Limit on the axion decay constant from the cooling neutron star in Cassiopeia A

Hamaguchi, Koichi; Nagata, Natsumi; Yanagi, Keisuke; Zheng, Jiaming

doi:10.1103/physrevd.98.103015

Cited by 106 publications

(109 citation statements)

References 62 publications

(70 reference statements)

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“…Constraining cooling models with multiple temperature observations can provide fundamental knowledge on the properties of the NS interior, such as critical temperatures for superconductivity and superfluidity (e.g., Shternin et al 2011;Page et al 2011;Ho et al 2015). Other possibilities include fast or rotationally induced neutrino cooling (Negreiros et al 2013;Taranto et al 2016), magnetic field decay (Bonanno et al 2014), slow thermal relaxation (Blaschke et al 2012(Blaschke et al , 2013, stellar fluid oscillations (Yang et al 2011), and transition to axions or quark matter (Noda et al 2013;Sedrakian 2013;Leinson 2014;Hamaguchi et al 2018).…”

Section: Introductionmentioning

confidence: 99%

Diffusive nuclear burning in cooling simulations and application to new temperature data of the Cassiopeia A neutron star

Wijngaarden

Chang

et al. 2019

Monthly Notices of the Royal Astronomical Society

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A critical relation in the study of neutron star cooling is the one between surface temperature and interior temperature. This relation is determined by the composition of the neutron star envelope and can be affected by the process of diffusive nuclear burning (DNB), which occurs when elements diffuse to depths where the density and temperature are sufficiently high to ignite nuclear burning. We calculate models of H-He and He-C envelopes that include DNB and obtain analytic temperature relations that can be used in neutron star cooling simulations. We find that DNB can lead to a rapidly changing envelope composition and prevents the build-up of thermally stable hydrogen columns y H 10 7 g cm −2 , while DNB can make helium envelopes more transparent to heat flux for surface temperatures T s 2× 10 6 K. We perform neutron star cooling simulations in which we evolve temperature and envelope composition, with the latter due to DNB and accretion from the interstellar medium. We find that a time-dependent envelope composition can be relevant for understanding the longterm cooling behaviour of isolated neutron stars. We also report on the latest Chandra observations of the young neutron star in the Cassiopeia A supernova remnant; the resulting 13 temperature measurements over more than 18 years yield a ten-year cooling rate of ≈ 2%. Finally, we fit the observed cooling trend of the Cassiopeia A neutron star with a model that includes DNB in the envelope.

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Section: Introductionmentioning

confidence: 99%

Diffusive nuclear burning in cooling simulations and application to new temperature data of the Cassiopeia A neutron star

Wijngaarden

Chang

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…Regarding the ambiguity in the choice of pairing gaps, there is a hint from the observation. The recently observed rapid cooling of the NS in the supernova remnant Cassiopeia A (Cas A) may be the first observational signature of the neutron superfluidity in the NS core [52,[104][105][106][107]. The measured decline in temperature is explained with a large proton gap such as the CCDK model and a small neutron gap with the critical temperature of T c 5 × 10 8 K, which is about a factor of 2 smaller than that for the "a" model.…”

Section: Discussionmentioning

confidence: 89%

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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“…Interestingly, PBF processes can trap axions at the late stages of cooling if f a ≤ 10 6 GeV due to the inverse proton PBF, as has been pointed out in Ref. [17]. The f a -values discussed below are all above this limit, therefore we will ignore the possibility of axions being trapped.…”

Section: A Overviewmentioning

confidence: 84%

“…The transient behavior of the Cas A has been studied in Refs. [16,17] to this end and useful limits were obtained assuming that the data reflect per se the fast cooling of this object. The cooling behavior of peculiarly "hot" CCO HESS J1731-347 has been analyzed in the context of axionic cooling in Ref.…”

Section: Introductionmentioning

confidence: 99%

Axion cooling of neutron stars. II. Beyond hadronic axions

Sedrakian

2019

Phys. Rev. D

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We study the axion cooling of neutron stars within the Dine-Fischler-Srednicki-Zhitnitsky (DFSZ) model, which allows for tree level coupling of electrons to the axion and locks the Peccei-Quinn charges of fermions via an angle parameter. This extends our previous study [Phys. Rev. D 93, 065044 (2016)] limited to hadronic models of axions. We explore the two-dimensional space of axion parameters within the DFSZ model by comparing the theoretical cooling models with the surface temperatures of a few stars with measured surface temperatures. It is found that axions masses ma ≥ 0.06 to 0.12 eV can be excluded by x-ray observations of thermal emission of neutron stars (in particular by those of Cas A), the precise limiting value depending on the angle parameter of the DFSZ model. It is also found that axion emission by electron bremsstrahlung in neutron star crusts is negligible except for the special case where neutron Peccei-Quinn charge is small enough, so that the coupling of neutrons to axions can be neglected.

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Limit on the axion decay constant from the cooling neutron star in Cassiopeia A

Cited by 106 publications

References 62 publications

Diffusive nuclear burning in cooling simulations and application to new temperature data of the Cassiopeia A neutron star

Diffusive nuclear burning in cooling simulations and application to new temperature data of the Cassiopeia A neutron star

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

Axion cooling of neutron stars. II. Beyond hadronic axions

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