Search

We present a narrowband [O III] imaging survey of 111 AGN hosts and 17 merging-galaxy systems, in search of distant extended emission-line regions (EELRs) around AGN (either extant or faded). Our data reach deeper than detection from the broadband SDSS data, and cover a wider field than some early emission-line surveys used to study extended structure around AGN. Spectroscopic followup confirms two new distant AGN-ionized clouds, in the merging systems NGC 235 and NGC 5514, projected at 26 and 75 kpc from the nuclei (respectively). We also recover the previously-known region in NGC 7252. These results strengthen the connection between EELRs and tidal features; kinematically quiescent distant EELRs are virtually always photoionized tidal debris. We see them in ~10% of the galaxies in our sample with tidal tails. Energy budgets suggest that the AGN in NGC 5514 has faded by >3 times during the extra light-travel time ~250,000 years from the nucleus to the cloud and then to the observer; strong shock emission in outflows masks the optical signature of the AGN. For NGC 235 our data are consistent with but do not unequivocally require variation over ~85,000 years. In addition to these very distant ionized clouds, luminous and extensive line emission within four galaxies - IC 1481, ESO 362-G08, NGC 5514, and NGC 7679. IC 1481 shows apparent ionization cones, a rare combination with its LINER AGN spectrum. In NGC 5514, we measure a 7-kpc shell expanding at ~370 km/s west of the nucleus., Accepted for MNRAS

The Galactic emission-line object MWC 349A is one of the brightest radio stars in the sky. The central object is embedded in an almost edge-on oriented Keplerian rotating thick disc that seems to drive a rotating bipolar wind. The dense disc is also the site of hot molecular emission such as the CO bands with its prominent band heads in the near-infrared spectral range. Despite numerous studies, the nature of MWC 349A is still controversial with classifications ranging from a pre-main sequence object to an evolved supergiant. We collected new high-resolution near-infrared spectra in the K- and L-bands using the GNIRS spectrograph at Gemini-North to study the molecular disc of MWC 349A, and in particular to search for other molecular species such as SiO and the isotope 13CO. The amount of 13CO, obtained from the 12CO/13CO ratio, is recognized as an excellent tool to discriminate between pre-main sequence and evolved massive stars. We find no signatures of SiO band emission, but detect CO band emission with considerably lower intensity and CO gas temperature compared to previous observations. Moreover, from detailed modelling of the emission spectrum, we derive an isotope ratio of 12CO/13CO = 4 +- 1. Based on this significant enrichment of the circumstellar environment in 13CO we conclude that MWC 349A belongs to the group of B[e] supergiants, and we discuss possible reasons for the drop in CO intensity., 8 pages 5 figures, accepted for publication in MNRAS

The elemental abundances in the broad-line regions of high-redshift quasars trace the chemical evolution in the nuclear regions of massive galaxies in the early universe. In this work, we study metallicity-sensitive broad emission-line flux ratios in rest-frame UV spectra of 25 high-redshift (5.8 < z < 7.5) quasars observed with the VLT/X-shooter and Gemini/GNIRS instruments, ranging over $\log(M_{\rm{BH}}/M_{\odot})= 8.4-9.8$ in black hole mass and $\log(L_{\rm{bol}}/\rm{erg\, s}^{-1})= 46.7-47.7$ in bolometric luminosity. We fit individual spectra and composites generated by binning across quasar properties: bolometric luminosity, black hole mass, and blueshift of the \civ\, line, finding no redshift evolution in the emission-line ratios by comparing our high-redshift quasars to lower-redshift (2.0 < z < 5.0) results presented in the literature. Using Cloudy-based locally optimally-emitting cloud photoionisation model relations between metallicity and emission-line flux ratios, we find the observable properties of the broad emission lines to be consistent with emission from gas clouds with metallicity that are at least 2-4 times solar. Our high-redshift measurements also confirm that the blueshift of the CIV emission line is correlated with its equivalent width, which influences line ratios normalised against CIV. When accounting for the CIV blueshift, we find that the rest-frame UV emission-line flux ratios do not correlate appreciably with the black hole mass or bolometric luminosity., MNRAS accepted, 24 pages, 17 figures, 4 tables

