Kavli Affiliate: Eric Miller
| First 5 Authors: Arnab Sarkar, Arnab Sarkar, , ,
| Summary:
We present $sim$500 ks XRISM observations covering the central and two
northern regions of the Abell 2029 galaxy cluster. Resolve enables us to
distinguish multiple emission lines from hydrogen-like and helium-like iron
(Fe) ions. This study focuses on the multi-temperature structure of Abell 2029
using line-ratio diagnostics. Using a single-temperature collisionally ionized
equilibrium model, we measure average plasma temperatures of 6.73 keV, 7.61
keV, and 8.14 keV in the central, inner northern, and outer northern regions,
respectively, spanning a radial range up to 700 kpc. To further investigate
thermal structure, we derive excitation and ionization temperatures by
comparing observed emission-line flux ratios with atomic database predictions.
Significant deviations from the single-temperature CIE model in the central and
inner northern regions indicate the presence of multi-phase gas. The excitation
and ionization temperatures range from 2.85 keV to 8.5 keV in the central
region, 4.3 keV to 9.8 keV in the inner northern region, and 8.3 keV to 10.4
keV in the outer northern region. These temperature distributions are largely
consistent with the previously observed temperature gradient of A2029. However,
Resolve detects two notably cooler components–3.42 keV in the central region
and $sim$4.3 keV in the inner northern region–likely associated with
displaced cool gas due to gas sloshing. Additionally, we thermally resolve a
2.85 keV gas component at the core of A2029–potentially a significant
development in our understanding of gas cooling. We propose that this cooler
gas is a direct product of ongoing cooling processes in A2029, having already
cooled to its present temperature. If this temperature structure is stable and
no heating mechanism is present, this reservoir is likely to cool to even lower
temperatures and form stars.
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