Unification Scheme Research Articles

ON THE BL LACERTAE OBJECTS/RADIO QUASARS AND THE FR I/II DICHOTOMY

In the frame of unification schemes for radio-loud active galactic nuclei (AGNs), FR I radio galaxies are believed to be BL Lacertae (BL Lac) objects with the relativistic jet misaligned to our line of sight, and FR II radio galaxies correspond to misaligned radio quasars. The Ledlow-Owen dividing line for FR I/FR II dichotomy in the optical absolute magnitude of host galaxy-radio luminosity (M_R-L_Rad) plane can be translated to the line in the black hole mass-jet power (M_bh-Q_jet) plane by using two empirical relations: Q_jet-L_Rad and M_bh}-M_R. We use a sample of radio quasars and BL Lac objects with measured black hole masses to explore the relation of the jet power with black hole mass, in which the jet power is estimated from the extended radio emission. It is found that the BL Lac objects are clearly separated from radio quasars by the Ledlow & Owen FR I/II dividing line in the M_bh-Q_jet plane. This strongly supports the unification schemes for FR I/BL Lac object and FR II/radio quasar. We find that the Eddington ratios L_bol/L_Edd of BL Lac objects are systematically lower than those of radio quasars in the sample with a rough division at L_bol/L_Edd 0.01, and the distribution of Eddington ratios of BL Lac objects/quasars exhibits a bimodal nature, which imply that the accretion mode of BL Lac objects may be different from that of radio quasars.

Schemes of metabolic patterns of anabolic androgenic steroids for the estimation of metabolites of designer steroids in human urine

Unified metabolism schemes of anabolic androgenic steroids (AAS) in human urine based on structure classification of parent molecules are presented in this paper. Principal components analysis (PCA) was applied to AAS molecules referred in the World Anti-Doping Agency (WADA) list of prohibited substances, resulting to their classification into six distinct groups related to structure features where metabolic alterations usually occur. The metabolites of the steroids participating to these six groups were treated using the Excel© classification filters showing that common metabolism routes are derived for each of the above PCA classes, leading to the proposed metabolism schemes of the present study. This rule-based approach is proposed for the prediction of the metabolism of unknown, chemically modified steroids, otherwise named as designer steroids. The metabolites of three known, in the literature, AAS are estimated using the proposed metabolism schemes, confirming that their use could be a useful tool for the prediction of metabolic pathways of unknown AAS.

PRINCIPAL COMPONENT ANALYSIS OF THE SPECTRAL ENERGY DISTRIBUTION AND EMISSION LINE PROPERTIES OF RED 2MASS ACTIVE GALACTIC NUCLEI

We analyze the spectral energy distributions (SEDs) and emission line properties of the red (J-K$_S$ > 2) 2MASS AGN observed by Chandra using principle component analysis. The sample includes 44 low redshift AGN with low or moderate obscuration (N_H < 10^{23} cm^{-2}) as indicated by X-rays and SED modeling. The obscuration of the AGN allows us to see weaker emission components (host galaxy emission, AGN scattered light) which are usually outshone by the AGN. The first four eigenvectors explain 70% of the variance in the sample. The dominant cause of variance in the sample (eigenvector 1) is the L/Ledd ratio strengthened by intrinsic absorption. Eigenvector 2 is related to host galaxy (relative to the observed AGN) emission and eigenvectors 3 and 4 distinguish between two sources of obscuration: host galaxy absorption and circumnuclear absorption. Although our analysis is consistent with unification schemes where inclination dependent obscuration is important in determining the AGN SEDs, the L/Ledd ratio is the most important factor, followed by host galaxy emission.

