Informace o publikaci

Witnessing the growth of the nearest galaxy cluster: thermodynamics of the Virgo Cluster outskirts



Rok publikování 2017
Druh Článek v odborném periodiku
Časopis / Zdroj Monthly Notices of the Royal Astronomical Society
Fakulta / Pracoviště MU

Přírodovědecká fakulta

Klíčová slova galaxies: clusters: individual: Virgo; galaxies: clusters: intracluster medium; X-rays: galaxies: clusters
Popis We present results from Suzaku Key Project observations of the Virgo Cluster, the nearest galaxy cluster to us, mapping its X-ray properties along four long 'arms' extending beyond the virial radius. The entropy profiles along all four azimuths increase with radius, then level out beyond similar to 0.5r(200), while the average pressure at large radii exceeds Planck Sunyaev-Zel'dovich measurements. These results can be explained by enhanced gas density fluctuations (clumping) in the cluster's outskirts. Using a standard Navarro, Frenk and White model, we estimate a virial mass, radius and concentration parameter of M-200 = 1.05 +/- 0.02 x 10(14) M-circle dot, r(200) = 974.1 +/- 5.7 kpc and c = 8.8 +/- 0.2, respectively. The inferred cumulative baryon fraction exceeds the cosmic mean at r similar to r(200) along the major axis, suggesting enhanced gas clumping possibly sourced by a candidate large-scale structure filament along the north-south direction. The Suzaku data reveal a large-scale sloshing pattern, with two new cold fronts detected at radii of 233 and 280 kpc along the western and southern arms, respectively. Two high-temperature regions are also identified 1 Mpc towards the south and 605 kpc towards the west of M87, likely representing shocks associated with the ongoing cluster growth. Although systematic uncertainties in measuring the metallicity for low-temperature plasma remain, the data at large radii appear consistent with a uniform metal distribution on scales of similar to 90 x 180 kpc and larger, providing additional support for the early chemical enrichment scenario driven by galactic winds at redshifts of 2-3.

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