The jet collimation profile at high resolution in BL Lacertae

dc.contributorAalto Universityen
dc.contributor.authorCasadio, C.en_US
dc.contributor.authorMacDonald, N. R.en_US
dc.contributor.authorBoccardi, B.en_US
dc.contributor.authorJorstad, S. G.en_US
dc.contributor.authorMarscher, A. P.en_US
dc.contributor.authorKrichbaum, T. P.en_US
dc.contributor.authorHodgson, J. A.en_US
dc.contributor.authorKim, J. Y.en_US
dc.contributor.authorTraianou, E.en_US
dc.contributor.authorWeaver, Z. R.en_US
dc.contributor.authorGómez Garrido, M.en_US
dc.contributor.authorGonzález García, J.en_US
dc.contributor.authorKallunki, J.en_US
dc.contributor.authorLindqvist, M.en_US
dc.contributor.authorSánchez, S.en_US
dc.contributor.authorYang, J.en_US
dc.contributor.authorZensus, J. A.en_US
dc.contributor.departmentMetsähovi Radio Observatoryen
dc.contributor.organizationInstitute of Electronic Structure and Laseren_US
dc.contributor.organizationMax-Planck-Institut für Radioastronomieen_US
dc.contributor.organizationBoston Universityen_US
dc.contributor.organizationSejong Universityen_US
dc.contributor.organizationObservatorio de Yebesen_US
dc.contributor.organizationMetsähovi Radio Observatoryen_US
dc.contributor.organizationChalmers University of Technologyen_US
dc.contributor.organizationInstituto de Radioastronomía Milimétricaen_US
dc.descriptionFunding Information: Acknowledgements. We thank Eduardo Ros for the valuable suggestions that helped improve this manuscript. This research has been consulting data from the MOJAVE database that is maintained by the MOJAVE team (Lister et al. 2009). C. Casadio acknowledges support from the European Research Council (ERC) under the European Union Horizon 2020 research and innovation programme under the grant agreement No. 771282. The research at Boston University was supported by NASA through Fermi Guest Investigator program grants NNX17K0649 an 80NSSC20K1567. This research has made use of data obtained with the Global Millimeter VLBI Array (GMVA), which consists of telescopes operated by the MPIfR, IRAM, Onsala, Metsahovi, Yebes, the Korean VLBI Network, the Greenland Telescope, the Green Bank Observatory and the Very Long Baseline Array (VLBA). The VLBA is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The data were correlated at the correlator of the MPIfR in Bonn, Germany. We thank W. Alef, A. Bertarini, H. Rottmann and I. Wagner for their support at the MPIfR VLBI correlator. We also thank Pablo Torne for his help at the IRAM 30m telescope. Publisher Copyright: © ESO 2021.
dc.description.abstractContext. Controversial studies on the jet collimation profile of BL Lacertae (BL Lac), the eponymous blazar of the BL Lac objects class, complicate the scenario in this already puzzling class of objects. Understanding the jet geometry in connection with the jet kinematics and the physical conditions in the surrounding medium is fundamental for better constraining the formation, acceleration, and collimation mechanisms in extragalactic jets. Aims. With the aim of investigating the jet geometry in the innermost regions of the BL Lac jet, and resolving the controversy, we explore the radio jet in this source using high-resolution millimeter-wave VLBI data. Methods. We collect 86 GHz GMVA and 43 GHz VLBA data to obtain stacked images that we use to infer the jet collimation profile by means of two comparable methods. We analyze the kinematics at 86 GHz, and we discuss it in the context of the jet expansion. Finally, we consider a possible implication of the Bondi sphere in shaping the jet of BL Lac. Results. The jet in BL Lac expands with an overall conical geometry. A higher expanding rate region is observed between ∼5 and 10 pc (de-projected) from the black hole. Such a region is associated with the decrease in brightness usually observed in high-frequency VLBI images of BL Lac. The jet retrieves the original jet expansion around 17 pc, where the presence of a recollimation shock is supported by both the jet profile and the 15 GHz kinematics (MOJAVE survey). The change in the jet expansion profile occurring at ∼5 pc could be associated with a change in the external pressure at the location of the Bondi radius (∼3.3 × 105RS).en
dc.description.versionPeer revieweden
dc.identifier.citationCasadio, C, MacDonald, N R, Boccardi, B, Jorstad, S G, Marscher, A P, Krichbaum, T P, Hodgson, J A, Kim, J Y, Traianou, E, Weaver, Z R, Gómez Garrido, M, González García, J, Kallunki, J, Lindqvist, M, Sánchez, S, Yang, J & Zensus, J A 2021, ' The jet collimation profile at high resolution in BL Lacertae ', Astronomy and Astrophysics, vol. 649, 153 .
dc.identifier.otherPURE UUID: 50d7d02d-2094-4481-b0be-175e419dd405en_US
dc.identifier.otherPURE ITEMURL:
dc.identifier.otherPURE LINK:
dc.identifier.otherPURE FILEURL:
dc.publisherEDP SCIENCES
dc.relation.ispartofseriesAstronomy and Astrophysicsen
dc.relation.ispartofseriesVolume 649en
dc.subject.keywordBL Lacertae objects: individual: BL Lacertaeen_US
dc.subject.keywordGalaxies: activeen_US
dc.subject.keywordGalaxies: jetsen_US
dc.subject.keywordInstrumentation: high angular resolutionen_US
dc.subject.keywordInstrumentation: interferometersen_US
dc.titleThe jet collimation profile at high resolution in BL Lacertaeen
dc.typeA1 Alkuperäisartikkeli tieteellisessä aikakauslehdessäfi