GT ICR - Antoine Marchal - IViS: Towards Green, Scalable Imaging of diffuse emission lines for the SKA Era

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1. IViS: Towards Green, Scalable Imaging of diffuse emission lines for the SKA Era ! Antoine Marchal - CRCN CNRS @LPENS GT-ICRÑFeb 2026 Processing the GASKAP-HI full-survey w/ the GASKAP-HI collaboration imaging team Hiep Nguyen, David McConnell, James Dempsey, Naomi McClure-GrifÞths, Nick Pingel, Callum Lynn, Jackie Ma, Jo Dawson
2. 2 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Synthesis imaging with mosaicking/joint deconvolution using a non-linear optimization approach Today..
3. 3 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Imaging of Òlarge objectsÓ (Cornwell 1988, Sault et al. 1996) Beams
4. 4 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Imaging of Òlarge objectsÓ (Cornwell 1988, Sault et al. 1996) Beams Visibilities Subset of the FT
5. 5 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Imaging of Òlarge objectsÓ (Cornwell 1988, Sault et al. 1996) Beams Visibilities Subset of the FT
6. 6 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Imaging of Òlarge objectsÓ (Cornwell 1988, Sault et al. 1996) Beams Visibilities Subset of the FT
7. 7 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Imaging of Òlarge objectsÓ (Cornwell 1988, Sault et al. 1996) Beams Visibilities Subset of the FT Joint Deconvolution
8. 8 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Imaging of Òlarge objectsÓ (Cornwell 1988, Sault et al. 1996) Beams Visibilities Subset of the FT Joint Deconvolution How do we do that?
9. 9 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging A brief (& biased) history of HI surveys (in the local Universe) Instruments Sorted by end-date of observations
10. 10 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging A brief (& biased) history of HI surveys (in the local Universe) Imaging methods Sorted by end-date of observations
11. 11 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Multi-scale CLEAN vs MEM ? Multi-scale CLEAN Maximum entropy method For HI, see Stanimirović et al 2002 Cornwell et al 2008 See review by Narayan & Nityananda 1986 1986 ÒParametricÓ multi-Gaussian model Multi-scale CLEAN vs MEM ?
12. 12 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Multi-scale CLEAN vs MEM ? For HI, see Stanimirović et al 2002 Cornwell et al 2008 See review by Narayan & Nityananda 1986 1986 Multi-scale CLEAN Maximum entropy method ÒParametricÓ multi-Gaussian model Multi-scale CLEAN vs MEM ?
13. 13 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Multi-scale CLEAN vs MEM ? || ˜ − ||2 Σ − 1 ζ ∑ i Ii ln ( Ii Mi ) For HI, see Stanimirović et al 2002 Cornwell et al 2008 See review by Narayan & Nityananda 1986 1986 Multi-scale CLEAN Maximum entropy method ÒParametricÓ multi-Gaussian model Non -parametric model Multi-scale CLEAN vs MEM ?
14. 14 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Multi-scale CLEAN vs MEM ? || ˜ − ||2 Σ − 1 ζ ∑ i Ii ln ( Ii Mi ) For HI, see Stanimirović et al 2002 Cornwell et al 2008 See review by Narayan & Nityananda 1986 1986 1- Positivity 2- Smoothness ÒParametricÓ multi-Gaussian model Non -parametric model Multi-scale CLEAN Maximum entropy method
15. 15 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging A brief (& biased) history of HI surveys (in the local Universe) Imaging methods Sorted by end-date of observations
16. 16 08/12/2025 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging A brief (& biased) history of HI surveys (in the local Universe) Imaging methods Sorted by end-date of observations ?
