We measure spin-down of the 59?ms X-ray pulsar Calvera by comparing the XMM-Newton discovery data from 2009 with new Chandra timing observations taken in 2013. Its period derivative is , which corresponds to spin-down luminosity ?erg?s–1, characteristic age yr, and surface dipole magnetic field strength Bs = 4.4 × 1011 G. These values rule out a mildly recycled pulsar, but Calvera could be an orphaned central compact object (anti-magnetar), with a magnetic field that was initially buried by supernova debris and is now reemerging and approaching normal strength. We also performed unsuccessful searches for high-energy γ-rays from Calvera in both imaging and timing of 100 MeV Fermi photons. Even though the distance to Calvera is uncertain by an order of magnitude, an upper limit of d 2 kpc inferred from X-ray spectra implies a γ-ray luminosity limit of 3.3 × 1032?erg?s–1, which is less than that of any pulsar of comparable . Calvera shares some properties with PSR J1740+1000, a young radio pulsar that we show by virtue of its lack of proper motion was born outside of the Galactic disk. As an energetic, high-Galactic-latitude pulsar, Calvera is unique in being undetected in both radio and γ-rays to faint limits, which should place interesting constraints on models for particle acceleration and beam patterns in pulsar magnetospheres.
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