Search

The great capability and exible nature of the OSIRIS-GTC tunable filters make them the most efficient tool to study systematically the environment of RLQSOs and RQQSOs in the range 2 z 4. In this work we present our first results on simulations performed in order to define our optimal observational strategy.

Context. Most of the optically classified low-ionisation, narrow emission-line regions (LINERs) nuclei host an active galactic nucleus (AGN). However, how they fit into the unified model (UM) of AGN is still an open question. Aims. The aims of this work are to study at mid-infrared (mid-IR) (1) the Compton-thick nature of LINERs (i.e. hydrogen column densities of NH > 1:5 10 24 cm 2 ) and (2) the disappearance of the dusty torus in LINERs predicted from theoretical arguments. Methods. We have compiled all the available low spectral-resolution, mid-IR spectra of LINERs from the InfraRed Spectrograph (IRS) onboard Spitzer. The sample contains 40 LINERs. We have complemented the LINER sample with Spitzer/IRS spectra of PG QSOs, Type-1 Seyferts (S1s), Type-2 Seyferts (S2s), and StarBurst (SB) nuclei. We studied the AGN compared to the starburst content in our sample using di erent indicators: the equivalent width of the polycyclic aromatic hydrocarbon at 6.2 m, the strength of the silicate feature at 9.7 m, and the steepness of the mid-IR spectra. We classified the spectra as SB-dominated and AGN-dominated, according to these diagnostics and compared the average mid-IR spectra of the various classes. Moreover, we studied the correlation between the 12 m luminosity, L (12 m), and the 2 10 keV energy band X-ray luminosity, LX(2 10 keV). Results. In 25 out of the 40 LINERs (i.e. 62.5%), the mid-IR spectra are not SB-dominated, similar to the comparison S2 sample (67.7%). The average spectra of both SB-dominated LINERs and S2s are very similar to the average spectrum of the SB class. The average spectrum of AGN-dominated LINERs is di erent from the average spectra of the other optical classes, showing a rather flat spectrum at 6 28 m. We find that the average spectrum of AGN-dominated LINERs with X-ray luminosities LX(2 10 keV) > 10 41 erg/s is similar to the average mid-IR spectrum of AGN-dominated S2s. However, faint LINERs (i.e. LX(2 10 keV) < 10 41 erg/s) show flat spectra di erent from any of the other optical classes. The correlation between L (12 m) and LX(2 10 keV) for AGN nicely extends towards low luminosities only if SB-dominated LINERs are excluded and if the 2 10 keV band X-ray luminosity is corrected in Compton-thick LINER candidates. Conclusions. We find that LINERs proposed as Compton-thick candidates at X-ray wavelengths may be confirmed according to the X-ray to mid-IR luminosity relation. We show evidence that the dusty-torus disappear when their bolometric luminosity is below Lbol ’ 10 42 erg/s. We suggest that the dominant emission at mid-IR of faint LINERs might be a combination of an elliptical galaxy host (characterised by the lack of gas), a starburst, a jet, and/or ADAF emission. Alternatively, the mid-IR emission of some of these faint LINERs could be a combination of elliptical galaxy plus carbon-rich planetary nebulae. To reconcile the Compton-thick nature of a large number of LINERs without dusty-torus signatures, we suggest that the material producing the Compton-thick X-ray obscuration is free of dust.

We study the FeII properties of double-peaked broad low-ionization emission line AGN (dbp emitters) using a sample of 27 dbp emitters from SDSS (DR4), with mean value $\sigma_{H\alpha_{B}}\sim3002\pm139{\rm km\cdot s^{-1}}$. Our first result is that the line spectra in the wavelength range from 4100$\AA$ to 5800$\AA$ can be best fitted by an elliptical accretion disk model, assuming the same double-peaked line profiles for H$\beta$, FeII, H$\gamma$ and HeII$\lambda4686\AA$ as that of double-peaked broad H$\alpha$ for all the 27 dbp emitters, except the object SDSS J2125-0813 which we have discussed in a previous paper. The best fitted results indicate that the optical FeII emission lines of dbp emitters originate from the same region in the accretion disk where the double-peaked Balmer emission lines originate. Some correlations between FeII emission lines and the other broad emission lines for normal AGN can be confirmed for dbp emitters. However, these results should be taken with caution due to the small number of objects and the bias in selecting strong FeII emitters. We show that for dbp emitters, BH masses seems to have more influence on FeII properties than dimensionless accretion rate. We also find that the dbp emitters in the sample are all radio quiet quasars except one dbp emitter with $R_r> 1$ according to the definition by Ivezi$\rm{\acute{c}}$ et al. (2002) and 6 objects undiscovered by FIRST., Comment: Accepted by Rev. Mex. A&A

