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First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multiwavelength Observations, Data Processing, and Calibration

Journal Article · · Astrophys.J.Lett.
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  1. MIT, LNS; Natl. Astron. Observ. of Japan; Harvard U. (main)
  2. Granada U., Theor. Phys. Astrophys.
  3. Bonn, Max Planck Inst., Radioastron.
  4. Malaya U.
  5. Harvard U. (main); Harvard-Smithsonian Ctr. Astrophys.; Texas U., San Antonio
  6. Academia Sinica, Taiwan
  7. Bonn, Max Planck Inst., Radioastron.; Valencia U., Astro. Astrophys.; Valencia U., IFIC
  8. Arizona U., Astron. Dept. - Steward Observ.
  9. Yale Ctr. Astron. Astrophys.
  10. MIT, LNS
  11. Illinois U., Urbana
  12. Fermilab; Chicago U., Astron. Astrophys. Ctr.
  13. Subaru Telescope
  14. Harvard U. (main); Harvard-Smithsonian Ctr. Astrophys.
  15. Harvard-Smithsonian Ctr. Astrophys.
  16. Caltech
  17. Gemini Observ., Hilo; Hawaii U.
  18. McGill U.
  19. IRAM, St. Martin d'Heres
  20. Nijmegen U., IMAPP
  21. Perimeter Inst. Theor. Phys.; Waterloo U.; Waterloo U., IQC
  22. Massachusetts U., Amherst
  23. KASI, DaeJeon; KAIST, Taejon
  24. Chicago U., Astron. Astrophys. Ctr.; Chicago U., KICP; Chicago U.; Chicago U., EFI
  25. Chalmers U. Tech.
  26. Princeton U., PCTS; Baltimore, Space Telescope Sci.
  27. Arizona U., Astron. Dept. - Steward Observ.; Arizona U.
  28. Cornell U., Radio. Space Res. Ctr.
  29. Gemini Observ., Hilo
  30. Shanghai, Astron. Observ.; Nanjing U. Sci. Tech.
  31. KASI, DaeJeon
  32. Fairfield U.
  33. Harvard-Smithsonian Ctr. Astrophys.; Illinois U., Urbana, Astron. Dept.
  34. Chicago U., Astron. Astrophys. Ctr.; Chicago U., KICP
  35. Frankfurt U.
  36. Tsung-Dao Lee Inst., Shanghai; KASI, DaeJeon; Tokyo, Grad. U. Adv. Stud.; Natl. Astron. Observ. of Japan
  37. Nijmegen U., IMAPP; Columbia U., Astron. Astrophys.; CCA, New York
  38. Frankfurt U.; Naples U.; INFN, Naples
  39. U. Witwatersrand, Johannesburg, Sch. Phys.; Pretoria U.; Rhodes U.
  40. Subaru Telescope; ASTRON, Dwingeloo
  41. Bonn, Max Planck Inst., Radioastron.; LESIA, Meudon
  42. Colorado U.
  43. Bonn, Max Planck Inst., Radioastron.; IRAM, St. Martin d'Heres
  44. Bonn, Max Planck Inst., Radioastron.; NAOC, Beijing
  45. Las Cumbres Observ.; UC, Santa Barbara
  46. NRAO, Charlottesville
  47. MIT; Unlisted, US, MA
  48. Bonn, Max Planck Inst., Radioastron.; Frankfurt U.; Wurzburg U.
  49. Harvard U. (main); Harvard-Smithsonian Ctr. Astrophys.; Harvard U.; Harvard U., Phys. Dept.
  50. Illinois U., Urbana; Illinois U., Urbana, Astron. Dept.
  51. Cagliari U.; Cagliari Observ.
  52. Frankfurt U.; Southern Denmark U., CP3-Origins
