Pulsar Planets

PSR B0329+54 is back!

On The Existence of Planets Around the Pulsar PSR B0329+54
https://arxiv.org/abs/1710.01153

Quote :

Results of timing measurements of the pulsar PSR B0329+54 obtained in 1968--2012 using the Big Scanning Antenna of the Pushchino Radio Astronomy Observatory (at 102 and 111 MHz), the DSS 13 and DSS 14 telescopes of the Jet Propulsion Laboratory (2388 MHz), and the 64 m telescope of the Kalyazin Radio Astronomy Observatory (610 MHz) are presented. The astrometric and rotational parameters of the pulsar are derived at a new epoch. Periodic variations in the barycentric timing residuals have been found, which can be explained by the presence of a planet orbiting the pulsar, with an orbital period P1 = 27.8 yr, mass \textit{mc}sin\textit{i} = 2M⊕, and orbital semi-major axis a = 10.26 AU. The results of this study do not confirm existence of a proposed second planet with orbital period P2 = 3 yr.

Well, quite longer orbital period but that's certainly a great return.

Listed in EPE:

http://exoplanet.eu/catalog/psr_b0329%2B54_b/

Along with quite an unnoticed multiplanet system with two gas giants:

http://exoplanet.eu/catalog/psr_b0943%2B10_b/
http://exoplanet.eu/catalog/psr_b0943%2B10_c/

That's been out for three years and nobody knew about it?

Yes, right. Moreover a couple of Jovian planets around a neutron star is not a negligible a piece of news, both survived to the supernova phase.

PSR B0943+10 is an interesting one, unfortunately the papers claiming planets are paywalled and the only non-paywalled reference I can find is in Russian - at least I think it's Russian, unfortunately it isn't playing nice with copy/paste so I can't try Google Translate's "Detect language" feature. Not sure what to make of it or why it hasn't attracted more attention, but this pulsar does seem to be notable for mode-switching behaviour, not sure whether that would lead to planet-mimicking effects.

Edit: Note that the link to the paper pdf now appears to be dead, I have updated it to the ADS info page. See Daniel's later post for an English-language version.

The results of timing observations of the pulsar PSR B0943+10 demonstrating
mode swithing phenomenon at radio and X-ray frequencies are presented. Observations were
carried out at 112 MHz over MJD span 54150-57660. Additional circumstances have been found pointing to the presence of two planets orbiting the pulsar with periods of about 792 and 1583 days

Lazarus wrote:

PSR B0943+10 is an interesting one, unfortunately the papers claiming planets are paywalled and the only non-paywalled reference I can find is in Russian (pdf) - at least I think it's Russian, unfortunately it isn't playing nice with copy/paste so I can't try Google Translate's "Detect language" feature. Not sure what to make of it or why it hasn't attracted more attention, but this pulsar does seem to be notable for mode-switching behaviour, not sure whether that would lead to planet-mimicking effects.

I Found the free version in english of this paper, I've download for free,it's a fascinating Pulsar Planetary System.  

Detection of Regular Variations in the Intensity and Pulse Time of Arrival of the Anomalous Pulsar PSR B0943+10

https://www.researchgate.net/publication/268386644_Detection_of_Regular_Variations_in_the_Intensity_and_Pulse_Time_of_Arrival_of_the_Anomalous_Pulsar_PSR_B094310

Is It PSR B0943+10 planetary system different of  PSR B0329+54 planetary system? Is it supposed have a separate page just for PSR B0943+10?

Daniel wrote:

I Found the free version in english of this paper, I've download for free,it's a fascinating Pulsar Planetary System.  

Detection of Regular Variations in the Intensity and Pulse Time of Arrival of the Anomalous Pulsar PSR B0943+10

https://www.researchgate.net/publication/268386644_Detection_of_Regular_Variations_in_the_Intensity_and_Pulse_Time_of_Arrival_of_the_Anomalous_Pulsar_PSR_B094310

Thanks for finding that! Will be interesting to see if the proposed system holds up in terms of dynamical stability.

Going back to the pulsar mentioned in the thread title, Elena Starovoit's presentation at the IAU 2018 meeting included both PSR B0329+54 and PSR B0525+21. Regarding PSR B0525+21, again I find a reference that is in Russian: http://adsabs.harvard.edu/abs/2018ATsir1642....1R

Daniel wrote:

Is It PSR B0943+10 planetary system different of PSR B0329+54 planetary system? Is it supposed have a separate page just for PSR B0943+10?