We present a 3-dimensional study of the local ($\leq 100 h^{-1}$ kpc) and the large scale ($\leq$ 1 $h^{-1}$ Mpc) environment of Bright IRAS Galaxies (BIRGs). For this purpose we use 87 BIRGs located at high galactic latitudes (with 0.008$\leq z \leq$0.018) as well as a control sample of non-active galaxies having the same morphological, redshift and diameter size distributions as the corresponding BIRG sample. Using the Center for Astrophysics (CfA2) and Southern Sky Redshift Survey (SSRS) galaxy catalogues ($m_b\lesssim 15.5$)as well as our own spectroscopic observations ($m_b\lesssim19.0$) for a subsample of the original BIRG sample, we find that the fraction of BIRGs with a close neighbor is significantly higher than that of their control sample. Comparing with a related analysis of Sy1 and Sy2 galaxies of Koulouridis et al. (2006) we find that BIRGs have a similar environment as Sy2s, although the fraction of BIRGs with a bright close neighbor is even higher than that of Sy2 galaxies. An additional analysis of the relation between FIR colors and the type of activity of each BIRG shows a significant difference between the colors of strongly-interacting and non-interacting starbursts and a resemblance between the colors of non-interacting starbursts and Sy2s. Our results support the view where close interactions can drive molecular clouds towards the galactic center, triggering starburst activity and obscuring the nuclear activity. When the close neighbor moves away, starburst activity is reduced with the simultaneous appearance of an obscured (type 2) AGN. Finally, the complete disentanglement of the pair gives birth to an unobscured (type 1) AGN., Accepted for publication in The Astrophysical Journal,10 pages, 4 figures

We report the results from an homogeneous analysis of the X-ray (Chandra-ACIS) data available for a sample of 51 LINER galaxies selected from the catalogue by Carrillo et al. (1999) and representative of the population of bright LINER sources. The nuclear X-ray morphology has been classified attending to their nuclear compactness in the hard band (4.5-8.0 keV) into 2 categories: Active Galactic Nuclei (AGN) candidates (with a clearly identified unresolved nuclear source) and Starburst (SB) candidates (without a clear nuclear source). 60% of the total sample are classified as AGNs, with a median luminosity of LX(2-10 keV)=2.5 x 10^(40)erg/s, which is an order of magnitude higher than that for SB-like nuclei. The spectral fitting allows to conclude that most of the objects need a non-negligible power-law contribution. When no spectral fitting can be performed (data with low signal-to-noise ratio), the Color-Color diagrams allow us to roughly estimate physical parameters such as column density, temperature of the thermal model or spectral index for a power-law and therefore to better constrain the origin of the X-ray emission. All together the X-ray morphology, the spectra and the Color-Color diagrams allow us to conclude that a high percentage of LINER galaxies, at least ~60%, could host AGN nuclei, although contributions from High Mass X-ray Binaries or Ultra-luminous X-ray sources cannot be ruled out for some galaxies., Accepted for publication in A&A. Higher quality version of the figures anf whole set of images 3 and 5 to appear in the electronic version available at http://www.iaa.es/~omaira

We derive black hole masses for a sample of about 300 AGNs in the redshift range 0 < z < 2.5. We use the same virial velocity measure (FWHM Hbeta broad component) for all sources which represents a significant improvement over previous studies. We review methods and caveats for determining AGN black hole masses via the virial assumption for motions in the gas producing low ionization broad emission lines. We derive a corrected FWHM measure for the broad component of H-beta that better estimates the virialized line emitting component by comparing our FWHM measures with a sample of reverberated sources with H-beta radial velocity dispersion measures. We also consider the FWHM of the FeII 4570 blend as a potential alternative velocity estimator. We find a range of black hole mass between log M ~ 6 - 10, where the black hole mass M is in solar masses. Estimates using corrected FWHM, as well as FWHM(Fe II) measures, reduce the number of sources with log M > 9.5 and suggest that extremely large M values (log M >~ 10) may not be realistic. Derived Eddington ratio values values show no evidence for a significant population of super-Eddington radiators especially after correction is made for sources with extreme orientation to our line of sight. Sources with FWHM(Hbeta broad component), Comment: Accepted for publication in Astronomy & Astrophysics

