Broad Absorption Line QSOs Research Articles

The central structure of Broad Absorption Line QSOs: observational characteristics in the cm-mm wavelength domain

Accounting for ∼20% of the total QSO population, Broad Absorption Line QSOs are still an unsolved problem in the AGN context. They present wide troughs in the UV spectrum, due to material with velocities up to 0.2 c toward the observer. The two models proposed in literature try to explain them as a particular phase of the evolution of QSOs or as normal QSOs, but seen from a particular line of sight.We built a statistically complete sample of Radio-Loud BAL QSOs, and carried out an observing campaign to piece together the whole spectrum in the cm wavelength domain, and highlight all the possible differences with respect to a comparison sample of Radio-Loud non-BAL QSOs. VLBI observations at high angular resolution have been performed, to study the pc-scale morphology of these objects. Finally, we tried to detect a possible dust component with observations at mm-wavelengths.Results do not seem to indicate a young age for all BAL QSOs. Instead a variety of orientations and morphologies have been found, constraining the outflows foreseen by the orientation model to have different possible angles with respect to the jet axis.

Radio properties of 0.4 < z < 0.8 BAL QSOs

We present MERLIN 18 cm radio continuum observations of three 0.4 < z < 0.8 broad-absorption-line (BAL) quasi-stellar objects (QSOs). The question, whether BAL QSOs can be interpreted in a pure orientation scheme, or whether evolutionary aspects have to be taken into account, is still a matter of debate. Radio-interferometric observations can provide additional information about both aspects. The presence of jets, their orientation, and beaming can provide clues on the orientation of the nuclear components. On the other hand, the compactness of the nuclear radio emission and its spectral index can provide information about the evolutionary state of the AGN, and of starbursts, if present.

THE NATURE OF LoBAL QSOs. I. SEDs AND MID-INFRARED SPECTRAL PROPERTIES

We have obtained Spitzer IRS spectra and MIPS 24, 70, and 160 micron photometry for a volume-limited sample of 22 SDSS-selected Low-ionization Broad Absorption Line QSOs (LoBALs) at 0.5 < z < 0.6. By comparing their mid-IR spectral properties and far-IR SEDs with those of a control sample of 35 non-LoBALs matched in M_i, we investigate the differences between the two populations in terms of their infrared emission and star formation activity. Twenty five percent of the LoBALs show PAH features and 45% have weak 9.7 micron silicate dust emission. We model the SEDs and decouple the AGN and starburst contributions to the far-infrared luminosity in LoBALs and in non-LoBALs. Their median total, starburst, and AGN infrared luminosities are comparable. Twenty percent (but no more than 60%) of the LoBALs and 26% of the non-LoBALs are ultra-luminous infrared galaxies (ULIRGs; L_IR>10^12*L_sun). We estimate star formation rates (SFRs) corrected for the AGN contribution to the FIR flux and find that LoBALs have comparable levels of star formation activity to non-LoBALs when considering the entire samples. However, the SFRs of the IR-luminous LoBALs are 80% higher than those of their counterparts in the control sample. The median contribution of star formation to the total far-infrared flux in LoBALs and in non-LoBALs is estimated to be 40-50%, in agreement with previous results for PG QSOs. Overall, our results show that there is no strong evidence from the mid- and far-IR properties that LoBALs are drawn from a different parent population than non-LoBALs.

Probing the time variability of five Fe low broad absorption-line quasars★

We study the time variability of five Fe Low ionization Broad Absorption Line (FeLoBAL) QSOs using repeated spectroscopic observations with the 2m telescope at IUCAA Girawali observatory (IGO) spanning an interval of upto 10 years. We report a dramatic variation in Al III and Fe III fine-structure lines in the spectra of SDSS J221511.93-004549.9 (z_em ~ 1.478). However, there is no such strong variability shown by the C IV absorption. This source is known to be unusual with (i) the continuum emission dominated by Fe emission lines, (ii) Fe III absorption being stronger than Fe II and (iii) the apparent ratio of Fe III UV 48 to Fe III UV 34 absorption suggesting an inverted population ratio. This is the first reported detection of time variability in the Fe III fine-structure lines in QSO spectra. There is a strong reduction in the absorption strength of these lines between year 2000 and 2008. Using the template fitting techniques, we show that the apparent inversion of strength of UV lines could be related to the complex spectral energy distribution of this QSO. The observed variability can be related to change in the ionization state of the gas or due to transverse motion of this absorbing gas. The shortest variability timescale of Al III line gives a lower limit on the electron density of the absorbing gas as n_e >= 1.1 x 10^4 cm^-3. The remaining 4 FeLoBALs do not show any changes beyond the measurement uncertainties either in optical depth or in the velocity structure. We present the long-term photometric light curve for all of our sources. Among them only SDSS J221511.93-004549.9 shows significant (>= 0.2 mag) variability.