These are two different pulsars, so yes this thread seems to have undergone a bit of "scope creep"

Lazarus wrote:

Daniel wrote:

I Found the free version in english of this paper, I've download for free,it's a fascinating Pulsar Planetary System.  

Detection of Regular Variations in the Intensity and Pulse Time of Arrival of the Anomalous Pulsar PSR B0943+10

https://www.researchgate.net/publication/268386644_Detection_of_Regular_Variations_in_the_Intensity_and_Pulse_Time_of_Arrival_of_the_Anomalous_Pulsar_PSR_B094310

Thanks for finding that! Will be interesting to see if the proposed system holds up in terms of dynamical stability.

Going back to the pulsar mentioned in the thread title, Elena Starovoit's presentation at the IAU 2018 meeting included both PSR B0329+54 and PSR B0525+21. Regarding PSR B0525+21, again I find a reference that is in Russian: http://adsabs.harvard.edu/abs/2018ATsir1642....1R

Daniel wrote:

Is It PSR B0943+10 planetary system different of  PSR B0329+54 planetary system? Is it supposed have a separate page just for PSR B0943+10?

These are two different pulsars, so yes this thread seems to have undergone a bit of "scope creep"

About PSR B0525+21 I found this:

https://astronomy2018.univie.ac.at/abstractsiaus348

Third pulsar in the same thread will mess it even more

Do we need to make this a general pulsar planet thread?
Certainly with their discovery rate, it's not like it'll be that long a thread.

Yeah... so... using that equation on wikipedia's Apsidal Precession page, I get an apsidal precession that's actually slightly less than Mercury's. 4.112e-7 for PSR B0525+21 b, vs 5.028e-7 for Mercury (in radians per second?).

Elena Starovot wrote:

Additionally, the precession of the planet's line of apses has been measured, and it is dφ = -0.77 rad/period.

Can someone explain this? Am I misunderstanding this? I get the impression from that quote that the orbit precesses at like 45 degrees per orbit. Something I was fine with until a friend of mine questioned it with me, causing me to calculate the periapsis was a whole ~0.3 AU, which caused me to try to calculate the precession rate. Now I don't know what's going on. Incorrect abstract? Relativistic weirdness near the pulsar?

Oh wow, somehow the units didn't register with me. That's a completely insane rate of precession, definitely looks like it's far beyond anything GR would do. The Russian paper I linked upthread gives a slightly different but still extremely problematic value of -0.67 radians/period, so looks like if the values are in error, this is consistent with the previous work.

Unfortunately don't know any Russian to see whether there's any attempt to physically justify that precession value. If the value is correct, I wouldn't be surprised if it implies that the variations are not caused by reflex motion due to a planet.

I know well russian but seldom read it, I will read the paper soon.

Well, here's a thread bump, albeit delayed (February 2020!)

The 31-year Rotation History of the Millisecond Pulsar J1939+2134 (B1937+21)

Quote :

The timing properties of the millisecond pulsar PSR J1939+2134 -- very high rotation frequency, very low time derivative of rotation frequency, no timing glitches and relatively low timing noise -- are responsible for its exceptional timing stability over decades. It has been timed by various groups since its discovery, at diverse radio frequencies, using different hardware and analysis methods. Most of this timing data is now available in the public domain in two segments, which have not been combined so far. This work analyzes the combined data by deriving uniform methods of data selection, derivation of Dispersion Measure (DM), accounting for correlation due to "red" noise, etc. The timing noise of this pulsar is very close to a sinusoid, with a period of approximately 31 years. The main results of this work are (1) The clock of PSR J1939+2134 is stable at the level of almost one part in 1015 over about 31 years, (2) the power law index of the spectrum of electron density fluctuations in the direction of PSR J1939+2134 is 3.86±0.04, (3) a Moon sized planetary companion, in an orbit of semi major axis about 11 astronomical units and eccentricity ≈0.2, can explain the timing noise of PSR J1939+2134, (4) Precession under electromagnetic torque with very small values of oblateness and wobble angle can also be the explanation, but with reduced confidence, and (5) there is excess timing noise of about 8 μs amplitude during the epochs of steepest DM gradient, of unknown cause.