Computing the basic accretion parameters for the supermassive black holes expected to be present in quasars is still a major challenge. In this paper we stress how a systematization of observational properties through the so‐called “eigenvector 1” of quasars helps to develop a clearer view of the structure and dynamics of the Broad Line Region. “Eigenvector 1”‐based results also provide guidelines for more reliable estimates of the black hole mass and Eddington ratio over a wide redshift range, 0 ≲ z ≲ 2.5. We summarize the results of computations for a sample of ≈ 300 low and intermediate redshift quasars, and we suggest that black hole masses may not generally exceed ≈ 5 ⋅ 109 M⊙. We also found no convincing evidence of sources radiating above the Eddington limit.

We present a three-dimensional study of the local (, Comment: accepted for publication in ApJ, Abstract size reduced (according to new rules) and corrected references

We present BVR photometric observations of the blazar PKS 0736+017. These observations were carried out with three telescopes in Mexico and two in Spain between December 1998 and April 2003. PKS 0736+017 shows remarkable variation at different timescales and amplitudes. Maximum brightness was detected on December 19, 2001 (B=14.90+/-0.01, V=14.34+/-0.01, and R=13.79+/-0.01). A peculiar tendency to redden with increased brightness was detected throughout our observations. Moreover, in one season a good correlation between flux level and spectral slope is shown. This "anomalous" behaviour cannot be described by common flare models of blazars. The flux vs. spectral slope correlation observed in this and other blazars is worth further study., Comment: 8 pages, 6 figures, accepted for publication in Astronomy & Astrophysics

We present multicolor broad band BVRI photometry for a sample of 42 mixed morphology binary galaxies taken from the “Karachentsev Catalogue of Isolated Pairs of Galaxies” (KPG). Images were obtained with 0.84m and 1.5m telescopes of the Observatorio Astronomico Nacional, San Pedro Martir, Baja California, Mexico, operated by the Instituto de Astronomia, UNAM. Our goal is to identify and isolate some structural and photometric properties of disk galaxies and elliptical galaxies at different stages of interaction.

We present H alpha observations of the isolated interacting galaxy pair NGC 5426/27 using the scanning Fabry-Perot interferometer PUMA. The velocity field, various kinematical parameters and rotation curve for each galaxy were derived. The FWHM map and the residual velocities map were also computed to study the role of non-circular motions of the gas. Most of these motions can be associated with the presence of spiral arms and structure such as central bars. We found a small bar-like structure in NGC 5426, a distorted velocity field for NGC 5427 and a bridge-like feature between both galaxies which seems to be associated with NGC 5426. Using the observed rotation curves, a range of possible masses was computed for each galaxy. These were compared with the orbital mass of the pair derived from the relative motion of the participants. The rotation curve of each galaxy was also used to fit different mass distribution models considering the most common theoretical dark halo models. An analysis of the interaction process is presented and a possible 3D scenario for this encounter is also suggested., Comment: 27 pages, 15 figures, to be published in Astronomy & Astrophysics

We present Fabry-Perot and multi-object spectroscopy of the galaxies in Hickson compact group 31 (HCG31). Based upon our H$\alpha$ data cubes, galaxies A and C are a single entity, showing no discontinuity in their kinematics. Kinematically, galaxy E is probably a component of the A+C complex; otherwise it is a recently detached fragment. Galaxy F appears, both kinematically and chemically, to have formed from material tidally removed from the A+C complex. Galaxies B and G are kinematically distinct from this complex. Galaxy Q also has a radial velocity compatible with group membership. Galaxies A, B, C, and F have nearly identical oxygen abundances, despite spanning a luminosity range of 5$ $mag. Galaxy B's oxygen abundance is normal for its luminosity, while galaxy F's abundance is that expected given its origin as a tidal fragment of the A+C complex. The oxygen abundances in galaxies A and C are also understandable if the A+C complex is a late-type spiral suffering strong gas inflow and star formation as a result of a tidal interaction. Given the kinematics of both the galaxies and the \ion{H}{i} gas, the oxygen abundances, and the position of galaxy G, we propose that an interaction of galaxy G with the A+C complex, rather than a merger of galaxies A and C, is a more complete explanation for the tidal features and other properties of HCG31. In this case, the A+C complex need not be a merger in progress, though this is not ruled out., Comment: accepted for publication by Astronomy & Astrophysics

