A Two-Phase Low-velocity Outflow in the Seyfert 1 Galaxy Ark~564. (arXiv:1301.6138v1 [astro-ph.HE])

A Two-Phase Low-velocity Outflow in the Seyfert 1 Galaxy Ark~564. (arXiv:1301.6138v1 [astro-ph.HE]):
The Seyfert 1 galaxy Ark 564 was observed with Chandra high energy
transmission gratings for 250 ks. We present the high resolution X-ray spectrum
that shows several associated absorption lines. The photoionization model
requires two warm absorbers with two different ionization states
(logU=0.39\pm0.03 and logU=-0.99\pm0.13), both with moderate outflow velocities
(~100 km s^-1) and relatively low line of sight column densities (logNH=20.94
and 20.11 cm^-2). The high ionization phase produces absorption lines of OVII,
OVIII, NeIX, NeX, MgXI, FeXVII and FeXVIII while the low ionization phase
produces lines at lower energies (OVI & OVII). The pressure--temperature
equilibrium curve for the Ark 564 absorber does not have the typical "S" shape,
even if the metallicity is super-solar; as a result the two warm-absorber
phases do not appear to be in pressure balance. This suggests that the
continuum incident on the absorbing gas is perhaps different from the observed
continuum. We also estimated the mass outflow rate and the associated kinetic
energy and find it to be at most 0.006% of the bolometric luminosity of
Ark~564. Thus it is highly unlikely that these outflows provide significant
feedback required by the galaxy formation models.