Nuclear Luminosities and Radio Loudness of Seyfert Nuclei

Ho, Luis C.; Peng, Chien Y.

doi:10.1086/321524

Cited by 220 publications

(289 citation statements)

References 113 publications

(203 reference statements)

Supporting

Mentioning

265

Contrasting

Unclassified

Order By: Relevance

“…He showed that L H traces the optical continuum luminosity with a slope of 1:05 AE 0:03, consistent with unity and very similar to the slope found here (1:157 AE 0:005). Similarly, from an analysis of AGNs ranging from nearby low-luminosity Seyfert galaxies to quasars, Ho & Peng (2001) found that the luminosity of the broad H line, from $10 38 to 10 44 ergs s À1 , correlates strongly with the B-band continuum luminosity, roughly of the form L H / L 0:9 B . While this slope is formally shallower than that found in our sample (1:133 AE 0:005), the measurements for the lowluminosity sources in the sample of Ho & Peng are also considerably more uncertain, making it difficult to judge the significance of the apparent discrepancy.…”

Section: Discussionmentioning

confidence: 89%

“…We achieve this in two steps. First, we revisit the well-known empirical correlation between optical continuum luminosity and Balmer emission-line luminosity (Yee 1980;Shuder 1981;Ho & Peng 2001), which now can be established with much greater precision using large, homogeneous samples of AGNs. This allows us to replace L 5100 with L H , which has the advantage of being relatively straightforward to measure even for low-luminosity or galaxy-dominated sources (e.g., Ho et al 1997;Greene & Ho 2004).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Estimating Black Hole Masses in Active Galaxies Using the Hα Emission Line

Greene¹,

Ho²

2005

ApJ

Self Cite

703

797

View full text Add to dashboard Cite

It has been established that virial masses for black holes in low-redshift active galaxies can be estimated from measurements of the optical continuum strength and the width of the broad H line. Under various circumstances, however, both of these quantities can be challenging to measure or can be subject to large systematic uncertainties. To mitigate these difficulties, we present a new method for estimating black hole masses. From analysis of a new sample of broad-line active galactic nuclei, we find that H luminosity scales almost linearly with optical continuum luminosity and that a strong correlation exists between H and H line widths. These two empirical correlations allow us to translate the standard virial mass system to a new one based solely on observations of the broad H emission line.

show abstract

Section: Discussionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Estimating Black Hole Masses in Active Galaxies Using the Hα Emission Line

Greene¹,

Ho²

2005

ApJ

Self Cite

703

797

View full text Add to dashboard Cite

show abstract

“…This period is typically much longer than the observed period unless a approaches extraordinarily close to 0. On the other hand, the radio-loudness parameter of NGC5548ʼs nucleus is  = log 1.24 (Ho & Peng 2001), meaning that it is only marginally radio-loud. The global spectral energy distribution for NGC5548 also suggests that the 5100 Å continuum predominantly stems from an accretion disk (Chiang & Blaes 2003;Mehdipour et al 2015).…”

Section: Precessing Jet Modelmentioning

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

View full text Add to dashboard Cite

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.

show abstract

“…Then, normalizing to the X-ray Ñux, the absolute magnitude in the B band is found to be M B \ [22.4. Alternatively, the Hb correlation for luminosityÈM B type 1 Seyfert galaxies and QSOs (Ho & Peng 2001) gives Note, however, that the Hb luminosities M B \ [21.2. adopted in Ho & Peng (2001) are a combination of the broad and narrow components, and the broad component dominates in type 1 QSOs. We used only the narrow component of Hb for Cygnus A, and therefore this last value of should be regarded as an upper limit (i.e., a lower limit M B on the B-band luminosity).…”

Section: T He Hidden Nucleusmentioning

confidence: 99%

AChandraX‐Ray Study of Cygnus A. II. The Nucleus

Young¹,

Wilson²,

Terashima³

et al. 2002

ApJ

View full text Add to dashboard Cite

We report Chandra Advanced CCD Imaging Spectrometer and quasi-simultaneous Rossi X-Ray T iming Explorer (RXT E) observations of the nearby, powerful radio galaxy Cygnus A, with the present paper focusing on the properties of the active nucleus. In the Chandra observation, the hard ([a few keV) X-ray emission is spatially unresolved with a size (1.5 kpc, km s~1 Mpc~1) and coin-[1A H 0 \ 50 cides with the radio and near-infrared nuclei. In contrast, the soft (\2 keV) emission exhibits a bipolar nebulosity that aligns with the optical bipolar continuum and emission-line structures and approximately with the radio jet. In particular, the soft X-ray emission corresponds very well with the [O III] j5007 and Ha ] [N II] jj6548, 6583 nebulosity imaged with Hubble Space T elescope. At the location of the nucleus, there is only weak soft X-ray emission, an e †ect that may be intrinsic or result from a dust lane that crosses the nucleus perpendicular to the source axis. The spectra of the various X-ray components have been obtained by simultaneous Ðts to the six detectors. The compact nucleus is detected to 100 keV and is well described by a heavily absorbed power-law spectrum with (similar to other ! h \ 1.52~0 .12 0.12 narrow-line radio galaxies) and equivalent hydrogen column cm~2. This N H (nuc) \ 2.0~0 .2 0.1 ] 1023 column is compatible with the dust obscuration to the near-infrared source for a normal gas-to-dust ratio. The soft (\2 keV) emission from the nucleus may be described by a power-law spectrum with the same index (i.e., although direct Ðts suggest a slightly larger value for Narrow emission lines ! l \ ! h ), ! l . from highly ionized neon and silicon, as well as a "" neutral ÏÏ Fe Ka line, are detected in the nucleus and its vicinity kpc). The equivalent width (EW) of the Fe Ka line eV) is in good agreement (r [ 2 (182~5 4 40 with theoretical predictions for the EW versus relationship in various geometries. An Fe K edge N H (nuc) is also seen. The RXT E observations indicate a temperature of keV for the cluster gas kT \ 6.9~1 .0 0.3 (discussed in Paper III of this series) and cluster emission lines of Fe Ka and Fe Kb and/or Ni Ka.We consider the possibility that the extended soft X-ray emission is electron-scattered nuclear radiation. Given that 1% of the unabsorbed 2È10 keV nuclear radiation would have to be scattered, the necessary gas column cm~2] would absorb the X-rays rather than scatter [N H (scattering)^3.5 ] 1022 them if the gas is cold. Thus, the scattering plasma must be highly ionized. If this ionization is achieved through photoionization by the nucleus, the ionization parameter m [ 1 ergs cm s~1 and the electron density cm~3 given the observed distance of the soft X-ray emission from the nucleus. The elecn e^6 tron column density inferred from the X-ray observations is much too low to account for the extended optical scattered light, strongly suggesting that the polarized optical light is scattered by dust. The presence of highly ionized Ne lines in the soft X-ray spectrum requires 20...

show abstract

Nuclear Luminosities and Radio Loudness of Seyfert Nuclei

Cited by 220 publications

References 113 publications

Estimating Black Hole Masses in Active Galaxies Using the Hα Emission Line

Estimating Black Hole Masses in Active Galaxies Using the Hα Emission Line

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

AChandraX‐Ray Study of Cygnus A. II. The Nucleus

Contact Info

Product

Resources

About