Figure 4 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Radial velocity (RV) curve of 4FGL J1910.7−5320. We folded it on the orbital period of P = 0.34847592 days with the phase zero at BJD 2453584.0121.
Source publication
We present the study of multiwavelength observations of an unidentified Fermi Large Area Telescope (LAT) source, 4FGL J1910.7−5320, a new candidate redback millisecond pulsar binary. In the 4FGL 95% error region of 4FGL J1910.7−5320, we find a possible binary with a 8.36 hr orbital period from the Catalina Real-Time Transient Survey, confirmed by o...
Context in source publication
Context 1
... best-fit parameters are an orbital period of 0.34847592(21) days, a mean CRTS magnitude of 19.015 ± 0.018 mag, a CRTS amplitude of 0.506 ± 0.029 mag, K 2,obs = 218 ± 8 km s −1 , γ = − 17 ± 6 km s −1 , and the phase zero at BJD 2453584.0121(31). We use the best-fit parameters of P = 0.34847592 days and phase zero at BJD 2453584.0121 to fold both the CRTS light and the RV curves, which are plotted in Figures 3 and 4, respectively. ...
Citations
... Crawford et al. 2013;C. G. Bassa et al. 2014;M. Li et al. 2014;J. Strader et al. 2014J. Strader et al. , 2016S. D. Bates et al. 2015;D. Salvetti et al. 2015;J. W. Broderick et al. 2016;J. S. Deneva et al. 2016;K.-L. Li et al. , 2018K. Stovall et al. 2016;C. T. Britt et al. 2017;J. P. Halpern et al. 2017;M. Linares 2018;R. H. D. Corbet et al. 2022;K.-Y. Au et al. 2023;C. J. Clark et al. 2023;E. F. Lewis et al. 2023;M. Turchetta et al. 2023;A. Zic et al. 2024;J. A. Simpson et al. 2025). As discussed in Section 4, searches for orbital signatures in the optical and X-ray emission did not yield any candidate orbital periods, and we did not detect any absorption lines from the companion of either source. W ...
We report the discovery of two new Galactic accreting compact objects consistent with the respective positions of the unassociated Fermi-LAT γ -ray sources 4FGL J0639.1-8009 and 4FGL J1824.2+1231. A combination of new and archival X-ray data from Chandra, XMM-Newton, Swift/XRT, and eROSITA reveals a variable X-ray source in each γ -ray error ellipse. Both candidate counterparts show power-law spectra with photon indices Γ ∼ 1.7–1.9. Optical follow-up photometry and spectroscopy show rapid high-amplitude variability unrelated to orbital motion and persistent accretion disk spectra for both objects. We demonstrate that the properties of these X-ray/optical sources are at odds with the known phenomenology of accreting white dwarfs, but are consistent with the observed properties of the subluminous disk state of transitional millisecond pulsars. This brings the census of confirmed or candidate transitional millisecond pulsars in the Galactic field to nine. We show this potentially represents ≲10% of the total population of transitional millisecond pulsars within 8 kpc.
... tMSPs and other redbacks host pulsars in tight orbits with their stellar companions, with 68% of observed orbital periods of Galactic field redbacks in the range 0.20-0.59 d (Archibald et al. 2010;Romani & Shaw 2011;Kaplan et al. 2012;Ray et al. 2012;Crawford et al. 2013;Bassa et al. 2014;Li et al. 2014;Strader et al. 2014;Bates et al. 2015;Salvetti et al. 2015;Broderick et al. 2016;Deneva et al. 2016;Li et al. 2016;Stovall et al. 2016;Strader et al. 2016;Britt et al. 2017;Halpern et al. 2017;Li et al. 2018;Linares 2018;Corbet et al. 2022;Au et al. 2023;Clark et al. 2023a,b;Lewis et al. 2023;Turchetta et al. 2023;Zic et al. 2024;Simpson et al. 2025). As discussed in Section 4, searches for orbital signatures in the optical and X-ray emission did not yield any candidate orbital periods, and we did not detect any absorption lines from the companion of either source. ...
We report the discovery of two new Galactic accreting compact objects consistent with the respective positions of the unassociated Fermi-LAT gamma-ray sources 4FGL J0639.1--8009 and 4FGL J1824.2+1231. A combination of new and archival X-ray data from Chandra, XMM-Newton, Swift/XRT, and eROSITA reveals a variable X-ray source in each gamma-ray error ellipse. Both candidate counterparts show power-law spectra with photon indices . Optical follow-up photometry and spectroscopy show rapid high-amplitude variability unrelated to orbital motion and persistent accretion disk spectra for both objects. We demonstrate that the properties of these X-ray/optical sources are at odds with the known phenomenology of accreting white dwarfs, but are consistent with the observed properties of the sub-luminous disk state of transitional millisecond pulsars. This brings the census of confirmed or candidate transitional millisecond pulsars in the Galactic field to nine. We show this potentially represents of the total population of transitional millisecond pulsars within 8 kpc.