Dynamically evolving Mg ii broad absorption line flow in SDSS J133356.02+001229.1

ABSTRACT We report a dynamically evolving low-ionization broad absorption line (BAL) flow in the QSO SDSS J133356.02+001229.1 (at zem∼ 0.9197). These observations are part of our ongoing monitoring of low-ionization BAL QSOs with the 2-m telescope at IUCAA Girawali Observatory (IGO). The broad Mg ii absorption with an ejection velocity of 1.7 × 104 km s−1, found in the Sloan Digital Sky Survey (SDSS) spectra, has disappeared completely in our IGO spectra. We found an emerging new component at an ejection velocity of 2.8 × 104 km s−1. During our monitoring period this component has shown strong evolution both in its velocity width and optical depth and nearly disappeared in our latest observations. Acceleration of a low-velocity component seen in SDSS spectrum to a higher velocity is unlikely as the Mg ii column densities are always observed to be higher for the new component. We argue that the observed variations may not be related to ionization changes and are consistent with absorption produced by multistreaming flow transiting across our line of sight. We find a possible connection between flux variation of the QSO and N(Mg ii) of the newly emerged component. This could mean the ejection being triggered by changes in the accretion disc or dust reddening due to the outflowing gas.

DISCOVERY OF HYDROGEN FLUORIDE IN THE CLOVERLEAF QUASAR AT z = 2.56

We report the first detection of hydrogen fluoride (HF) toward a high redshift quasar. Using the Caltech Submillimeter Observatory (CSO) we detect the HF J = 1 - 0 transition in absorption toward the Cloverleaf, a broad absorption line (BAL) quasi-stellar object (QSO) at z=2.56. The detection is statistically significant at the ~ 6 sigma level. We estimate a lower limit of 4 \times 1014 cm-2 for the HF column density and using a previous estimate of the hydrogen column density, we obtain a lower limit of 1.7 \times 10-9 for the HF abundance. This value suggests that, assuming a Galactic N(HF)/NH ratio, HF accounts for at least ~10% of the fluorine in the gas phase along the line of sight to the Cloverleaf quasar. This observation corroborates the prediction that HF should be a good probe of the molecular gas at high redshift. Measurements of the HF abundance as a function of redshift are urgently needed to better constrain the fluorine nucleosynthesis mechanism(s).

X-ray and optical properties of broad absorption line quasars in the Canada-France-Hawaii Telescope Legacy Survey

We study the X-ray and optical properties of 16 Broad Absorption Line (BAL) quasars detected in about 3 degree square region common to the wide synoptic (W-1) component of the Canada-France-HawaiiTelescope Legacy Survey (CFHTLS) and the XMM Large Scale Structure survey (XMM-LSS). The BAL fraction is found to be 10% in full sample, 7% for the optical colour selected QSOs and as high as 33% if we consider QSOs selected from their IR colours. The X-ray detected non-BAL and BAL quasars have a mean observed X-ray-to-optical spectral slope of -1.47 +/- 0.13 and -1.66 +/- 0.17 respectively. We also find that the BAL QSOs have alpha_ox systematically smaller than what is expected from the relationship between optical luminosity and alpha_ox as derived from our sample. Based on this, we show, as already reported in the literature for quasars with high optical luminosities, our new sample of BAL QSOs have X-ray luminosity a factor of three smaller than what has been found for non-BAL QSOs with similar optical luminosities. Comparison of hardness ratio of the BAL and non-BAL QSOs suggests a possible soft X-ray weakness of BAL QSOs. Combining our sample, of relatively fainter QSOs, with others from the literature we show that larger balnicity index (BI) and maximum velocity (V_max) of the C IV absorption are correlated with steeper X-ray to optical spectral index. We argue that this is most likely a consequence of the existence of a lower envelope in the distribution of BI (or V_max) values versus optical luminosity. Our results thus show that the previously known X-ray weakness of BAL QSOs extends to lower optical luminosities as well.

