ORCID Profile
0000-0002-7730-4956
Current Organisations
Biological Research Centre
,
Rheinische Friedrich-Wilhelms-Universität Bonn Argelander-Institut für Astronomie
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Publications
The High Time Resolution Universe Pulsar Survey – XVII. PSR J1325−6253, a low eccentricity double neutron star system from an ultra-stripped supernova
Publisher: Oxford University Press (OUP)
Date: 24-03-2022
Abstract: The observable population of double neutron star (DNS) systems in the Milky Way allow us to understand the nature of supernovae and binary stellar evolution. Until now, all DNS systems in wide orbits (Porb & 1 d) have been found to have orbital eccentricities, e & 0.1. In this paper, we report the discovery of pulsar PSR J1325−6253: a DNS system in a 1.81-d orbit with a surprisingly low eccentricity of just e = 0.064. Through, 1.4 yr of dedicated timing with the Parkes radio telescope we have been able to measure its rate of advance of periastron, $\\dot{\\omega }=0{_{.}^{\\circ}}138\\pm 0{_{.}^{\\circ}}002\\, \\mathrm{yr}^{-1}$. If this induced $\\dot{\\omega }$ is solely due to general relativity then the total mass of the system is, Msys = 2.57 ± 0.06 M⊙. Assuming an edge-on orbit the minimum companion mass is constrained to be Mc, min & 0.98 M⊙ which implies the pulsar mass is Mp, max & 1.59 M⊙. Its location in the P–$\\dot{P}$ diagram suggests that, like other DNS systems, PSR J1325−6253 is a recycled pulsar and if its mass is similar to the known ex les (& .3 M⊙), then the companion neutron star is probably less than ∼1.25 M⊙ and the system is inclined at about 50°–60°. The low eccentricity along with the wide orbit of the system strongly favours a formation scenario involving an ultra-stripped supernova explosion.
Discovery of 37 new pulsars through GPU-accelerated reprocessing of archival data of the Parkes multibeam pulsar survey
Publisher: Oxford University Press (OUP)
Date: 17-02-2023
Abstract: We present the discovery of 37 pulsars from ∼ 20 yr old archival data of the Parkes Multibeam Pulsar Survey using a new FFT-based search pipeline optimized for discovering narrow-duty cycle pulsars. When developing our pulsar search pipeline, we noticed that the signal-to-noise ratios of folded and optimized pulsars often exceeded that achieved in the spectral domain by a factor of two or greater, in particular for narrow duty cycle ones. Based on simulations, we verified that this is a feature of search codes that sum harmonics incoherently and found that many promising pulsar candidates are revealed when hundreds of candidates per beam even with modest spectral signal-to-noise ratios of S/N∼5–6 in higher-harmonic folds (up to 32 harmonics) are folded. Of these candidates, 37 were confirmed as new pulsars and a further 37 would have been new discoveries if our search strategies had been used at the time of their initial analysis. While 19 of these newly discovered pulsars have also been independently discovered in more recent pulsar surveys, 18 are exclusive to only the Parkes Multibeam Pulsar Survey data. Some of the notable discoveries include: PSRs J1635−47 and J1739−31, which show pronounced high-frequency emission PSRs J1655−40 and J1843−08 belong to the nulling/intermittent class of pulsars and PSR J1636−51 is an interesting binary system in a ∼0.75 d orbit and shows hints of eclipsing behaviour – unusual given the 340 ms rotation period of the pulsar. Our results highlight the importance of reprocessing archival pulsar surveys and using refined search techniques to increase the normal pulsar population.
A Poly-ADP-Ribose Trigger Releases the Auto-Inhibition of a Chromatin Remodeling Oncogene
Publisher: Elsevier BV
Date: 12-2017
DOI: 10.1016/J.MOLCEL.2017.11.019
Abstract: DNA damage triggers chromatin remodeling by mechanisms that are poorly understood. The oncogene and chromatin remodeler ALC1/CHD1L massively decompacts chromatin in vivo yet is inactive prior to DNA-damage-mediated PARP1 induction. We show that the interaction of the ALC1 macrodomain with the ATPase module mediates auto-inhibition. PARP1 activation suppresses this inhibitory interaction. Crucially, release from auto-inhibition requires a poly-ADP-ribose (PAR) binding macrodomain. We identify tri-ADP-ribose as a potent PAR-mimic and synthetic allosteric effector that abrogates ATPase-macrodomain interactions, promotes an ungated conformation, and activates the remodeler's ATPase. ALC1 fragments lacking the regulatory macrodomain relax chromatin in vivo without requiring PARP1 activation. Further, the ATPase restricts the macrodomain's interaction with PARP1 under non-DNA damage conditions. Somatic cancer mutants disrupt ALC1's auto-inhibition and activate chromatin remodeling. Our data show that the NAD
Related Organisations
Rheinische Friedrich-Wilhelms-Universität Bonn Argelander-Institut Für Astronomie
Location: Germany
Related Funding Activities
No related grants have been discovered for Jompoj wongphechauxsorn.