Turbulence properties in interstellar medium around Geminga TeV halo

doi:10.7523/j.ucas.2022.076

Abstract

Abstract: Space power spectrum analysis is a common method to study the turbulence property of interstellar medium. In this paper, we applied this method to analyze a neutral hydrogen cloud near Geminga with data from the GALFA (galactic Arecibo L-band feed array) HI survey. The spatial power spectrum of the cloud can be well described by a power-law with an index of -4.0±0.1 which is steeper than the turbulent power spectrum of local galactic interstellar medium (the spectral index is larger than -3.0). We considered several physical conditions that may lead to the steeper spectrum and found none of the thin HI slice along the line of sight direction, highly ordered magnetic field perpendicular to line of sight direction or energy loss during the energy cascade be responsible for the steeper spectrum. This indicates that the turbulence property around Geminga is very different to the local galactic interstellar medium which may account for the abnormally low diffusion coefficient in Gemninga TeV halo.

Key words: interstellar medium, turbulence, Geminga, space power spectrum analysis

CLC Number:

P155

CHENG Haolin, ZHU Hui, CHEN Tianlu, TIAN Wenwu, CUI Xiaohong, WU Dan, GAO Qi. Turbulence properties in interstellar medium around Geminga TeV halo[J]. Journal of University of Chinese Academy of Sciences, 2024, 41(3): 306-311.