Emphasis mine, of course.

So does this (more recent) one sound interesting

The GBT 350-MHz Drift Scan Pulsar Survey. III. Detection of a magnetic field in the eclipsing material of PSR J2256-1024

Quote :

We present the first measurement of a non-zero magnetic field in the eclipsing material of a black widow pulsar. Black widows are millisecond pulsars which are ablating their companions; therefore they are often proposed as one potential source of isolated millisecond pulsars. PSR J2256-1024 is an eclipsing black widow discovered at radio wavelengths and later also observed in the X-ray and gamma parts of the spectrum. Here we present the radio timing solution for PSR J2256-1024, polarization profiles at 350, 820, and 1500~MHz and an investigation of changes in the polarization profile due to eclipsing material in the system. In the latter we find evidence of Faraday rotation in the linear polarization shortly after eclipse, measuring a rotation measure of 0.44(6) rad per meter squared and a corresponding line-of-sight magnetic field of 3.5(17) mG.

Companion's (minimum) mass is about 31-33 M_Jup.

Quote :

About PSR B0525+21 I found this:

https://astronomy2018.univie.ac.at/abstractsiaus348

Third pulsar in the same thread will mess it even more

The planet hypothesis is still considered with additional details too.

A Putative Planet Orbiting the Pulsar PSR B0525+21

Quote :

Using the example of the pulsar B0525+21, a fundamentally new explanation has been proposed for the abrupt period changes observed in many pulsars, namely the presence of a companion orbiting the pulsar in a highly eccentric orbit. A model is presented describing the behavior of the barycentric timing residuals of B0525+21 in observations with the DSS 13 and DSS 14 radio telescopes of the Jet Propulsion Laboratory and the Jodrell Bank Lovell radio telescope. The proposed model describes the motion of PSR B0525+21 in a binary system with a planetary secondary moving in an elliptical orbit with period P = 27.74 years, semi-major axis a = 10.35 AU, eccentricity e = 0.96, and mass mc = 0.39M⊕. The angular velocity of the pericenter motion ω˙=0.67ω˙=0.67 rad/period has been measured; the presence of this motion provides evidence for a gas–dust disk or asteroid belt around the pulsar.

Also this one is very interesting (and open access...)

Periodic activity from fast radio burst FRB180916 explained in the frame of the orbiting asteroid model

Quote :

Observation of fast radio bursts (FRBs) are rising very quickly with the advent of specialized instruments and surveys, and it has recently been shown that some of them repeat quasi-periodically. In particular, evidence of a P = 16.35 d period has been reported for FRB 180916.J0158+65. We seek an explanation within the frame of our orbiting asteroid model, whereby FRBs are produced in the plasma wake of asteroids immersed in the wind of a pulsar or a magnetar. We used the data reported by the CHIME/FRB collaboration in order to infer the orbital characteristics of asteroid swarms, and performed parametric studies to explore the possible characteristics of the pulsar, its wind, and of the asteroids, under the constraint that the latter remain dynamically and thermally stable. We found a plausible configuration in which a young pulsar is orbited by a main ~10^-3 M⊙ companion with a period 3P = 49 d, three times longer than the apparent periodicity P. Asteroids responsible for FRBs are located in three dynamical swarms near the L3, L4, and L5 Lagrange points, in a 2:3 orbital resonance akin to the Hildas class of asteroids in the Solar system. In addition, asteroids could be present in the Trojan swarms at the L4 and L5 Lagrange points. Together, these swarms form a carousel that explains the apparent P periodicity and dispersion. We estimated that the presence of at least a few thousand asteroids, of size ~20 km, is necessary to produce the observed burst rate. We show how radius-to-frequency mapping in the wind and small perturbations by turbulence can suffice to explain downward-drifting sub-pulses, micro-structures, and narrow spectral occupancy.

Several pulsar planet candidates, the most robust one at PSR J2007+3120.

