The High Time Resolution Universe Pulsar survey - XVIII. The reprocessing of the HTRU-S Low Lat survey around the Galactic Centre using a Fast Folding Algorithm pipeline for accelerated pulsars

The HTRU-S Low Latitude survey data within 1 degrees of the Galactic Centre (GC) were searched for pulsars using the Fast Folding Algorithm (FFA). Unlike traditional Fast Fourier Transform (FFT) pipelines, the FFA optimally folds the data for all possible periods over a given range, which is particularly advantageous for pulsars with low-duty cycles. For the first time, a search over acceleration was included in the FFA to improve its sensitivity to binary pulsars. The steps in dispersion measure (DM) and acceleration were optimized, resulting in a reduction of the number of trials by 86 percent. This was achieved over a search period range from 0.6 to 432-s, i.e. 10 percent of the observation time (4320s), with a maximum DM of 4000pccm(-3) and an acceleration range of +/- 128ms(-2). The search resulted in the re-detections of four known pulsars, including a pulsar that was missed in the previous FFT processing of this survey. This result indicates that the FFA pipeline is more sensitive than the FFT pipeline used in the previous processing of the survey within our parameter range. Additionally, we discovered a 1.89-s pulsar, PSR J1746-2829, with a large DM, located 0.5 from the GC. Follow-up observations revealed that this pulsar has a relatively flat spectrum (alpha = -0.9 +/- 0.1) and has a period derivative of similar to 1.3 x 10(-12)ss(-1), implying a surface magnetic field of similar to 5.2 x 10(13)G and a characteristic age of similar to 23000yr. While the period, spectral index, and surface magnetic field strength are similar to many radio magnetars, other characteristics such as high linear polarization are absent.