TY - JOUR

T1 - The MPIfR-MeerKAT Galactic Plane Survey

T2 - II. The eccentric double neutron star system PSR J1208a-5936 and a neutron star merger rate update

AU - Colom I Bernadich, M.

AU - Balakrishnan, V.

AU - Barr, E.

AU - Berezina, M.

AU - Burgay, M.

AU - Buchner, S.

AU - Champion, D. J.

AU - Chen, W.

AU - Desvignes, G.

AU - Freire, P. C.C.

AU - Grunthal, K.

AU - Kramer, M.

AU - Men, Y.

AU - Padmanabh, P. V.

AU - Parthasarathy, A.

AU - Pillay, D.

AU - Rammala, I.

AU - Sengupta, S.

AU - Venkatraman Krishnan, V.

N1 - Funding Information: The MeerKAT telescope is operated by the South African Radio Astronomy Observatory, which is a facility of the National Research Foundation, an agency of the Department of Science and Innovation. The Parkes radio telescope is part of the ATNF, which is funded by the Australian Government for operation as a National Facility managed by the Commonwealth Scientific and Industrial Research Organisation. We acknowledge the Wiradjuri people as the Traditional Owners of the Observatory site. SARAO acknowledges the ongoing advice and calibration of GPS systems by the National Metrology Institute of South Africa (NMISA) and the time space reference systems department of the Paris Observatory. Observations used the FBFUSE and APSUSE computing clusters for data acquisition, storage and analysis. These clusters were funded and installed by the MPIfR and the Max-Planck-Gesellschaft (MPG). All authors affiliated with the MPG acknowledge its constant support. Marina Berezina acknowledges support from the Bundesministerium für Bildung und Forschung D-MeerKAT award 05A17VH3 (Verbundprojekt D-MeerKAT). Marta Burgay acknowledges support through the research grant ‘iPeska’ (PI: A. Possenti) funded under the INAF national call Prin-SKA/CTA approved with the Presidential Decree 70/2016. Vivek Venkatraman Krishnan acknowledges financial support from the European Research Council (ERC) starting grant ‘COMPACT’ (grant agreement number: 101078094). We also thank Alessandro Ridolfi for providing a working version of pysolator.py and for his input in Sect. 5, Norbert Wex for his comments on the interpretations of the NS merger rate results in Sect. 6, and Livia Silva Rocha and Robert Main for their general feedback on this manuscript. The data underlying this work will be shared on reasonable request to the MMGPS Collaboration.

PY - 2023/10

Y1 - 2023/10

N2 - The MPIfR-MeerKAT Galactic Plane survey at L-band (MMGPS-L) is the most sensitive pulsar survey in the Southern Hemisphere, providing 78 discoveries in an area of 900 sq. deg. Here, we present a follow-up study of one of these new discoveries, PSR J1208a-5936, a 28.71-ms recycled pulsar in a double neutron star system with an orbital period of Pb=0.632 days and an eccentricity of e=0.348, merging within the Hubble time. Through timing of almost one year of observations, we detected the relativistic advance of periastron ( Ì = 0.918(1) deg yra-1), resulting in a total system mass of Mt=2.586(5) M·. We also achieved low-significance constraints on the amplitude of the Einstein delay and Shapiro delay, in turn yielding constraints on the pulsar mass (Mp = 1.26a-0.25+0.13 M·), the companion mass (Mc = 1.32a-0.13+0.25 M·), and the inclination angle (i=57 ± 12). This system is highly eccentric compared to other Galactic field double neutron stars with similar periods, possibly hinting at a larger-than-usual supernova kick during the formation of the second-born neutron star. The binary will merge within 7.2(2) Gyr due to the emission of gravitational waves, making it a progenitor of the neutron star merger events seen by ground-based gravitational wave observatories. With the improved sensitivity of the MMGPS-L, we updated the Milky Way neutron star merger rate to be RMWnew = 25a-9+19 Myra-1 within 90% credible intervals, which is lower than previous studies based on known Galactic binaries owing to the lack of further detections despite the highly sensitive nature of the survey. This implies a local cosmic neutron star merger rate of Rlocalnew = 293a-103+222 Gpca-3 yra-1, which is consistent with LIGO and Virgo O3 observations. With this, we also predict the observation of 10a-4+8 neutron star merger events during the LIGO-Virgo-KAGRA O4 run. We predict the uncertainties on the component masses and the inclination angle will be reduced to 5- 10a-3 M· and 0.4 after two decades of timing, and that in at least a decade from now the detection of b and the sky proper motion will serve to make an independent constraint of the distance to the system.

AB - The MPIfR-MeerKAT Galactic Plane survey at L-band (MMGPS-L) is the most sensitive pulsar survey in the Southern Hemisphere, providing 78 discoveries in an area of 900 sq. deg. Here, we present a follow-up study of one of these new discoveries, PSR J1208a-5936, a 28.71-ms recycled pulsar in a double neutron star system with an orbital period of Pb=0.632 days and an eccentricity of e=0.348, merging within the Hubble time. Through timing of almost one year of observations, we detected the relativistic advance of periastron ( Ì = 0.918(1) deg yra-1), resulting in a total system mass of Mt=2.586(5) M·. We also achieved low-significance constraints on the amplitude of the Einstein delay and Shapiro delay, in turn yielding constraints on the pulsar mass (Mp = 1.26a-0.25+0.13 M·), the companion mass (Mc = 1.32a-0.13+0.25 M·), and the inclination angle (i=57 ± 12). This system is highly eccentric compared to other Galactic field double neutron stars with similar periods, possibly hinting at a larger-than-usual supernova kick during the formation of the second-born neutron star. The binary will merge within 7.2(2) Gyr due to the emission of gravitational waves, making it a progenitor of the neutron star merger events seen by ground-based gravitational wave observatories. With the improved sensitivity of the MMGPS-L, we updated the Milky Way neutron star merger rate to be RMWnew = 25a-9+19 Myra-1 within 90% credible intervals, which is lower than previous studies based on known Galactic binaries owing to the lack of further detections despite the highly sensitive nature of the survey. This implies a local cosmic neutron star merger rate of Rlocalnew = 293a-103+222 Gpca-3 yra-1, which is consistent with LIGO and Virgo O3 observations. With this, we also predict the observation of 10a-4+8 neutron star merger events during the LIGO-Virgo-KAGRA O4 run. We predict the uncertainties on the component masses and the inclination angle will be reduced to 5- 10a-3 M· and 0.4 after two decades of timing, and that in at least a decade from now the detection of b and the sky proper motion will serve to make an independent constraint of the distance to the system.

KW - Binaries: close

KW - Celestial mechanics

KW - Ephemerides

KW - Gravitational waves

KW - Stars: fundamental parameters

KW - Stars: neutron

UR - http://www.scopus.com/inward/record.url?scp=85176106962&partnerID=8YFLogxK

U2 - 10.48550/arXiv.2308.16802

DO - 10.48550/arXiv.2308.16802

M3 - Article

AN - SCOPUS:85176106962

VL - 678

JO - Astronomy and astrophysics

JF - Astronomy and astrophysics

SN - 0004-6361

M1 - A187

ER -