[Abridged] Context: The advent of 8-10m class telescopes makes possible for the first time detailed comparison of quasars with similar luminosity and very different redshifts. Aims: A search for z-dependent gradients in line emission diagnostics and derived physical properties by comparing, in a narrow bolometric luminosity range (log L ~ 46.1 +/- 0.4 [\ergss]), some of the most luminous local (z < 0.6) quasars with some of the lowest luminosity sources yet found at redshift z = 2.1 ~ 2.5. Method: Spectra for 22 high z sources were obtained with the 10.4m Gran Telescopio Canarias (GTC) while the HST (largely FOS) archive provides a low redshift control sample. Comparison is made in the context of the 4D Eigenvector 1 formalism meaning that we divide both source samples into high accreting Population A and low accreting Population B sources. Results: CIV 1549 shows very similar properties at both redshifts confirming at high redshift the CIV profile differences between Pop. A and B that are well established in local quasars. The CIV blueshift that appears quasi- ubiquitous in higher L sources is found in only half (Pop. A) of quasars observed in both of our samples. A CIV evolutionary Baldwin effect is certainly disfavored. We find evidence for lower metallicity in the GTC sample that may point toward a gradient with z. No evidence for a gradient in black hole mass or Eddington ratio is found. Conclusions: Spectroscopic differences established at low redshift are also present in much higher redshift quasars. Given that our samples involve sources with very similar luminosity the evidence for a systematic metallicity decrease, if real, points toward an evolutionary effect. Our samples appear representative of a slow evolving quasar population likely present at all redshifts., To appear in Astronomy & Astrophysics

We compared the environment and host galaxies of “Narrow Line” Seyfert 1 with those of Sy1, Sy2, and non-active galaxies. We found that NLSyls are hosted in smaller galaxies than Sy1s. This result supports the idea of NLSy1s as Sy1s with higher Eddington ratio. NLSy1 hosts may be more isolated and farther away from bright companions than Sy2s and normal galaxies.

We compared the environment of LINERs and Bright IRAS galaxies with those of Seyfert 1, Seyfert 2, and non-active galaxies. Interacting and merging systems are more frequently found among LINERs and Bright IRAS galaxies than among Seyfert 1 and normal galaxies. The environment of LINERs and Bright IRAS galaxies resembles that of Seyfert 2 galaxies. A notable exception are LINERs showing a broad component in Hα, whose environment is apparently similar to that of Seyfert 1s.

We study the relation between gaseous absorbing column density (N$_{\rm H}$), infrared colors and detectability of the broad lines in a large sample of Seyfert 2 galaxies(Sy2s). We confirm that Sy2s without polarized broad lines tend to have cooler 60$\mu$m/25$\mu$m colors; this correlation was previously ascribed to the effect of obscuration towards the nuclear region. We find some evidence that Sy2s without polarized broad lines have larger absorbing column density (N$_{\rm H}$) and that a fraction of them are characterized by dust lanes crossing their nuclei. However, we find that the IR colors do not correlate with N$_{\rm H}$, in disagreement with the obscuration scenario. Also, Sy2s without polarized broad lines follow the same radio-FIR relation as normal and starburst galaxies, at variance with Sy2s with polarized broad lines. These results indicate that the lack of broad lines in the polarized spectrum of Sy2s is mostly due to the contribution/dilution from the host galaxy or from a circumnuclear starburst, though at a lower extent the obscuration toward the nuclear region also plays a role., Comment: 6 pages, 4 figures, to appear in A&Ap

