J/A+A/695/A233 VLBI core fluxes and brightness temperatures (Roeder+, 2025)
A multi-frequency study of sub-parsec jets with the Event Horizon Telescope.
Roeder J., Wielgus M., Lobanov A.P., Krichbaum T.P., Nair D.G., Lee S.-S.,
Ros E., Fish V.L., Blackburn L., Chan C.-K., Issaoun S., Janssen M.,
Johnson M.D., Doeleman S.S., Bower G.C., Crew G.B., Tilanus R.P.J.,
Savolainen T., Impellizzeri C.M.V., Alberdi A., Baczko A.-K., Gomez J.L.,
Lu R.-S., Paraschos G.F., Traianou E., Goddi C., Kim D., Lisakov M.,
Kovalev Y.Y., Voitsik P.A., Sokolovsky K.V., Akiyama K., Albentosa-Ruiz E.,
Alef W., Algaba J.C., Anantua R., Asada K., Azulay R., Bach U., Ball D.,
Balokovic M., Bandyopadhyay B., Barrett J., Bauboeck M., Benson B.A.,
Bintley D., Blundell R., Bouman K.L., Bremer M., Brinkerink C.D.,
Brissenden R., Britzen S., Broderick A.E., Broguiere D., Bronzwaer T.,
Bustamante S., Byun D.-Y., Carlstrom J.E., Ceccobello C., Chael A.,
Chang D.O., Chatterjee K., Chatterjee S., Chen M.-T., Chen Y., Cheng X.,
Cho I., Christian P., Conroy N.S., Conway J.E., Cordes J.M., Crawford T.M.,
Cruz-Osorio A., Cui Y., Curd B., Dahale R., Davelaar J., De Laurentis M.,
Deane R., Dempsey J., Desvignes G., Dexter J., Dhruv V., Dihingia I.K.,
Taylor Dougall S., Dzib S.A., Eatough R.P., Emami R., Falcke H., Farah J.,
Fomalont E., Ford H.A., Foschi M., Fraga-Encinas R., Freeman W.T.,
Friberg P., Fromm C.M., Fuentes A., Galison P., Gammie C.F., Garcia R.,
Gentaz O., Georgiev B., Gold R., Gomez-Ruiz A.I., Gu M., Gurwell M.,
Hada K., Haggard D., Haworth K., Hecht M.H., Hesper R., Heumann D., Ho L.C.,
Ho P., Honma M., Huang C.-W.L., Huang L., Hughes D.H., Ikeda S., Inoue M.,
James D.J., Jannuzi B.T., Jeter B., Jiang W., Jimenez-Rosales A.,
Jorstad S., Joshi A.V., Jung T., Karami M., Karuppusamy R., Kawashima T.,
Keating G.K., Kettenis M., Kim D.-J., Kim J.-Y., Kim J., Kim J., Kino M.,
Koay J.Y., Kocherlakota P., Kofuji Y., Koyama S., Kramer C., Kramer J.A.,
Kramer M., Kuo C.-Y., La Bella N., Lauer T.R., Lee D., Leung P.K., Levis A.,
Li Z., Lico R., Lindahl G., Lindqvist M., Liu J., Liu K., Liuzzo E.,
Lo W.-P., Loinard L., Lonsdale C.J., Lowitz A.E., MacDonald N.R., Mao J.,
Marchili N., Markoff S., Marrone D.P., Marscher A.P., Marti-Vidal I.,
Matsushita S., Matthews L.D., Medeiros L., Menten K.M., Michalik D.,
Mizuno I., Mizuno Y., Moran J.M., Moriyama K., Moscibrodzka M., Mulaudzi W.,
Mueller C., Mueller H., Mus A., Musoke G., Myserlis I., Nadolski A.,
Nagai H., Nagar N.M., Nakamura M., Narayanan G., Natarajan I., Nathanail A.,
Navarro Fuentes S., Neilsen J., Neri R., Ni C., Noutsos A., Nowak M.A.,
Oh J., Okino H., Olivares Sanchez H.R., Ortiz-Leon G.N., Oyama T., Oezel F.,
Palumbo D.C.M., Park J., Parsons H., Patel N., Pen U.-L., Pesce D.W.,
Pietu V., Plambeck R., PopStefanija A., Porth O., Poetzl F.M., Prather B.,
Preciado-Lopez J.A., Principe G., Psaltis D., Pu H.-Y., Ramakrishnan V.,
Rao R., Rawlings M.G., Ricarte A., Ripperda B., Roelofs F., Rogers A.,
Romero-Canizales C., Roshanineshat A., Rottmann H., Roy A.L., Ruiz I.,
Ruszczyk C., Rygl K.L.J., Sanchez S., Sanchez-Argueelles D.,
Sanchez-Portal M., Sasada M., Satapathy K., Schloerb F.P., Schonfeld J.,
Schuster K.-F., Shao L., Shen Z., Small D., Won Sohn B., SooHoo J.,
Sosapanta Salas L.D., Souccar K., Stanway J.S., Sun H., Tazaki F.,
Tetarenko A.J., Tiede P., Titus M., Torne P., Toscano T., Trent T.,
Trippe S., Turk M., van Bemmel I., van Langevelde H.J., van Rossum D.R.,
Vos J., Wagner J., Ward-Thompson D., Wardle J., Washington J.E.,
Weintroub J., Wharton R., Wiik K., Witzel G., Wondrak M.F., Wong G.N.,
Wu Q., Yadlapalli N., Yamaguchi P., Yfantis A., Yoon D., Young A., Young K.,
