Persistent Asymmetric Structure of Sagittarius A* on Event Horizon Scales

aut.relation.journalThe Astrophysical Journalen_NZ
aut.researcherKassabova, Diana
dc.contributor.authorFish, VLen_NZ
dc.contributor.authorJohnson, MDen_NZ
dc.contributor.authorDoeleman, SSen_NZ
dc.contributor.authorBroderick, AEen_NZ
dc.contributor.authorPsaltis, Den_NZ
dc.contributor.authorLu, R-Sen_NZ
dc.contributor.authorAkiyama, Ken_NZ
dc.contributor.authorAlef, Wen_NZ
dc.contributor.authorAlgaba, JCen_NZ
dc.contributor.authorAsada, Ken_NZ
dc.contributor.authorBeaudoin, Cen_NZ
dc.contributor.authorBertarini, Aen_NZ
dc.contributor.authorBlackburn, Len_NZ
dc.contributor.authorBlundell, Ren_NZ
dc.contributor.authorBower, GCen_NZ
dc.contributor.authorBrinkerink, Cen_NZ
dc.contributor.authorCappallo, Ren_NZ
dc.contributor.authorChael, AAen_NZ
dc.contributor.authorChamberlin, Ren_NZ
dc.contributor.authorChan, C-Ken_NZ
dc.contributor.authorCrew, GBen_NZ
dc.contributor.authorDexter, Jen_NZ
dc.contributor.authorDexter, Men_NZ
dc.contributor.authorDzib, SAen_NZ
dc.contributor.authorFalcke, Hen_NZ
dc.contributor.authorFreund, Ren_NZ
dc.contributor.authorFriberg, Pen_NZ
dc.contributor.authorGreer, CHen_NZ
dc.contributor.authorGurwell, MAen_NZ
dc.contributor.authorHo, PTPen_NZ
dc.contributor.authorHonma, Men_NZ
dc.contributor.authorInoue, Men_NZ
dc.contributor.authorJohannsen, Ten_NZ
dc.contributor.authorKim, Jen_NZ
dc.contributor.authorKrichbaum, TPen_NZ
dc.contributor.authorLamb, Jen_NZ
dc.contributor.authorLeón-Tavares, Jen_NZ
dc.contributor.authorLoeb, Aen_NZ
dc.contributor.authorLoinard, Len_NZ
dc.contributor.authorMacMahon, Den_NZ
dc.contributor.authorMarrone, DPen_NZ
dc.contributor.authorMoran, JMen_NZ
dc.contributor.authorMościbrodzka, Men_NZ
dc.contributor.authorOrtiz-León, GNen_NZ
dc.contributor.authorOyama, Ten_NZ
dc.contributor.authorÖzel, Fen_NZ
dc.contributor.authorPlambeck, RLen_NZ
dc.contributor.authorPradel, Nen_NZ
dc.contributor.authorPrimiani, RAen_NZ
dc.contributor.authorRogers, AEEen_NZ
dc.contributor.authorRosenfeld, Ken_NZ
dc.contributor.authorRottmann, Hen_NZ
dc.contributor.authorRoy, ALen_NZ
dc.contributor.authorRuszczyk, Cen_NZ
dc.contributor.authorSmythe, DLen_NZ
dc.contributor.authorSooHoo, Jen_NZ
dc.contributor.authorSpilker, Jen_NZ
dc.contributor.authorStone, Jen_NZ
dc.contributor.authorStrittmatter, Pen_NZ
dc.contributor.authorTilanus, RPJen_NZ
dc.contributor.authorTitus, Men_NZ
dc.contributor.authorVertatschitsch, Len_NZ
dc.contributor.authorWagner, Jen_NZ
dc.contributor.authorWardle, JFCen_NZ
dc.contributor.authorWeintroub, Jen_NZ
dc.contributor.authorWoody, Den_NZ
dc.contributor.authorWright, Men_NZ
dc.contributor.authorYamaguchi, Pen_NZ
dc.contributor.authorYoung, Aen_NZ
dc.contributor.authorYoung, KHen_NZ
dc.contributor.authorZensus, JAen_NZ
dc.contributor.authorZiurys, LMen_NZ
dc.description.abstractThe Galactic Center black hole Sagittarius A* (Sgr A*) is a prime observing target for the Event Horizon Telescope (EHT), which can resolve the 1.3 mm emission from this source on angular scales comparable to that of the general relativistic shadow. Previous EHT observations have used visibility amplitudes to infer the morphology of the millimeter-wavelength emission. Potentially much richer source information is contained in the phases. We report on 1.3 mm phase information on Sgr A* obtained with the EHT on a total of 13 observing nights over 4 years. Closure phases, the sum of visibility phases along a closed triangle of interferometer baselines, are used because they are robust against phase corruptions introduced by instrumentation and the rapidly variable atmosphere. The median closure phase on a triangle including telescopes in California, Hawaii, and Arizona is nonzero. This result conclusively demonstrates that the millimeter emission is asymmetric on scales of a few Schwarzschild radii and can be used to break 180-degree rotational ambiguities inherent from amplitude data alone. The stability of the sign of the closure phase over most observing nights indicates persistent asymmetry in the image of Sgr A* that is not obscured by refraction due to interstellar electrons along the line of sight.en_NZ
dc.identifier.citationThe Astrophysical Journal, 820(2), 90.
dc.publisherIOP Publishing
dc.rightsThe American Astronomecal Society (AAS) grants authors the non-exclusive right of republication, subject only to authors giving appropriate credit to the journal in which their article is published. This non-exclusive right of republication includes author's right to allow reproduction of parts of their article wherever they wish, and permits authors to post the published (PDF) version of their article on their personal web site. To protect the copyright in author's article, the original copyright notice as it appears in the journal should be included in the credit.
dc.subjectGalaxy: Center; Submillimeter: General; Techniques: High angular resolution; Techniques: Interferometric
dc.titlePersistent Asymmetric Structure of Sagittarius A* on Event Horizon Scalesen_NZ
dc.typeJournal Article
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