Optical microvariability properties of BALQSOs

We present optical light curves of 19 radio quiet (RQ) broad absorption line (BAL) QSOs and study their rapid variability characteristics. Systematic CCD observations, aided by a careful data analysis procedure, have allowed us to clearly detect any such microvariability exceeding 0.01--0.02 mag. Our observations cover a total of 13 nights (~72 hours) with each quasar monitored for about 4 hours on a given night. Our sample size is a factor of three larger than the number of radio-quiet BALQSOs previously searched for microvariability. We introduce a scaled F-test statistic for evaluating the presence of optical microvariability and demonstrate why it is generally preferable to the statistics usually employed for this purpose. Considering only unambiguous detections of microvariability we find that ~11 per cent of radio-quiet BALQSOs (two out of 19 sources) show microvariability for an individual observation length of about 4 hr. This new duty cycle of 11 per cent is similar to the usual low microvariability fraction of normal RQQSOs with observation lengths similar to those of ours. This result provides support for models where radio-quiet BALQSO do not appear to be a special case of the RQQSOs in terms of their microvariability properties.

Gas, dust and stars in the SCUBA galaxy, SMM J0136: the EVLA reveals a colossal galactic nursery

We present new multiwavelength observations of the first submillimetre-selected galaxy (SMG) SMM J02399−0136 at z= 2.8. These observations include mapping of the CO J=1→0 emission using elements of the Expanded Very Large Array, as well as high-resolution 1.4-GHz imaging and optical/infrared (IR) data from the Very Large Array, Hubble Space Telescope, Spitzer and Keck-I. Together, these new data provide fundamental insights into the mass and distribution of stars, gas and dust within this archetypal SMG. The CO J=1→0 emission, with its minimal excitation and density requirements, traces the bulk of the metal-rich molecular gas, and reveals a molecular gas mass of ∼1011 M⊙, extending over approximately 5 arcsec (∼25 kpc in the source plane), although there is tentative evidence that it may be significantly larger. Our data suggest that three or more distinct structures are encompassed by this molecular gas reservoir, including the broad absorption line (BAL) quasar from which the redshift of the SMG was initially determined. In particular, the new rest-frame near-IR observations identify a massive, obscured, starburst which is coincident with a previously known Lyα cloud. This starburst dominates the far-IR emission from the system and requires a re-assessment of previous claims that the gas reservoir resides in a massive, extended disc around the BAL quasi-stellar object (QSO). Instead, it appears that SMM J02399−0136 comprises a merger between a far-IR-luminous, but highly obscured starburst, the BAL QSO host and a faint third component. Our findings suggest that this archetypal SMG and its immediate environment mark a vast and complex galactic nursery and that detailed studies of other SMGs are likely to uncover a similarly rich diversity of properties.

ON THE SCATTERING ENHANCEMENT OF N V λ1240 EMISSION LINE OF QUASI-STELLAR OBJECTS

The Nv emission line of active galactic nuclei shows peculiar behavior in the line--continuum correlation, which may be indicative of an extra line component in addition to that from the normal broad emission line region. In this paper, we investigate possible contribution to the Nv emission via resonant scattering of both continuum and Ly alpha in a broad absorption line (BAL) outflow, by performing the Sobolev Monte Carlo simulations. The contribution is dependent on the covering factor, optical depth and velocity profile of the outflow, as well as the equivalent width (EW) of Ly alpha. Adopting model parameters constrained by observations, we find that the measured Nv EW in the spectra of non-BAL quasi-stellar objects (QSOs) could have been enhanced by a factor of 1.82~2.73 on average, while there is only moderate absorption of Ly alpha along the BAL outflow direction. Our model can produce a relatively narrow scattering line profile. About 80% of the total scattered flux falls within the central +-4500km/s. We find that the resonant scattering can produce a prominent polarized emission line around Nv. Both the broad excess emission and the unusually large polarized flux observed around Nv in BAL QSOs are considered as strong evidence for the scattering enhancement. Future spectropolarimetric observations and spectroscopic monitoring of luminous QSOs may offer crucial tests for this interpretation, and provide useful information on the physical and geometrical properties of QSO outflows. We argue that the scattering offers a promising and robust process for producing the peculiar behavior of Nv emission compared to the other processes proposed previously.