Younsi Z., Yu W., Yuan F., Yuan Y.-F., Zensus J.A., Zhang S., Zhao G.-Y.,
Zhao S.S. (the Event Horizon Telescope Collaboration)
<Astron. Astrophys. 695, A233 (2025)>
=2025A&A...695A.233R 2025A&A...695A.233R (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; QSOs ; VLBI ; BL Lac objects
Keywords: techniques: interferometric - galaxies: active - galaxies: jets -
galaxies: nuclei - quasars: general -
quasars: supermassive black holes
Abstract:
The 2017 observing campaign of the Event Horizon Telescope (EHT)
delivered the first very long baseline interferometry (VLBI) images at
the observing frequency of 230GHz, leading to a number of unique
studies on black holes and relativistic jets from active galactic
nuclei (AGN). In total, eighteen sources were observed, including the
main science targets, Sgr A* and M 87, and various calibrators.
Sixteen sources were AGN.
We investigated the morphology of the sixteen AGN in the EHT 2017 data
set, focusing on the properties of the VLBI cores: size, flux density,
and brightness temperature. We studied their dependence on the
observing frequency in order to compare it with the Blandford-Koenigl
(BK) jet model. In particular, we aimed to study the signatures of jet
acceleration and magnetic energy conversion.
We modeled the source structure of seven AGN in the EHT 2017 data set
using linearly polarized circular Gaussian components (1749+096,
1055+018, BL Lac, J0132-1654, J0006-0623, CTA 102, and 3C 454.3) and
collected results for the other nine AGN from dedicated EHT
publications, complemented by lower frequency data in the 2-86GHz
range. Combining these data into a multifrequency EHT+ data set, we
studied the dependences of the VLBI core component flux density, size,
and brightness temperature on the frequency measured in the AGN host
frame (and hence on the distance from the central black hole),
characterizing them with power law fits. We compared the observations
with the BK jet model and estimated the magnetic field strength
dependence on the distance from the central black hole.
Our observations spanning event horizon to parsec scales indicate a
deviation from the standard BK model, particularly in the decrease of
the brightness temperature with the observing frequency. Only some of
the discrepancies may be alleviated by tweaking the model parameters
or the jet collimation profile. Either bulk acceleration of the jet
material, energy transfer from the magnetic field to the particles, or
both are required to explain the observations. For our sample, we
estimate a general radial dependence of the Doppler factor
δ∝r<=0.5. This interpretation is consistent with a
magnetically accelerated sub-parsec jet. We also estimate a steep
decrease of the magnetic field strength with radius B∝r-3,
hinting at jet acceleration or efficient magnetic energy dissipation.
Description:
We present an analysis of the 16 active galactic nuclei observed
during the 2017 EHT campaign. First, we modeled the sources which had
thus far remained unpublished with polarized circular Gaussian
components. We then measured the flux densities and sizes of the VLBI
cores of all AGN, obtaining the brightness temperature in the process.
Further, we derived the magnetic field strength in the cores and their
distance to central black hole. Contextualizing the 230GHz EHT data
with measurements at lower frequencies, we analyzed the trends of the
measured and modeled quantities with frequency, and in turn, with
distance to the black hole. We find the results to be incompatible
with the well-established Blandford- Koenigl jet model, requiring jet
acceleration over large scales or deviations from energy
equipartition.