... Spider systems can also be identified through the variable optical emission of their companion stars (e.g. Salvetti et al. 2015;Linares et al. 2017;Au et al. 2023). The shape of their light curves is primarily determined by the degree of heating from the pulsar wind, which in turn depends on the system's orbital period, the compan-ion star's intrinsic 'base' temperature and the pulsar's spin-down luminosity (Turchetta et al. 2023). ...
We present the discovery of the variable optical counterpart to PSR J2055+1545, a redback millisecond pulsar, and the first radial velocity curve of its companion star. The multi-band optical light curves of this system show a 0.4 amplitude modulation with a single peak per orbit and variable colours, suggesting that the companion is mildly irradiated by the pulsar wind. We find that the flux maximum is asymmetric and occurs at orbital phase , anticipating the superior conjunction of the companion (where the optical emission of irradiated redback companions is typically brightest). We ascribe this asymmetry, well fit with a hot spot in our light curve modelling, to irradiation from the intrabinary shock between pulsar and companion winds. The optical spectra obtained with the \textit{Gran Telescopio Canarias} reveal a G-dwarf companion star with temperatures of and at its inferior and superior orbital conjunctions, respectively, and a radial velocity semi-amplitude of . Our best-fit model yields a neutron star mass of and a companion mass of . Based on the close similarity between the optical light curve of PSR~J2055+1545 and those observed from PSR J1023+0038 and PSR J1227-4853 during their rotation-powered states, we suggest this system may develop an accretion disc in the future and manifest as a transitional millisecond pulsar.
... Among the known spider MSPs, periodic variations in the optical observations have been discovered (S. J. Swihart et al. 2021Swihart et al. , 2022b; J. P. Halpern 2022; J. P. Halpern et al. 2022;K.-Y. Au et al. 2023). There are two main causes for these optical periodicities: pulsar irradiation and ellipsoidal modulation. The former effect is due to the fact that the side of the companion facing the pulsar is hotter and thus brighter, while the latter is attributed to tidal distortion of the companion. Based on follow-up observations combining the ...
Spider pulsars represent a unique subclass of radio millisecond pulsars in binaries, and are further categorized into black widows and redbacks according to the mass of the low-mass companion. These pulsars, observable across multiple wavelengths, exhibit periodic variability in optical. The discovery and study of additional spider-type pulsars are crucial for a fuller understanding the evolution of binary stars in close orbits and the recycling theory of millisecond pulsars. In this work, we systematically searched for spider pulsar binary systems using time-domain variability data from the Zwicky Transient Facility and unassociated gamma-ray sources from the Fermi 4FGL-DR3 catalog. We developed a time-domain data processing pipeline that employs the Lomb–Scargle periodogram algorithm. As a result, we identified a total of 194 ellipsoidal variables and irradiation-type binary stars. Further refinement using the Gaia Hertzsprung–Russell diagram resulted in a selection of 24 spider pulsar candidates. Incorporating the 4FGL 95% confidence error ellipse reduced the sample to 19 candidates. An additional filter using the Gaia color-reduced proper motion diagram yielded nine “gold sample” candidates. These newly identified spider pulsar candidates will guide future observational campaigns in radio, X-ray, and optical spectroscopy, aiding in the comprehensive validation of their nature.
... Among the known spider MSPs, periodic variations in the optical observations have been discovered (Swihart et al. 2021(Swihart et al. , 2022bHalpern 2022;Halpern et al. 2022;Au et al. 2023), and there are two main causes for these optical periodicity: pulsar irradiation and ellipsoidal modulation. The former effect is due to the fact that the side of the companion facing the pulsar is hotter and thus brighter, while the latter is attributed to tidal distortion of the companion. ...
Spider pulsars constitute a distinct subset within the domain of radio millisecond pulsars, divided further into the categories of black widows and redbacks. Evident across multiple wavelengths, these pulsars manifest periodic variations and reside within binary systems. Investigating and discovering additional spider-type pulsars carries significant implications for comprehending the evolution of high-mass stars. Particularly crucial is the validation of the "Recycling" theory of millisecond pulsar genesis. In this investigation, we systematically explore spider pulsar binary systems utilizing time-domain variability data from the Zwicky Transient Facility, in conjunction with Fermi unassociated gamma-ray sources sourced from the 4FGL-DR3 catalog. We have implemented a time-domain data processing pipeline utilizing the Lomb-Scargle Periodogram algorithm, integrated with the wget data crawling technology. This approach has led to the identification of 194 ellipsoidal variables and irradiation-type binary stars. Subsequent refinement through the Gaia Hertzsprung-Russell diagram has culled a selection of 24 spider pulsar gold sample candidates. By incorporating the 4FGL 95\% confidence error ellipse, the pool was narrowed down to 19 gold sample candidates. Utilizing the Gaia color-reduced proper motion diagram further refined the selection to 9 gold sample candidates. These newly identified spider pulsar candidates will inform subsequent observational campaigns across radio, X-ray, and optical spectroscopy, thereby facilitating a deeper validation of their physical characteristics.
