X-Ray Temperature and Mass Measurements to the Virial Radius of Abell 1413 with Suzaku

We present X-ray observations of the northern outskirts of the relaxed galaxy cluster A 1413 with Suzaku, whose XIS instrument has the low intrinsic background needed to make measurements of these low surface brightness regions. We excised 15 point sources superimposed on the image above a flux of 1 × 10⁻¹⁴erg cm⁻²s⁻¹ (2–10 keV) using XMM-Newton and Suzaku images of the cluster. We quantified all known systematic errors as part of our analysis, and showed that our statistical errors encompass them for the most part. Our results extend previous measurements with Chandra and XMM-Newton, and show a significant temperature drop to about 3 keV at the virial radius, r₂₀₀. Our entropy profile in the outer region ($> $0.5r₂₀₀) joins smoothly onto that of XMM-Newton, and shows a flatter slope compared with simple models, similar to a few other clusters observed at the virial radius. The integrated mass of the cluster at the virial radius is approximately 7.5 × 10¹⁴ M_, and varies by about 30%, depending on the particular method used to measure it.