{"title":"用FAST对仙女座星系m31的新连续观测","authors":"wenjun Zhang, Xiaohui Sun, Jie Wang","doi":"10.1088/1674-4527/acfae1","DOIUrl":null,"url":null,"abstract":"Abstract We present a new total intensity image of M31 at 1.248 GHz, observed with the Five-hundred-meter Aperture Spherical radio telescope (FAST) with an angular resolution of <?CDATA $4^{\\prime} $?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mn>4</mml:mn> <mml:mo accent=\"false\">′</mml:mo> </mml:math> and a sensitivity of about 16 mK. The new FAST image clearly reveals weak emission outside the ring due to its high sensitivity on large-scale structures. We derive a scale length of 2.7 kpc for the cosmic ray electrons and find that the cosmic ray electrons propagate mainly through diffusion by comparing the scale length at 4.8 GHz. The spectral index of the total intensity varies along the ring, which can be attributed to the variation of the spectra of synchrotron emission. This variation is likely caused by the change of star formation rates along the ring. We find that the azimuthal profile of the non-thermal emission can be interpreted by an axisymmetric large-scale magnetic field with varying pitch angle along the ring, indicating a complicated magnetic field configuration in M31.","PeriodicalId":54494,"journal":{"name":"Research in Astronomy and Astrophysics","volume":"1 1","pages":"0"},"PeriodicalIF":1.8000,"publicationDate":"2023-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"New continuum observations of the Andromeda galaxy M 31 with FAST\",\"authors\":\"wenjun Zhang, Xiaohui Sun, Jie Wang\",\"doi\":\"10.1088/1674-4527/acfae1\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Abstract We present a new total intensity image of M31 at 1.248 GHz, observed with the Five-hundred-meter Aperture Spherical radio telescope (FAST) with an angular resolution of <?CDATA $4^{\\\\prime} $?> <mml:math xmlns:mml=\\\"http://www.w3.org/1998/Math/MathML\\\" overflow=\\\"scroll\\\"> <mml:mn>4</mml:mn> <mml:mo accent=\\\"false\\\">′</mml:mo> </mml:math> and a sensitivity of about 16 mK. The new FAST image clearly reveals weak emission outside the ring due to its high sensitivity on large-scale structures. We derive a scale length of 2.7 kpc for the cosmic ray electrons and find that the cosmic ray electrons propagate mainly through diffusion by comparing the scale length at 4.8 GHz. The spectral index of the total intensity varies along the ring, which can be attributed to the variation of the spectra of synchrotron emission. This variation is likely caused by the change of star formation rates along the ring. We find that the azimuthal profile of the non-thermal emission can be interpreted by an axisymmetric large-scale magnetic field with varying pitch angle along the ring, indicating a complicated magnetic field configuration in M31.\",\"PeriodicalId\":54494,\"journal\":{\"name\":\"Research in Astronomy and Astrophysics\",\"volume\":\"1 1\",\"pages\":\"0\"},\"PeriodicalIF\":1.8000,\"publicationDate\":\"2023-10-17\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Research in Astronomy and Astrophysics\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1088/1674-4527/acfae1\",\"RegionNum\":4,\"RegionCategory\":\"物理与天体物理\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Research in Astronomy and Astrophysics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1088/1674-4527/acfae1","RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
New continuum observations of the Andromeda galaxy M 31 with FAST
Abstract We present a new total intensity image of M31 at 1.248 GHz, observed with the Five-hundred-meter Aperture Spherical radio telescope (FAST) with an angular resolution of 4′ and a sensitivity of about 16 mK. The new FAST image clearly reveals weak emission outside the ring due to its high sensitivity on large-scale structures. We derive a scale length of 2.7 kpc for the cosmic ray electrons and find that the cosmic ray electrons propagate mainly through diffusion by comparing the scale length at 4.8 GHz. The spectral index of the total intensity varies along the ring, which can be attributed to the variation of the spectra of synchrotron emission. This variation is likely caused by the change of star formation rates along the ring. We find that the azimuthal profile of the non-thermal emission can be interpreted by an axisymmetric large-scale magnetic field with varying pitch angle along the ring, indicating a complicated magnetic field configuration in M31.
期刊介绍:
Research in Astronomy and Astrophysics (RAA) is an international journal publishing original research papers and reviews across all branches of astronomy and astrophysics, with a particular interest in the following topics:
-large-scale structure of universe formation and evolution of galaxies-
high-energy and cataclysmic processes in astrophysics-
formation and evolution of stars-
astrogeodynamics-
solar magnetic activity and heliogeospace environments-
dynamics of celestial bodies in the solar system and artificial bodies-
space observation and exploration-
new astronomical techniques and methods