PROBING THE ACCRETION DISK AND CENTRAL ENGINE STRUCTURE OF NGC 4258 WITHSUZAKUANDXMM-NEWTONOBSERVATIONS

[abridged] We present an X-ray study of the low-luminosity active galactic nucleus (AGN) in NGC4258 using data from Suzaku, XMM-Newton, and the Swift/BAT survey. We find that signatures of X-ray reprocessing by cold gas are very weak in the spectrum of this Seyfert-2 galaxy; a weak, narrow fluorescent-Kalpha emission line of cold iron is robustly detected in both the Suzaku and XMM-Newton spectra but at a level much below that of most other Seyfert-2 galaxies. We conclude that the circumnuclear environment of this AGN is very "clean" and lacks the Compton-thick obscuring torus of unified Seyfert schemes. From the narrowness of the iron line, together with evidence for line flux variability between the Suzaku and XMM-Newton observations, we constrain the line emitting region to be between $3\times 10^3r_g$ and $4\times 10^4r_g$ from the black hole. We show that the observed properties of the iron line can be explained if the line originates from the surface layers of a warped accretion disk. In particular, we present explicit calculations of the expected iron line from a disk warped by Lens-Thirring precession from a misaligned central black hole. Finally, the Suzaku data reveal clear evidence for large amplitude 2-10keV variability on timescales of 50ksec as well as smaller amplitude flares on timescales as short as 5-10ksec. If associated with accretion disk processes, such rapid variability requires an origin in the innermost regions of the disk ($r\approx 10r_g$ or less).

CONSTRAINTS ON THE SIZE OF EXTRA DIMENSIONS FROM THE ORBITAL EVOLUTION OF BLACK-HOLE X-RAY BINARIES

One of the plausible unification schemes in physics considers the observable universe to be a four-dimensional surface (the brane) embedded in a higher dimensional curved spacetime (the bulk). In such braneworld gravity models with infinitely large extra dimensions, black holes evaporate fast through the emission of the additional gravitational degrees of freedom, resulting in lifetimes of stellar-mass black holes that are significantly smaller than the Hubble time. We show that the predicted evaporation rate leads to a change in the orbital period of X-ray binaries harboring black holes that is observable with current instruments. We obtain an upper limit on the rate of change of the orbital period of the binary A0620–00 and use it to constrain the asymptotic curvature radius of the extra dimension to a value comparable to the one obtained by table-top experiments. Furthermore, we argue that any measurement of a period increase for low-mass X-ray binaries with a high mass ratio is evidence for new physics beyond general relativity and the standard model.

An X-Ray Study of Lobe-Dominated Radio-Loud Quasars with XMM-Newton

We report on our results of X-ray spectral analysis for a sample of radio-loud quasars covering a wide range of the radio core-dominance Parameter, R, from core-dominated to lobe-dominated objects, using data obtained mostly with the XMM-Newton Observatory. We find that the spectral shape of the underlying power-law continuum is flat even for the lobe-dominated objects (average photon index similar to 1.5), indistinguishable from that of core-dominated quasars. For lobe-dominated objects, contribution of X-rays from the jets is expected to be very small based on previous unification schemes, more than one order of magnitude lower than the observed X-ray luminosities. Assuming that radio-loud quasars follow the same X-ray-UV/optical luminosity relation for the disk-corona. emission as found for radio-quiet quasars, we estimate the X-ray flux contributed by the disk-corona component from the optical/UV continuum. We find that neither the luminosity, nor the spectral shape, of the disk-corona X-ray emission can account for the bulk of the observed X-ray properties. Thus in lobe-dominated quasars, either the disk-corona X-ray emission is much enhanced in strength and flatter in spectral shape (photon index similar to 1.5) compared to normal radio-quiet quasars, or their jet X-ray emission is much enhanced compared to their weak radio core-jet emission. If the latter is the case, our result may imply that the jet emission in X-rays is less Doppler beamed than that in the radio. As a demonstrating example, we test this hypothesis by using a specific model in which the X-ray jet has a larger opening angle than the radio jet.

