Results 21 to 30 of about 38,366 (276)
NGC 1808: active galactic nucleus or starburst? [PDF]
Monthly Notices of the Royal Astronomical Society, 1992 We present optical and near-infrared images, together with long-slit spectra at red wavelengths, of NGC 1808. The complex morphology of hotspots seen at short wavelengths may be the result of dust obscuration. Our data (namely the equivalent width of the Ca II triplet and broad-band colours) suggest the presence of red supergiants, associated with a ...
D. A. Forbes, C. Boisson, M. J. Ward
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Black hole variability and the star formation-active galactic nucleus connection : do all star-forming galaxies host an active galactic nucleus? [PDF]
, 2014 We investigate the effect of active galactic nucleus (AGN) variability on the observed connection between star formation and black hole accretion in extragalactic surveys.
Alexander, D.M. +6 more
core +2 more sources
ACTIVE GALACTIC NUCLEUS FEEDBACK WORKS BOTH WAYS [PDF]
The Astrophysical Journal, 2013 Simulations of galaxy growth need to invoke strong negative feedback from active galactic nuclei (AGNs) to suppress the formation of stars and thus prevent the over-production of very massive systems. While some observations provide evidence for such negative feedback, other studies find either no feedback or even positive feedback, with increased star
Zinn, Peter C. +3 more
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AN OFF-CENTERED ACTIVE GALACTIC NUCLEUS IN NGC 3115 [PDF]
The Astrophysical Journal, 2014 NGC 3115 is an S0 galaxy that has always been considered to have a pure absorption-line spectrum. Some recent studies have detected a compact radio-emitting nucleus in this object, coinciding with the photometric center and with a candidate for the X-ray nucleus. This is evidence of the existence of a low-luminosity active galactic nucleus (AGN) in the
R. B. Menezes +2 more
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A quasi-periodic oscillation in the blazar J1359+4011 [PDF]
, 2013 The OVRO 40-m telescope has been monitoring the 15 GHz radio flux density of over 1200 blazars since 2008. The 15 GHz light curve of the flat spectrum radio quasar J1359+4011 shows a strong and persistent quasi-periodic oscillation. The time-scale of the
Hovatta, T. +8 more
core +4 more sources
The Changing Active Galactic Nucleus Population
The Astrophysical Journal, 2003 We investigate how the fraction of broad-line sources in the active galactic nucleus (AGN) population changes with X-ray luminosity and redshift. We first construct the rest-frame hard-energy (2-8 keV) X-ray luminosity function (HXLF) at z = 0.1-1 using Chandra Lockman Hole-Northwest wide-area data, Chandra Deep Field-North 2 Ms data, other Chandra ...
A. T. Steffen +4 more
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3C 273 WITHNuSTAR: UNVEILING THE ACTIVE GALACTIC NUCLEUS [PDF]
The Astrophysical Journal, 2015 We present results from a 244 ks NuSTAR observation of 3C 273 obtained during a cross-calibration campaign with the Chandra, INTEGRAL, Suzaku, Swift, and XMM-Newton observatories. We show that the spectrum, when fit with a power-law model using data from all observatories except INTEGRAL over the 1–78 keV band, leaves significant residuals in the ...
Kristin K. Madsen +19 more
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ACTIVE GALACTIC NUCLEUS PAIRS: CHANCE SUPERPOSITIONS OR BLACK HOLE BINARIES? [PDF]
The Astrophysical Journal, 2010 Several active galactic nuclei (AGNs) with multiple sets of emission lines (ELs) separated by over 2000 km s-1 have been observed recently. These have been interpreted as being due to massive black hole (MBH) recoil following a black hole merger, MBH binaries, or chance superpositions of AGNs in galaxy clusters. Moreover, a number of double-peaked AGNs
Dotti, M, Ruszkowski, M
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FRAMEx. IV. Mechanical Feedback from the Active Galactic Nucleus in NGC 3079
The Astrophysical Journal, 2023 Using the Very Long Baseline Array, we observed the active galactic nucleus (AGN) in NGC 3079 over a span of six months to test for variability in the two main parsec-scale radio components, A and B , which lie on either side of the AGN.
Luis C. Fernandez +3 more
doaj +1 more source
Active galactic nucleus outflows in galaxy discs [PDF]
Monthly Notices of the Royal Astronomical Society, 2018 22 pages, 22 figures, published in ...
Hartwig, Tilman +2 more
openaire +3 more sources