We investigate the molecular gas content of z~6 quasar host galaxies using the IRAM / Northern Extended Millimeter Array. We target the 3mm dust continuum, and the line emission from CO(6-5), CO(7-6), [CI]2-1 in 10 infra-red-luminous quasars that have been previously studied in their 1mm dust continuum and [CII] line emission. We detect CO(7-6) at various degrees of significance in all the targeted sources, thus doubling the number of such detections in z~6 quasars. The 3mm to 1mm flux density ratios are consistent with a modified black body spectrum with a dust temperature $T_{dust}$~47 K and an optical depth $\tau_{\nu}$=0.2 at the [CII] frequency. Our study provides us with four independent ways to estimate the molecular gas mass, $M_{H2}$, in the targeted quasars. This allows us to set constraints on various parameters used in the derivation of molecular gas mass estimates, such as the mass per luminosity ratios $\alpha_{CO}$ and $\alpha_{[CII]}$, the gas-to-dust ratio $\delta_{g/d}$, and the carbon abundance [C]/H2. Leveraging either on the dust, CO, [CI], or [CII] emission yields mass estimates of the entire sample in the range $M_{H2}$~$10^{10}$ to $10^{11}$ M$_{\odot}$. We compare the observed luminosities of dust, [CII], [CI], and CO(7-6) with predictions from photo-dissociation and X-ray dominated regions. We find that the former provide better model fits to our data, assuming that the bulk of the emission arises from dense ($n_H>10^4$ cm$^{-3}$) clouds with a column density $N_{H}$~$10^{23}$ cm$^{-2}$, exposed to a radiation field with intensity $G_0$~$10^3$ (in Habing units). Our analysis reiterates the presence of massive reservoirs of molecular gas fueling star formation and nuclear accretion in $z$~6 quasar host galaxies. It also highlights the power of combined 3mm and 1mm observations for quantitative studies of the dense gas content in massive galaxies at cosmic dawn., Comment: 13 pages, 7 figures. Accepted for publication in A&A

The last few years have seen the confirmation of several trends associated with the quasar main sequence. The idea of a main sequence for quasars is relatively recent, and its full potential for the observational classification and contextualization of quasars' properties has yet to be fully exploited. The main sequence drivers are discussed in terms of the properties of extreme objects. We briefly summarize developments that constrain the viewing angle of the accretion disk in a particular class of quasars (extreme Population B, radiating at low Eddington ratio), as well as inferences on the chemical composition of the broad line emitting gas, and on the nature of radio emission along the quasar main sequence. © 2021 Wiley-VCH GmbH., N. Bon and E. Bon acknowledge the support of Serbian Ministry of Education, Science and Technological Development, through the contract number 451-03-68/2020-14/200002., With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709.