... This has included the majority of spider-type systems (e.g. Barr et al. 2013 ;Bhattacharyya et al. 2013 ;Camilo et al. 2015 ;Cromartie et al. 2016 ;Au et al. 2023 ;Clark et al. 2023b ). There is also growing population of convincing spider candidates (lacking detections of pulses at radio or γ -ray wavelengths) identified by follow-up of Fermi sources at X-ray and optical wavelengths (e.g. ...
Large widefield surveys make possible the serendipitous discovery of rare subclasses of pulsars. One such class are ‘spider’-type pulsar binaries, comprised of a pulsar in a compact orbit with a low-mass (sub)stellar companion. In a search for circularly polarized radio sources in Australian Square Kilometre Array Pathfinder (ASKAP) Pilot Survey observations, we discovered highly variable and circularly polarized emission from a radio source within the error region of the γ-ray source 4FGL J1646.5−4406. The variability is consistent with the eclipse of a compact, steep-spectrum source behind ablated material from a companion in an ∼5.3 h binary orbit. Based on the eclipse properties and spatial coincidence with 4FGL J1646.5−4406, we argue that the source is likely a recycled pulsar in a ‘redback’ binary system. Using properties of the eclipses from ASKAP and Murchison Widefield Array observations, we provide broad constraints on the properties of the eclipse medium. We identified a potential optical/infrared counterpart in archival data consistent with a variable low-mass star. Using the Parkes radio telescope ‘Murriyang’ and the Meer Karoo Array Telescope (MeerKAT) , we searched extensively for radio pulsations but yielded no viable detections of pulsed emission. We suggest that the non-detection of pulses is due to scattering in the intra-binary material, but scattering from the interstellar medium can also plausibly explain the pulse non-detections if the interstellar dispersion measure exceeds ∼600 pc cm−3. Orbital constraints derived from optical observations of the counterpart would be highly valuable for future γ-ray pulsation searches, which may confirm the source nature as a pulsar.
... In particular, optical studies allow one to clarify the spectral type of the companion star, its mass and irradiation efficiency by the pulsar, the distance to the system, the binary inclination, and the pulsar mass. Only about four dozen confirmed spiders and about one dozen of candidates have been detected in the optical so far (Strader et al. 2019 ;Miller et al. 2020 ;Swihart et al. 2020Swihart et al. , 2021Swihart et al. , 2022Au et al. 2023 ;Karpova et al. 2023 ;Yap, Kong & Li 2023 ). Parameters of many of them are poorly constrained due to the faintness of these objects. ...
An unidentified γ-ray source 4FGL J1838.2+3223 has been proposed as a pulsar candidate. We present optical time-series multi-band photometry of its likely optical companion obtained with the 2.1-m telescope of Observatorio Astronómico Nacional San Pedro Mártir, Mexico. The observations and the data from the Zwicky Transient Facility revealed the source brightness variability with a period of ≈4.02 h likely associated with the orbital motion of the binary system. The folded light curves have a single sine-like peak per period with an amplitude of about three magnitude accompanied by fast sporadic flares up to one magnitude level. We reproduce them modelling the companion heating by the pulsar. As a result, the companion side facing the pulsar is strongly heated up to 11300±400 K, while the temperature of its back side is only 2300±700 K. It has a mass of 0.10±0.05 M⊙ and underfills its Roche lobe with a filling factor of . This implies that 4FGL J1838.2+3223 likely belongs to the ‘spider’ pulsar family. The estimated distance of ≈3.1 kpc is compatible with Gaia results. We detect a flare from the source in X-rays and ultraviolet using Swift archival data and another one in X-rays with the eROSITA all-sky survey. Both flares have X-ray luminosity of ∼1034 erg s−1 which is two orders of magnitude higher than the upper limit in quiescence obtained from eROSITA assuming spectral shape typical for spider pulsars. If the spider interpretation is correct, these are ones of the strongest flares seen from non-accreting spider pulsars.