References

[1] Biermann L. Origin and propagation of cosmic rays[J]. Annual Review of Nuclear Science, 1953, 2: 335-364. DOI:10.1146/annurev.ns.02.120153.002003.
[2] Strong A W, Moskalenko I V, Ptuskin V S. Cosmic-ray propagation and interactions in the galaxy[J]. Annual Review of Nuclear and Particle Science, 2007, 57: 285-327. DOI:10.1146/annurev.nucl.57.090506.123011.
[3] Hinton J A, Hofmann W. Teraelectronvolt astronomy[J]. Annual Review of Astronomy and Astrophysics, 2009, 47: 523-565. DOI:10.1146/annurev-astro-082708-101816.
[4] Tatischeff V, Gabici S. Particle acceleration by supernova shocks and spallogenic nucleosynthesis of light elements[J]. Annual Review of Nuclear and Particle Science, 2018, 68: 377-404. DOI:10.1146/annurev-nucl-101917-021151.
[5] Reynolds S P. Supernova remnants at high energy[J]. Annual Review of Astronomy and Astrophysics, 2008, 46: 89-126. DOI:10.1146/annurev.astro.46.060407.145237.
[6] Abeysekara A U, Albert A, Alfaro R, et al. Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth[J]. Science, 2017, 358(6365): 911-914. DOI:10.1126/science.aan4880.
[7] Yuan Q, Lin S J, Fang K, et al. Propagation of cosmic rays in the AMS-02 era[J]. Physical Review D, 2017, 95(8): 083007. DOI:10.1103/physrevd.95.083007.
[8] Aguilar M, Cavasonza L A, Ambrosi G, et al. Precision measurement of the boron to carbon flux ratio in cosmic rays from 1.9 GV to 2.6 TV with the alpha magnetic spectrometer on the International Space Station[J]. Physical Review Letters, 2016, 117(23): 231102. DOI:10.1103/PhysRevLett.117.231102.
[9] Breitschwerdt D, Tautz R C, Avillez M A. Impact of supernovae on the interstellar medium and the heliosphere[M]//Handbook of Supernovae. Cham: Springer, 2016, DOI:10.1007/978-3-319-20794-0_18-1.
[10] Stutzki J, Bensch F, Heithausen A et al. On the fractal structure of molecular clouds[J]. Astronomy and Astrophysics, 1998, 336: 697-720.
[11] Stanimirović S, Staveley-Smith L, Dickey J M, et al. The large-scale HI structure of the small magellanic cloud[J]. Monthly Notices of the Royal Astronomical Society, 1999, 302(3): 417-436. DOI:10.1046/j.1365-8711.1999. 02013.x.
[12] Elmegreen B G, Kim S, Staveley-Smith L. A fractal analysis of the HI emission from the large magellanic cloud[J]. The Astrophysical Journal Letters, 2001, 548(2): 749-769. DOI:10.1086/319021.
[13] Crovisier J, Dickey J M. The spatial power spectrum of galactic neutral hydrogen from observations of the 21-cm emission line[J]. Astronomy & Astrophysics, 1983, 122: 282-296.
[14] Deshpande A A, Dwarakanath K S, Goss W M. Power spectrum of the density of cold atomic gas in the galaxy toward Cassiopeia A and cygnus A[J]. The Astrophysical Journal Letters, 2000, 543(1): 227-234. DOI:10.1086/317104.
[15] Peek J E G, Heiles C, Douglas K A, et al. The GALFA-HI survey: data release 1[J]. The Astrophysical Journal Letters Supplement Series, 2011, 194(2): 20. DOI:10.1088/0067-0049/194/2/20.
[16] Faherty J, Walter F M, Anderson J. The trigonometric parallax of the neutron star Geminga[J]. Astrophysics and Space Science, 2007, 308: 225-230. DOI:10.1007/s10509-007-9368-0.
[17] Kulkarni S R, Heiles C. The atomic component[M]//Interstellar Processes. Dordrecht: Springer Netherlands, 1987: 87-122. DOI:10.1007/978-94-009-3861-8_5.
[18] Miville-Deschênes M A, Joncas G, Falgarone E, et al. High resolution 21 cm mapping of the Ursa Major Galactic Cirrus: power spectra of the high-latitude HI gas[J]. Astronomy & Astrophysics, 2003, 411(2): 109-121. DOI:10.1051/0004-6361: 20031297.
[19] Koch E W, Rosolowsky E W, Boyden R D, et al. TurbuStat: turbulence statistics in Python[J]. The Astronomical Journal, 2019, 158(1): 1. DOI:10.3847/1538-3881/ab1cc0.
[20] Armstrong J W, Rickett B J, Spangler S R. Electron density power spectrum in the local interstellar medium[J]. The Astrophysical Journal Letters, 1995, 443: 209. DOI:10.1086/175515.
[21] Ferrière K. Plasma turbulence in the interstellar medium[J]. Plasma Physics and Controlled Fusion, 2020, 62(1): 014014. DOI:10.1088/1361-6587/ab49eb.
[22] Green D A. A power spectrum analysis of the angular scale of galactic neutral hydrogen emission towards l = 140°, b = 0°[J]. Monthly Notices of the Royal Astronomical Society, 1993, 262(2): 327-342. DOI:10.1093/mnras/262.2.327.
[23] Dickey J M, Mcclure-Griffiths N M, Stanimirović S, et al. Southern galactic plane survey measurements of the spatial power spectrum of interstellar HI in the inner galaxy[J]. The Astrophysical Journal Letters, 2001, 561(1): 264-271. DOI:10.1086/323409.
[24] Choudhuri S, Roy N. Turbulent power spectrum in warm and cold neutral medium using the galactic HI 21 cm emission[J]. Monthly Notices of the Royal Astronomical Society, 2019, 483(3): 3437-3443. DOI:10.1093/mnras/sty3342.
[25] Kalberla P M W, Haud U. Turbulent power distribution in the local interstellar medium[J]. Astronomy & Astrophysics, 2019, 627: A112. DOI:10.1051/0004-6361/201834533.
[26] Kolmogorov A. The local structure of turbulence in incompressible viscous fluid for very large Reynolds numbers[J]. Proceedings of the Royal Society of London Series A: Mathematical and Physical Sciences, 1991, 434(1890): 9-13. DOI:10.1098/rspa.1991.0075.
[27] Radhakrishnan V, Murray J D, Lockhart P, et al. The Parkes survey of 21-centimeter absorption in discrete-source spectra. II. Galactic 21-centimeter observations in the direction of 35 extragalactic sources[J]. The Astrophysical Journal Letters Supplement Series, 1972, 24: 15. DOI:10.1086/190248.
[28] Kalberla P M W, Kerp J, Haud U, et al. HI anisotropies associated with radio-polarimetric filaments： steep power spectra associated with cold gas[J]. Astronomy & Astrophysics, 2017, 607: A15. DOI:10.1051/0004-6361/201629627.
[29] Berezinskii V, Bulanov S, Dogiel V, et al. Astrophysics of cosmic rays[M]. Amsterdam: North Holland, 1990.
[30] Nan R D. Five hundred meter aperture spherical radio telescope (FAST)[J]. Science in China Series G, 2006, 49(2): 129-148. DOI:10.1007/s11433-006-0129-9.