MOLECULAR GAS AND THE HOST-GALAXY SYSTEM OF THEz∼ 0.3 QSO PG 1700+518

The detection of CO(1→0) emission in the massive (i.e., MH ~ –26.13 mag), z ~ 0.3 host-galaxy system of the broad absorption line quasi-stellar object (QSO) PG1700+518 is reported. The host system has a CO luminosity of L'_CO ~ 1.4 × 10^(10) K km s^(–1) pc^2, and thus a star-forming molecular gas mass of M(H_2) ~ 6 × 10^(10) M_☉ (adopting an α = 4 M_☉[K km s^(–1) pc^2]^(–1)), making it one of the most molecular gas-rich Palomar-Green QSO hosts observed to date. New Hubble Space Telescope WFPC2 direct and NICMOS coronagraphic images show the highest resolution view yet of the host and companion. The new NICMOS image reveals the underlying, apparently tidally disrupted structure seen previously from high-resolution ground-based optical imaging. Light from the host galaxy is overwhelmed by the central point source in the WFPC2 images. The companion galaxy is well resolved in both data sets, and the WFPC2 provides for the first time a clear picture of the optically visible ring structure. The CO redshift is within the range of redshifts derived from optical QSO emission lines, thus the observed CO is associated with the QSO host. However, it cannot be ruled out that the companion has at least ~10^(10) M_☉ of molecular gas. Finally, if the far-infrared luminosity, which is 1/5 of the bolometric luminosity, is the luminosity of the starburst population, the star formation rate is estimated to be ~210 M_☉ yr^(–1). There is thus sufficient molecular gas in the QSO host galaxy to fuel both star formation and QSO activity for another ~10^8 yr. We speculate that we may be witnessing the fueling event in progress that resulted from a collision between the QSO host and the companion galaxy, and that there is an accompanying expulsion of material along our line of sight in the form of broad absorption line gas.

A CATALOG OF BROAD ABSORPTION LINE QUASARS IN SLOAN DIGITAL SKY SURVEY DATA RELEASE 5

We present a catalog of 5039 broad absorption line (BAL) quasars (QSOs) in the Sloan Digital Sky Survey (SDSS) Data Release 5 (DR5) QSO catalog that have absorption troughs covering a continuous velocity range >= 2000 km/s. We have fit ultraviolet (UV) continua and line emission in each case, enabling us to report common diagnostics of BAL strengths and velocities in the range -25,000 to 0 km/s for SiIV $\lambda$1400, CIV $\lambda$1549, AlIII $\lambda$1857, and MgII $\lambda$2799. We calculate these diagnostics using the spectrum listed in the DR5 QSO catalog, and also for spectra from additional SDSS observing epochs when available. In cases where BAL QSOs have been observed with Chandra or XMM-Newton, we report the X-ray monochromatic luminosities of these sources. We confirm and extend previous findings that BAL QSOs are more strongly reddened in the rest-frame UV than non-BAL QSOs and that BAL QSOs are relatively X-ray weak compared to non-BAL QSOs. The observed BAL fraction is dependent on the spectral signal-to-noise (S/N); for higher-S/N sources, we find an observed BAL fraction of approximately 15%. BAL QSOs show a similar Baldwin effect as for non-BAL QSOs, in that their CIV emission equivalent widths decrease with increasing continuum luminosity. However, BAL QSOs have weaker CIV emission in general than do non-BAL QSOs. Sources with higher UV luminosities are more likely to have higher-velocity outflows, and the BAL outflow velocity and UV absorption strength are correlated with relative X-ray weakness. These results are in qualitative agreement with models that depend on strong X-ray absorption to shield the outflow from over-ionization and enable radiative acceleration....

THE CORRELATION BETWEEN X-RAY AND UV PROPERTIES OF BAL QSOs

We compile a large sample of broad absorption line (BAL) quasars with X-ray observations from the XMM-Newton archive data and Sloan Digital Sky Survey Data Release 5. The sample consists of 41 BAL QSOs. Among 26 BAL quasars detected in X-ray, spectral analysis is possible for 12 objects. X-ray absorption is detected in all of them. Complementary to that of Gallagher et?al., our sample spans wide ranges of both BALnicity index (BI) and maximum outflow velocity (v max). Combining our sample with that of Gallagher et?al., we find very significant correlations between the intrinsic X-ray weakness and both BI and the maximum velocity of the absorption trough. We do not confirm the previously claimed correlation between absorption column density and BAL parameters. Our tentative interpretation is that X-ray absorption is necessary to the production of the BAL outflow, but the properties of the outflow are largely determined by intrinsic spectral energy distribution of the quasars.