  53. INAOE, Puebla; Conacyt, Mexico
  54. Shanghai, Astron. Observ.
  55. KASI, DaeJeon; Tokyo, Grad. U. Adv. Stud.; Natl. Astron. Observ. of Japan
  56. Groningen U.
  57. Peking U.; Peking U., Beijing, KIAA
  58. Academia Sinica, Taiwan; Subaru Telescope
  59. KASI, DaeJeon; Tokyo, Grad. U. Adv. Stud.; Natl. Astron. Observ. of Japan; Tokyo U.
  60. INAOE, Puebla
  61. Natl. Astron. Observ. of Japan; Tokyo, Inst. Statistical Math.; Tokyo U., IPMU
  62. NRAO, Charlottesville; Leiden Observ.
  63. Harvard-Smithsonian Ctr. Astrophys.; Baltimore, Space Telescope Sci.
  64. Unlisted, US, MA
  65. Boston U.
  66. Perimeter Inst. Theor. Phys.; Waterloo U.
  67. Tokyo U., ICRR
  68. ASTRON, Dwingeloo
  69. Bonn, Max Planck Inst., Radioastron.; KASI, DaeJeon; Kyungpook Natl. U.
  70. Arizona U., Astron. Dept. - Steward Observ.; Caltech
  71. Natl. Astron. Observ. of Japan; Kogakuin U.
  72. KASI, DaeJeon; Tokyo U.
  73. Academia Sinica, Taiwan; Niigata U.
  74. Academia Sinica, Taiwan; Taiwan, Natl. Normal U.; Taiwan, Natl. Taiwan U.
  75. Hong Kong, Chinese U.
  76. Nanjing U., Dept. Astron.; Nanjing U.
  77. Granada U., Theor. Phys. Astrophys.; Bologna, Ist. Radioastronomia
  78. Bologna Observ.
  79. Academia Sinica, Taiwan; Taiwan, Natl. Taiwan U.
  80. UNAM, Morelia, Inst. Radioastron. Astrophys.; UNAM, Inst. Astron.
  81. Bonn, Max Planck Inst., Radioastron.; Shanghai, Astron. Observ.; Nanjing U. Sci. Tech.
  82. Yunnan Observ.; NAOC, Beijing
  83. Bonn, Max Planck Inst., Radioastron.; Bologna Observ.
  84. U. Amsterdam, GRAPPA
  85. Valencia U., Astro. Astrophys.; Valencia U., IFIC
  86. Arizona U., Astron. Dept. - Steward Observ.; Naval Research Lab, Wash., D.C.; Cornell U., Radio. Space Res. Ctr.; Princeton, Inst. Advanced Study
  87. Chicago U., Astron. Astrophys. Ctr.; ESTEC, Noordwijk
  88. Frankfurt U.; Tsung-Dao Lee Inst., Shanghai; Shanghai Jiaotong U.
  89. MIT, LNS; Frankfurt U.; KASI, DaeJeon
  90. Bonn, Max Planck Inst., Radioastron.; Nijmegen U., IMAPP
  91. Nijmegen U., IMAPP; U. Amsterdam, GRAPPA
  92. IRAM, Granada
  93. Illinois U., Urbana, Astron. Dept.
  94. Natl. Astron. Observ. of Japan; Tokyo, Grad. U. Adv. Stud.
  95. Concepcion U.
  96. Academia Sinica, Taiwan; Hachinohe Inst. Tech.
  97. U. Witwatersrand, Johannesburg, Sch. Phys.; South African Astron. Observ.
  98. Frankfurt U.; Athens U.
  99. Villanova U.
  100. Washington U., St. Louis
  101. Sejong U.
  102. Bonn, Max Planck Inst., Radioastron.; UNAM, Inst. Astron.
  103. Academia Sinica, Taiwan; Baltimore, Space Telescope Sci.
  104. Academia Sinica, Taiwan; Perimeter Inst. Theor. Phys.; Canadian Inst. Theor. Astrophys.; Toronto U., Astron. Dept.; Canadian Inst. Advanced Res.
