On the vanishing orbital X-ray variability of the eclipsing binary millisecond pulsar 47 Tuc W

Hebbar, Pavan R.; Heinke, C. O.; Kandel, D.; Romani, Roger W.; Freire, P. C. C.

doi:10.1093/mnras/staa3072

Cited by 8 publications

(5 citation statements)

References 73 publications

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“…These were folded using PRESTO's prepfold and the ephemeris published by Deneva et al (2016). However, it is well known that many RBs and BWs show a strong orbital variability (Shaifullah et al 2016;Bak Nielsen et al 2020;Hebbar et al 2021), often causing an old ephemeris not to be able to predict the actual orbital phase at a future time. This results in a wrong correction for the orbital Rømer delay (Blandford & Teukolsky 1976) and, consequently, the pulsed emission can be missed when folding.…”

Section: Radio Timing Analysismentioning

confidence: 99%

Evidence of intra-binary shock emission from the redback pulsar PSR J1048+2339

Zanon

D’Avanzo

Ridolfi

et al. 2021

A&A

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We present simultaneous multiwavelength observations of the 4.66 ms redback pulsar PSR J1048+2339. We performed phase-resolved spectroscopy with the Very Large Telescope (VLT) searching for signatures of a residual accretion disk or intra-binary shock emission, constraining the companion radial velocity semi-amplitude (K2), and estimating the neutron star mass (MNS). Using the FORS2-VLT intermediate-resolution spectra, we measured a companion velocity of 291 < K2 < 348 km s−1 and a binary mass ratio of 0.209 < q < 0.250. Combining our results for K2 and q, we constrained the mass of the neutron star and the companion to (1.0 < MNS < 1.6) sin−3 i M⊙ and (0.24 < M2 < 0.33) sin−3i M⊙, respectively, where i is the system inclination. The Doppler map of the Hα emission line exhibits a spot feature at the expected position of the companion star and an extended bright spot close to the inner Lagrangian point. We interpret this extended emission as the effect of an intra-binary shock originating from the interaction between the pulsar relativistic wind and the matter leaving the companion star. The mass loss from the secondary star could be either due to Roche-lobe overflow or to the ablation of its outer layer by the energetic pulsar wind. Contrastingly, we find no evidence for an accretion disk. We report on the results of the Sardinia Radio Telescope (SRT) and the Low-Frequency Array (LOFAR) telescope simultaneous radio observations at three different frequencies (150 MHz, 336 MHz, and 1400 MHz). No pulsed radio signal is found in our search. This is probably due to both scintillation and the presence of material expelled from the system which can cause the absorption of the radio signal at low frequencies. The confirmation of this hypothesis is given by another SRT observation (L-band) taken in 2019, in which a pulsed signal is detected. Finally, we report on an attempt to search for optical pulsations using IFI+Iqueye mounted at the 1.2 m Galileo telescope at the Asiago Observatory.

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Section: Radio Timing Analysismentioning

confidence: 99%

Evidence of intra-binary shock emission from the redback pulsar PSR J1048+2339

Zanon

D’Avanzo

Ridolfi

et al. 2021

A&A

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“…Seq.263 (W29): This source is known as a redback system with a MSP accreting from a main-sequence companion (Edmonds et al 2002). Periodic variation at ∼ 3.19 hr in the optical and X-rays were found by Bogdanov et al (2005), understood as a changing view of the intra-binary shock between the pulsar wind and the stellar wind from its companion, as described in Hebbar et al (2021). The radio counterpart, first detected by Camilo et al (2000) using the Parkes radio telescope, with a pulsating period of 2.35 ms and an orbital period of 3.2 hr, exhibits eclipsing-like behavior in the radio light curve for ∼25% of its orbit.…”

Section: Seq423 (W1)mentioning

confidence: 99%

Periodic X-ray sources in the Massive Globular Cluster 47 Tucanae: Evidence for Dynamically Formed Cataclysmic Variables

