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A method for checking high-redshift identification of radio AGNs
An, Tao1; Zhang, Yingkang1,2; Frey, Sandor3,4
2020-09-01
Source PublicationMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
ISSN0035-8711
Volume497Issue:2Pages:2260-2264
AbstractIn large-scale optical spectroscopic surveys, there are many objects found to have multiple redshift measurements due to the weakness of their emission lines and the different automatic identification algorithms used. These include some suspicious high-redshift (z greater than or similar to 5) active galactic nuclei (AGNs). Here, we present a method for inspecting the high-redshift identification of such sources provided that they are radio-loud and have very long baseline interferometry (VLBI) imaging observations of their milli-arcsec (mas) scale jet structure available at multiple epochs. The method is based on the determination of jet component proper motions, and the fact that the combination of jet physics (the observed maximal values of the bulk Lorentz factor) and cosmology (the time dilation of observed phenomena in the early Universe) constrain the possible values of apparent proper motions. As an example, we present the case of the quasar J2346 + 0705 that was reported with two different redshifts, z(1) = 5.063 and z(2) = 0.171, in the literature. We measured the apparent proper motions (mu) of three components identified in its radio jet by utilizing VLBI data taken from 2014 to 2018. We obtained mu(J1) = 0.334 +/- 0.099 mas yr(-1), mu(J2) = 0.116 +/- 0.029 mas yr(-1), and mu(J3) = 0.060 +/- 0.005 mas yr(-1). The maximal proper motion is converted to an apparent transverse speed of beta(app) = 41.2 +/- 12.2 c, if the source is at redshift 5.063. This value exceeds the blazar jet speeds known to date. This and other arguments suggest that J2346 + 0705 is hosted by a low-redshift galaxy. Our method may be applicable for other high-redshift AGN candidates lacking unambiguous spectroscopic redshift determination or having photometric redshift estimates only, but showing prominent radio jets allowing for VLBI measurements of fast jet proper motions.
Keywordgalaxies: nuclei quasars: individual: J2346+0705
Funding OrganizationNational Key Research and Development Programme of China ; National Key Research and Development Programme of China ; Hungarian National Research, Development and Innovation Office ; Hungarian National Research, Development and Innovation Office ; National Aeronautics and Space Administration ; National Aeronautics and Space Administration ; National Key Research and Development Programme of China ; National Key Research and Development Programme of China ; Hungarian National Research, Development and Innovation Office ; Hungarian National Research, Development and Innovation Office ; National Aeronautics and Space Administration ; National Aeronautics and Space Administration ; National Key Research and Development Programme of China ; National Key Research and Development Programme of China ; Hungarian National Research, Development and Innovation Office ; Hungarian National Research, Development and Innovation Office ; National Aeronautics and Space Administration ; National Aeronautics and Space Administration ; National Key Research and Development Programme of China ; National Key Research and Development Programme of China ; Hungarian National Research, Development and Innovation Office ; Hungarian National Research, Development and Innovation Office ; National Aeronautics and Space Administration ; National Aeronautics and Space Administration
DOI10.1093/mnras/staa2132
WOS KeywordACTIVE GALACTIC NUCLEI ; DIGITAL SKY SURVEY ; QUASARS ; KINEMATICS ; MOTION
Language英语
Funding ProjectNational Key Research and Development Programme of China[2018YFA0404603] ; Hungarian National Research, Development and Innovation Office[20182.1.14-TET-CN-2018-00001] ; National Aeronautics and Space Administration
Funding OrganizationNational Key Research and Development Programme of China ; National Key Research and Development Programme of China ; Hungarian National Research, Development and Innovation Office ; Hungarian National Research, Development and Innovation Office ; National Aeronautics and Space Administration ; National Aeronautics and Space Administration ; National Key Research and Development Programme of China ; National Key Research and Development Programme of China ; Hungarian National Research, Development and Innovation Office ; Hungarian National Research, Development and Innovation Office ; National Aeronautics and Space Administration ; National Aeronautics and Space Administration ; National Key Research and Development Programme of China ; National Key Research and Development Programme of China ; Hungarian National Research, Development and Innovation Office ; Hungarian National Research, Development and Innovation Office ; National Aeronautics and Space Administration ; National Aeronautics and Space Administration ; National Key Research and Development Programme of China ; National Key Research and Development Programme of China ; Hungarian National Research, Development and Innovation Office ; Hungarian National Research, Development and Innovation Office ; National Aeronautics and Space Administration ; National Aeronautics and Space Administration
WOS Research AreaAstronomy & Astrophysics
WOS SubjectAstronomy & Astrophysics
WOS IDWOS:000574924500072
PublisherOXFORD UNIV PRESS
Citation statistics
Document Type期刊论文
Identifierhttp://ir.bao.ac.cn/handle/114a11/81830
Collection中国科学院国家天文台
Corresponding AuthorAn, Tao
Affiliation1.Chinese Acad Sci, Key Lab Radio Astron, Shanghai Astron Observ, 80 Nandan Rd, Shanghai 200030, Peoples R China
2.Univ Chinese Acad Sci, 19A Yuquanlu, Beijing 100049, Peoples R China
3.Konkoly Observ Budapest, Res Ctr Astron & Earth Sci, Konkoly Thege Miklos Ut 15-17, H-1121 Budapest, Hungary
4.Eotvos Lorand Univ, Inst Phys, Pazmany Peter Setany 1-A, H-1117 Budapest, Hungary
Recommended Citation
GB/T 7714
An, Tao,Zhang, Yingkang,Frey, Sandor. A method for checking high-redshift identification of radio AGNs[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2020,497(2):2260-2264.
APA An, Tao,Zhang, Yingkang,&Frey, Sandor.(2020).A method for checking high-redshift identification of radio AGNs.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,497(2),2260-2264.
MLA An, Tao,et al."A method for checking high-redshift identification of radio AGNs".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 497.2(2020):2260-2264.
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