The first statistical study of the environment of Seyfert galaxies (of both types 1 and 2) was done by Petrosian (1982), who found that Sy2 galaxies had an excess of nearby companion galaxies with respect to field galaxies. Dahari (1985) made a similar study, and obtained that both types of Seyfert galaxies are found five times more often in interacting systems that “normal” galaxies. Fuentes-Williams & Stocke (1988) obtained the opposite result: that Seyfert galaxies have no significative excess of nearby companions, and MacKenty (1989) obtained the same result as Petrosian. The last papers appeared in 1995: Rafanelli, Violato & Baruffolo (1995) obtained a similar result as Dahari. Laurikainen & Salo (1995) made a careful attempt to understand the discrepancies; they concluded that the incompatibilities in the results were mainly due to control sample selection, and problems in background galaxy determination. Their work confirmed the result of the first study. However, in order to explain the discrepancies between previous results, they also used incorrectly defined control samples. Objections can be made against all of these works for this only reason. We have repeated the study using, for the first time, the digitized Palomar Sky Survey plates (POSS), an automated selection procedure, and correctly defined control samples (Osterbrock 1993).

After the publication of our article we realized that in Table 1 there was a vertical shift in the alignment of the redshifts between the entries of NGC 6104 and NGC 3660. The corrected Table 1 is given here; we have also deleted the galaxy 1319 164, already present in the table under a different name (MCG 03.34.063). A fewminor changes, regarding the categorization of a few Seyfert galaxies, have also been made to this table, and the celestial coordinates of NGC 3516 have been corrected to 110647.5, +72 3400700 (the erroneous coordinates appeared in both original Tables 1 and 2). Finally, there is a division sign missing in between N and V in equation (2); this should read

Here we present results of the long-term (1987-2010) optical spectral monitoring of the broad line radio galaxy Arp 102B, a prototype of active galactic nuclei with the double-peaked broad emission lines, usually assumed to be emitted from an accretion disk. To explore the structure of the broad line region (BLR), we analyze the light curves of the broad H\alpha and H\beta lines and the continuum flux. We aim to estimate the dimensions of the broad-line emitting regions and the mass of the central black hole. We use the CCF to find lags between the lines and continuum variations. We investigate in more details the correlation between line and continuum fluxes, moreover we explore periodical variations of the red-to-blue line flux ratio using Lomb-Scargle periodograms. The line and continuum light curves show several flare-like events. The fluxes in lines and in the continuum are not showing a big change (around 20%) during the monitoring period. We found a small correlation between the line and continuum flux variation, that may indicate that variation in lines has weak connection with the variation of the central photoionization source. In spite of a low line-continuum correlation, using several methods, we estimated a time lag for H\beta around 20 days. The correlation between the H\beta and H\alpha flux variation is significantly higher than between lines and continuum. During the monitoring period, the H\beta and H\alpha lines show double-peaked profiles and we found an indication for a periodical oscillation in the red-to-blue flux ratio of the H\alpha line. The estimated mass of the central black hole is \sim 1.1 \times 10^8 M\odot that is in an agreement with the mass estimated from the M-\sigma* relation., Comment: Accepted for publication in A&A

We report on some striking differences between radio loud and quiet emitters that we found in a comparative analysis of the high and low ionization lines for 52 low redshift AGN (31 loud; 21 quiet).

A widely accepted model for BL Lac objects is that they are radio galaxies with a relativistic jet pointing almost directly towards us. But we need a clear trigger mechanism for these jets. One possibility is the close interaction between the BL Lac host and the closeby galaxies (e.g. Heckman et al. 1986). This interaction has been seen many times in the case of quasars (Hutchings et al. 1989) but not so much is known about the close surroundings of the BL Lac objects although there has been some pioneer work like Stickel et al. (1993). The problem has usually been that the images are not deep enough and that the seeing has not been so good. To clarify the situation we have started an observing program to get very deep images in the subarcsecond seeing conditions from the whole 1 Jy sample (Stickel et al. 1991) of BL Lac objects. The aims of this study are: 1. to search for very close companions to the BL Lacs, 2. to study the large scale galaxy clustering around the BL Lacs and 3. to study the BL Lac hosts themselves.

