Abstract
Observations of the Crab pulsar at 327 MHz were made at the Toyokawa Observatory of the Institute for Space-Earth Environmental Research, during the solar occultation in mid-June 2018 to investigate the coronal plasma density in the weak sunspot cycle, Cycle 24. The dispersion measurements (DMs) were determined using giant pulses detected from observations of the Crab pulsar. The systematic increase in DM over the background level, observed during the period of the closest approach of the Crab pulsar’s line-of-sight to the Sun, was ascribed to the effect of the coronal plasma. A coronal density model assuming spherical symmetry was determined by fitting it to the DM data, and was compared with those determined in past solar cycles. The best-fit model had large errors, and indicated a systematically higher value than those derived from past observations. The results obtained here are likely to be significantly affected by latitude/longitude variation in coronal plasma density, the time variation of the interstellar medium, mainly the Crab nebula, and increased measurement errors due to the reduced occurrence of giant pulses. Hence, further observations are needed to derive conclusions about a change of coronal density in the current cycle.
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Notes
Pulsar timing observations provide various kinds of information in astrophysics, since a small change in integrated plasma density along the line-of-sight causes significant time delay in pulse arrival times, accurate correction of the solar wind variation is required for high precision pulsar timing (Madison et al., 2019; Tiburzi et al., 2019).
References
Bisoi, S.K., Janardhan, P., Ingale, M., Subramanian, P., Ananthakrishnan, S., Tokumaru, M., Fujiki, K.: 2014, A study of density modulation index in the inner heliospheric solar wind during Solar Cycle 23. Astrophys. J.795, 69. DOI.
Brueckner, G.E., Howard, R.A., Koomen, M.J., Korendyke, C.M., Michels, D.J., Moses, J.D., Socker, D.G., Dere, K.P., Lamy, P.L., Llebaria, A., Bout, M.V., Schwenn, R., Simnett, G.M., Bedford, D.K., Eyles, C.J.: 1995, The Large Angle Spectroscopic Coronagraph (LASCO). Solar Phys.162, 357. DOI.
Cognard, I., Bourgois, G., Lestrade, J.F., Biraud, F., Aubry, D., Darchy, B., Drouhin, J.P.: 1996, High-precision timing observations of the millisecond pulsar PSR 1821–24 at Nancay. Astron. Astrophys.311, 179.
Cordes, J.M., Bhat, N.D.R., Hankins, T.H., McLaughlin, M.A., Kern, J.: 2004, The brightest pulses in the universe: multifrequency observations of the Crab pulsar’s giant pulses. Astrophys. J.612, 375. DOI.
Counselman, C.C., Rankin, J.M.: 1972, Density of the solar corona from occultations of NP 0532. Astrophys. J.175, 843. DOI.
Counselman, C.C., Rankin, J.M.: 1973, Changes in the distribution of density and radio scattering in the solar corona in 1971. Astrophys. J.185, 357. DOI.
Counselman, C.C., Shapiro, I. I.: 1968, Scientific uses of pulsars. Science166, 352. DOI.
Edwards, R.T., Hobbs, G.B., Manchester, R.N.: 2006, TEMPO2, a new pulsar timing package – II. The timing model and precision estimates. Mon. Not. Roy. Astron. Soc.372, 1549. DOI.
Eselevich, M., Eselevich, V., Fujiki, K.: 2007, Streamer belt and chains as the main sources of quasi-stationary slow solar wind. Solar Phys.240, 135. DOI.
Isaacman, R., Rankin, J.M.: 1977, The Crab nebula pulsar: variability of dispersion and scattering. Astrophys. J.214, 214. DOI.
Janardhan, P., Bisoi, S.K., Ananthakrishnan, S., Tokumaru, M., Fujiki, K.: 2011, The prelude to the deep minimum between Solar Cycles 23 and 24: interplanetary scintillation signatures in the inner heliosphere. Geophys. Res. Lett.38, L20108. DOI.