A search for planetary companions around 800 pulsars from the Jodrell Bank pulsar timing programme

Quote :

We have searched for planetary companions around 800 pulsars monitored at the Jodrell Bank Observatory, with both circular and eccentric orbits of periods between 20 days and 17 years and inclination-dependent planetary masses from 10−4 to 100M⊕. Using a Bayesian framework, we simultaneously model pulsar timing parameters and a stationary noise process with a power-law power spectral density. We put limits on the projected masses of any planetary companions, which reach as low as 1/100th of the mass of the Moon (∼10−4M⊕). We find that two-thirds of our pulsars are highly unlikely to host any companions above 2−8M⊕. Our results imply that fewer than 0.5% of pulsars could host terrestrial planets as large as those known to orbit PSR B1257+12 (∼4M⊕); however, the smaller planet in this system (∼0.02M⊕) would be undetectable in 95% of our sample, hidden by both instrumental and intrinsic noise processes, although it is not clear if such tiny planets could exist in isolation. We detect significant periodicities in 15 pulsars, however we find that intrinsic quasi-periodic magnetospheric effects can mimic the influence of a planet, and for the majority of these cases we believe this to be the origin of the detected periodicity. Notably, we find that the highly periodic oscillations in PSR B0144+59 are correlated with changes in the pulse profile and therefore can be attributed to magnetospheric effects. We believe the most plausible candidate for planetary companions in our sample is PSR J2007+3120.

Circumbinary pulsar planet? With neutron star host itself binary with a substellar companion (0.06 M_Sol).

Is the black-widow pulsar PSR J1555-2908 in a hierarchical triple system?

Quote :

The 559 Hz black-widow pulsar PSR J1555-2908, originally discovered in radio, is also a bright gamma-ray pulsar. Timing its pulsations using 12 yr of Fermi-LAT gamma-ray data reveals long-term variations in its spin frequency that are much larger than is observed from other millisecond pulsars. While this variability in the pulsar rotation rate could be intrinsic "timing noise", here we consider an alternative explanation: the variations arise from the presence of a very-low-mass third object in a wide multi-year orbit around the neutron star and its low-mass companion. With current data, this hierarchical-triple-system model describes the pulsar's rotation slightly more accurately than the best-fitting timing-noise model. Future observations will show if this alternative explanation is correct.

Excerpt from the paper:

Quote :

The binary mass function may be used to estimate the mass of the outer companion (see Fig. 2). For common pulsar masses 1.4 < Mp < 2.0 M_Sol, an inner companion mass M_i = 0.06 M_Sol (Kennedy et al. 2022, submitted), and inclination angles 30◦-90◦, the outer companion would have roughly a Mercury-like mass 0.02M⊕ < Mo < 0.06M⊕. To date, this companion would still be listed among the four lowest-mass extrasolar planets.

Apologies if I'm insisting on this latter paper, but I find it very interesting, worth being mentioned in EPE

Periodic activity from fast radio burst FRB180916 explained in the frame of the orbiting asteroid model

Quote :

Observation of fast radio bursts (FRBs) are rising very quickly with the advent of specialized instruments and surveys, and it has recently been shown that some of them repeat quasi-periodically. In particular, evidence of a P = 16.35 d period has been reported for FRB 180916.J0158+65. We seek an explanation within the frame of our orbiting asteroid model, whereby FRBs are produced in the plasma wake of asteroids immersed in the wind of a pulsar or a magnetar. We used the data reported by the CHIME/FRB collaboration in order to infer the orbital characteristics of asteroid swarms, and performed parametric studies to explore the possible characteristics of the pulsar, its wind, and of the asteroids, under the constraint that the latter remain dynamically and thermally stable. We found a plausible configuration in which a young pulsar is orbited by a main ~10^-3 M⊙ companion with a period 3P = 49 d, three times longer than the apparent periodicity P. Asteroids responsible for FRBs are located in three dynamical swarms near the L3, L4, and L5 Lagrange points, in a 2:3 orbital resonance akin to the Hildas class of asteroids in the Solar system. In addition, asteroids could be present in the Trojan swarms at the L4 and L5 Lagrange points. Together, these swarms form a carousel that explains the apparent P periodicity and dispersion. We estimated that the presence of at least a few thousand asteroids, of size ~20 km, is necessary to produce the observed burst rate. We show how radius-to-frequency mapping in the wind and small perturbations by turbulence can suffice to explain downward-drifting sub-pulses, micro-structures, and narrow spectral occupancy.

