Unified models for active galactic nuclei and quasars
01 Jan 1993-Annual Review of Astronomy and Astrophysics (Annual Reviews 4139 El Camino Way, P.O. Box 10139, Palo Alto, CA 94303-0139, USA)-Vol. 31, Iss: 1, pp 473-521
TL;DR: The straw person model (SPM) as mentioned in this paper has been proposed to explain the orientation effects of active galactic nuclei (AGN) and quasars in the line of sight (LOS) images.
Abstract: Because the critical central regions of Active Galactic Nuclei (AGN) and quasars are strongly nonspherical but spatially unresolved, orientation effects have been the source of much confusion. In fact, it now appears that much of the variety in AGN types is just the result of varying orientation relative to the line of sight. We can define an extreme hypothesis,, the straw person model (SPM), in which there are two basic types of AGN: the radio quiets and the radio louds. For each type there is a range in intrinsic luminosity, and the luminosity controls some properties such as the Fanaroff and Riley classes. However, at a given intrinsic luminosity, all other properties such as spectroscopic classification and VLBI component speeds are ascribed to orientation. This model is only a caricature of the unification idea, and is already ruled out on many grounds, but it will be useful for organizing the discussion. I’ll describe what I consider to be convincing evidence that orientation effects are important and widespread. The true situation may be in some sense half way between the SPM and the hypothesis that orientation doesn’t affect classification at aIl. To us optimists, the orienration cup is half full rather than half empty. Although it is too soon to say for sure, the hypothesis that most objects’ classifications would be different if seen from other directions is a tenable one today.
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TL;DR: In this paper, a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) is presented.
Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These
9,929 citations
TL;DR: In this paper, the authors examined the properties of the host galaxies of 22 623 narrow-line active galactic nuclei (AGN) with 0.02 < z < 0.3 selected from a complete sample of 122 808 galaxies from the Sloan Digital Sky Survey.
Abstract: We examine the properties of the host galaxies of 22 623 narrow-line active galactic nuclei (AGN) with 0.02 < z < 0.3 selected from a complete sample of 122 808 galaxies from the Sloan Digital Sky Survey. We focus on the luminosity of the [O III] λ5007 emission line as a tracer of the strength of activity in the nucleus. We study how AGN host properties compare with those of normal galaxies and how they depend on L[O III]. We find that AGN of all luminosities reside almost exclusively in massive galaxies and have distributions of sizes, stellar surface mass densities and concentrations that are similar to those of ordinary early-type galaxies in our sample. The host galaxies of low-luminosity AGN have stellar populations similar to normal early types. The hosts of high-luminosity AGN have much younger mean stellar ages. The young stars are not preferentially located near the nucleus of the galaxy, but are spread out over scales of at least several kiloparsecs. A significant fraction of high-luminosity AGN have strong Hδ absorption-line equivalent widths, indicating that they experienced a burst of star formation in the recent past. We have also examined the stellar populations of the host galaxies of a sample of broad-line AGN. We conclude that there is no significant difference in stellar content between type 2 Seyfert hosts and quasars (QSOs) with the same [O III] luminosity and redshift. This establishes that a young stellar population is a general property of AGN with high [O III] luminosities.
3,781 citations
TL;DR: In this article, the authors present the formalism of weak gravitational lensing and light propagation in arbitrary space-times, and discuss how weak-lensing effects can be measured.
2,117 citations
TL;DR: In this article, an evolutionary model for starbursts, quasars, and spheroidal galaxies is presented, in which mergers between gas-rich galaxies drive nuclear inflows of gas, producing starburst and feeding the buried growth of supermassive black holes (BHs) until feedback expels gas and renders a briefly visible optical quasar.