17. 17 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging A brief (& biased) history of HI surveys (in the local Universe) Australian Square Kilometer PathÞnder ASKAP antennas PAF - 36 antennas (12m diam. each) - Freq. range 700 MHz - 1.8 GHz - Bandwidth 300 MHz - FoV ~30 square degrees - Baseline up to 6 km - 8 Survey Science Projects A B C ASKAP: a survey machine
18. 18 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging A brief (& biased) history of HI surveys (in the local Universe) ASKAP: a survey machine GASKAP-HI survey with the ASKAP 4000h of observations 50h / field 30h / field 200h / field
19. 19 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging What are the challenges ? 2- Image quality and fidelity 1- Deep integration ! 3- Green and Scalable ? A brief (& biased) history of HI surveys (in the local Universe)
20. 20 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging What are the challenges ? 2- Image quality and fidelity 1- Deep integration ! 3- Green and Scalable ? A brief (& biased) history of HI surveys (in the local Universe)
21. 21 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging IViS (Interferometric Visibility-domain Inversion Software) Re-inventing the wheel: A (not so new) non-linear optimization approach to join deconvolution
22. 22 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Re-inventing the wheel: A (not so new) non-linear optimization approach to join deconvolution Parkes telescope An open source code Ñ written in PyTorch framework (with ReadtheDocs, notebooks, É)
23. 23 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Re-inventing the wheel: A (not so new) non-linear optimization approach to join deconvolution Parkes telescope A modular framework
24. 24 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Re-inventing the wheel: A (not so new) non-linear optimization approach to join deconvolution 108 beams I(r) ˜ k (I′ k ; u, v) ≃ Beams
25. 25 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Re-inventing the wheel: A (not so new) non-linear optimization approach to join deconvolution 108 beams Projected sky image I(r) ˜ k (I′ k ; u, v) ≃ I′ k (ℓ, m) Beams
26. 26 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Re-inventing the wheel: A (not so new) non-linear optimization approach to join deconvolution 108 beams Projected sky image I(r) ˜ k (I′ k ; u, v) ≃ I′ k (ℓ, m) × Ak (ℓ, m) Primary beam Beams
27. 27 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Re-inventing the wheel: A (not so new) non-linear optimization approach to join deconvolution 108 beams Projected sky image I(r) ˜ k (I′ k ; u, v) ≃ ℱ[ I′ k (ℓ, m) × Ak (ℓ, m)] Primary beam NuFFT (GPU) Beams similar to MPol (by Ian Czekala, see Zawadzki et al. 2023) Beams
28. 28 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Re-inventing the wheel: A (not so new) non-linear optimization approach to join deconvolution L1,k (I′ k ) = ˜ k (I′ k ) − k Jk (I′ k ) = 1 2 ∑ u,v ( L1,k(I′ k) Σ1,k ) 2 108 residual Q(I′ k ) = 108 ∑ k Jk (I′ k ) + R(I(r)) Spatial regularisation Joint deconvolution with spatial regularisation One cost function 108 chi square
29. 29 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Re-inventing the wheel: A (not so new) non-linear optimization approach to join deconvolution Parkes telescope Visualising the optimization at one frequency
30. 30 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Re-inventing the wheel: A (not so new) non-linear optimization approach to join deconvolution Visualising A PPV cube GASKAP-HI survey with the ASKAP
31. 31 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Re-inventing the wheel: A (not so new) non-linear optimization approach to join deconvolution Visualising A PPV cube GASKAP-HI survey with the ASKAP 4000h of observations
32. 32 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Re-inventing the wheel: A (not so new) non-linear optimization approach to join deconvolution GASKAP-HI survey with the ASKAP 4000h of observations Visualising A PPV cube
33. 33 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Re-inventing the wheel: A (not so new) non-linear optimization approach to join deconvolution GASKAP-HI survey with the ASKAP 4000h of observations Visualising A PPV cube
34. 34 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Validation ?
35. 35 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Validation using synthetic observations fBm with CASA and MeerKAT CASA 10h observation with MeerKAT Measurement set
36. 36 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Validation using synthetic observations fBm with CASA and MeerKAT CASA 10h observation with MeerKAT Measurement set
37. 37 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Validation using synthetic observations fBm with CASA and MeerKAT CASA 10h observation with MeerKAT Measurement set
38. 38 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Validation using synthetic observations fBm with CASA and MeerKAT
39. 39 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Validation using synthetic observations fBm with CASA and MeerKAT
40. 40 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Validation using synthetic observations fBm with CASA and MeerKAT Joint deconvolution ? Linear mosaicking ?
41. 41 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Validation using synthetic observations fBm with CASA and MeerKAT Joint deconvolution Linear mosaicking
42. 42 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Validation using synthetic observations fBm with CASA and MeerKAT
43. 43 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Mosaicking vs joint deconvolution ?
44. 44 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Mosaicking vs joint deconvolution Using ASKAP data Joint deconvolution Linear mosaicking
45. 45 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Mosaicking vs joint deconvolution Using ASKAP data Joint deconvolution Linear mosaicking
46. 46 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Mosaicking vs joint deconvolution Using ASKAP data Joint deconvolution Linear mosaicking
47. 47 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Mosaicking vs joint deconvolution Using ASKAP data Joint deconvolution Linear mosaicking
48. 48 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging GASKAP-HI Full Survey Green & Scalable ? !
49. 49 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging GASKAP-HI Full Survey: Green & Scalable ? ! ! ANR grant (2 Postdocs and 1 Research Engineer ) Stay tuned for job offers
50. 50 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Surveys SKA era A brief (& biased) history of HI surveys (in the local Universe) Sorted by end-date of observations Science verification of SKA-Mid
51. 51 Antoine MARCHAL | IViS: Towards Green, Scalable Imaging Thanks!