The Presence of Thermally Unstable X-ray Filaments and the Production of
  Cold Gas in the NGC 5044 Group
  We present the results of a deep Chandra observation of the X-ray bright,
moderate cooling flow group NGC 5044 along with the observed correlations
between the ionized, atomic, and molecular gas in this system. The Chandra
observation shows that the central AGN has undergone two outbursts in the past
100 Myrs, based on the presence of two pairs of nearly bipolar X-ray cavities.
The molecular gas and dust within the central 2kpc is aligned with the
orientation of the inner pair of bipolar X-ray cavities, suggesting that the
most recent AGN outburst had a dynamical impact on the molecular gas. NGC 5044
also hosts many X-ray filaments within the central 8kpc, but there are no
obvious connections between the X-ray and H$\alpha$ filaments and the more
extended X-ray cavities that were inflated during the prior AGN outburst. Using
the linewidth of the blended Fe-L line complex as a diagnostic for multiphase
gas, we find that the majority of the multiphase, thermally unstable gas in NGC
5044 is confined within the X-ray filaments. While the cooling time and entropy
of the gas within the X-ray filaments are very similar, not all filaments show
evidence of gas cooling or an association with Ha emission. We suggest that the
various observed properties of the X-ray filaments are suggestive of an
evolutionary sequence where thermally unstable gas begins to cool, becomes
multiphased, develops Ha emitting plasma, and finally produces cold gas.