We describe a method for estimating physical conditions in the broad-line region (BLR) for a significant subsample of Seyfert 1 nuclei and quasars. Several diagnostic ratios based on intermediate (Al III {lambda}1860, Si III] {lambda}1892) and high (C IV {lambda}1549, Si IV {lambda}1397) ionization lines in the UV spectra of quasars are used to constrain density, ionization, and metallicity of the emitting gas. We apply the method to two extreme Population A quasars-the prototypical NLSy1 I Zw 1 and higher z source SDSS J120144.36+011611.6. Under assumptions of spherical symmetry and pure photoionization we infer BLR physical conditions: low ionization (ionization parameter

We present the results of a long-term (1999--2010) spectral optical monitoring campaign of the active galactic nucleus (AGN) Ark 564, which shows a strong Fe II line emission in the optical. This AGN is a narrow line Seyfert 1 (NLS1) galaxies, a group of AGNs with specific spectral characteristics. We analyze the light curves of the permitted Ha, Hb, optical Fe II line fluxes, and the continuum flux in order to search for a time lag between them. Additionally, in order to estimate the contribution of iron lines from different multiplets, we fit the Hb and Fe II lines with a sum of Gaussian components. We found that during the monitoring period the spectral variation (F_max/F_min) of Ark 564 was between 1.5 for Ha to 1.8 for the Fe II lines. The correlation between the Fe II and Hb flux variations is of higher significance than that of Ha and Hb (whose correlation is almost absent). The permitted-line profiles are Lorentzian-like, and did not change shape during the monitoring period. We investigated, in detail, the optical Fe II emission and found different degrees of correlation between the Fe II emission arising from different spectral multiplets and the continuum flux. The relatively weak and different degrees of correlations between permitted lines and continuum fluxes indicate a rather complex source of ionization of the broad line emission region., Comment: Accepted for publication in ApJS

A detailed study of the mixed-morphology galaxy pair CPG 29 (Arp 119, VV 347) shows spectacular spectroscopic peculiarities in the southern (spiral) component (Mkn 984) including a spatially resolved region, roughly aligned along the minor axis of the galaxy, with multiple emission-line components redshifted by as much as 1300 km s$^{-1}$ with respect to the LINER nucleus. Strong [OI]\l6300 and [SII]\l\l6716,6731 emission suggest shock ionization. The rest of the galaxy's disk is spectroscopically undistinguished, with emission lines characteristic of disk H II regions and, in large part, ordered rotation. We discuss the following four possible explanations for the morphological and spectroscopic peculiarities in the spiral: (1) a super--wind scenario, supported by the high FIR luminosity of the spiral, and by emission line activity similar to that observed in FIR strong galaxies; (2) motion of the spiral through a hot, relatively dense intergalactic medium, possibly associated with the elliptical, that could affect the star formation rate and create a brightened disk rim; (3) a faint companion in direct collision with the disk, at $\Delta v_r \sim 1000$ \kms, that would straightforwardly explain the existence of the different redshift systems; (4) a pole on collision by the elliptical, that could produce the disturbed morphology and other properties of the spiral. The elliptical/spiral pole--on collision explains the high velocity line emitting regions as tidally stripped gas, and accounts for the presence of gas ionized by moterate velocity shocks. The morphology of Mrk 984 is consistent, Comment: 40 pp. + 9 figures available upon request, AASTeX, no preprint number

Optical photometric observations of the Seyfert nucleus NGC 7469 are reported. In August 1990, all‐night monitoring was done during 5 photometric nights (∼29 hours) using differential photometry techniques. After a very thorough discrimination of errors and their analysis, we conclude that random variability was present during the first four nights with average amplitude ∼0m.040 (at a σ≥4.5 level) on averagetime scales of ∼13 minutes. During the fifth night the variability nearly disappeared. A maximum Δm∼0m.081 (9.3σ) was observed in Δt=2.35 hrs. The average fluctuations imply an 8% variation in the luminosity of the unresolved nucleus and a rate of change of ΔLvar/Δt∼6×1037 erg sec−2. Our observations favor the black hole model and may be explained by the development of instabilities in the accretion disk. There is also strong evidence for tidal interaction of this galaxy with it companion, IC 5283, and for the existence of a circumnuclear starburst, making NGC 7469 a most suitable galaxy to study the r...

