Characterizing and Mitigating Intraday Variability: Reconstructing Source Structure in Accreting Black Holes with mm-VLBI
Loinard L; Lu RS; Pen UL; Wondrak MF; Ho LC; Bower GC; Prather B; Carlstrom JE; Desvignes G; Nagar NM; Dempsey J; Cruz-Osorio A; Yamaguchi P; Oyama T; Lisakov M; Small D; van Langevelde HJ; Young A; Rezzolla L; Algaba JC; Kim DJ; Liu J; Savolainen T; Mizuno I; Matsushita S; Chatterjee K; Moscibrodzka M; Wielgus M; Johnson MD; James DJ; Akiyama K; Mus A; Bouman KL; Jeter B; Keating GK; Doeleman SS; Liuzzo E; Bremer M; Brissenden R; Young K; Friberg P; Blundell R; Fraga-Encinas R; Okino H; Asada K; Olivares H; Inoue M; Hesper R; Ward-Thompson D; Souccar K; Dougal S; Lee SS; Porth O; Karuppusamy R; Ni CC; Lindqvist M; De Laurentis M; Dzib SA; Mao JR; Huang L; Jiang W; Yuan YF; Tilanus RPJ; Kino M; Janssen M; Ruszczyk C; Haggard D; Broderick AE; Haworth K; Potzl FM; Natarajan I; Nathanail A; Tazaki F; Marrone DP; Koyama S; Yoon D; Muller C; Witzel G; Broguiere D; Hughes DH; Conroy NS; Falcke H; Koay JY; Pietu V; Georgiev B; Pu HY; Baczko AK; Parsons H; Alberdi A; Zhao GY; Myserlis I; Ceccobello C; Kuo CY; Roshanineshat A; van Rossum DR; Hada K; Gurwell M; Britzen S; Matthews LD; Liu K; Rawlings MG; Lonsdale CJ; Menten KM; Sohn BW; Marti-Vidal I; Younsi Z; Moran JM; Christian P; Bach U; Trent T; Ricarte A; Ruiz I; Lico R; Jannuzi BT; Chen MT; Freeman WT; Vos J; Wex N; Fomalont E; Neilsen J; Gomez-Ruiz AI; Ripperda B; Emami R; Jorstad S; Trippe S; Markoff S; Romero-Canizales C; Boyce H; Traianou E; Koch PM; Schonfeld J; Wagner J; Chan CK; Gold R; Roelofs F; Shao LJ; Park J; Galison P; Eatough RP; Wardle J; Ikeda S; Cheng XP; Mizuno Y; Palumbo DCM; Satapathy K; Davelaar J; Paraschos GF; Hecht MH; Yuan F; Jung T; Bintley D; Fromm CM; Conway JE; Lo WP; Deane R; Wu QW; Cordes JM; Rottmann H; Ho P; Kawashima T; Schuster KF; PopStefanija A; Chael A; Wong GN; Oh J; Farah J; Byun DY; Patel N; Joshi AV; Cho I; Zensus JA; Azulay R; Kofuji Y; La Bella N; Kocherlakota P; Krichbaum TP; Leung PK; Neri R; Ball D; Lobanov AP; Lee D; Gomez JL; Ros E; Fuentes SN; Karami M; Weintroub J; Ford HA; Cui YZ; Benson BA; Huang CWL; Zhang S; Issaoun S; Sasada M; Roy AL; Shen ZQ; Plambeck R; Turk M; Alef W; Lindahl G; Noutsos A; Levis A; Crew GB; Baubock M; Kettenis M; Sanchez-Portal M; Brinkerink CD; Musoke G; SooHoo J; Dhruv V; Anantua R; Balokovic M; Raymond AW; Titus M; Torne P; Rogers A; Bustamante S; Garcia R; Ortiz-Leon GN; Kramer M; Ramakrishnan V; Moriyama K; Nowak MA; Kramer C; Kim J; Chen YJ; Wharton R; Sanchez S; Nakamura M; Goddi C; Tiede P; Sanchez-Arguelles D; Chatterjee S; Gentaz O; Li ZY; Zhao SS; Crawford TM; Fuentes A; Michalik D; Sun H; Nagai H; Preciado-Lopez JA; Jimenez-Rosales A; Schloerb FP; Bronzwaer T; Barrett J; Marchili N; Kim JY; Gammie CF; Narayan R; Heumann D; Nadolski A; Dexter J; Tetarenko AJ; Blackburn L; Rao R; Wiik K; van Bemmel I; Gu MF; Honma M; Lauer TR; Pesce DW; Fish VL; Rygl KLJ; Impellizzeri CMV; Narayanan G; Marscher AP
https://urn.fi/URN:NBN:fi-fe2022081154969
Tiivistelmä
The extraordinary physical resolution afforded by the Event Horizon Telescope has opened a window onto the astrophysical phenomena unfolding on horizon scales in two known black holes, M87* and Sgr A*. However, with this leap in resolution has come a new set of practical complications. Sgr A* exhibits intraday variability that violates the assumptions underlying Earth aperture synthesis, limiting traditional image reconstruction methods to short timescales and data sets with very sparse (u, v) coverage. We present a new set of tools to detect and mitigate this variability. We develop a data-driven, model-agnostic procedure to detect and characterize the spatial structure of intraday variability. This method is calibrated against a large set of mock data sets, producing an empirical estimator of the spatial power spectrum of the brightness fluctuations. We present a novel Bayesian noise modeling algorithm that simultaneously reconstructs an average image and statistical measure of the fluctuations about it using a parameterized form for the excess variance in the complex visibilities not otherwise explained by the statistical errors. These methods are validated using a variety of simulated data, including general relativistic magnetohydrodynamic simulations appropriate for Sgr A* and M87*. We find that the reconstructed source structure and variability are robust to changes in the underlying image model. We apply these methods to the 2017 EHT observations of M87*, finding evidence for variability across the EHT observing campaign. The variability mitigation strategies presented are widely applicable to very long baseline interferometry observations of variable sources generally, for which they provide a data-informed averaging procedure and natural characterization of inter-epoch image consistency.
Kokoelmat
- Rinnakkaistallenteet [19207]