Imaging black holes with sparse modeling

International Meeting on High-Dimensional Data-Driven Science 2015

Honma, Mareki^1,2 ; Akiyama, Kazunori^1,3,4 ; Tazaki, Fumie^1 ; Kuramochi, Kazuki^1,3 ; Ikeda, Shiro^5,6 ; Hada, Kazuhiro^1 ; Uemura, Makoto^7

Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, Hoshigaoka, Ohshu, Iwate

023-0861, Japan^1

Department of Astronomical Science, SOKENDAI (The Graduate University for Advanced Studies), Hoshigaoka, Ohshu, Iwate

023-0861, Japan^2

Department of Astronomy, Graduate School of Science, University of Tokyo, Hongo, Bunkyo-ku, Tokyo

113-0033, Japan^3

Haystack Observatory, Massachusetts Institute of Technology, Route 40, Westford

MA

01886, United States^4

Institute of Statistical Mathematics, Tachikawa, Tokyo

190-8562, Japan^5

Department of Statistical Science, SOKENDAI (The Graduate University for Advanced Studies), Tachikawa, Tokyo

190-8562, Japan^6

Astrophysical Science Center, Hiroshima University, Higashi-Hiroshima, Hiroshima

739-8526, Japan^7

关键词: Astronomical images;    Fourier transformations;    Incomplete samplings;    Massive black holes;    Radio interferometry;    Scattering effects;    Spatial frequency domains;    Under-determined;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/699/1/012006/pdf
DOI  :  10.1088/1742-6596/699/1/012006

来源: IOP

【 摘 要 】

We introduce a new imaging method for radio interferometry based on sparse- modeling. The direct observables in radio interferometry are visibilities, which are Fourier transformation of an astronomical image on the sky-plane, and incomplete sampling of visibilities in the spatial frequency domain results in an under-determined problem, which has been usually solved with 0 filling to un-sampled grids. In this paper we propose to directly solve this under-determined problem using sparse modeling without 0 filling, which realizes super resolution, i.e., resolution higher than the standard refraction limit. We show simulation results of sparse modeling for the Event Horizon Telescope (EHT) observations of super-massive black holes and demonstrate that our approach has significant merit in observations of black hole shadows expected to be realized in near future. We also present some results with the method applied to real data, and also discuss more advanced techniques for practical observations such as imaging with closure phase as well as treating the effect of interstellar scattering effect.