Active galactic nuclei (AGNs) are among the most luminous sources observed in the Universe - their overall luminosity can be over 12-15 orders of magnitude more luminous than our Sun’s. They harbour supermassive black holes at their centres that are estimated to have masses up to 10 billion solar masses and possess immense gravitational potential. When matter falls towards a black hole due to this potential, it gets heated up and shines. This is the only way to observe AGNs and their immediate environment. Quasars can be observed from cosmological distances and they can be excellent, not yet appreciated, indicators of the universe’s expansion rate. The analysis of several, mutually related issues regarding quasars is presented in this dissertation which will later facilitate the use of quasars in cosmology and tie them with the evolution of galaxies across cosmic time. Matter in-falling under the action of the gravity of the central supermassive black hole loses angular momentum while being accreted onto the black hole. This manifests in the form of an accretion disk around the black hole which in turn makes these systems non-spherically symmetric. The accreted matter gets heated up and radiates. The photon energy of the dissipated radiation spans from the near-infrared to the ultraviolet/X-rays and the radiation then illuminates the material surrounding the accretion disk. This phenomenon leads to the formation and emission of strong and broad emission lines. The size of this region, named broad-line region (BLR) extends from a few tens to a few thousand gravitational radii. These broad emission lines allow measuring the mass of the central supermassive black hole and underlie the use of quasars for cosmological applications, in addition to their vital role in estimating the driving parameters of the central engine and statistical studies that help address the diversity in AGN. Some of these emission lines are produced from the disk outflows which are highly ionized and are known as High-Ionization Lines (HILs, ionization potential, IP > 50 eV). On the other hand, emission lines from other ionic species are low ionized (IP < 20 eV) and are produced in a less ionized medium. These are called the Low-Ionization Lines (LILs). In this thesis, I concentrate on these Low-Ionization emission lines which are more reliable for black hole mass measurements. The emission line shapes, their intensity ratios and broadband spectral indices lead to the classifications of quasars. Principal Component Analysis (PCA) - a dimensionality reduction technique, that allowed to extract meaningful information from large datasets containing diverse quasar populations. A clear pattern originates from the analysis of the optical plane, i.e. the anti-correlation between the strength of the Fe II λ4570 (also known as RFeII) and the full width at half maximum (FWHM) of Hβ, and is known as the Quasar Main Sequence. The main sequence of quasars is an analogous scheme to the Hertzsprung-Rusell diagram. The stellar main sequence in the Hertzsprung-Rusell diagram is easy to understand since stars are characterized solely by their mass. Unlike stars, quasars are more complex. Their appearance is defined by the mass of the black hole, the accretion rate, spin and their inclination angle to the observer. The first issue is an attempt to have a deeper understanding of why such complex objects form an almost one-parameter family in the optical plane. Therefore, I introduce a physically motivated model which can explain these emission lines’ statistics. This model takes into account the underlying geometry of the active nucleus, including black hole mass, radiation from the accretion disk surrounding the black hole, the presence of hot corona, and the BLR gas cloud at the right distance from the centre. This ionized BLR gas cloud absorbs the radiation and re-emits in the form of the emission lines that are then observed in a spectrum. The radiative transfer in these media is solved to obtain the emission line ratios and line kinematic widths reflecting the motion of the line emitting clouds. The results from these model predictions are compared with available measurements of the emission line properties in ∼1 million quasars from the publicly available quasar catalogues. The model successfully reproduces the Main Sequence trend. In particular, iron emission calculations in the optical range require taking into account the iron atom model containing 371 levels with 68,535 transitions. The program shows that the model reproduces the behaviour of the quasar well if one also considers the complex relationship between the chemical composition and the density of the BLR clouds with the accretion rate. The higher the accretion rate, the more elements such as iron must be produced. This issue is addressed for the first time (Panda et al., 2018) by systematic theoretical modelling of the spectra of active galaxies. The results published in the first work required further clarification. Subsequently, I also include an additional spectral component - a warm corona (an inner warm comptonizing region to produce the soft X-ray excess) in the model (Panda et al., 2019a), and then incorporate the role of the viewing angle at which we observe the AGN (Panda et al., 2019c; Panda et al., 2020a). Treating the aspect of viewing angle and the distribution of the BLR clouds appropriately, I confirm the dependence of the Main Sequence on the Eddington ratio and the related observational trends - as a function of the shape of the ionizing continuum, cloud density, and composition, verified from prior observations. This allows me to affirm that quasars with different properties populate different parts of the Quasar Main Sequence. The results show that quasars that have very strong iron emission, accrete close to the Eddington limit and are seen under relatively small angles. These sources can serve as “standardizable” luminosity candles to probe the expansion of the Universe. The Fe II emission is observed from the ultraviolet to the near-infrared and acts as one of the main coolants of the BLR. However, the complex electronic structure of Fe II owing to varied excitation mechanisms makes it difficult to model the atom. In the concluding chapter of the thesis, the physical properties and location of the low ionization lines using the NIR Ca II triplet emission as a reliable proxy to the Fe II are explored. In the first part of the series (Panda et al., 2020b), the observational correlation between the strengths of the two species is updated and various photoionization models are tested taking into account (a) the ionization parameter, (b) the cloud density, (c) the metallicity, and (d) the column density, and, recover a linear, almost one-to-one relationship between the strengths of the two species. In the second part (Panda, 2021), synthetic equivalent widths (EWs) are derived accounting for reasonable covering fractions for these low-ionization species and a significant overlap in the emitting regions of the two species is recovered. This work also highlights the role of metallicity and cloud sizes in the study of accreting quasars and in addition the effect of the inclusion of microturbulence allows to limit the metal content in the BLR for the adequate Fe II emission. The collection of works in this thesis has shown that (i) the broad-line regions of active galaxies have an almost universal local density, (ii) there exists a coupling between the Eddington ratio and the metal content in these ionized media which validates the co-evolution of the host galaxy and the AGN, and (iii) the quasars can be used as reliable cosmological probes to investigate the expansion of our Universe., Supported by the Polish Funding Agency National Science Centre, grants 2015/17/B/ST9/03436/(OPUS 9) and 2017/26/A/ST9/00756 (MAESTRO 9)