The compact structure of radio-loud broad absorption line quasars

We present the results of EVN+MERLIN very long baseline interferometry (VLBI) polarization observations of eight broad absorption line (BAL) quasars at 1.6 GHz, including four low-ionization BAL quasars (LoBALs) and four high-ionization BAL quasars (HiBALs) with either steep or flat spectra on Very Large Array (VLA) scales. Only one steep-spectrum source, J1122+3124, shows two-sided structure on the scale of 2 kpc. The other four steep-spectrum sources and three flat-spectrum sources display either an unresolved image or a core–jet structure on scales of less than 300 pc. In all cases, the marginally resolved core is the dominant radio component. Linear polarization in the cores has been detected in the range of a few to 10 per cent. Polarization, together with high brightness temperatures (from 2 × 10 9 to 5 × 10 10 K), suggests a synchrotron origin for the radio emission. There is no apparent difference in the radio morphologies or polarization between low-ionization and high-ionization BAL quasi-stellar objects (QSOs) or between flat- and steep-spectrum sources. We discuss the orientation of BAL QSOs with both flat and steep spectra, and consider a possible evolutionary scenario for BAL QSOs. In this scenario, BAL QSOs are probably a young population of radio sources that are compact steep spectrum or GHz peaked radio source analogues at the low end of radio power.

XMM-Newton Observations of Broad Absorption Line Quasars with Polar Outflows

We have selected a sample of broad absorption line (BAL) quasars which show significant radio variations, indicating the presence of polar BAL outflows. We obtained snapshot XMM observations of four polar BAL QSOs, to check whether strong X-ray absorption, one of the most prominent characteristics of most BAL QSOs, also exists in polar outflows. Two of the sources are detected in the X-ray. Spectral fittings show that they are X-ray normal with no intrinsic X-ray absorption, suggesting the X-ray shielding gas might be absent in polar BAL outflows. Comparing to non-BAL QSOs, one of two X-ray-nondetected sources remains consistent with X-ray normal, while the other one, which is an iron low-ionization BAL (FeLoBAL), shows an X-ray weakness factor of >19, suggesting strong intrinsic X-ray absorption. Alternative explanations for the nondetection of strong X-ray absorption in the two X-ray-detected sources are that (1) the absorption is more complex than a simple neutral absorber, such as partial covering absorption or ionized absorption; (2) there might be significant jet contribution to the detected X-ray emission. Current data are insufficient to test these possibilities, and further observations are required to understand the X-ray nature of polar BAL outflows.

Quasar Broad Absorption Line Variability on Multiyear Timescales

We use quantitative metrics to characterize the variation of C IV λ1549 broad absorption lines (BALs) over 3-6 (rest-frame) years in a sample of 13 quasars at 1.7 ≤ z≤ 2.8 and compare the results to previous studies of BAL variability on shorter timescales. The strong BALs in our study change in complex ways over 3-6 yr. Variation occurs in discrete regions only a few thousand kilometers per second wide, and the distribution of the change in absorption equivalent width broadens over time. We constrain the typical C IV BAL lifetime to be at least a few decades. While we do not find evidence to support a scenario in which the variation is primarily driven by photoionization on multiyear timescales, there is some indication that the variation is produced by changes in outflow geometry. We do not observe significant changes in the BAL onset velocity, indicating that the absorber is either far from the source or is being continually replenished and is azimuthally symmetric. It is not possible in a human lifetime to expand the timescales in our study by more than a factor of a few using optical spectroscopy. However, the strong variation we have observed in some BALs indicates that future studies of large numbers of BAL QSOs will be valuable to constrain BAL lifetimes and the physics of variation.

