Multi-frequency synthesis in space very long baseline radio interferometry

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Abstract

The paper examines the possibilities of using multi-frequency synthesis methods for very long baseline (VLBI) space radio interferometers to improve the (u, v) coverage and the quality of the resulting synthesized images. To evaluate the contribution of multi-frequency synthesis methods, simulations of VLBI observations were performed using the example of the space VLBI concept that is based on a combination of circular near-Earth orbits.

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About the authors

A. G. Rudnitskiy

Astro Space Center, P. N. Lebedev Physical Institute, Russian Academy of Sciences

Author for correspondence.
Email: arud@asc.rssi.ru
Russian Federation, Moscow

M. A. Shchurov

Astro Space Center, P. N. Lebedev Physical Institute, Russian Academy of Sciences

Email: shurovma@lebedev.ru
Russian Federation, Moscow

S. V. Chernov

Astro Space Center, P. N. Lebedev Physical Institute, Russian Academy of Sciences

Email: chernov@td.lpi.ru
Russian Federation, Moscow

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Supplementary files

Supplementary Files
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1. JATS XML
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2. Fig. 1. M87 source models: 230 GHz (a), 375 GHz (b), and 690 GHz (c). The color scale is normalized to the peak pixel intensity for each model.

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3. Fig. 2. Simulated plane filling for frequencies: 230 (blue dots), 375 (red dots) and 690 GHz (gray dots). The duration of simulated observations was 20 hours.

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4. Fig. 3. Reconstructed images of M87 at 230 GHz (a), 375 GHz (b), and 690 GHz (c). The synthesized radiation pattern is shown in the lower left corner of each image as a gray circle with the following dimensions: 7.1 × 5.7 µas , PA: –38.79° (a), 4.4 × 3.6 µas , PA: –36.47° (b), 2.4 × 1.9 µas , PA: –35.52° (c). PA is the position angle of the principal axis of the elliptical synthesized radiation pattern. The integral flux S is shown in each image. The color scale is normalized to the peak intensity value for each image.

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5. Fig. 4. Reconstructed images of M87 using the MCS: 230+375 GHz (a), 230+690 GHz (b), 230+375+690 GHz (c). The synthesized radiation pattern in each image is shown in the lower left corner as a gray circle with the following dimensions: 4.7 × 3.8 µas, PA: –35.29° (a), 3.3 × 2.5 µas , PA: –39.84° (b), 2.9 × 2.3 µas , PA: –36.62° (c). PA is the position angle of the main axis of the elliptical synthesized radiation pattern. The value of the integral flux S is shown in each image. The color scale is normalized to the peak intensity value for each image.

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6. Fig. 5. Spectrum of the simulated source. Red squares correspond to the integral flux of the source model, blue squares to the flux obtained by reconstructing images at frequencies of 230, 375 and 690 GHz, black squares to the value of the integral flux interpolated using multifrequency synthesis methods.

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