Kojima, M., Kakinuma, T.: 1990, Solar cycle dependence of global distribution of the solar wind speed. Space Sci. Rev.53, 173. DOI.
Kojima, M., Tokumaru, M., Fujiki, K., Hayashi, K., Jackson, B.V.: 2007, IPS tomographic observations of 3D solar wind structure. Astron. Astrophys. Trans.26, 467. DOI.
Kuz’min, A.D., Belyatsky, Y.A., Dumsky, D.V., Izvekova, V.A., Lapaev, K.A., Logvinenko, S.V., Losovsky, B.Y., Pugachev, V.D.: 2011, Monitoring of the radio emission of the Crab nebula pulsar at low frequencies. Astron. Rep.55, 416. DOI.
Leblanc, Y., Dulk, G.A., Bougeret, J.-L.: 1998, Tracing the electron density from the corona to 1 AU. Solar Phys.183, 165. DOI.
Lundgren, S.C., Cordes, J.M., Ulmer, M., Matz, S.M., Lomatch, S., Foster, R.S., Hankins, T.: 1995, Giant pulses from the Crab pulsar: a joint radio and gamma-ray study. Astrophys. J.453, 433. DOI.
Lyne, A.G., Graham-Smith, F.: 1998, Pulsar Astronomy, Cambridge University Press, Cambridge.
Lyne, A.G., Pritchard, R.S., Smith, F.G.: 1988, Crab pulsar timing 1982–87. Mon. Not. Roy. Astron. Soc.233, 667.
Lyne, A.G., Pritchard, R.S., Smith, F.G.: 1993, 23 years of crab pulsar rotational history. Mon. Not. Roy. Astron. Soc.265, 1003. DOI.
Lyne, A.G., Roberts, M.E., Jordan, C.A.: 2018, Jodrell Bank Crab pulsar timing results. Monthly ephemeris (http://www.jb.man.ac.uk/pulsar/crab/crabnotes.ps).
Madison, D.R., Cordes, J.M., Arzoumanian, Z., Chatterjee, S., Crowter, K., DeCesar, M.E., Demorest, P.B., Dolch, T., Ellis, J.A., Ferdman, R.D., Ferrara, E.C., Fonseca, E., Gentile, P.A., Jones, G., Jones, M.L., Lam, M.T., Levin, L., Lorimer, D.R., Lynch, R.S., McLaughlin, M.A., Mingarelli, C.M.F., Ng, C., Nice, D.J., Pennucci, T.T., Ransom, S.M., Ray, P.S., Spiewak, R., Stairs, I.H., Stoval, K., Swiggum, J.K., Zhu, W.W.: 2019, The NANOGrav 11 yr data set: solar wind sounding through pulsar timing. Astrophys. J.872, 150. DOI.
McComas, D.J., Ebert, R.W., Elliott, H.A., Goldstein, B.E., Gosling, J.T., Schwadron, N.A., Skoug, R.M.: 2008, Weaker solar wind from the polar coronal holes and the whole Sun. Geophys. Res. Lett.35, L18103. DOI.
McComas, D.J., Angold, N., Elliott, H.A., Livadiotis, G., Schwadron, N.A., Skoug, R.M., Smith, C.W.: 2013, Weakest solar wind of the space and the current “mini” solar maximum. Astrophys. J.779, 10. DOI.
McKee, J.W., Lyne, A.G., Stappers, B.W., Bassa, C.G., Jordan, C.A.: 2018, Temporal variations in scattering and dispersion measure in the Crab pulsar and their effect on timing precision. Mon. Not. Roy. Astron. Soc.479, 4216. DOI.
Popov, M., Soglasnov, V., Kondratiev, V., Bilous, A., Moshkina, O., Oreshiko, V., Ilyasov, Y., Sekido, M., Kondo, T.: 2009, Multifrequency study of giant radio pulses from the Crab pulsar with the K5 VLBI recording terminal. Publ. Astron. Soc. Japan61, 1197. DOI.