Emphasis mine.

Another planetary-mass companion to a black widow-type pulsar, but here the orbital period is quite longer than other similar systems (17.5 hours = 0.73024 d), very close to that of Hot Jupiters. Could this be a "survivor planet"?

Pulsar searches of Fermi unassociated sources with the Effelsberg telescope

Quote :

Using the 100-m Effelsberg radio telescope operating at 1.36 GHz, we have performed a targeted radio pulsar survey of 289 unassociated γ-ray sources discovered by the Large Area Telescope (LAT) aboard the Fermi satellite and published in the 1FGL catalogue (Abdo et al. 2010a). This survey resulted in the discovery of millisecond pulsar J1745+1017, which resides in a short-period binary system with a low-mass companion, M_c,min ∼ 0.0137 M_⊙, indicative of "black widow" type systems. A 2-yr timing campaign has produced a refined radio ephemeris, accurate enough to allow for phase-folding of the LAT photons, resulting in the detection of a dual-peaked γ-ray light curve, proving that PSR J1745+1017 is the source responsible for the γ-ray emission seen in 1FGL J1745.5+1018 (2FGL J1745.6+1015; Nolan et al. 2012). We find the γ-ray spectrum of PSR J1745+1017 to be well modelled by an exponentially cut-off power law with cut-off energy 3.2 GeV and photon index 1.6. The observed sources are known to contain a further 10 newly discovered pulsars which were undetected in this survey. Our radio observations of these sources are discussed and in all cases limiting flux densities are calculated. The reasons behind the seemingly low yield of discoveries are also discussed.

Quote :

Another planetary-mass companion to a black widow-type pulsar, but here the orbital period is quite longer than other similar systems (17.5 hours = 0.73024 d), very close to that of Hot Jupiters. Could this be a "survivor planet"?

Pulsar searches of Fermi unassociated sources with the Effelsberg telescope

Quote :

Using the 100-m Effelsberg radio telescope operating at 1.36 GHz, we have performed a targeted radio pulsar survey of 289 unassociated γ-ray sources discovered by the Large Area Telescope (LAT) aboard the Fermi satellite and published in the 1FGL catalogue (Abdo et al. 2010a). This survey resulted in the discovery of millisecond pulsar J1745+1017, which resides in a short-period binary system with a low-mass companion, M_c,min ∼ 0.0137 M_⊙, indicative of "black widow" type systems. A 2-yr timing campaign has produced a refined radio ephemeris, accurate enough to allow for phase-folding of the LAT photons, resulting in the detection of a dual-peaked γ-ray light curve, proving that PSR J1745+1017 is the source responsible for the γ-ray emission seen in 1FGL J1745.5+1018 (2FGL J1745.6+1015; Nolan et al. 2012). We find the γ-ray spectrum of PSR J1745+1017 to be well modelled by an exponentially cut-off power law with cut-off energy 3.2 GeV and photon index 1.6. The observed sources are known to contain a further 10 newly discovered pulsars which were undetected in this survey. Our radio observations of these sources are discussed and in all cases limiting flux densities are calculated. The reasons behind the seemingly low yield of discoveries are also discussed.

Listed but there's a zero too much in the orbital separation, the "planet" is not that close:

http://exoplanet.eu/catalog/psr_j1745+1017_b/

Here is instead a likely circumbinary BD third body in binary pulsar system:

Signature of the presence of a third body orbiting around XB 1916-053

Quote :