The third operational rehearsal of WEAVE-LOFAR has produced 7273 model optical spectra of radio-selected star-forming galaxies. It is the most realistic simulation of what we expect WEAVE's performance to be. The purpose of this research is to build an algorithm which can reliably extract emission line properties from the model spectra in preparation for the bulk arrival of the WEAVE-LOFAR data by the end of 2020. Spectral fitting software already exists; however, the algorithm described in this thesis has been designed to specifically model simulated WEAVE spectra. The algorithm uses Markov chain Monte Carlo (MCMC) techniques to determine posterior distributions of the emission line parameters, and is designed to accurately model low signal-to-noise (SNR) spectra of radio sources. The data preparation stages and the process of modelling the continuum, dust attenuation and the broad and narrow emission lines are discussed in detail in this thesis. The fundamental aim is to gain an insight into what we expect the real WEAVE data to resemble and understand everything we can prior to its arrival. This thesis presents evidence that reliable emission line diagnostics can be retrieved, even from low SNR spectra, by comparing their flux measurements to the input spectra. These emission line measurements are used to classify the targets into star-forming galaxies or AGN, with an accuracy of 89%. Hα fluxes are dust corrected using the Balmer decrement, from which star formation rates (SFR) are derived and compared to those derived from the SKA simulated skies LOFAR 150 MHz measurements. The purpose of this comparison is to understand how representative the radio derived measurements are of the SFR and whether a strong case can be made to use non-thermal radio continuum as an alternative SFR indicator. Radio surveys are very sensitive, impervious to dust and can survey the sky at fast speeds, therefore the use of this diagnostic will be highly beneficial to star formation research. During the process of this analysis, any complications or limitations presented by the model spectra are thoroughly investigated and reviewed. A potential issue with the flux calibration is highlighted which appears to distort the shape of the continuum, offsets the blue and red arm spectra and results in a 25% systematic offset from the input fluxes. Furthermore, the presence of skyline residuals, particularly at longer wavelengths, showed evidence of poor sky subtraction. Despite these issues, the research in this thesis provides a proof of principle that MCMC-based codes can be used in bulk to classify and recover physical information from WEAVE spectra.

We have obtained new spectropolarimetric observations at visible wavelengths of the changing-look active galactic nucleus (AGN) Mrk 1018. The AGN direct spectrum shows an extremely weak continuum with faint broad H$\beta$ and H$\alpha$ emission lines. Both lines can be fit with a single very broad emission line component of full width at half maximum FWHM $\simeq$ 7200 km s$^{-1}$, with no evidence of the additional 3000 km s$^{-1}$-wide component that was previously detected. While this is in agreement with line formation in a Keplerian disk, the line profile variability suggests that the broad emission line region is likely more complex. The continuum polarization of Mrk 1018 is low; it is not higher in the current faint state compared to the past bright state, confirming that dust obscuration is not the mechanism at the origin of the change of look. The polarization profile of the H$\alpha$ line is asymmetric with no rotation of the polarization angle, which possibly reveals line formation in a polar outflow. Alternatively, the polarization profile may be the consequence of a time delay between the direct and the polarized light. Interestingly, the polarization signatures predicted for broad lines emitted around supermassive binary black holes are not observed., Comment: Accepted for publication in Astronomy and Astrophysics (Letters)