A survey for redshifted molecular and atomic absorption lines - II. Associated H i, OH and millimetre lines in thez≳ 3 Parkes quarter-Jansky flat-spectrum sample

We present the results of a z>2.9 survey for HI 21-cm and molecular absorption in the hosts of radio quasars using the GMRT and the Tidbinbilla 70-m telescope. Previously published searches, which are overwhelmingly at redshifts of z<1, exhibit a 42% detection rate (31 out of 73 sources), and the inclusion of our survey yields a 17% detection rate (2 out of 12 sources) at z>2.5. We therefore believe that our high redshift selection is responsible for our exclusive non-detections, and find that at ultra-violet luminosities of >10e23 W/Hz, 21-cm absorption has never been detected. We also find this to not only apply to our targets, but also those at low redshift exhibiting similar luminosities, giving zero detections out of a total of 16 sources over z=0.24 to 3.8. This is in contrast to the < 10e23 W/Hz sources where there is a near 50% detection rate of 21-cm absorption. The mix of 21-cm detections and non-detections is currently attributed to orientation effects, where according to unified schemes of active galactic nuclei, 21-cm absorption is more likely to occur in sources designated as radio galaxies (type-2 objects, where the nucleus is viewed through dense obscuring circumnuclear gas) than in quasars(type-1 objects, where we have a direct view to the nucleus). However, due to the exclusively high ultra-violet luminosities of our targets it is not clear whether orientation effects alone can wholly account for the distribution, although there exists the possibility that the large luminosities are indicative of a changing demographic of galaxy types. We also find that below luminosities of ~10e23 W/Hz, both type-1 and type-2 objects have a 50% likelihood of exhibiting 21-cm absorption.

Improvements and applications of entrainment control for nonlinear dynamical systems

This paper improves the existing entrainment control approaches and develops unified schemes to chaos control and generalized (lag, anticipated, and complete) synchronization of nonlinear dynamical systems. By introducing impulsive effects to the open-loop control method, we completely remove its restrictions on goal dynamics and initial conditions, and derive a sufficient condition to estimate the upper bound of impulsive intervals to ensure the global asymptotic stability. We then propose two effective ways to implement the entrainment strategy which combine open-loop and closed-loop control, and we prove that the feedback gains can be chosen according to a lower bound or be tuned with an adaptive control law. Numerical examples are given to verify the theoretical results and to illustrate their applications.

Doppler factors, Lorentz factors and viewing angles for quasars, BL Lacertae objects and radio galaxies

<i>Aims. <i/>We have calculated variability Doppler boosting factors, Lorentz factors, and viewing angles for a large sample of sources by using total flux density observations at 22 and 37 GHz and VLBI data.<i>Methods. <i/>We decomposed the flux curves into exponential flares and determined the variability brightness temperatures of the fastest flares. By assuming the same intrinsic brightness temperature for each source, we calculated the Doppler boosting factors for 87 sources. In addition we used new apparent jet speed data to calculate the Lorentz factors and viewing angles for 67 sources.<i>Results. <i/>We find that all quasars in our sample are Doppler-boosted and that the Doppler boosting factors of BL Lacertae objects are lower than of quasars. The new Lorentz factors are about twice as high as in earlier studies, which is mainly due to higher apparent speeds in our analyses. The jets of BL Lacertae objects are slower than of quasars. There are some extreme sources with very high derived Lorentz factors of the order of a hundred. These high Lorentz factors could be real. It is also possible that the sources exhibit such rapid flares that the fast variations have remained undetected in monitoring programmes, or else the sources have a complicated jet structure that is not amenable to our simple analysis. Almost all the sources are seen in a small viewing angle of less than 20 degrees. Our results follow the predictions of basic unification schemes for AGN.