We report the results of a detailed statistical analysis of the Mid and Far IR (MIR/FIR) emission properties in a mixed morphology (E+S) sample of galaxy pairs from the Karachentsev (1972) Catalogue. The sample is large and diverse enough (≃ 130 pairs) to permit discrimination of pairs by morphological types and interaction classes. It samples a large enough volume to enable a non-parametric estimate of a Far-Infrared Luminosity Function (FIRLF). We find average factors of 3 and 5 enhancement in FIR and 25μm luminosities of the late-type pair components relative to an isolated galaxy control sample from Karachentseva (1973) Catalogue. This is interpreted as the MIR/FIR signature of the link between interaction and star formation. Although the spirals in (E+S) pairs fail to show a trend towards higher FIR luminosity with decreasing companion separation, a high-order comparison that takes into account information on the interaction classes, morphological types and the HI content suggests that:•a clear correlation between the IR luminosities and interaction classes is present suggesting that a subsample of the (E+S) pairs is more closely related to recent events of star formation,•the ratio of present to past star formation (as measured by the IR luminosities scaled to LB luminosity), increases measurably along the sequence Sa-Sc in paired spirals,•no Hɪ depletion in the star formation-enhanced spirals in mixed pairs is found, and•the high mass (M ≥ 10 M⊙) star formation rate (SFR) in paired Sc spirals is higher than that of the isolated Sc’s by a factor ~ 2 – 3.

We present preliminary results of the kinematics of the Wolf-Rayet galaxy pairs: NGC 1741 and NGC 7714/7715.

We recently completed the first comparison of high- and low-ionization broad lines in a sample of 52 AGN. We summarize here the principal results of a correlation analysis for this sample. We then briefly outline a model for the broad-line structure in radio-quiet AGN that is suggested by the correlation analysis.

A multidimensional statistical analysis of observed properties of Seyfert galaxies has been carried out using Principal Component Analysis (PCA) applied to X-ray, optical, near and far IR and radio data for all the Seyfert galaxies types 1 and 2 for the catalog by Lipovtsky et al. (1987).

We report optical photometric observations of the Seyfert nucleus NGC 7469. During the first observing run in 1989, night-to-night measurements were done during 13 photometric nights spanning November 3-30. The largest variation, Δm=0 m .403, within a 20 arcsec diaphragm, occurred in eleven days and a decrease in brightness of Δm=0 m .337 (∼70% of the luminosity of the unresolved nuclear component) occurred in only five days. During the second run in August 1990, all-night monitoring was done during five photometric nights (∼29 hr) using differential photometry techniques

New observations of the broad-line quasar PG 1416-129 reveal a large decline in its continuum luminosity over the past 10 years. In response to the continuum change, the "classical" broad component of Hβ has almost completely disappeared (a factor of 10 decrease in flux). In its place there remains a redshifted/redward asymmetric very broad emission line component. The significance of this change is multifold. (1) It confirms the existence of a distinct redshifted very broad line region (VBLR) component that persists after the demise of the broad component and that is frequently observed, along with the broad component, in radio-loud sources. (2) The smaller (decrease by a factor of 2) intensity change in the Hβ very broad component supports the previously advanced idea that the VBLR is physically distinct and likely to arise in an optically thin region close to the central source. (3) The presence of a strong very broad component in the radio-quiet quasar PG 1416-129 reinforces the notion that such "population B" quasars share similar spectroscopic (and hence geometrical and kinematical) properties to radio-loud sources. (4) AGNs can show broad, very broad, or both line components simultaneously, making statistical comparisons of source profile widths difficult. (5) The interpretation, in reverberation studies, of the presence or lack of correlated response in broad-line wings will be affected by this composite BLR/VBLR structure.

Narrow-line Seyfert 1s (NLSy1s) are an ill-defined class. Work done over the past 20 years as well as recent analyses show a continuity in properties (e.g., Balmer line profiles, blueshifts of high-ionization lines) between sources with FWHM above and below 2000 km/s, the defining boundary of NLSy1s. This finding alone suggests that comparisons between samples of NLSy1s and rest of broad-line AGNs are most likely biased. NLSy1s can be properly contextualized by their location on the quasar main sequence originally defined by Sulentic et al 2000. At one end, NLSy1s encompass sources with strong FeII emission and associated with high Eddington ratio that hold the promise of becoming useful distance indicators; at the other end, at least some of them are sources with broad profiles seen face-on. Any rigid FWHM limit gives rise to some physical ambiguity, as the FWHM of low-ionization lines depends in a complex way on mass, Eddington ratio, orientation, and luminosity. In addition, if the scaling derived from luminosity and virial dynamics applies to the broad line regions, NLSy1s at luminosity higher than 1E47 erg/s become physically impossible. Therefore, in a broader context, a proper subdivision of two distinct classes of AGNs and quasars may be achieved by the distinction between Pop. A and B with boundary at = 4000 km/s in samples at z < 1, or on the basis of spectrophotometric properties which may ultimately be related to differences in accretion modes if high-luminosity quasars are considered., Contribution presented at the meeting Revisiting narrow-line Seyfert 1 galaxies and their place in the Universe, held at the Padova Botanical Garden, Italy, on 9-13 April 2018

