The Dynamical State and Blue Straggler Population of the Globular Cluster NGC 6266 (M62)

We have used a proper combination of multiband high-resolution {\itHST-WFPC2} and wide-field ground based observations to image the galacticglobular cluster NGC 6266 (M62). The extensive photometric data set allows usto determine the center of gravity and to construct the most extended radialprofile ever published for this cluster including, for the first time, detailedstar counts in the very inner region. The star density profile is wellreproduced by a standard King model with an extended core ($\sim 19''$) and amodest value of the concentration parameter ($c=1.5$), indicating that thecluster has not-yet experienced core collapse. The millisecond pulsar population (whose members are all in binary systems)and the X-ray emitting population (more than 50 sources within the cluster halfmass radius) suggest that NGC 6266 is in a dynamical phase particularly activein generating binaries through dynamical encounters. UV observations of thecentral region have been used to probe the population of blue straggler stars,whose origin might be also affected by dynamical interactions. The comparisonwith other globular clusters observed with a similar strategy shows that theblue straggler content in NGC 6266 is relatively low, suggesting that theformation channel that produces binary systems hosting neutron stars or whitedwarfs is not effective in significantly increasing the blue stragglerpopulation. Moreover, an anticorrelation between millisecond pulsar content andblue straggler specific frequency in globular cluster seems emerging withincreasing evidence.Comment: 30 pages, 8 figures, accepted for publication in A