Luminous Optical and X-Ray Flaring of the Putative Redback Millisecond Pulsar 1FGL J0523.5–2529

Halpern, J. P.; Perez, Karen I.; Bogdanov, Slavko

doi:10.3847/1538-4357/ac8161

Cited by 7 publications

(7 citation statements)

References 97 publications

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“…It is unclear whether this picture may describe all flares from the source. We note that similar flares at X-ray and optical wavelengths are observed in other similar systems (see e.g., Halpern et al 2022 and references therein) -flaring emission in the candidate redback 1FGL J0523.5−2529 has a non-thermal shape in the optical range, suggesting that flares come from above the photosphere of the star, which is possibly related to reconnection of the striped pulsar magnetic field compressed in the IBS (Halpern et al 2022). In any case, the possible analogy of pulses and flares seems hardly reconcilable with the lack of any flux variation in the U and in the g band 11 , correlated with the X-ray pulses (see Table 2).…”

Section: Discussionsupporting

confidence: 85%

A puzzling 2-hour X-ray periodicity in the 1.5-hour orbital period black widow PSR J1311−3430

Luca

Marelli

Mereghetti

et al. 2022

A&A

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Time-domain analysis of an archival XMM-Newton observation unveiled a very unusual variability pattern in the soft X-ray emission of PSR J1311−3430, a black widow millisecond pulsar in a tight binary (P B = 93.8 min) with a very low-mass (M ∼ 0.01 M ⊙ ) He companion star, known to show flaring emission in the optical and in the X-rays. A series of six pulses with a regular recurrence time of ∼ 124 min is apparent in the 0.2−10 keV light curve of the system, also featuring an initial, bright flare and a quiescent phase lasting several hours. The X-ray spectrum does not change when the pulses are seen and is consistent with a power law with photon index Γ ∼ 1.6, also describing the quiescent emission. The peak luminosity of the pulses is of several 10 32 erg s −1 . Simultaneous observations in the U band with the Optical Monitor onboard XMM and in the g' band from the Las Cumbres Observatory do not show any apparent counterpart of the pulses and only display the well-known orbital modulation of the system. We consider different hypotheses to explain the recurrent pulses: we investigate their possible analogy with other phenomena already observed in this pulsar and in similar systems and we also study possible explanations related to the interaction of the energetic pulsar wind with intrabinary material, but we found none of these pictures to be convincing. We identify simultaneous X-ray observations and optical spectroscopy as a possible way to constrain the nature of the phenomenon.

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Section: Discussionsupporting

confidence: 85%

A puzzling 2-hour X-ray periodicity in the 1.5-hour orbital period black widow PSR J1311−3430

Luca

Marelli

Mereghetti

et al. 2022

A&A

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“…The observing conditions were similar during each SOAR night, and we used the exact same set of comparison stars in our analysis, so we conclude the variations we see in the photometry are real. These flaring optical light curves are not uncommon in spider binaries, with similar phenomenology seen in the black widow candidate 4FGL J0935.3+0901 (Halpern 2022) and in a few confirmed and candidate redbacks (Cho et al 2018;Halpern et al 2022).…”

Section: Optical Light Curvesupporting

confidence: 67%

“…Setting aside disk-dominated spectra of transitional MSPs or candidate members of this class, there are 15 redbacks with published optical spectroscopy. Of these, 5 (33%) show prominent emission lines: 1FGL J0523.5-2529 (Halpern et al 2022), 3FGL J0838.8-2829(Halpern et al 2017, PSR J1048+2339 (Strader et al 2019), PSR J1306-40 (Swihart et al 2019), and PSR J1628-3205 (Strader et al 2019). Both of the huntsman sources 1FGL J1417.7-4407 (Strader et al 2015;Swihart et al 2018) and 2FGL J0846.0+2820 (Swihart et al 2017) also show emission, as does the subgiant-MSP binary PSR J1740-5340A in the globular cluster NGC 6397 (Sabbi et al 2003).…”

Section: Emission Linesmentioning

confidence: 98%

“…For example, in the candidate redback 1FGL J0523.5-2529, Halpern et al (2022) infer the optical flaring and spectral emission features are nonthermal, coming from above the photosphere of the secondary and presumably associated with the companion wind outflow and/or the intrabinary shock. A similar conclusion was reached for the origin of the emission lines in the "huntsmen" MSP 1FGL J1417.7-4402 (Swihart et al 2018).…”

Section: Emission Linesmentioning

confidence: 99%

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A New Flaring Black Widow Candidate and Demographics of Black Widow Millisecond Pulsars in the Galactic Field