Broad Emission Lines are the most characteristic features of Active Galaxies, but the mechanism of creating a medium able to emit these intense lines is not quite clear. Observations clearly indicate that the motion of the material is predominantly Keplerian, with traces of inflow and clear signatures of outflow, but this still does not point out whether the lines partially come from the disk surface, or exclusively from the circumnuclear material, and whether this material originates from the disk as a wind, or comes, at least partially, from outside. I review the basic scenarios for the formation of the Broad Line Region (BLR), and the recent progress in modelling the physical conditions in the emitting medium. The current state is the the outer radius of the BLR is fixed by the dust sublimation temperature in the medium exposed to the irradiation from the central source, the inner radius is likely fixed by the dust sublimation temperature in the atmosphere of the non-illuminated accretion disk, and the local cloud density is a universal number fixed by the radiation pressure confinement. The time-dependent aspects of the BLR formation, however, still wait for serious modelling effort matching the quality of the observational data., Comment: Open Astronomy, in press. Proceedings of the conference 12th Serbian Conference on Spectral Line Shapes in Astrophysics, Vrdnik, Serbia, June 3-7, 2019

The Multi-Unit Spectroscopic Explorer (MUSE) is a large integral field unit mounted on the ESO Very Large Telescope. Its spatial (60 arcsecond field) and wavelength (4800&ndash, 9300&Aring, ) coverage is well suited to detailed imaging spectroscopy of extended planetary nebulae, such as in the Galaxy. An overview of the capabilities of MUSE applied to Planetary Nebulae (PNe) is provided together with the specific advantages and disadvantages. Some examples of archival MUSE observations of PNe are provided. MUSE datacubes for two targets (NGC 3132 and NGC 7009) are analyzed in detail, and they are used to show the advances achievable for planetary nebulastudies. Prospects for further MUSE observations of PNe and a broader analysis of existing datasets are outlined.

Quasars accreting matter at very high rates (known as extreme Population A [xA] quasars, possibly associated with super-Eddington accreting massive black holes) may provide a new class of distance indicators covering cosmic epochs from present day up to less than 1 Gyr from the Big Bang. At a more fundamental level, xA quasars are of special interest in studies of the physics of AGNs and host galaxy evolution. However, their observational properties are largely unknown. xA quasars can be identified in relatively large numbers from major optical surveys over a broad range of redshifts, and efficiently separated from other type-1 quasars thanks to selection criteria defined from the systematically-changing properties along the quasars main sequence. It has been possible to build a sample of ~250 quasars at low and intermediate redshift, and larger samples can be easily selected from the latest data releases of the Sloan Digital Sky Survey. A large sample can clarify the main properties of xA quasars which are expected—unlike the general population of quasars—to radiate at an extreme, well-defined Eddington ratio with small scatter. As a result of the small scatter in Eddington ratio shown by xA quasars, we propose a method to derive the main cosmological parameters based on redshift-independent “virial luminosity” estimates from measurements of emission line widths, roughly equivalent to the luminosity estimates based from line width in early and late type galaxies. A major issue related to the cosmological application of the xA quasar luminosity estimates from line widths is the identification of proper emission lines whose broadening is predominantly virial over a wide range of redshift and luminosity. We report on preliminary developments using the AlIIIλ1860 intermediate ionization line and the Hydrogen Balmer line Hβ as virial broadening estimators, and we briefly discuss the perspective of the method based on xA quasars. © Copyright © 2020 Dultzin, Marziani, de Diego, Negrete, Del Olmo, Martínez-Aldama, D'Onofrio, Bon, Bon and Stirpe., This research is part of the projects 176001-Astrophysical spectroscopy of extragalactic objects and 176003-Gravitation and the large scale structure of the Universe, funded by Ministry of Education, Science and Technological Development of the Republic of Serbia.

