Old but Still Warm: Far-UV Detection of PSR B0950+08<sup>*</sup>

Pavlov, G. G.; Rangelov, Blagoy; Kargaltsev, Oleg; Reisenegger, Andreas; Guillot, Sebastien; Reyes, Claudia

doi:10.3847/1538-4357/aa947c

Cited by 40 publications

(45 citation statements)

References 36 publications

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“…The obtained upper bound also constrains the properties of reheating mechanisms proposed for old, nonrecycled, pulsars, especially when combined with our recent temperature measurement for PSR B0950+08 (hereafter "B0950"; Pavlov et al 2017), which requires some heating mechanisms to explain its substantially higher surface temperature, 130,000-250,000 K. Figure 5 shows a selection of thermal evolution models for B0950 (upper panel) and J2144 (lower panel) un- Figure 5. Thermal evolution models for PSR B0950+08 (upper panel) and PSR J2144-3933 (lower panel), constrained by the temperature measurement of Pavlov et al (2017) and the upper bound obtained in this work.…”

Section: Discussionsupporting

confidence: 64%

Hubble Space Telescope Nondetection of PSR J2144–3933: The Coldest Known Neutron Star^∗

Guillot

Pavlov

Reyes

et al. 2019

ApJ

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We report non-detections of the ∼ 3 × 10 8 yr old, slow, isolated, rotation-powered pulsar PSR J2144-3933 in observations with the Hubble Space Telescope in one optical band (F475X) and two farultraviolet bands (F125LP and F140LP), yielding upper bounds F F475X < 22.7 nJy, F F125LP < 5.9 nJy, F F140LP < 19.5 nJy, at the pivot wavelengths 4940Å, 1438Å and 1528Å, respectively. Assuming a blackbody spectrum, we deduce a conservative upper bound on the surface (unredshifted) temperature of the pulsar of T < 42, 000 K. This makes PSR J2144-3933 the coldest known neutron star, allowing us to study thermal evolution models of old neutron stars. This temperature is consistent with models with either direct or modified Urca reactions including rotochemical heating, and, considering frictional heating from the motion of neutron vortex lines, it puts an upper bound on the excess angular momentum in the neutron superfluid, J < 10 44 erg s.

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Section: Discussionsupporting

confidence: 64%

Hubble Space Telescope Nondetection of PSR J2144–3933: The Coldest Known Neutron Star^∗

Guillot

Pavlov

Reyes

et al. 2019

ApJ

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“…Its surface temperature is obtained with a power-low plus blackbody spectrum fit in Ref. [29] as (1 − 3) × 10 5 K, with other parameters such as the pulsar radius varied in a plausible range.…”

Section: Observations Of Neutron Star Temperaturesmentioning

confidence: 99%

“…The surface temperature of ∼ 10 5 K for such an old NS cannot be explained by the cooling theory without heating. Further evidences of old "warm" NSs are provided by the MSP J2124-3358 [27] and ordinary pulsars J0108-1431 [28] and B0950+08 [29]. On the other hand, the observation of the ordinary old pulsar J2144-3933 imposes an upper limit on its surface temperature, T ∞ s < 4.2×10 4 K [30], giving an evidence for the presence of an old "cold" NS.…”

Section: Introductionmentioning

confidence: 97%

Cooling theory faced with old warm neutron stars: role of non-equilibrium processes with proton and neutron gaps

Yanagi

Hamaguchi

2020

Monthly Notices of the Royal Astronomical Society

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Recent observations have found several candidates for old warm neutron stars whose surface temperatures are above the prediction of the standard neutron star cooling scenario, and thus require some heating mechanism. Motivated by these observations, we study the nonequilibrium beta process in the minimal cooling scenario of neutron stars, which inevitably occurs in pulsars. This out-of-equilibrium process yields the late time heating in the core of a neutron star, called the rotochemical heating, and significantly changes the time evolution of the neutron star surface temperature. To perform a realistic analysis of this heating effect, we include the singlet proton and triplet neutron pairing gaps simultaneously in the calculation of the rate and emissivity of this process, where the dependence of these pairing gaps on the nucleon density is also taken into account. We then compare the predicted surface temperature of neutron stars with the latest observational data. We show the simultaneous inclusion of both proton and neutron gaps is advantageous for the explanation of the old warm neutron stars since it enhances the heating effect. It is then found that the observed surface temperatures of the old warm millisecond pulsars, J2124-3358 and J0437-4715, are explained for various choices of nucleon gap models. The same setup is compatible with the observed temperatures of ordinary pulsars including old warm ones, J0108-1431 and B0950+08, by choosing the initial rotational period of each neutron star accordingly. In particular, the upper limit on the surface temperature of J2144-3933 can be satisfied if its initial period is 10 ms.