  105. UC, Berkeley
  106. Frankfurt U.; U. Amsterdam, GRAPPA
  107. Bonn, Max Planck Inst., Radioastron.; University Coll., Cork
  108. Perimeter Inst. Theor. Phys.
  109. Academia Sinica, Taiwan; Taiwan, Natl. Normal U.
  110. Concepcion U.; Turku U.; Aalto U.
  111. Subaru Telescope; Gemini Observ., Hilo
  112. Frankfurt U.; Frankfurt U., FIAS; Trinity Coll., Dublin
  113. CCA, New York; Princeton U., Astrophys. Sci. Dept.
  114. Harvard U. (main); Harvard-Smithsonian Ctr. Astrophys.; Nijmegen U., IMAPP
  115. KASI, DaeJeon; Tokyo Inst. Tech.; Hiroshima U.
  116. Bonn, Max Planck Inst., Radioastron.; Aalto U.
  117. Bonn, Max Planck Inst., Radioastron.; Peking U., Beijing, KIAA
  118. KASI, DaeJeon; KAIST, Taejon; Yonsei U.
  119. Baltimore, Space Telescope Sci.; Texas Tech.
  120. Arizona U., Astron. Dept. - Steward Observ.; Nijmegen U., IMAPP; Leiden Observ.; NWO, The Hague
  121. Bonn, Max Planck Inst., Radioastron.; IRAM, Granada
  122. Granada U., Theor. Phys. Astrophys.; Bonn, Max Planck Inst., Radioastron.
  123. Seoul Natl. U.
  124. Leiden Observ.; ASTRON, Dwingeloo; New Mexico U.
  125. Central Lancashire U.
  126. Brandeis U.
  127. Tuorla Observ.
  128. Princeton, Inst. Advanced Study; Princeton U.
  129. Hua-Zhong U. Sci. Tech.
  130. Frankfurt U.; Mullard Space Sci. Lab.
  131. Shanghai, Astron. Observ.; Beijing, GUCAS
  132. Hefei, CUST
  133. Bard Coll.
  134. European Southern Obs., Chile
  135. Bonn, Max Planck Inst., Radioastron.; Bonn U.
  136. NRAO, Socorro
  137. Bonn, Max Planck Inst., Radioastron.; European Southern Obs., Chile
  138. Netherlands Meteorological Inst.
  139. Manchester U., NRAL; European Southern Observ.
  140. Subaru Telescope; NASA, Ames
  141. Bonn, Max Planck Inst., Radioastron.; European Southern Obs., Chile; Chile U., Catolica
  142. U. Michigan, Dept. Astron.
  143. European Southern Obs., Chile; NRAO, Charlottesville
+ Show Author Affiliations
We present Event Horizon Telescope (EHT) 1.3 mm measurements of the radio source located at the position of the supermassive black hole Sagittarius A* (Sgr A*), collected during the 2017 April 5–11 campaign. The observations were carried out with eight facilities at six locations across the globe. Novel calibration methods are employed to account for Sgr A*'s flux variability. The majority of the 1.3 mm emission arises from horizon scales, where intrinsic structural source variability is detected on timescales of minutes to hours. The effects of interstellar scattering on the image and its variability are found to be subdominant to intrinsic source structure. The calibrated visibility amplitudes, particularly the locations of the visibility minima, are broadly consistent with a blurred ring with a diameter of ∼50 μas, as determined in later works in this series. Contemporaneous multiwavelength monitoring of Sgr A* was performed at 22, 43, and 86 GHz and at near-infrared and X-ray wavelengths. Several X-ray flares from Sgr A* are detected by Chandra, one at low significance jointly with Swift on 2017 April 7 and the other at higher significance jointly with NuSTAR on 2017 April 11. The brighter April 11 flare is not observed simultaneously by the EHT but is followed by a significant increase in millimeter flux variability immediately after the X-ray outburst, indicating a likely connection in the emission physics near the event horizon. We compare Sgr A*’s broadband flux during the EHT campaign to its historical spectral energy distribution and find that both the quiescent emission and flare emission are consistent with its long-term behavior.
