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The imprints of AGN feedback within a supermassive black hole's sphere of influence

Accepted version
Peer-reviewed

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Type

Article

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Authors

Russell, HR 
Fabian, AC 
McNamara, BR 
Miller, JM 
Nulsen, PEJ 

Abstract

We present a new 300 ks Chandra observation of M87 that limits pileup to only a few per cent of photon events and maps the hot gas properties closer to the nucleus than has previously been possible. Within the supermassive black hole's gravitational sphere of influence, the hot gas is multiphase and spans temperatures from 0.2 to 1 keV. The radiative cooling time of the lowest temperature gas drops to only 0.1-0.5 Myr, which is comparable to its free fall time. Whilst the temperature structure is remarkably symmetric about the nucleus, the density gradient is steep in sectors to the N and S, with ρr−1.5±0.1, and significantly shallower along the jet axis to the E, where ρr−0.93±0.07. The density structure within the Bondi radius is therefore consistent with steady inflows perpendicular to the jet axis and an outflow directed E along the jet axis. By putting limits on the radial flow speed, we rule out Bondi accretion on the scale resolved at the Bondi radius. We show that deprojected spectra extracted within the Bondi radius can be equivalently fit with only a single cooling flow model, where gas cools from 1.5 keV down below 0.1 keV at a rate of 0.03 M/yr. For the alternative multi-temperature spectral fits, the emission measures for each temperature component are also consistent with a cooling flow model. The lowest temperature and most rapidly cooling gas in M87 is therefore located at the smallest radii at ~100 pc and may form a mini cooling flow. If this cooling gas has some angular momentum, it will feed into the cold gas disk around the nucleus, which has a radius of ~80 pc and therefore lies just inside the observed transition in the hot gas structure.

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Keywords

galaxies: clusters: M87, intergalactic medium, X-rays: galaxies: clusters

Journal Title

Monthly Notices of the Royal Astronomical Society

Conference Name

Journal ISSN

0035-8711
1365-2966

Volume Title

477

Publisher

Oxford University Press (OUP)
Sponsorship
European Research Council (340442)
Science and Technology Facilities Council (ST/P004636/1)
Science and Technology Facilities Council (ST/N000927/1)