Abstract: We present an evolutionary model for starbursts, quasars, and spheroidal galaxies in which mergers between gas-rich galaxies drive nuclear inflows of gas, producing starbursts and feeding the buried growth of supermassive black holes (BHs) until feedback expels gas and renders a briefly visible optical quasar. The quasar lifetime and obscuring column density depend on both the instantaneous and peak quasar luminosity, and we determine this dependence using a large set of galaxy merger simulations varying galaxy properties, orbital geometry, and gas physics. We use these fits to deconvolve observed quasar luminosity functions and obtain the evolution of the formation rate of quasars with peak luminosity, (Lpeak, z). Quasars spend extended periods at luminosities well below peak, so (Lpeak) has a maximum corresponding to the break in the observed luminosity function. From (Lpeak) and our simulations, we obtain self-consistent hard and soft X-ray and optical luminosity functions and predict many observables at multiple redshifts, including column density distributions of optical and X-ray samples, the luminosity function of broad-line quasars in X-ray samples and broad-line fraction versus luminosity, active BH mass functions, the distribution of Eddington ratios, the mass function of relic BHs and total BH mass density, and the cosmic X-ray background. In every case, our predictions agree well with observed estimates, without invoking ad hoc assumptions about source properties or distributions. We provide a library of Monte Carlo realizations of our models for comparison with observations.
1,970 citations
Cites background from "Unified models for active galactic ..."
...…the fraction of broad-line or obscured quasars is a function of luminosity, which cannot be accounted for in traditional static “torus” models (e.g., Antonucci 1993) or accurately reproduced in even modified luminosity-dependent torus models (Lawrence 1991), an observation that is naturally…...
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...Traditional unification models (Antonucci 1993) have postulated a static torus as the explanation for the existence of the Type 2 population, with such objects viewed through the dusty torus and thus optically obscured....
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TL;DR: In this paper, the authors quantify the importance of mass accretion during AGN phases in the growth of supermassive black holes (BH) by comparing the mass function of black holes in the local universe with that expected from AGN relics, which are black holes grown entirely with mass accumulation during AGNs phases.
Abstract: We quantify the importance of mass accretion during AGN phases in the growth of supermassive black holes (BH) by comparing the mass function of black holes in the local universe with that expected from AGN relics, which are black holes grown entirely with mass accretion during AGN phases. The local BH mass function (BHMF) is estimated by applying the well-known correlations between BH mass, bulge luminosity and stellar velocity dispersion to galaxy luminosity and velocity functions. We find that different correlations provide the same BHMF only if they have the same intrinsic dispersion. The density of supermassive black holes in the local universe which we estimate is ρBH = 4.6 +1.9 −1.4 h 2.7 × 10 5 M⊙ Mpc −3 . The relic BHMF is derived from the continuity equation with the only assumption that AGN activity is due to accretion onto massive BH’s and that merging is not important. We find that the relic BHMF at z = 0 is generated mainly at z 10 9 M⊙ but can become as large as ∼ 10 9 yr for the lowest acceptable ǫ and λ values.
1,586 citations
References
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TL;DR: In this paper, a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) is presented.
Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These
9,929 citations
"Unified models for active galactic ..." refers methods in this paper
...Kay (1990) and Tran et al (1992) have fo und more Seyfert 2s with broad permitted lines in the polarized fl ux, but the FC polarizations are generally much less than that of NGC 1068....
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Journal Article•
TL;DR: There are now at least 23 radio sources in which apparent superluminal motion has been found as mentioned in this paper, and the effect is not limited to the classic examples like 3C 345, but is found in objects with a wide range of characteristic properties.
Abstract: There are now at least 23 radio sources in which apparent superluminal motion has been found The effect is not limited to the “classic” examples like 3C 345, but is found in objects with a wide range of characteristic properties We review the observations of the phenomenon and present an up-to-date list of the known superluminal sources
402 citations
01 Jan 1992
254 citations
"Unified models for active galactic ..." refers background in this paper
...It also follows immediately that the optical and X-ray blazar components are highly anisotropic, because we don't see them from the misdirected parent objects.5 (See also Wills et al 1992a, Makino et al 1991, and Shastri 1991.)...
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Book•
10 Oct 1985
218 citations
"Unified models for active galactic ..." refers background in this paper
...Phinney (1984) gives a nice introduction to the theoretical expectations....
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100 citations