On the relationship between BL Lacertae objects and radio galaxies

We present deep radio images at 1.4 GHz of a large and complete sample of BL Lacertae objects (BL Lacs) selected from the Deep X-ray Radio Blazar Survey (DXRBS). We have observed 24 northern sources with the Very Large Array (VLA) in both its A and C configurations and 15 southern sources with the Australia Telescope Compact Array (ATCA) in its largest configuration. We find that in the DXRBS, as in the 1-Jy survey, which has a radio flux limit roughly ten times higher than the DXRBS, a considerable number (about a third) of BL Lacs can be identified with the relativistically beamed counterparts of Fanaroff-Riley type II (FR II) radio galaxies. We attribute the existence of FR II-BL Lacs, which is not accounted for by current unified schemes, to an inconsistency in our classification scheme for radio-loud active galactic nuclei (AGN). Taking the extended radio power as a suitable measure of intrinsic jet power, we find similar average values for low- (LBL) and high-energy peaked BL Lacs (HBL), contrary to the predictions of the blazar sequence.

On the anomalous silicate emission features of active galactic nuclei: a possible interpretation based on porous dust

Abstract The recent Spitzer detections of the 9.7 μm Si–O silicate emission in type 1 active galactic nuclei (AGN) provide support for the AGN unification scheme. The properties of the silicate dust are of key importance to understand the physical, chemical and evolutionary properties of the obscuring dusty torus around the AGN. Compared to that of the Galactic interstellar medium (ISM), the 10 μm silicate emission profile of type 1 AGN is broadened and has a clear shift of peak position to longer wavelengths. In literature, this is generally interpreted as an indication of the deviations of the silicate composition, size and degree of crystallization of the AGN from that of the Galactic ISM. In this Letter, we show that the observed peak shift and profile broadening of the 9.7 μm silicate emission feature can be explained in terms of porous composite dust consisting of ordinary interstellar amorphous silicate, amorphous carbon and vacuum. Porous dust is naturally expected in the dense circumnuclear region around the AGN, as a consequence of grain coagulation.

Difference in Narrow-Emission-Line Spectra of Seyfert 1 and 2 Galaxies

In the unification scheme of Seyfert galaxies, a dusty torus blocks the continuum source and broad line region in Seyfert 2 galaxies. However it is not clear whether or not and to what extent the torus affects the narrow line spectra. In this paper, we show that Seyfert 1 and Seyfert 2 galaxies have different distributions on the [OIII]/H$\beta $ vs [NII]/H$\alpha$ diagram (BPT diagram) for narrow lines. Seyfert 2 galaxies display a clear left boundary on the BPT diagram and only 7.3% of them lie on the left. By contrast, Seyfert 1 galaxies do not show such a cutoff and 33.0% of them stand on the left side of the boundary. Among Seyfert 1 galaxies, the distribution varies with the extinction to broad lines. As the extinction increases, the distribution on BPT diagram moves to larger [NII]/H$\alpha$ value. We interpret this as an evidence for the obscuration of inner dense narrow line region by the dusty torus. We also demonstrate that the [OIII] and broad line luminosity correlation depends on the extinction of broad lines in the way that high extinction objects have lower uncorrected [OIII] luminosities, suggesting that [OIII] is partially obscured in these objects. Therefore, using [OIII] as an indicator for the nuclear luminosity will systematically under-estimate the nuclear luminosity of Seyfert 2 galaxies.

The toroidal obscuration of active galactic nuclei

Observations give strong support for the unification scheme of active galactic nuclei. The scheme is premised on toroidal obscuration of the central engine by dusty clouds that are individually very optically thick. These lectures summarize the torus properties, describe the handling and implications of its clumpy nature and present speculations about its dynamic origin.

An introduction to active galactic nuclei: Classification and unification

In this article I present a summary of AGN classification, followed by a critical review of attempts to understand aspects of the classification in terms of orientation-based unified schemes. Concentrating on radio-loud AGN, I show that the unified schemes based on anisotropy induced both by beaming in relativistic jets and by absorption in dusty torus structures, work well in a broad-brush sense. However, they represent simplifications of a situation that is, in reality, likely to be more complex. In particular, the AGN selected in radio flux limited samples encompass a wide range of intrinsic X-ray/UV/optical/infrared properties for a given radio power, reflecting a number of variable factors in addition to orientation (e.g. large scale environment, accretion rate onto central black hole). There is also a growing recognition that AGN are dynamic, evolving objects that strongly influence their immediate surroundings, including the distribution of circum-nuclear gas and dust.

