Using Suzaku data, we had found a $3.4\sigma$ evidence for the X-ray emitting warm-hot circumgalactic medium (CGM) in the L$^\star$ galaxy NGC 3221. Here we present XMM-Newton data and outline an efficient, rigorous and well-defined method to extract the faint CGM signal. We confirm the CGM detection at $4\sigma$ significance within 30-200 kpc of the galaxy. We claim with $99.62\%$ confidence that the CGM is extended beyond $150$ kpc. The average temperature of the CGM is 2.0$^{+0.2}_{-0.3} \times 10^6$ K, but it is not isothermal. We find suggestive evidence for a declining temperature gradient out to 125 kpc and for super-virial temperature within 100 kpc. While a super-virial temperature component has been detected in the Milky Way CGM, this is the first time a temperature gradient has been observed in the warm-hot CGM of any spiral galaxy. The emission measure profile is well-fit with either a $\beta-$ model or a constant density profile. Deeper data are required to constrain the temperature and density profiles. We also confirm the Suzaku result that the warm-hot CGM is one of the most massive baryon components of NGC 3221 and can account for the missing galactic baryons.

中文翻译：

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NGC 3221 的暖热、扩展、大质量环绕星系介质：XMM-牛顿发现

使用 Suzaku 数据，我们发现了 $3.4\sigma$ 证据表明 L$^\star$ 星系 NGC 3221 中发射 X 射线的暖热环星系介质 (CGM)。这里我们展示了 XMM-牛顿数据并概述了一个有效的，严格且定义明确的方法来提取微弱的 CGM 信号。我们确认了在银河系 30-200 kpc 范围内以 $4\sigma$ 显着的 CGM 检测。我们以 99.62 美元\%$ 的信心声称 CGM 超出了 150 美元 kpc。CGM 的平均温度为 2.0$^{+0.2}_{-0.3} \times 10^6$ K，但不是等温的。我们发现了温度梯度下降到 125 kpc 和超病毒温度在 100 kpc 内的暗示性证据。虽然已经在银河系 CGM 中检测到超病毒温度分量，但这是第一次在任何螺旋星系的暖热 CGM 中观察到温度梯度。排放测量剖面与 $\beta-$ 模型或恒定密度剖面非常吻合。需要更深入的数据来约束温度和密度分布。我们还确认了朱雀的结果，即暖热的 CGM 是 NGC 3221 中质量最大的重子组成之一，可以解释丢失的银河重子。