Research Organization:
ASTRON, Dwingeloo; Aalto U.; Academia Sinica, Taiwan; Arizona U.; Arizona U., Astron. Dept. - Steward Observ.; Athens U.; Baltimore, Space Telescope Sci.; Bard Coll.; Beijing, GUCAS; Bologna Observ.; Bologna, Ist. Radioastronomia; Bonn U.; Bonn, Max Planck Inst., Radioastron.; Boston U.; Brandeis U.; CCA, New York; Cagliari Observ.; Cagliari U.; Caltech; Canadian Inst. Advanced Res.; Canadian Inst. Theor. Astrophys.; Central Lancashire U.; Chalmers U. Tech.; Chicago U.; Chicago U., Astron. Astrophys. Ctr.; Chicago U., EFI; Chicago U., KICP; Chile U., Catolica; Colorado U.; Columbia U., Astron. Astrophys.; Conacyt, Mexico; Concepcion U.; Cornell U., Radio. Space Res. Ctr.; ESTEC, Noordwijk; European Southern Obs., Chile; European Southern Observ.; Fairfield U.; Fermi National Accelerator Laboratory (FNAL), Batavia, IL (United States); Frankfurt U.; Frankfurt U., FIAS; Gemini Observ., Hilo; Granada U., Theor. Phys. Astrophys.; Groningen U.; Hachinohe Inst. Tech.; Harvard U.; Harvard U. (main); Harvard U., Phys. Dept.; Harvard-Smithsonian Ctr. Astrophys.; Hawaii U.; Hefei, CUST; Hiroshima U.; Hong Kong, Chinese U.; Hua-Zhong U. Sci. Tech.; INAOE, Puebla; INFN, Naples; IRAM, Granada; IRAM, St. Martin d'Heres; Illinois U., Urbana; Illinois U., Urbana, Astron. Dept.; KAIST, Taejon; KASI, DaeJeon; Kogakuin U.; Kyungpook Natl. U.; LESIA, Meudon; Las Cumbres Observ.; Leiden Observ.; MIT; MIT, LNS; Malaya U.; Manchester U., NRAL; Massachusetts U., Amherst; McGill U.; Mullard Space Sci. Lab.; NAOC, Beijing; NASA, Ames; NRAO, Charlottesville; NRAO, Socorro; NWO, The Hague; Nanjing U.; Nanjing U. Sci. Tech.; Nanjing U., Dept. Astron.; Naples U.; Natl. Astron. Observ. of Japan; Naval Research Lab, Wash., D.C.; Netherlands Meteorological Inst.; New Mexico U.; Niigata U.; Nijmegen U., IMAPP; Peking U.; Peking U., Beijing, KIAA; Perimeter Inst. Theor. Phys.; Pretoria U.; Princeton U.; Princeton U., Astrophys. Sci. Dept.; Princeton U., PCTS; Princeton, Inst. Advanced Study; Rhodes U.; Sejong U.; Seoul Natl. U.; Shanghai Jiaotong U.; Shanghai, Astron. Observ.; South African Astron. Observ.; Southern Denmark U., CP3-Origins; Subaru Telescope; Taiwan, Natl. Normal U.; Taiwan, Natl. Taiwan U.; Texas Tech.; Texas U., San Antonio; Tokyo Inst. Tech.; Tokyo U.; Tokyo U., ICRR; Tokyo U., IPMU; Tokyo, Grad. U. Adv. Stud.; Tokyo, Inst. Statistical Math.; Toronto U., Astron. Dept.; Trinity Coll., Dublin; Tsung-Dao Lee Inst., Shanghai; Tuorla Observ.; Turku U.; U. Amsterdam, GRAPPA; U. Michigan, Dept. Astron.; U. Witwatersrand, Johannesburg, Sch. Phys.; UC, Berkeley; UC, Santa Barbara; UNAM, Inst. Astron.; UNAM, Morelia, Inst. Radioastron. Astrophys.; University Coll., Cork; Unlisted, US, MA; Valencia U., Astro. Astrophys.; Valencia U., IFIC; Villanova U.; Washington U., St. Louis; Waterloo U.; Waterloo U., IQC; Wurzburg U.; Yale Ctr. Astron. Astrophys.; Yonsei U.; Yunnan Observ.
Sponsoring Organization:
US Department of Energy
Grant/Contract Number:
AC02-07CH11359
OSTI ID:
1868460
Report Number(s):
FERMILAB-PUB-22-418-PPD; oai:inspirehep.net:2080892; arXiv:2311.08679
Journal Information:
Astrophys.J.Lett., Journal Name: Astrophys.J.Lett. Journal Issue: 2 Vol. 930
Country of Publication:
United States
Language:
English

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