermal equilibrium curve, indicating that the torus is most likely the
origin of warm absorbing gas in Mrk 290. During the XMM-Newton observation, the
ionizing luminosity was 50% lower compared to the one in the Chandra
observation. Neither the ionization parameter nor the column density of the two
absorbing components varied significantly, compared to the results from Chandra
observations. However, the outflow velocities of both components were 1260
km/s. We suggest that an entirely new warm absorber from the torus passed
through our line of sight. Assuming the torus wind model, the estimated mass
outflow rate is about 1 Solar mass per year.
