9 research outputs found
The MPIfR-MeerKAT Galactic Plane Survey II. The eccentric double neutron star system PSR J1208-5936 and a neutron star merger rate update
The MMGPS-L is the most sensitive pulsar survey in the Southern Hemisphere.
We present a follow-up study of one of these new discoveries, PSR J1208-5936, 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. Through timing of almost one
year of observations, we detected the relativistic advance of periastron
(0.918(1) deg/yr), resulting in a total system mass of Mt=2.586(5) Mo. 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=1.26(+0.13/-0.25) Mo), the companion mass (Mc=1.32(+0.25/-0.13) Mo, and the
inclination angle (i=57(2) degrees). 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. With the improved sensitivity of the MMGPS-L,
we updated the Milky Way neutron star merger rate to be 25(+19/-9) Myr
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 293(+222/-103} Gpc/yr, consistent with LIGO and Virgo O3
observations. With this, we predict the observation of 10(+8/-4) 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
5x10 Mo and 0.4 degrees after two decades of timing, and that in at
least a decade from now the detection of the shift in Pb and the sky proper
motion will serve to make an independent constraint of the distance to the
system
Revival of the magnetar PSR J1622-4950: observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR
New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and
NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a
quiescent state since at least early 2015, reactivated between 2017 March 19
and April 5. The radio flux density, while variable, is approximately 100x
larger than during its dormant state. The X-ray flux one month after
reactivation was at least 800x larger than during quiescence, and has been
decaying exponentially on a 111+/-19 day timescale. This high-flux state,
together with a radio-derived rotational ephemeris, enabled for the first time
the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV
pulsed fraction is comparable to the smallest observed for magnetars. The
overall pulsar geometry inferred from polarized radio emission appears to be
broadly consistent with that determined 6-8 years earlier. However, rotating
vector model fits suggest that we are now seeing radio emission from a
different location in the magnetosphere than previously. This indicates a novel
way in which radio emission from magnetars can differ from that of ordinary
pulsars. The torque on the neutron star is varying rapidly and unsteadily, as
is common for magnetars following outburst, having changed by a factor of 7
within six months of reactivation.Comment: Published in ApJ (2018 April 5); 13 pages, 4 figure
The MPIfR-MeerKAT Galactic Plane Survey
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 J1208−5936, 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 (ω̇ = 0.918(1) deg yr−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 (), the companion mass (), 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 Myr−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 Gpc−3 yr−1, which is consistent with LIGO and Virgo O3 observations. With this, we also predict the observation of 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 × 10−3 M⊙ and 0.4° after two decades of timing, and that in at least a decade from now the detection of Ṗb and the sky proper motion will serve to make an independent constraint of the distance to the system
The 1.28 GHz MeerKAT Galactic Center Mosaic
International audienceThe inner ~200 pc region of the Galaxy contains a 4 million M⊙ supermassive black hole (SMBH), significant quantities of molecular gas, and star formation and cosmic-ray energy densities that are roughly two orders of magnitude higher than the corresponding levels in the Galactic disk. At a distance of only 8.2 kpc, the region presents astronomers with a unique opportunity to study a diverse range of energetic astrophysical phenomena, from stellar objects in extreme environments, to the SMBH and star-formation-driven feedback processes that are known to influence the evolution of galaxies as a whole. We present a new survey of the Galactic center conducted with the South African MeerKAT radio telescope. Radio imaging offers a view that is unaffected by the large quantities of dust that obscure the region at other wavelengths, and a scene of striking complexity is revealed. We produce total-intensity and spectral-index mosaics of the region from 20 pointings (144 hr on-target in total), covering 6.5 square degrees with an angular resolution of 4″ at a central frequency of 1.28 GHz. Many new features are revealed for the first time due to a combination of MeerKAT's high sensitivity, exceptional u, v-plane coverage, and geographical vantage point. We highlight some initial survey results, including new supernova remnant candidates, many new nonthermal filament complexes, and enhanced views of the Radio Arc bubble, Sagittarius A, and Sagittarius B regions. This project is a South African Radio Astronomy Observatory public legacy survey, and the image products are made available with this article
Revival of the Magnetar PSR J1622–4950: Observations with MeerKAT, Parkes, XMM-Newton, Swift, Chandra, and NuSTAR
© 2018. The American Astronomical Society.. New radio (MeerKAT and Parkes) and X-ray (XMM-Newton, Swift, Chandra, and NuSTAR) observations of PSR J1622-4950 indicate that the magnetar, in a quiescent state since at least early 2015, reactivated between 2017 March 19 and April 5. The radio flux density, while variable, is approximately 100 larger than during its dormant state. The X-ray flux one month after reactivation was at least 800 larger than during quiescence, and has been decaying exponentially on a 111 19 day timescale. This high-flux state, together with a radio-derived rotational ephemeris, enabled for the first time the detection of X-ray pulsations for this magnetar. At 5%, the 0.3-6 keV pulsed fraction is comparable to the smallest observed for magnetars. The overall pulsar geometry inferred from polarized radio emission appears to be broadly consistent with that determined 6-8 years earlier. However, rotating vector model fits suggest that we are now seeing radio emission from a different location in the magnetosphere than previously. This indicates a novel way in which radio emission from magnetars can differ from that of ordinary pulsars. The torque on the neutron star is varying rapidly and unsteadily, as is common for magnetars following outburst, having changed by a factor of 7 within six months of reactivation