Results 11 to 20 of about 4,173,094 (217)

The radio emission from active galactic nuclei [PDF]

Astronomy & Astrophysics, 2021
Context. For nearly seven decades, astronomers have been studying active galaxies, that is to say, galaxies with actively accreting central supermassive black holes: active galactic nuclei (AGN). A small fraction are characterized by luminous, powerful radio emission: This class is known as radio-loud AGN.
J. F. Radcliffe, P. D. Barthel, M. A. Garrett, R. J. Beswick, A. P. Thomson, T. W. B. Muxlow   +5 more
openaire   +8 more sources

Radio-loud and Radio-quiet Active Galactic Nuclei [PDF]

The Astronomical Journal, 1999
We generated a sample of 409 AGNs for which both the radio luminosity at 5 GHz and the line luminosity in [OIII] 5007 have been measured. The radio luminosity spans a range of ten orders of magnitude, and the [OIII] line luminosity spans a range of eight orders of magnitude --- both considerably larger than the ranges in previous studies.
Xu, Chun, Livio, Mario, Baum, Stefi A.
openaire   +3 more sources

NGC 5252: a pair of radio-emitting active galactic nuclei? [PDF]

Monthly Notices of the Royal Astronomical Society: Letters, 2016
Abstract The X-ray source CXO J133815.6+043255 has counterparts in the UV, optical, and radio bands. Based on the multiband investigations, it has been recently proposed by Kim et al. as a rarely seen off-nucleus ultraluminous X-ray (ULX) source with a black hole mass of ≥104 M⊙ in the nearby Seyfert galaxy NGC 5252. To explore its radio
Yang, Xiaolong, Yang, Jun, Paragi, Z., Liu, Xiang, An, T., Bianchi, Stefano, Ho, Luis C., Cui, Lang, Zhao, Wei, Wu, Xiaocong   +9 more
openaire   +6 more sources

Compact radio cores in radio-quiet active galactic nuclei [PDF]

Astronomy & Astrophysics, 2016
Context. The mechanism of radio emission in radio-quiet (RQ) active galactic nuclei (AGNs) is still debated and might arise from the central AGN, from star formation activity in the host, or from either of these sources. A direct detection of compact and bright radio cores embedded in sources that are classified as RQ can unambiguously determine ...
MAINI, ALESSANDRO, Prandoni, I., Norris, R. P., GIOVANNINI, GABRIELE, Spitler, L. R.   +4 more
openaire   +6 more sources

Quasars and active galactic nuclei: high resolution radio imaging. [PDF]

Proceedings of the National Academy of Sciences, 1995
The 12th colloquium in the series organized by the National Academy of Sciences, Quasars and Active Galactic Nuclei: High Resolution Radio Imaging, was held at the NAS Beckman Center in Irvine, California, on March 24 and 25, 1995. The meeting brought together 138 scientists from 17 countries. The majority of the participants were radio astronomers,
Cohen, Marshall H., Kellerman, Kenneth I.   +1 more
openaire   +5 more sources

The origin of radio emission from radio-quiet active galactic nuclei [PDF]

Nature Astronomy, 2019
The central nuclei of galaxies, where supermassive black holes (SMBHs) are thought to reside, can experience phases of activity when they become active galactic nuclei (AGNs). An AGN can eject winds and jets and produce radiation across the entire electromagnetic spectrum.
Francesca Panessa, Ranieri Diego Baldi, Ari Laor, Paolo Padovani, Ehud Behar, Ian McHardy   +5 more
openaire   +5 more sources

Investigating the Star Formation Characteristics of Radio Active Galactic Nuclei

The Astrophysical Journal
The coevolution of supermassive black holes and their host galaxies represents a fundamental question in astrophysics. One approach to investigating this question involves comparing the star formation rates (SFRs) of active galactic nuclei (AGNs) with ...
Bojun Zhang, Fan Zou, W. N. Brandt, Shifu Zhu, Nathan Cristello, Qingling Ni, Yongquan Xue, Zhibo Yu   +7 more
doaj   +4 more sources

Multifrequency Studies of Active Galactic Nuclei in the Planck Satellite Era

Galaxies, 2016
The multi-epoch single-survey Planck satellite data have given a rare glimpse into how the radio spectra of active galactic nuclei (AGN) evolve in time.
Anne Lähteenmäki, the Planck Collaboration   +1 more
doaj   +2 more sources

Radio Near-infrared Imaging of Dual Active Galactic Nuclei Candidates

The Astrophysical Journal
We report the results of a pilot study that searched for dual active galactic nuclei (AGN) in local ( z  10 ^8 K) radio sources that indicate the presence of either a parsec-scale-separation dual AGN ( d _sep  ∼ 90 and ∼56 pc, respectively) or a radio ...
Makoto A. Johnstone, Ilsang Yoon, Emmanuel Momjian, Loreto Barcos-Muñoz, A. S. Evans, Bjorn Emonts, Eilat Glikman, Dong-Chan Kim, Ji Hoon Kim, Minjin Kim, Mark Lacy, George C. Privon, Devaky Kunneriath, Jaya Nagarajan-Swenson, Núria Torres-Albà, Kara N. Green   +15 more
doaj   +3 more sources

The radio dichotomy of active galactic nuclei [PDF]

Publications of the Astronomical Society of Japan, 2022
Abstract The question of radio dichotomy in active galactic nuclei (AGNs) is still in debate, even though it has been discussed for more than 40 years. In order to solve this old riddle, we collect a sample of AGNs with optical B band and radio 6 cm wavelength data to analyze the radio loudness log R. Our results indicate a separation of
Xiao, Hubing, Zhu, Jingtian, Fu, Liping, Zhang, Shaohua, Fan, Junhui   +4 more
openaire   +2 more sources