The main sequence offers a method for the systematization of quasar spectral proper- ties. Extreme FeII emitters (or Extreme Population A,xA) are believed to be sources accreting matter at very high rates. Along the quasar main sequence, they are eas- ily identifiable in large spectroscopic surveys over a broad redshift range. The very high accretion rate makes it possible that massive black holes hosted in xA quasars radiate at a stable, extreme luminosity-to-mass ratio. After reviewing basic trends associated with the main sequence, we show that the analysis of of optical and UV xA quasar spectra supports the possibility of identifying a virial broadening esti- mators from low-ionization line widths, and provide evidence of the the conceptual validity of redshift-independent luminosities based on virial broadening for a known luminosity-to-mass ratio., Slides on the contributed talk presented on Oct. 8, 2019 at the IAU Symp. No 356 held in Addis Ababa.

If the disappearance of the broad emission lines observed in changing-look quasars originates from the obscuration of the quasar core by dusty clouds moving in the torus, high linear optical polarization would be expected in those objects. We then measured the rest-frame UV-blue linear polarization of a sample of 13 changing-look quasars, 7 of them being in a type 1.9-2 state. For all quasars but one the polarization degree is lower than 1%. This suggests that the disappearance of the broad emission lines cannot be attributed to dust obscuration, and supports the scenario in which changes of look are caused by a change in the rate of accretion onto the supermassive black hole. Such low polarization degrees also indicate that these quasars are seen under inclinations close to the system axis. One type 1.9-2 quasar in our sample shows a high polarization degree of 6.8%. While this polarization could be ascribed to obscuration by a moving dusty cloud, we argue that this is unlikely given the very long time needed for a cloud from the torus to eclipse the broad emission line region of that object. We propose that the high polarization is due to the echo of a past bright phase seen in polar-scattered light. This interpretation raises the possibility that broad emission lines observed in the polarized light of some type 2 active galactic nuclei can be echoes of past type 1 phases and not evidence of hidden broad emission line regions., Accepted for publication in Astronomy and Astrophysics

The well-known quasar SDSS J095253.83+011421.9 (J0952+0114) at z=3.02 has one of the most peculiar spectra discovered so far, showing the presence of narrow Ly$\alpha$ and broad metal emission lines. Although recent studies have suggested that a Proximate Damped Ly$\alpha$ system (PDLA) causes this peculiar spectrum, the origin of the gas associated with the PDLA is unknown. Here we report the results of MUSE observations that reveal a new giant ($\approx$ 100 physical kpc) Lyman $\alpha$ nebula. The detailed analysis of the Ly$\alpha$ velocity, velocity dispersion, and surface brightness profiles suggests that the J0952+0114 Ly$\alpha$ nebula shares similar properties of other QSO nebulae previously detected with MUSE, implying that the PDLA in J0952+0144 is covering only a small fraction of the QSO emission solid angle. We also detected bright and spectrally narrow CIV$\lambda$1550 and HeII$\lambda$1640 extended emission around J0952+0114 with velocity centroids similar to the peak of the extended and central narrow Ly$\alpha$ emission. The presence of a peculiarly bright, unresolved, and relatively broad HeII$\lambda$1640 emission in the central region at exactly the same PDLA redshift hints at the possibility that the PDLA originates in a clumpy outflow with a bulk velocity of about 500 km/s. The smaller velocity dispersion of the large scale Ly$\alpha$ emission suggests that the high-speed outflow is confined to the central region. Lastly, the derived spatially resolved HeII/Ly$\alpha$ and CIV/Ly$\alpha$ maps show a positive gradient with the distance to the QSO hinting at a non-homogeneous ionization parameter distribution., Comment: 17 pages, 13 figures and 2 tables; Accepted for publication in ApJ