Swihart

Strader

Chomiuk

et al. 2022

ApJ

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We present the discovery of a new optical/X-ray source likely associated with the Fermi γ-ray source 4FGL J1408.6–2917. Its high-amplitude periodic optical variability, large spectroscopic radial-velocity semiamplitude, evidence for optical emission lines and flaring, and X-ray properties together imply the source is probably a new black widow millisecond pulsar binary. We compile the properties of the 41 confirmed and suspected field black widows, finding a median secondary mass of 0.027 ± 0.003 M ⊙. Considered jointly with the more massive redback millisecond pulsar binaries, we find that the “spider” companion mass distribution remains strongly bimodal, with essentially zero systems having companion masses of between ∼0.07 and 0.1 M ⊙. X-ray emission from black widows is typically softer and less luminous than in redbacks, consistent with less efficient particle acceleration in the intrabinary shock in black widows, excepting a few systems that appear to have more efficient “redback-like” shocks. Together black widows and redbacks dominate the census of the fastest spinning field millisecond pulsars in binaries with known companion types, making up ≳80% of systems with P spin < 2 ms. Similar to redbacks, the neutron star masses in black widows appear on average significantly larger than the canonical 1.4 M ⊙, and many of the highest-mass neutron stars claimed to date are black widows with M NS ≳ 2.1 M ⊙. Both of these observations are consistent with an evolutionary picture where spider millisecond pulsars emerge from short orbital period progenitors that had a lengthy period of mass transfer initiated while the companion was on the main sequence, leading to fast spins and high masses.

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“…While a detailed heating model was applied by Shahbaz et al (2017) to the original light curves of Linares et al (2017), it is now apparent that different results would necessarily be obtained at other epochs. The now familiar variability of redback companion light curves (Li et al 2014;Bellm et al 2016;van Staden & Antoniadis 2016;Cho et al 2018;Clark et al 2020;Halpern et al 2022) can be attributed to one or more causes: changing Roche-lobe filling factor, starspots, variable photospheric heating by the intrabinary shock, and/or heating by the magnetically ducted pulsar wind.…”

Section: Light-curve Variabilitymentioning

confidence: 99%

Green Bank Telescope Discovery of the Redback Binary Millisecond Pulsar PSR J0212+5321

Perez

Bogdanov

Halpern

et al. 2023

ApJ

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We report the discovery of a 2.11 ms binary millisecond pulsar during a targeted search of the redback optical candidate coincident with the γ-ray source 3FGL J0212.5+5320 using the Robert C. Byrd Green Bank Telescope (GBT) with the Breakthrough Listen backend at L band. Over a seven month period, five pointings were made near inferior conjunction of the pulsar in its 20.9 hr orbit, resulting in two detections, lasting 12 and 42 minutes. The pulsar dispersion measure (DM) of 25.7 pc cm−3 corresponds to a distance of 1.15 kpc in the NE2001 Galactic electron density model, consistent with the Gaia parallax distance of 1.16 ± 0.03 kpc for the companion star. We suspect the pulsar experiences wide orbital eclipses, similar to other redbacks, as well as scintillation and DM delays caused by its interaction with its companion and surroundings. Although the pulsar was only detected over ≈3.7% of the orbit, its measured acceleration is consistent with published binary parameters from optical radial velocity spectroscopy and light-curve modeling of the companion star, and it provides a more precise mass ratio and a projected semimajor axis for the pulsar orbit. We also obtained a refined optical photometric orbit ephemeris, and observed variability of the tidally distorted companion over 7 yr. A hard X-ray light curve from NuSTAR shows expected orbit-modulated emission from the intrabinary shock. The pulsar parameters and photometric ephemeris greatly restrict the parameter space required to search for a coherent timing solution including pulsar spin-down rate, either using Fermi γ-rays or further radio pulse detections.

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Luminous Optical and X-Ray Flaring of the Putative Redback Millisecond Pulsar 1FGL J0523.5–2529

Cited by 7 publications

References 97 publications

A puzzling 2-hour X-ray periodicity in the 1.5-hour orbital period black widow PSR J1311−3430

A puzzling 2-hour X-ray periodicity in the 1.5-hour orbital period black widow PSR J1311−3430

A New Flaring Black Widow Candidate and Demographics of Black Widow Millisecond Pulsars in the Galactic Field

Green Bank Telescope Discovery of the Redback Binary Millisecond Pulsar PSR J0212+5321

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