2007/09/30 by A. Simionescu, Norbert Werner, N. Werner +5 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Atmospheric temperature range #Galactic halo #Galaxies: Formation, Evolution, Phenomena #Galaxy #Halo #Metallicity #Nuclear physics #Physics #Plasma #Spectral line #Stellar, planetary, and galactic studies #Thermal conduction #Thermodynamics #astro-ph
paper · pdf · doi:10.1051/0004-6361:20078749
18 pages, accepted for publication in A&A. Some significant changes following the referee report
arxiv created 2008/02/07 · openalex publication_date 2008/02/14 · arxiv updated 2009/12/01 · openalex created_date 2022/09/23 · openalex updated_date 2026/07/31
We use deep (~120 ks) XMM-Newton data of the M 87 halo to analyze its spatially resolved temperature structure and chemical composition. We focus particularly on the regions of enhanced X-ray brightness associated with the inner radio lobes, which are known not to be described very well by single-temperature spectral models. Compared to a simple two-temperature fit, we obtain a better and more physical description of the spectra using a model that involves a continuous range of temperatures in each spatial bin. The range of temperatures of the multiphase gas spans ~0.6–3.2 keV. Such a multiphase structure is only possible if thermal conduction is suppressed by magnetic fields. In the multi-temperature regions, we find a correlation between the amount of cool gas (with a temperature below that of the surrounding X-ray plasma) and the metallicity, and conclude that the cool gas is more metal-rich than the ambient halo. In the frame of the assumed thermal model, we estimate the average Fe abundance of the cool gas to ~2.2 solar. Our results thus point toward the key role of the active galactic nucleus (AGN) in transporting heavy elements into the intracluster medium through the uplift of cool, metal-rich gas from the galaxy. However, the abundance ratios of O/Si/S/Fe in and outside the X-ray arms are similar, indicating that the dominant fraction of metals in the gas halo was uplifted by AGN outbursts relatively recently compared to the age of M 87. Our best estimate for the mass of the cool gas is 5108 , which probably stems from a mixture of ICM, stellar mass loss, and Type Ia supernova products. ≈30–110 Myr are required to produce the observed metals in the cool gas. Finally, we put upper limits on possible non-thermal X-ray emission from M 87 and, combining it with the 90 cm radio maps, we put lower limits of around ~0.5–1.0 μG on the magnetic field strength.