I will review the most important results from near-IR spectroscopic observations of WISE/SDSS selected hyper-luminous (WISSH) quasars, designed to accurately probe the role of nuclear activity in SMBH-galaxy self-regulated growth via extended outflows. The total sample consists of 90 broad-line quasars at the brightest end of theAGNluminosity function (L_bol > 1014 L_sun) and at the peak of their number density (z ~ 2.5 - 3.5). We found that WISSH quasars are typically powered by highly accreting (0.3-3 Ledd), ten billion solar masses SMBHs, demonstrating that WISSH provides a simple and valuable tool to complete the census of the extreme SMBH population in the Universe. The huge luminosity drives very powerful winds both at BLR and NLR scales. We discovered [OIII] emission lines with a broad profile, tracing ionized outflows with kinetic power up to ~4% of L_bol in ~30% of the sample.Remarkably, the remaining 70% of quasars lacks [OIII] emission but shows strong winds traced by 3,000-8,000 km/s blueshifts of the CIV broad emission line, revealing strong radiatively driven winds that dominate the BLR kinematics. Finally, I will discuss nuclear and outflows properties of WISSH quasars in terms of inclination angle and fundamentalAGNparameters such as bolometric luminosity, SMBH mass, Eddington ratio and the shape of the UV-X-ray continuum.

Open Access.-Attribution 4.0 International (CC BY 4.0), The last 25 years saw a major step forward in the analysis of optical and UV spectroscopic data of large quasar samples. Multivariate statistical approaches have led to the definition of systematic trends in observational properties that are the basis of physical and dynamical modeling of quasar structure. We discuss the empirical correlates of the so-called >main sequence> associated with the quasar Eigenvector 1, its governing physical parameters and several implications on our view of the quasar structure, as well as some luminosity effects associated with the virialized component of the line emitting regions. We also briefly discuss quasars in a segment of the main sequence that includes the strongest FeII emitters. These sources show a small dispersion around a well-defined Eddington ratio value, a property which makes them potential Eddington standard candles.© Copyright © 2018 Marziani, Dultzin, Sulentic, Del Olmo, Negrete, Martínez-Aldama, D'Onofrio, Bon, Bon and Stirpe., AD and MM-A acknowledge financial support from the Spanish Ministry for Economy and Competitiveness through grants AYA2013-42227-P and AYA2016-76682-C3-1-P. DD and CN acknowledge support from grants PAPIIT108716, UNAM, and CONACyT221398. EB and NB acknowledge grants 176003 Gravitation and the large scale structure of the Universe and 176001 Astrophysical spectroscopy of extragalactic objects supported by the Ministry of Education and Science of the Republic of Serbia.

Here we investigate the connection of broad emission line shapes and continuum light curve variability time scales of type-1 Active Galactic Nuclei (AGN). We developed a new model to describe optical broad emission lines as an accretion disk model of a line profile with additional ring emission. We connect ring radii with orbital time scales derived from optical light curves, and using Kepler's third law, we calculate mass of central supermassive black hole (SMBH). The obtained results for central black hole masses are in a good agreement with {other methods. This indicates that the variability time scales of AGN may not be stochastic, but rather connected to the orbital time scales which depend on the central SMBH mass., Comment: 13 pages, 3 figures, Accepted on 11 May 2018 Front. Astron. Space Sci

International audience; Spectroscopic studies of active galactic nuclei (AGN) are powerful means of probing the physical properties of the ionized gas within them. In particular, near future observational facilities, such as the James Webb Space Telescope (JWST), will allow detailed statistical studies of rest-frame ultraviolet and optical spectral features of the very distant AGN with unprecedented accuracy. In this proceedings, we discuss the various ways of exploiting new dedicated photoionization models of the narrow-line emitting regions (NLR) of AGN for the interpretation of forthcoming revolutionary datasets.