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“…For instance, the surface temperature of the millisecond pulsar (MSP) J0437-4715, whose age is estimated to be t (6 − 7) × 10 9 yr, is measured to be T ∞ s ∼ 3 × 10 5 K [ [24][25][26], where T ∞ s represents the red-shifted temperature at the infinite distance. Other examples of NSs whose surface temperature is higher than the prediction in the standard cooling theory include the MSP J2124-3358 [27] and ordinary pulsars J0108-1431 [28] and B0950+08 [29]. On the other hand, for J2144-3933, there is only an upper bound on the surface temperature: T ∞ s < 4.2×10 4 K [30].…”

Section: Introductionmentioning

confidence: 99%

Dark matter heating vs. rotochemical heating in old neutron stars

Hamaguchi

Yanagi

2019

Physics Letters B

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Dark matter (DM) particles in the Universe accumulate in neutron stars (NSs) through their interactions with ordinary matter. It has been known that their annihilation inside the NS core causes late-time heating, with which the surface temperature becomes a constant value of Ts (2 − 3) × 10 3 K for the NS age t 10 6−7 years. This conclusion is, however, drawn based on the assumption that the beta equilibrium is maintained in NSs throughout their life, which turns out to be invalid for rotating pulsars. The slowdown in the pulsar rotation drives the NS matter out of beta equilibrium, and the resultant imbalance in chemical potentials induces late-time heating, dubbed as rotochemical heating. This effect can heat a NS up to Ts 10 6 K for t 10 6−7 years. In fact, recent observations found several old NSs whose surface temperature is much higher than the prediction of the standard cooling scenario and is consistent with the rotochemical heating. Motivated by these observations, in this letter, we reevaluate the significance of the DM heating in NSs, including the effect of the rotochemical heating. We then show that the signature of DM heating can still be detected in old ordinary pulsars, while it is concealed by the rotochemical heating for old millisecond pulsars. To confirm the evidence for the DM heating, however, it is necessary to improve our knowledge on nucleon pairing gaps as well as to evaluate the initial period of the pulsars accurately. In any cases, a discovery of a very cold NS can give a robust constraint on the DM heating, and thus on DM models. To demonstrate this, as an example, we also discuss the case that the DM is the neutral component of an electroweak multiplet, and show that an observation of a NS with Ts 10 3 K imposes a stringent constraint on such a DM candidate.

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Old but Still Warm: Far-UV Detection of PSR B0950+08^*

Cited by 40 publications

References 36 publications

Hubble Space Telescope Nondetection of PSR J2144–3933: The Coldest Known Neutron Star^∗

Hubble Space Telescope Nondetection of PSR J2144–3933: The Coldest Known Neutron Star^∗

Cooling theory faced with old warm neutron stars: role of non-equilibrium processes with proton and neutron gaps

Dark matter heating vs. rotochemical heating in old neutron stars

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Old but Still Warm: Far-UV Detection of PSR B0950+08*

Cited by 40 publications

References 36 publications

Hubble Space Telescope Nondetection of PSR J2144–3933: The Coldest Known Neutron Star∗

Hubble Space Telescope Nondetection of PSR J2144–3933: The Coldest Known Neutron Star∗

Cooling theory faced with old warm neutron stars: role of non-equilibrium processes with proton and neutron gaps

Dark matter heating vs. rotochemical heating in old neutron stars

Contact Info

Product

Resources

About

Old but Still Warm: Far-UV Detection of PSR B0950+08^*

Hubble Space Telescope Nondetection of PSR J2144–3933: The Coldest Known Neutron Star^∗

Hubble Space Telescope Nondetection of PSR J2144–3933: The Coldest Known Neutron Star^∗