A Two-Phase Low-velocity Outflow in the Seyfert 1 Galaxy Ark~564

TL;DR

This study presents high-resolution X-ray spectra of Ark 564 revealing two distinct warm absorber phases with low velocities, providing insights into the outflow characteristics and their limited impact on galaxy evolution.

Contribution

First detailed high-resolution X-ray spectral analysis of Ark 564 showing two warm absorber phases with different ionization states and velocities.

Findings

Two warm absorber phases with different ionization levels identified.

Outflow velocities are moderate (~100 km/s) and unlikely to significantly influence galaxy formation.

Absorber pressure-temperature curve lacks typical

Abstract

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.