The XMM-SSC survey of hard-spectrum XMM–Newton sources – I. Optically bright sources

We present optical and X-ray data for a sample of serendipitous XMM-Newton sources that are selected to have 0.5-2 versus 2-4.5 keV X-ray hardness ratios which are harder than the X-ray background. The sources have 2-4.5 keV X-ray flux , and in this paper we examine a subsample of 42 optically bright (r sources; this subsample is 100 per cent spectroscopically identified. All but one of the optical counterparts are extragalactic, and we argue that the single exception, a Galactic M star, is probably a coincidental association rather than the correct identification of the X-ray source. The X-ray spectra of all the sources are consistent with heavily absorbed power laws (21.8 10(44) erg s(-1), and two of these sources have optical spectra which are dominated by narrow emission lines, that is, are type 2 QSOs. Only a small fraction of the sources (7/42) show broad optical emission lines, and all of these have N(H) 100 times the Galactic gas-to-dust ratio are rare in AGN absorbers (at most a few per cent of the population), and may be restricted to broad absorption line QSOs. Seven objects appear to have an additional soft X-ray component in addition to the heavily absorbed power law; all seven are narrow emission-line objects with z 4 per cent of broad-line AGN (BLAGN) have ionized absorbers that attenuate their soft X-ray flux by > 50 per cent. In at least one of the X-ray-absorbed BLAGN in our sample the X-ray spectrum requires an ionized absorber, consistent with this picture.

Polarization of Quasars: Resonant Line Scattering in the Broad Absorption Line Region

Recent works showed that the absorbing material in broad absorption line (BAL) quasars is optically thick to major resonant absorption lines. This material may contribute significantly to the polarization in the absorption lines. In this paper, we present a detailed study of the resonant line scattering process using a Monte Carlo method to constrain the optical depth, the geometry, and the kinematics of the BAL region (BALR). By comparing our results with observed polarized spectra of BAL quasars, we find the following: (1) Resonant scattering can produce polarization up to 9% at the absorption trough for doublet transitions and up to 20% for singlet transitions in radially accelerated flows. To explain the large polarization degree in the C IV and N V absorption-line troughs detected in a small fraction of BAL QSOs, a nonmonotonic velocity distribution along the line of sight or/and additional contribution from the electron-scattering region is required. (2) The rotation of the flow can lead to the rotation of the polarization position angle (PA) in the line trough. A large extending angle of BALR is required to produce the observed large PA rotation in a few BAL QSOs. (3) A large extending angle of BALR is required to explain a subtrough in the polarized flux that was observed in a number of BAL QSOs. (4) The resonant scattering can contribute a significant part of N V emission line in some QSOs, and it may give rise to anomalous strong N V lines in these quasars. (5) The polarized flux and PA rotation produced by the resonant scattering regions is uniquely asymmetric, which may be used to test the presence of BALR in non-BAL QSOs.

The modelling of the line-locking effect in broad absorption line QSOs

AbstractWe present a unification model of the matter outflow from AGN. The model includes calculations of the hot gas dynamics, the dynamics of the cold clouds in the hot gas flow, and the radiation transfer in this two-phase medium. We used the model for calculation of the ultraviolet spectrum of the quasar q1303+308. The spectrum of this object is a well-know example of the line-locking effect. Our model calculations permits for the first time to obtain some thin details seen in the observed absorption spectrum, which confirms the validity of the main issues of our theory and model.

Evolutionary unification in composite active galactic nuclei

In this paper, we present an evolutionary unification scenario, involving supermassive black holes (SMBHs) and starbursts (SBs) with outflow (OF), that seems capable of explaining most of the observational properties (of at least part) of active galactic nuclei (AGN). The scenario includes a nuclear/circumnuclear SB closely associated with the AGN where the narrow-line region (NLR), broad-line region (BLR) and broad absorption line (BAL) region are produced in part by the OF process with shells and in compact supernova remnants (cSNRs). The OF process in BAL quasi-stellar objects (QSOs) with extreme infrared (IR) and Fe II emission is studied. In addition, the Fe II problem regarding the BLR of AGN is analysed. The correlations between the BAL, IR emission, Fe II intensity and the intrinsic properties of the AGN are not clearly understood. We suggest here that the behaviour of the BAL, IR and Fe II emission in AGN can be understood within an evolutionary and composite model for AGN. In our model, strong BAL systems and Fe II emission are present (and intense) in young IR objects. Parameters like the BALs, IR emission, Fe II/Hβ intensity ratio, Fe II equivalent width (EW), broad-line width, [O III] λ5007-A intensity and width, NLR size, X-ray spectral slope in radio quiet (RQ) AGN plus lobe separation, and lobe to core intensity ratio in radio loud (RL) AGN are proposed to be fundamentally time-dependent variables inside time-scales of the order of 10 8 yr. Orientation/obscuration effects take the role of a second parameter providing the segregation between Seyfert 1/Seyfert 2 galaxies (Sy1/Sy2) and broad-/narrow-line radio galaxies (BLRG/NLRG).