Quasars show a considerable spectroscopic diversity. However, the variety of quasar spectra at low redshifts is non-random: a principal component analysis applied to large samples customarily identifies two main eigenvectors. In this contribution we show that the range of quasar optical spectral properties observed at low-z and associated with the first eigenvector is preserved up to z ≈ 2 in a sample of high luminosity quasars. We also describe two major luminosity effects.

We present our recent spectrophotometric results of the infrared luminous Seyfert 2 galaxy NGC 7679. We find compelling evidence of the presence of a recent nuclear starburst, revealed by the observations of a) the spectral features of high order Balmer absorption lines, b) the weak equivalent widths for CaIIK $\lambda$3933, CN $\lambda$4200, G-band $\lambda$4300 and MgIb $\lambda$5173, and c) the suggested UV stellar wind resonance lines (N V $\lambda$1240, Si IV $\lambda$1400 and C IV $\lambda$1550) in the IUE spectrum. Using the simple stellar population synthesis model, we find that in the nuclear 2" $\times$ 2" region, the contributions from the old, intermediate and young components are 21.7%, 42.9% and 35.4%, respectively. These nuclear starburst activities might be triggered by the close encounter with NGC 7682, as suggested by recent numerical simulations., Comment: 8 pages, 3 figures, to be published in A&A

We present a deep V-band image of the BL Lac object OJ 287 and its close environment. Twenty-nine V images taken on 1994 January 18-21, when OJ 287 was at a low brightness level, were combined to obtain an image with a total integration time of 4.83 hr. The final image was processed using nonlinear restoration techniques (Lucy). The presence of a nebulosity surrounding OJ 287 can be distinctly seen for the first time in the deep image presented here. Comparing this image with radio maps obtained by Kollgaard et al. and Perlman & Stocke, we found that there is a coincidence between a faint optical elongation in the underlying nebulosity to the west of OJ 287 and the radio tail. Within 30'' of OJ 287, we can see several other interesting nearby features, such as three nearby companions at 34, 6'', and 10'' projected distance, with colors of distant galaxies, and another elongation which seems to emerge from OJ 287 followed by an alignment of at least four features along a position angle of 220°. We discuss the possibility of this structure (or part of it) consisting of knots that form an optical jet. We also have B, R, I, and K images taken a posteriori at other sites, some obtained under subarcsecond seeing, which were used to determine the magnitudes and colors of some of the most relevant features surrounding OJ 287.

We present first results of a comparison of emission line shift properties for the high (HILs) and low (LILs) ionization lines in 43 low-reshift quasars. We identify a core sample of C IV lambda 1549 and hydrogen beta profiles with a wide distribution of red- and blueshifts (less than or equal to +/- 1000 km/sec). We also identify two tails in this distribution: one with large hydrogen beta redshifts (greater than or equal to 2000 km/sec) and another with large C IV blueshifts (greater than or equal to 1500 km/sec). The tails are mutually exclusive. All objects with extreme hydrogen beta redshift are radio loud, and all objects with extreme C IV blueshift are radio quiet. The core samples of smaller shifts can be most simply divided into: (1) hydrogen beta - a redshifted radio-loud population (related to the tail) and a radio-quiet population with mean shift near zero, and (2) C IV - a blueshifted radio-quiet population (related to the tail) and a radio-loud population with mean shift near zero. The results suggest fundamentally different kinematics for the HILs and LILs. They also suggest very different kinematics for radio-loud and radio-quiet active galactic nuclei. They also favor a predominance of radial motion in a large fraction of the sample.