Sime, D.G., Rickett, B.J.: 1981, Coronal density and the solar wind speed at all latitudes. J. Geophys. Res.86, 8869.
Smirnova, T.V., Chashei, I.V., Shishov, V.I.: 2009, Radio sounding of the circumsolar plasma using polarized pulsar pulses. Astron. Rep.53, 252. DOI.
Tiburzi, C., Verbiest, J.P., Shaifullah, G.M., Janssen, G.H., Anderson, J.M., Horneffer, A., Künsemöller, J., Osłowski, S., Donner, J.Y., Kramer, M., Kumari, A., Porayko, N.K., Zucca, P., Ciardi, B., Dettmar, R.-J., Grießmeier, J.M., Hoeft, M., Serylak, M.: 2019, On the usefulness of existing solar wind models for pulsar time corrections. Mon. Not. Roy. Astron. Soc.487, 397. DOI.
Tokumaru, M.: 2013, Three-dimensional exploration of the solar wind using observations of interplanetary scintillation. Proc. Japan Acad. Ser. B, Phys. Biol. Sci.89, 67. DOI.
Tokumaru, M., Fujiki, K., Iju, T.: 2015, North-south asymmetry in global distribution of the solar wind speed during 1985–2013. J. Geophys. Res.120, 3283. DOI.
Tokumaru, M., Kojima, M., Fujiki, K.: 2010, Solar cycle evolution of the solar wind speed distribution from 1985 to 2008. J. Geophys. Res.115, A04102. DOI.
Tokumaru, M., Kojima, M., Fujiki, K.: 2012, Long-term evolution in the global distribution of solar wind speed and density fluctuations during 1997–2009. J. Geophys. Res.117, A06108. DOI.
Tokumaru, M., Kojima, M., Fujiki, K., Hayashi, K.: 2009, Non-dipolar solar wind structure observed in the Cycle 23/24 minimum. Geophys. Res. Lett.36, L09101. DOI.
Tokumaru, M., Kojima, M., Fujiki, K., Maruyama, K., Ito, H., Iju, T.: 2011, A newly developed UHF radiotelescope for interplanetary scintillation observations: solar wind imaging facility. Radio Sci.46, RS0F02. DOI.
Tokumaru, M., Shimoyama, T., Fujiki, K., Hakamada, K.: 2018, Rarefaction of the very-slow (<350 km/s) solar wind in Cycle 24 compared with Cycle 23. J. Geophys. Res.123, 2520. DOI.
Weisberg, J.M., Payne, R.R., Counselman, C.C.: 1976, Further changes in the distribution of density and radio scattering in the solar corona in 1973. Astrophys. J.209, 252. DOI.
Acknowledgements
This work was partly supported by a Grant-in-Aid for Scientific Research (A) (25237079) and also partly by the ISEE director’s leadership fund for FY2015. The DM data for the Crab pulsar at Jodrell Bank Observatory were obtained from http://www.jb.man.ac.uk/~pulsar/crab.html. The IPS observations were conducted under the solar wind program of the ISEE. Solar wind data derived from ISEE IPS observations were available from ftp://ftp.isee.nagoya-u.ac.jp/pub/vlist. The WSO observations were obtained from http://wso.stanford.edu/synsourcel.html. The synoptic map of LASCO C3 observations was obtained from https://lasco-www.nrl.mil. The authors would like to thank Ms. Yuka Miyauchi (KSTC, NICT) and Mr. Yasushi Maruyama (ISEE, Nagoya Univ.) for their assistance.
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Tokumaru, M., Tawara, K., Takefuji, K. et al. Radio Sounding Measurements of the Solar Corona Using Giant Pulses of the Crab Pulsar in 2018. Sol Phys 295, 80 (2020). https://doi.org/10.1007/s11207-020-01644-w
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DOI: https://doi.org/10.1007/s11207-020-01644-w