VLBI core flux densities, brightness temperatures, FWHM sizes,
magnetic field strengths, distances to the central black hole and
synchrotron luminosities, of the 16 AGN sources observed during the
2017 EHT campaign.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
eht_2017.dat 421 16 Name, VLBI core S, Tb, Theta, z, B, d_BH, Lsyn
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Byte-by-byte Description of file: eht_2017.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name B1950 source name (HHMM+DDd)
10- 18 E9.3 Jy 2GHzSnu ?=-999 2GHz VLBI core flux density
20- 28 E9.3 Jy 5GHzSnu ?=-999 5GHz VLBI core flux density
30- 38 E9.3 Jy 8GHzSnu ?=-999 8GHz VLBI core flux density
40- 48 E9.3 Jy 15GHzSnu ?=-999 15GHz VLBI core flux density
50- 58 E9.3 Jy 22GHzSnu ?=-999 22GHz VLBI core flux density
60- 68 E9.3 Jy 43GHzSnu ?=-999 43GHz VLBI core flux density
70- 78 E9.3 Jy 86GHzSnu ?=-999 86GHz VLBI core flux density
80- 87 E8.3 Jy 230GHzSnu 230GHz VLBI core flux density
89- 97 E9.3 K 2GHzTb ?=-999 2GHz VLBI core brightness temperature
99-107 E9.3 K 5GHzTb ?=-999 5GHz VLBI core brightness temperature
109-117 E9.3 K 8GHzTb ?=-999 8GHz VLBI core brightness temperature
119-127 E9.3 K 15GHzTb ?=-999 15GHz VLBI core brightness
temperature
129-137 E9.3 K 22GHzTb ?=-999 22GHz VLBI core brightness
temperature
139-147 E9.3 K 43GHzTb ?=-999 43GHz VLBI core brightness
temperature
149-157 E9.3 K 86GHzTb ?=-999 86GHz VLBI core brightness
temperature
159-166 E8.3 K 230GHzTb ?=-999 230GHz VLBI core brightness
temperature
168-175 E8.3 --- z Cosmological redshift
177-185 E9.3 mas 2GHzFWHM ?=-999 2GHz VLBI core FWHM size
187-195 E9.3 mas 5GHzFWHM ?=-999 5GHz VLBI core FWHM size
197-205 E9.3 mas 8GHzFWHM ?=-999 8GHz VLBI core FWHM size
207-215 E9.3 mas 15GHzFWHM ?=-999 15GHz VLBI core FWHM size
217-225 E9.3 mas 22GHzFWHM ?=-999 22GHz VLBI core FWHM size
227-235 E9.3 mas 43GHzFWHM ?=-999 43GHz VLBI core FWHM size
237-245 E9.3 mas 86GHzFWHM ?=-999 86GHz VLBI core FWHM size
247-254 E8.3 mas 230GHzFWHM 230GHz VLBI core FWHM size
256-263 E8.3 10-7W/Hz Lsyn230GHz Synchrotron spectral luminosity at 230GHz
(erg/s/Hz)
265-273 E9.3 gauss 2GHzB ?=-999 2GHz Core magnetic field strength
275-283 E9.3 gauss 5GHzB ?=-999 5GHz Core magnetic field strength
285-293 E9.3 gauss 8GHzB ?=-999 8GHz Core magnetic field strength
295-303 E9.3 gauss 15GHzB ?=-999 15GHz Core magnetic field strength
305-313 E9.3 gauss 22GHzB ?=-999 22GHz Core magnetic field strength
315-323 E9.3 gauss 43GHzB ?=-999 43GHz Core magnetic field strength
325-333 E9.3 gauss 86GHzB ?=-999 86GHz Core magnetic field strength
335-342 E8.3 gauss 230GHzB 230GHz Core magnetic field strength
344-352 E9.3 pc 2GHzDist ?=-999 2GHz Distance between black hole
and VLBI core
354-362 E9.3 pc 5GHzDist ?=-999 5GHz Distance between black hole
and VLBI core
364-372 E9.3 pc 8GHzDist ?=-999 8GHz Distance between black hole
and VLBI core
374-382 E9.3 pc 15GHzDist ?=-999 15GHz Distance between black hole
and VLBI core
384-392 E9.3 pc 22GHzDist ?=-999 22GHz Distance between black hole
and VLBI core
394-402 E9.3 pc 43GHzDist ?=-999 43GHz Distance between black hole
and VLBI core
404-412 E9.3 pc 86GHzDist ?=-999 86GHz Distance between black hole
and VLBI core
414-421 E8.3 pc 230GHzDist 230GHz Distance between black hole
and VLBI core
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Acknowledgements:
Jan Roeder, jroeder.astro(at)gmail.com
MPIfR, Germany & IAA-CSIC, Granada
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(End) Jan Roeder [MPIfR & IAA-CSIC], Patricia Vannier [CDS] 08-Jan-2025