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arXiv · 1402.6319

A Globular Cluster Toward M87 with a Radial Velocity < -1000 km/s: The First Hypervelocity Cluster

Nelson Caldwell·Jay Strader·Aaron J. Romanowsky·Jean P. Brodie·Ben Moore·Jurg Diemand·Davide Martizzi
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Abstract

We report the discovery of an object near M87 in the Virgo Cluster with an extraordinary blueshift of -1025 km/s, offset from the systemic velocity by >2300 km/s. Evaluation of photometric and spectroscopic data provides strong evidence that this object is a distant massive globular cluster, which we call HVGC-1 in analogy to Galactic hypervelocity stars. We consider but disfavor more exotic interpretations, such as a system of stars bound to a recoiling black hole. The odds of observing an outlier as extreme as HVGC-1 in a virialized distribution of intracluster objects are small; it appears more likely that the cluster was (or is being) ejected from Virgo following a three-body interaction. The nature of the interaction is unclear, and could involve either a subhalo or a binary supermassive black hole at the center of M87.

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Nelson Caldwell, Jay Strader, Aaron J. Romanowsky, Jean P. Brodie, Ben Moore, Jurg Diemand, Davide Martizzi. 2014-02-25. A Globular Cluster Toward M87 with a Radial Velocity < -1000 km/s: The First Hypervelocity Cluster. https://doi.org/10.1088/2041-8205/787/1/l11

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