Pulse Profiles and Polarization of Terzan 5 Pulsars

Abstract

Terzan 5 is a rich globular cluster within the galactic bulge that contains 39 known millisecond pulsars, the largest known population of any globular cluster. The Terzan 5 pulsars are faint, so that individual observations of most of the pulsars have too little signal-to-noise (S/N) to measure reliable flux density or polarization information. We combined over 5.2\,days of archival data, at each of 1.5\,GHz and 2.0\,GHz, taken with the Green Bank Telescope over the past 11\,years. We created high S/N profiles for 32 of the pulsars and determined precise rotation measures (RMs) for 28 of them. We used the RMs, and the known pulsar positions and dispersion measures (DMs), to map the projected parallel component of the Galactic magnetic field toward the cluster. The $⟨B_{||}⟩$ shows a rough gradient of $\sim$6\,nG/arcsec ($\sim$160\,nG/parsec), or fractionally, a change of $\sim$20$\%$ in the right ascension direction across the cluster, implying Galactic magnetic field variability at sub-parsec scales. We also measured average flux densities $S_{\nu }$ for the pulsars, ranging from $\sim$10\,$\mu$Jy to $\sim$2\,mJy, and an average spectral index $\alpha =-1.35$, where $S_{\nu }\propto {\nu }^{\alpha })$. This spectral index is flatter than most known pulsars, likely a selection effect due to the high frequencies used in pulsar searches to mitigate dispersion and scattering. The inferred pulsar luminosity function is roughly power-law, with slope $(d\log N)/(d\log L)=-1$ at the high-luminosity end. At the low-luminosity end, there are incompleteness effects implying that Terzan 5 contains many more pulsars to be found.

12 pages, 4 figures, Accepted to The Astrophysical Journal on November 7 2022. Updates from previous draft include: analysis of time variability of flux densities, inclusion of chi^2 of fits, and other slight modifications for clarity

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Cited by in corpus (12)

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• Modeling the chemical enrichment history of the Bulge Fossil Fragment Terzan 5
• Ultra-deep ATCA imaging of 47 Tucanae reveals a central compact radio source
• The FAST Globular Cluster Pulsar Survey (GC FANS)
• Discovery and Timing analysis of new pulsars in globular cluster NGC 5024: new observations from FAST
• A 34 Yr Timing Solution of the Redback Millisecond Pulsar Terzan 5A
• Algorithmic Pulsar Timer for Binaries
• Mining the time axis with TRON. I. Millisecond pulsars in Omega Centauri, Terzan 5 and 47 Tucanae detected through MeerKAT interferometric imaging
• Observability of HOFNARs with SRG/eROSITA
• A transition from mixed-fuel to pure-helium thermonuclear bursts in Terzan 5 X-3/Swift J174805.3-244637
• Digging deeper into the dense Galactic globular cluster Terzan 5 with Electron-Multiplying CCDs. Variable star detection and new discoveries
• Search for Periodic Radio Signals from Double Neutron Star System Companions Using the Fast Folding Algorithm