Is NGC6752 hiding a double black hole binary in its core ?

We report the discovery of five new millisecond pulsars in the globular cluster NGC 6440 and three new ones in NGC 6441; each cluster has one previously known pulsar. Four of the new pulsars are found in binary systems. One of the new pulsars, PSR J1748-2021B in NGC 6440, is notable for its eccentric (e = 0.57) and wide (P_b = 20.5 days) orbit. If the rate of advance of periastron is due solely to general relativity, we can estimate of the total mass of this binary system: 2....

(abridged) In this work we present the results of one year of upgraded Giant Metrewave Radio Telescope timing measurements of PSR~J0514$-$4002A, a 4.99-ms pulsar in a 18.8-day, eccentric ($e \, =\, 0.89$) orbit with a massive companion located in the globular cluster NGC~1851. Combining these data with earlier Green Bank Telescope data, we greatly improve the precision of the rate of advance of periastron, $\dot{\omega} \, = \, 0.0129592(16)\, \deg \, \rm yr^{-1}$ which, assu...

We present the results of observations aimed at discovering and studying pulsars in the core-collapsed globular cluster (GC) NGC 6522 performed by the MeerTIME and TRAPUM Large Survey Project with the MeerKAT telescope. We have discovered two new isolated pulsars bringing the total number of known pulsars in the cluster to six. PSR J1803$-$3002E is a mildly recycled pulsar with spin period of 17.9 ms while pulsar PSR J1803$-$3002F is a slow pulsar with spin period of 148.1 ms...

PSR J1024$-$0719 is a millisecond pulsar that was long thought to be isolated. However, puzzling results concerning its velocity, distance, and low rotational period derivative have led to reexamination of its properties. We present updated radio timing observations along with new and archival optical data that show PSR J1024$-$0719 is most likely in a long period (2$-$20 kyr) binary system with a low-mass ($\approx 0.4\,M_\odot$) low-metallicity ($Z \approx -0.9\,$ dex) main...

We report on a comprehensive multi-wavelength study of the pulsars in the globular cluster (GC) M5, including the discovery of M5G, a new compact non-eclipsing "black widow" pulsar. Thanks to the analysis of 34 years of radio data taken with the FAST and Arecibo telescopes, we obtained new phase-connected timing solutions for four pulsars in the clusters and improved those of the other three known pulsars. These have resulted in, among other things: a) much improved proper mo...

We report the discovery of an eclipsing binary millisecond pulsar in the globular cluster M92 (NGC6341) with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). PSR J1717+4308A, or M92A, has a pulse frequency of 316.5~Hz (3.16~ms) and a dispersion measure of 35.45 pc cm$^{-3}$. The pulsar is a member of a binary system with an orbital period of 0.20~days around a low-mass companion which has a median mass of $\sim$0.18~\Ms. From observations so far, at least two...

(abridged) PSR J1903+0327, a millisecond pulsar in an eccentric (e = 0.44) 95-day orbit with a (~ 1Msun) companion poses a challenge to our understanding of stellar evolution in binary and multiple-star systems. Here we describe optical and radio observations which rule out most of the scenarios proposed to explain formation of this system. Radio timing measurements of three post-Keplerian effects yield the most precise measurement of the mass of a millisecond pulsar to date:...

We present a scenario for the spin-up and evolution of binary millisecond pulsars. This can explain the observational properties of the recently discovered binary millisecond pulsar PSR J1740-5340, with orbital period 32.5 hrs, in the Globular Cluster NGC 6397. The optical counterpart of this system is a star as luminous as the cluster turnoff stars, but with a lower Teff (a larger radius) which we model with a star of initial mass compatible with the masses evolving in the c...

We present the discovery of three pulsars in Globular Cluster M15 (NGC 7078) by the Five-hundred-meter Aperture Spherical radio Telescope (FAST). In the three pulsars, PSR~J2129+1210J (M15J) is a millisecond pulsar with a spinning period of 11.84 ms and a dispersion measure of 66.68 pc cm$^{-3}$. Both PSR~J2129+1210K and L (M15K and L) are long period pulsars with spinning periods of 1928 ms and 3961 ms , respectively, while M15L is the GC pulsar with the longest spinning per...

PSRJ1910-5959A (J1910A) is a binary millisecond pulsar in a 0.837 day circular orbit around a helium white dwarf (HeWD) companion. This pulsar is located 6.3 arcmin away from the centre of the globular cluster NGC6752. Given the large offset, the association of the pulsar to NGC6752 has been debated. We have made use of two decades of archival Parkes 64-m "Murriyang" telescope data and recently carried out observations with the MeerKAT telescope. We obtained Pulse times of ar...