Context. The ultra-compact dipping source XB 1916-053 has an orbital period of close to 50 min and a companion star with a very low mass (less than 0.1 M⊙). The orbital period derivative of the source was estimated to be 1.5(3) × 10-11 s/s through analysing the delays associated with the dip arrival times obtained from observations spanning 25 years, from 1978 to 2002.
Aims: The known orbital period derivative is extremely large and can be explained by invoking an extreme, non-conservative mass transfer rate that is not easily justifiable. We extended the analysed data from 1978 to 2014, by spanning 37 years, to verify whether a larger sample of data can be fitted with a quadratic term or a different scenario has to be considered.
Methods: We obtained 27 delays associated with the dip arrival times from data covering 37 years and used different models to fit the time delays with respect to a constant period model.
Results: We find that the quadratic form alone does not fit the data. The data are well fitted using a sinusoidal term plus a quadratic function or, alternatively, with a series of sinusoidal terms that can be associated with a modulation of the dip arrival times due to the presence of a third body that has an elliptical orbit. We infer that for a conservative mass transfer scenario the modulation of the delays can be explained by invoking the presence of a third body with mass between 0.10-0.14 M⊙, orbital period around the X-ray binary system of close to 51 yr and an eccentricity of 0.28 ± 0.15. In a non-conservative mass transfer scenario we estimate that the fraction of matter yielded by the degenerate companion star and accreted onto the neutron star is β = 0.08, the neutron star mass is ≥2.2 M⊙, and the companion star mass is 0.028 M⊙. In this case, we explain the sinusoidal modulation of the delays by invoking the presence of a third body with orbital period of 26 yr and mass of 0.055 M⊙.
Conclusions: From the analysis of the delays associated with the dip arrival times, we find that both in a conservative and non-conservative mass transfer scenario we have to invoke the presence of a third body to explain the observed sinusoidal modulation. We propose that XB 1916-053 forms a hierarchical triple system.

Evidence of a non-conservative mass transfer for XTE J0929-314
https://arxiv.org/abs/1707.04453

There is an interesting note about the companion of neutron star XTE J0929-314 (=BW Antliae)

Quote :

The last piece of the puzzle was the mass of the companion, extracted by the mass function of the system, f_x = 2.7 × 10^-7 M_Sol, one of the smallest values ever found for such astronomical objects; under the hypothesis that the primary is a neutron star (NS) and has a mass of 1.4 M_Sol, the value for the minimum mass of the secondary is 0.0083M_Sol).

That is around 8.5 M_Jup, compatible with a planetary-mass secondary. In any case:

Quote :

Moreover, according to the small mass function of XTE J0929-314, a mass greater than 0.25M_Sol would require an inclination smaller than 2◦ , which is unlikely. The companion mass in this system is less than 0.03 M_Sol (at 95% confidence) for a uniform a priori distribution in cosi and for a neutron star mass of 2 M_Sol, close to the maximum mass for a neutron star.

Eclipse Timings of the LMXB XTE J1710-281 : Discovery of a third orbital period glitch
https://arxiv.org/abs/2209.13406

There's the possibility of a circumbinary substellar companion, planetesimal belt or exocomet.

Quote :

Taking extreme range of 0.01-1 M_Sol for the companion mass and simultaneously solving Equations 3 and 4, for P_orb∼ 11833 s, ΔP ∼ 1.5 ms, and M_NS = 1.4 M_Sol the mass of the third object interacting with the binary system is expected to be ≈ 10^23-24 g. Considering our solar system, although the cometary mass depends on its size and the mean density of its nucleus, nevertheless, the most massive comets are known to have mass in the range 10¹⁷-10¹⁹ g (Hughes 1985, 1990). But these comets are not known to induce a significant perturbation in the orbit of solar system satellites. So any hypothesis of labelling the third object in the XTE J1710-281 system as an exo-comet needs a strong argument.

Look what was hiding between the rows of ADS NASA service...

Periodic repeating fast radio bursts: interaction between a magnetized neutron star and its planet in an eccentric orbit

Quote :

Fast radio bursts (FRBs) are mysterious transient phenomena. The study of repeating FRBs may provide useful information about their nature due to their redetectability. The two most famous repeating sources are FRBs 121102 and 180916, with a period of 157 days and 16.35 days, respectively. Previous studies suggest that the periodicity of FRBs is likely associated with neutron star (NS) binary systems. Here we introduce a new model which proposes that periodic repeating FRBs are due to the interaction of a NS with its planet in a highly elliptical orbit. The periastron of the planet is very close to the NS so that it would be partially disrupted by tidal force every time it passes through the periastron. Fragments generated in the process could interact with the compact star through the Alfvén wing mechanism and produce FRBs. The model can naturally explain the repeatability of FRBs with a period ranging from a few days to several hundred days, but it generally requires that the eccentricity of the planet's orbit should be large enough. Taking FRBs 121102 and 180916 as examples, it is shown that the main features of the observed repeating behaviors can be satisfactorily accounted for.

This seems like an explanation that needs a lot of fine-tuning.