We combined Chandra ACIS observations of the globular cluster 47 Tucanae ( hereafter , 47 Tuc ) from 2000 , 2002 , and 2014-15 to create a deeper X-ray source list , and study some of the faint radio millisecond pulsars ( MSPs ) present in this cluster .
We have detected 370 X-ray sources within the half-mass radius ( 2 ^ { \prime } .79 ) of the cluster , 81 of which are newly identified , by including new data and using improved source detection techniques .
The majority of the newly identified sources are in the crowded core region , indicating cluster membership .
We associate five of the new X-ray sources with chromospherically active BY Dra or W UMa variables identified by Albrow et al .
( 2001 ) .
We present alternative positions derived from two methods , centroiding and image reconstruction , for faint , crowded sources .
We are able to extract X-ray spectra of the recently discovered MSPs 47 Tuc aa , 47 Tuc ab , the newly timed MSP 47 Tuc Z , and the newly resolved MSPs 47 Tuc S and 47 Tuc F. Generally , they are well fit by black body or neutron star atmosphere models , with temperatures , luminosities and emitting radii similar to those of other known MSPs in 47 Tuc , though 47 Tuc aa and 47 Tuc ab reach lower X-ray luminosities .
We limit X-ray emission from the full surface of the rapidly spinning ( 542 Hz ) MSP 47 Tuc aa , and use this limit to put an upper bound for amplitude of r-mode oscillations in this pulsar as \alpha < 2.5 \times 10 ^ { -9 } and constrain the shape of the r-mode instability window .