Analogy between the standard gauge model of the basic forces and hadronic mechanics

In this paper we review the standard gauge model of the basic (action-at-a-distance) forces in nature characterized by the conventional gauge-invariant substitution, &#948&#947&#968&#8594(-i(elhc)A&#947)&#936 for the electromagnetic field (in the Schrodinger or Dirac equation for the normal hydrogen atom in conventional quantum mechanics), and by &#948&#947&#968&#8594(- it&#945A&#945&#956)&#968 for the Yang-Mills field in the Weinberg-Glashow-Salam unification of electroweak forces (referred to as “standard” unified gauge model) which are based on conventional Einstein's special relativity theory, and indicate the analogy with the new generalizations of conventional quantum mechanics and the “standard” unified gauge model under the name “hadronic” mechanics to include not only action-at-a-distance forces but also a fifth (non-local, contact/overlap) force, represented by a Hulthen potential, in superdense matter (such as compressed hydrogen atom in a neutron star) and in condensed matter (such as a high-temperature cuprate superconductor). Hadronic Mechanics distinguishes Einstein's special relativity (for relative motion in vacuum) from “extended” relativity and general relativity, and provides a non-perturbative grand unification scheme for the basic forces in nature (including gravitation and the fifth force) that brings not only Oyibo's “grand unified theorem” but also superstring “theory of everything” within its purview. The “hadronic” mechanics representation of the neutron as a compressed H-atom n=(e-, p)HM , known as Rutherford-Santilli neutron, or as (e-vep)sub>HM = n, implies that the p-n, p-p and n-n binding in atomic nuclei of all chemical elements can be understood in terms of “hadronic” (strong interaction) chemistry, with potential application to development and production of clean fuels from “hadronic” energy.JONAMP Vol. 9 2005: pp. 1-30

The Origin of the Infrared Emission in Radio Galaxies. I. New Mid‐ to Far‐Infrared and Radio Observations of the 2 Jy Sample

As part of a large study to investigate the nature of the longer wavelength continuum emission of radio-loud AGNs, we present new mid- to far-infrared (MFIR) and high-frequency radio observations for a complete sample of 2 Jy powerful southern radio galaxies at intermediate redshifts (0.05 < z < 0.7). Utilizing the sensitivity of the Spitzer Space Telescope, we have made deep MIPS observations at wavelengths of 24, 70, and 160 mu m, detecting 100% of our sample at 24 mu m and 90% at 70 mu m. This high detection rate at MFIR wavelengths is unparalleled in samples of intermediate-redshift radio galaxies. Complementing these results, we also present new high-frequency observations (15-24 GHz) from the Australia Telescope Compact Array and the Very Large Array, which are used to investigate the potential contamination of the MFIR continuum by nonthermal synchrotron emission. With the latter observations we detect compact cores in 59% of our complete sample and deduce that nonthermal contamination of the MFIR continuum is significant in a maximum of 30% of our total sample. MFIR fluxes, radio fluxes, and spectral energy distributions for the complete sample are presented here, while in a second paper we will analyze these data and discuss the implications for our understanding of the heating mechanism for the warm/cool dust, star formation in the host galaxies, and the unified schemes for powerful radio sources.