Bao,

Li,

Cheng

2023

Preprint

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We present a systematic study of periodic X-ray sources in the massive globular cluster 47 Tuc, utilizing deep archival Chandra observations that resolve the cluster core and recently available eROSITA observations that cover the cluster outskirt. By applying the Gregory-Loredo algorithm, we detect 20 periodic signals among 18 X-ray sources, ranging between 205-95731 second. Fourteen periods are newly discovered in the X-ray band. We classify these periodic sources into four quiescent low-mass X-ray binaries, one milli-second pulsar, two coronally-active binaries and eleven cataclysmic variables (CVs), based on their X-ray temporal and spectral properties, as well as multi-band information. Despite a small sample subject to potential selection bias against faint and non-magnetic CVs, the 11 CVs together define an orbital period distribution significantly different from that of the CVs previously found in the solar neighborhood and the Galactic bulge. In particular, there exists in 47 Tuc an apparent paucity of short-period CVs below the period gap, which might be attributed to a high occupation fraction of non-magnetic CVs. Also characteristic of the 47 Tuc CVs are an overabundance of long-period CVs with a subgiant donor, a substantial fraction of CVs within the period gap, and a steep radial surface density profile. These are best understood as a group of CVs having recently formed via dynamical interactions in the dense cluster core. Despite sufficient sensitivity of the X-ray data, only one periodic source is found between one-third of the half-light radius and the tidal radius, the nature of which is unclear.

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“…These authors attributed this to a tail of material trailing the pulsar's companion. In the redback 47 Tuc W, Hebbar et al (2021) found that Chandra observations showed that orbital modulation of X-rays was not always present. They suggested that this was due to changes in the system IBS.…”

Section: Implications For 4fgl J17027−5655mentioning

confidence: 99%

Gamma-Ray Eclipses and Orbital Modulation Transitions in the Candidate Redback 4FGL J1702.7–5655

Corbet

Chomiuk

Coley

et al. 2022

ApJ

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Observations with the Fermi Large Area Telescope (LAT) of the gamma-ray source 4FGL J1702.7−5655, previously classified as a candidate millisecond pulsar, show highly significant modulation at a period of 0.2438033 days (∼5.85 hr). Further examination of the folded light curve indicates the presence of narrow eclipses, suggesting that this is a redback binary system. An examination of the long-term properties of the modulation over 13 years of LAT observations indicates that the orbital modulation of the gamma rays changed from a simple eclipse before early 2013 to a broader, more easily detected quasi-sinusoidal modulation. In addition, the time of the eclipse shifts to ∼0.05 later in phase. This change in the orbital modulation properties, however, is not accompanied by a significant overall change in gamma-ray flux or spectrum. The quasi-sinusoidal component peaks ∼0.5 out of phase with the eclipse, which would indicate inferior conjunction of the compact object in the system. Swift X-ray Telescope observations reveal a possible X-ray counterpart within the LAT error ellipse. However, radio observations obtained with the Australia Telescope Compact Array do not detect a source in the region. 4FGL J1702.7−5655 appears to have changed its state in 2013, perhaps related to changes in the intrabinary shock in the system. We compare the properties of 4FGL J1702.7−5655 to those of other binary millisecond pulsars that have exhibited orbital modulation in gamma-rays.

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On the vanishing orbital X-ray variability of the eclipsing binary millisecond pulsar 47 Tuc W

Cited by 8 publications

References 73 publications

Evidence of intra-binary shock emission from the redback pulsar PSR J1048+2339

Evidence of intra-binary shock emission from the redback pulsar PSR J1048+2339

Periodic X-ray sources in the Massive Globular Cluster 47 Tucanae: Evidence for Dynamically Formed Cataclysmic Variables

Gamma-Ray Eclipses and Orbital Modulation Transitions in the Candidate Redback 4FGL J1702.7–5655

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