Radio Continuum Survey of an Optically Selected Sample of Nearby Seyfert Galaxies

Ho, Luis C.; Ulvestad, J. S.

doi:10.1086/319185

Cited by 285 publications

(436 citation statements)

References 136 publications

(220 reference statements)

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“…This spectral index is typical of at least some AGN of comparable luminosity in quiescence (Ho & Ulvestad 2001). We subtract this model from our observed flux densities (Figure 1(a)) and find that the remaining transient component exhibits a synchrotron selfabsorbed spectral shape (F 5 2 n µ n ) below the peak frequency (Figure 1(b)).…”

Section: Archival Radio Observations and Arguments Against An Agn Flamentioning

confidence: 87%

DISCOVERY OF AN OUTFLOW FROM RADIO OBSERVATIONS OF THE TIDAL DISRUPTION EVENT ASASSN-14li

Alexander

Berger

Guillochon

et al. 2016

ApJL

229

290

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We report the discovery of transient radio emission from the nearby optically discovered tidal disruption event (TDE) ASASSN-14li (distance of 90 Mpc), making it the first typical TDE detected in the radio, and unambiguously pointing to the formation of a non-relativistic outflow with a kinetic energy of ≈(4-10)×10 47 erg, a velocity of ≈12,000-36,000 km s −1 , and a mass of ≈3×10 −5 -7 × 10 −4 M e . We show that the outflow was ejected on 2014 August 11-25, in agreement with an independent estimate of the timing of super-Eddington accretion based on the optical, ultraviolet, and X-ray observations, and that the ejected mass corresponds to about 1%-10% of the mass accreted in the super-Eddington phase. The temporal evolution of the radio emission also uncovers the circumnuclear density profile, R R 2.5 ( ) r µ -on a scale of about 0.01 pc, a scale that cannot be probed via direct measurements even in the nearest supermassive black holes. Our discovery of radio emission from the nearest well-studied TDE to date, with a radio luminosity lower than all previous limits, indicates that nonrelativistic outflows are ubiquitous in TDEs, and that future, more sensitive, radio surveys will uncover similar events.

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Section: Archival Radio Observations and Arguments Against An Agn Flamentioning

confidence: 87%

DISCOVERY OF AN OUTFLOW FROM RADIO OBSERVATIONS OF THE TIDAL DISRUPTION EVENT ASASSN-14li

Alexander

Berger

Guillochon

et al. 2016

ApJL

229

290

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“…If each black hole produces radio emission, the future Event Horizon Telescope, with an angular resolution of ∼20 μas (Fish et al 2013), will be capable of spatially resolving the radio core of NGC5548 (Ho & Ulvestad 2001) into two components separated by ∼22 light-days (∼50 μas). This will provide direct evidence for the SMBHB.…”

Section: Discussion On the Smbhb Scenariomentioning

confidence: 99%

Spectroscopic Indication of a Centi-Parsec Supermassive Black Hole Binary in the Galactic Center of Ngc 5548

Wang

et al. 2016

ApJ

Self Cite

111

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As a natural consequence of cosmological hierarchical structure formation, sub-parsec supermassive black hole binaries (SMBHBs) should be common in galaxies but thus far have eluded spectroscopic identification. Based on four decades of optical spectroscopic monitoring, we report that the nucleus of NGC5548, a nearby Seyfert galaxy long suspected to have experienced a major merger about 1 billion yr ago, exhibits long-term variability with a period of ∼14 yr in the optical continuum and broad Hβ emission line. Remarkably, the double-peaked profile of Hβ shows systematic velocity changes with a similar period. These pieces of observations plausibly indicate that an SMBHB resides in the center of NGC5548. The complex, secular variations in the line profiles can be explained by orbital motion of a binary with equal mass and a semimajor axis of ∼22 light-days (corresponding to ∼18 milli-parsec). At a distance of 75Mpc, NGC5548 is one of the nearest sub-parsec SMBHB candidates that offers an ideal laboratory for gravitational wave detection.

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“…It very likely contains a central compact core (<1 ) with an inverted spectrum, possibly due to free-free absorption (e.g. Falcke et al 2000;Ho & Ulvestad 2001). It shows an inverted spectrum at high frequencies, most likely too weak at low frequencies to confuse our observations, so ruled out.…”

Section: Confusion Analysismentioning

confidence: 84%

Investigation of flat spectrum radio sources by the interplanetary scintillation method at 111 MHz

Tyul’bashev

Augusto

2005

A&A

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Abstract. Interplanetary scintillation observations of 48 of the 55 Augusto et al. (1998) flat spectrum radio sources were carried out at 111 MHz using the interplanetary scintillation method on the Large Phased Array (LPA) in Russia. Due to the large size of the LPA beam (1 • × 0.5 • ) a careful inspection of all possible confusion sources was made using extant large radio surveys: 37 of the 48 sources are not confused. We were able to estimate the scintillating flux densities of 13 sources, getting upper limits for the remaining 35. Gathering more or improving extant VLBI data on these sources might significantly improve our results. This proof-of-concept project tells us that compact (<1 ) flat spectrum radio sources show strong enough scintillations at 111 MHz to establish/constrain their spectra (low-frequency end).

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Radio Continuum Survey of an Optically Selected Sample of Nearby Seyfert Galaxies

Cited by 285 publications

References 136 publications

DISCOVERY OF AN OUTFLOW FROM RADIO OBSERVATIONS OF THE TIDAL DISRUPTION EVENT ASASSN-14li

DISCOVERY OF AN OUTFLOW FROM RADIO OBSERVATIONS OF THE TIDAL DISRUPTION EVENT ASASSN-14li

Spectroscopic Indication of a Centi-Parsec Supermassive Black Hole Binary in the Galactic Center of Ngc 5548

Investigation of flat spectrum radio sources by the interplanetary scintillation method at 111 MHz

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