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We present the results of Chandra X-ray observations of the isolated,massive, compact, relic galaxies MRK 1216 and PGC 032873. Compact massivegalaxies observed at z>2, also called red nuggets, formed in quick dissipativeevents and later grew by dry mergers into the local giant ellipticals. Due tothe stochastic nature of mergers, a few of the primordial massive galaxiesavoided the mergers and remained untouched over cosmic time. We find that thehot atmosphere surrounding MRK 1216 extends far beyond the stellar populationand has an 0.5-7 keV X-ray luminosity of $L_{\rm X}=(7.0\pm0.2)\times10^{41}$erg s$^{-1}$, which is similar to the nearby X-ray bright giant ellipticals.The hot gas has a short central cooling time of $\sim50$ Myr and the galaxy hasa $\sim13$ Gyr old stellar population. The presence of an X-ray atmosphere witha short nominal cooling time and the lack of young stars indicate the presenceof a sustained heating source, which prevented star formation since thedissipative origin of the galaxy 13 Gyrs ago. The central temperature peak andthe presence of radio emission in the core of the galaxy indicate that theheating source is radio-mechanical AGN feedback. Given that both MRK 1216 andPGC 032873 appear to have evolved in isolation, the order of magnitudedifference in their current X-ray luminosity could be traced back to adifference in the ferocity of the AGN outbursts in these systems. Finally, wediscuss the potential connection between the presence of hot halos around suchmassive galaxies and the growth of super/over-massive black holes via chaoticcold accretion.

Digging for red nuggets: discovery of hot halos surrounding massive, compact, relic galaxies