... For known spiders, the median distance from the radio counterpart is 0.1 arcsec [radio timing locations are from Australia Telescope National Facility (ATNF) PSRCAT 5 ]. Three redbacks that were identified in the TRAPUM surv e y 6 by Clark et al. ( 2023 ) and Au et al. ( 2023 ) have a radio position accuracy of a few arcseconds with one Gaia source in the beam. Six Gaia candidates have larger than 0.2 arcsec separation from the radio position: PSR J1306 − 40, PSR J1723 − 2837, PSR J1908 + 2105, PSR J2129 − 0429, PSR J1959 + 2048, and PSR J2055 + 3829. ...
In this paper, we study compact binary millisecond pulsars with low- and very low-mass companion stars (spiders) in the Galactic field, using data from the latest Gaia data release (DR3). We infer the parallax distances of the optical counterparts to spiders, which we use to estimate optical and X-ray luminosities. We compare the parallax distances to those derived from radio pulse dispersion measures and find that they have systematically larger values, by 40% on average. We also test the correlation between X-ray and spin-down luminosities, finding that most redbacks have a spin-down to X-ray luminosity conversion efficiency of ∼0.1%, indicating a contribution from the intrabinary shock. On the other hand, most black widows have an efficiency of ∼0.01%, similar to the majority of the pulsar population. Finally, we find that the bolometric optical luminosity significantly correlates with the orbital period, with a large scatter due to different irradiated stellar temperatures and binary properties. We interpret this correlation as the effect of the increasing size of the Roche Lobe radius with the orbital period. With this newly found correlation, an estimate of the optical magnitude can be obtained from the orbital period and a distance estimate.
... A great success in unco v ering spider pulsars has been achieved thanks to the Fermi Gamma-ray Space Telescope. About two tens of promising RB and BW candidates are proposed through identifications of possible optical and/or X-ray counterparts to γ -ray sources Miller et al. 2020 ;Swihart et al. 2020Swihart et al. , 2021Swihart et al. , 2022Au et al. 2023 ). Ho we ver, the Data Release 3 of the fourth Fermi Large Area Telescope (LAT) catalogue (4FGL-DR3) contains more than 2000 unassociated γ -ray sources (Abdollahi et al. 2022 ). ...
The Fermi catalogue contains about 2000 unassociated γ-ray sources. Some of them were recently identified as pulsars, including so called redbacks and black widows, which are millisecond pulsars in tight binary systems with non- and partially-degenerate low-mass stellar companions irradiated by the pulsar wind. We study a likely optical and X-ray counterpart of the Fermi source 4FGL J2054.2+6904 proposed earlier as a pulsar candidate. We use archival optical data as well as Swift/XRT and SRG/eROSITA X-ray data to clarify its nature. Using Zwicky Transient Facility data in g and r bands spanning over 4.7 years, we find a period of ≈7.5 h. The folded light curve has a smooth sinusoidal shape with the peak-to-peak amplitude of ≈0.4 mag. The spectral fit to the optical spectral energy distribution of the counterpart candidate gives the star radius of 0.5±0.1 R⊙ and temperature of 5500±300 K implying a G2–G9-type star. Its X-ray spectrum is well fitted by an absorbed power law with the photon index of 1.0±0.3 and unabsorbed flux of ≈2 × 10−13 erg s−1 cm−2. All the properties of 4FGL J2054.2+6904 and its presumed counterpart suggest that it is a member of the redback family.
... A great success in uncovering spider pulsars has been achieved thanks to the Fermi Gamma-ray Space Telescope. About two tens of promising RB and BW candidates are proposed through identifications of possible optical and/or X-ray counterparts to -ray sources Miller et al. 2020;Swihart et al. 2020Swihart et al. , 2021Swihart et al. , 2022Au et al. 2023). However, the Data Release 3 of the fourth Fermi Large Area Telescope (LAT) catalog (4FGL-DR3) contains more than 2000 unassociated -ray sources (Abdollahi et al. 2022). ...
The Fermi catalogue contains about 2000 unassociated -ray sources. Some of them were recently identified as pulsars, including so called redbacks and black widows, which are millisecond pulsars in tight binary systems with non- and partially-degenerate low-mass stellar companions irradiated by the pulsar wind. We study a likely optical and X-ray counterpart of the Fermi source 4FGL J2054.2+6904 proposed earlier as a pulsar candidate. We use archival optical data as well as Swift/XRT and SRG/eROSITA X-ray data to clarify its nature. Using Zwicky Transient Facility data in g and r bands spanning over 4.7 years, we find a period of 7.5 h. The folded light curve has a smooth sinusoidal shape with the peak-to-peak amplitude of 0.4 mag. The spectral fit to the optical spectral energy distribution of the counterpart candidate gives the star radius of 0.50.1 and temperature of 5500300 K implying a G2--G9-type star. Its X-ray spectrum is well fitted by an absorbed power law with the photon index of 1.00.3 and unabsorbed flux of erg s cm. All the properties of 4FGL J2054.2+6904 and its presumed counterpart suggest that it is a member of the redback family.