Rapid variability in TeV blazars: the case of PKS 2155—304

Abstract Recent Cherenkov observations of BL Lacertae (BL Lac) objects showed that the TeV (teraelectron volt) flux of PKS 2155−304 changed by a factor of 2 in just 3–5 min. This fast variability can be accounted for if the emitting region is moving with a bulk Lorentz factor Γ∼ 50 and a similar relativistic Doppler factor. If this Γ is adopted, several models can fit the data, but, irrespective of the chosen model, the jet is matter dominated. The Doppler factor requires viewing angles of the order of 1° or less: if the entire jet is as narrow as this, then we have problems with current unification schemes. This suggests that there are small active regions, inside a larger jet, moving faster than the rest of the plasma, occasionally pointing at us. Coordinated X-ray/TeV variability can discriminate between the different scenarios.

SU(5)grand unification on a domain-wall brane from anE6-invariant action

An SU(5) grand unification scheme for effective 3+1-dimensional fields dynamically localized on a domain-wall brane is constructed. This is achieved through the confluence of the clash-of-symmetries mechanism for symmetry breaking through domain-wall formation, and the Dvali-Shifman gauge-boson localization idea. It requires an E{sub 6} gauge-invariant action, yielding a domain-wall solution that has E{sub 6} broken to differently embedded SO(10) x U(1) subgroups in the two bulk regions on opposite sides of the wall. On the wall itself, the unbroken symmetry is the intersection of the two bulk subgroups, and contains SU(5). A 4+1-dimensional fermion family in the 27 of E{sub 6} gives rise to localized left-handed zero modes in the 5*+10+1+1 representation of SU(5). The remaining ten fermion components of the 27 are delocalized exotic states, not appearing in the effective 3+1-dimensional theory on the domain-wall brane. The scheme is compatible with the type-2 Randall-Sundrum mechanism for graviton localization; the single extra dimension is infinite.

The Host Galaxy and the Extended Emission‐Line Region of the Radio Galaxy 3C 79

We present extensive ground-based spectroscopy and HST imaging of 3C79, an FR II radio galaxy associated with a luminous extended emission-line region (EELR). Surface brightness modeling of an emission-line-free HST R-band image reveals that the host galaxy is a massive elliptical with a compact companion 0.8 away and 4 magnitudes fainter. The host galaxy spectrum is best described by an intermediate-age (1.3 Gyr) stellar population (4% by mass), superimposed on a 10 Gyr old population and a power law (\alpha_{\lambda} = -1.8); the stellar populations are consistent with super-solar metallicities, with the best fit given by the 2.5 Z_sun models. We derive a dynamical mass of 4E11 M_sun within the effective radius from the velocity dispersion. The EELR spectra clearly indicate that the EELR is photoionized by the hidden central engine. Photoionization modeling shows evidence that the gas metallicity in both the EELR and the nuclear narrow-line region is mildly sub-solar (0.3 - 0.7 Z_sun) -- significantly lower than the super-solar metallicities deduced from typical active galactic nuclei in the SDSS. The more luminous filaments in the EELR exhibit a velocity field consistent with a common disk rotation. Fainter clouds, however, show high approaching velocities that are uncoupled with this apparent disk rotation. The striking similarities between this EELR and the EELRs around steep-spectrum radio-loud quasars provide further evidence for the orientation-dependent unification schemes. The metal-poor gas is almost certainly not native to the massive host galaxy. We suggest that the close companion galaxy could be the tidally stripped bulge of a late-type galaxy that is merging with the host galaxy. The interstellar medium of such a galaxy is probably the source for the low-metallicity gas in 3C79.

Hyperaccretion

I briefly review the physics of accretion at rates well above the Eddington value. In stellar-mass systems, the result is generally an ultraluminous X-ray binary, and I show how SS433 fits into this picture. Conditions are relatively less extreme in active galactic nuclei, as the greatest likely accretion rates are not far above the electron-scattering Eddington value. However, even quite modest mass inflow rates exceed the corresponding value for dust opacity. I show that the obscuring torus invoked in unified AGN schemes is the probable result, and note that the matter in the torus probably does not supply the matter accreting on to the central black hole and thus powering the AGN.