We present our recent results about the extended narrow-line region (ENLR) of two nearby Seyfert 2 galaxies (IC 5063 and NGC 7212) obtained by modelling the observed line profiles and spectra with composite models (photoionization+shocks) in the different regions surrounding the AGN. Then, we compare the Seyfert 2 ENLRs with the very extended one recently discovered in the narrow-line Seyfert 1 (NLS1) galaxy Mrk 783. We have found several evidences of interaction between the ISM of the galaxies and their radio jets, such as a) the contribution of shocks in ionizing the high velocity gas, b) the complex kinematics showed by the profile of the emission lines, c) the high fragmentation of matter, etc. The results suggest that the ENLR of IC 5063 have a hollow bi-conical shape, with one edge aligned to the galaxy disk, which may cause some kind of dependence on velocity of the ionization parameter. Regarding the Mrk 783 properties, it is found that the extension of the optical emission is almost twice the size of the radio one and it seems due to the AGN activity, although there is contamination by star formation around 12 arcsec from the nucleus. Diagnostic diagrams excluded the contribution of star formation in IC 5063 and NGC 7212, while the shock contribution was used to explain the spectra emitted by their high velocity gas., 9 pages, 2 figures, proceeding of the conference "Quasars at all cosmic epochs", accepted for publication in Front. Astron. Space Sci. - Milky Way and Galaxies

In this paper we explore the intermediate line region (ILR) by using the photoionisation simulations of the gas clouds present at different radial distances from the center, corresponding to the locations from BLR out to NLR in four types of AGNs. We let for the presence of dust whenever conditions allow for dust existence. All spectral shapes are taken from the recent multi-wavelength campaigns. The cloud density decreases with distance as a power law. We found that the slope of the power law density profile does not affect the line emissivity radial profiles of major emission lines: H${\beta}$, He~II, Mg~II, C~III] ~and [O~III]. When the density of the cloud at the sublimation radius is as high as 10$^{11.5}$ cm$^{-3}$, the ILR should clearly be seen in the observations independently of the shape of the illuminating radiation. Moreover, our result is valid for low ionization nuclear emission regions of active galaxies., Comment: 8 pages, 2 figures, Accepted for publication in the Journal Frontiers in Astronomy and Space Sciences

We develope a self-consistent description of the Broad Line Region based on the concept of the failed wind powered by the radiation pressure acting on dusty accretion disk atmosphere in Keplerian motion. The material raised high above the disk is illuminated, dust evaportes, and the matter falls back towards the disk. This material is the source of emission lines. The model predicts the inner and outer radius of the region, the cloud dynamics under the dust radiation pressure and, subsequently, just the gravitational field of the central black hole, which results in assymetry between the rise and fall. Knowledge of the dynamics allows to predict the shapes of the emission lines as functions of the basic parameters of an active nucleus: black hole mass, accretion rate, black hole spin (or accretion efficiency) and the viewing angle with respect to the symmetry axis. Here we show preliminary results based on analytical approximations to the cloud motion., Comment: Proceeding of the conference "Quasars at all cosmic epochs", held in Padova, April 2-7, 2017. Frontiers in Astronomy and Space Sciences (in press)

We analyze four extreme active galactic nuclei (AGN) transients to explore the possibility that they are caused by rare, high-amplitude microlensing events. These previously unknown type-I AGN are located in the redshift range 0.6-1.1 and show changes of > 1.5 mag in the g-band on a time-scale of ~years. Multi-epoch optical spectroscopy, from the William Herschel Telescope, shows clear differential variability in the broad line fluxes with respect to the continuum changes and also evolution in the line profiles. In two cases, a simple point-source, point-lens microlensing model provides an excellent match to the long-term variability seen in these objects. For both models, the parameter constraints are consistent with the microlensing being due to an intervening stellar mass object but as yet there is no confirmation of the presence of an intervening galaxy. The models predict a peak amplification of 10.3/13.5 and an Einstein time-scale of 7.5/10.8 yr, respectively. In one case, the data also allow constraints on the size of the CIII] emitting region, with some simplifying assumptions, to to be ~1.0-6.5 light-days and a lower limit on the size of the MgII emitting region to be > 9 light-days (half-light radii). This CIII] radius is perhaps surprisingly small. In the remaining two objects, there is spectroscopic evidence for an intervening absorber but the extra structure seen in the light curves requires a more complex lensing scenario to adequately explain., 23 pages, 17 figures; matches version published in MNRAS

Since the beginning of the new millennium, more than 100 $z\sim 6$ quasars have been discovered through several surveys and followed-up with multi-wavelength observations. These data provided a large amount of information on the growth of supermassive black holes at the early epochs, the properties of quasar host galaxies and the joint formation and evolution of these massive systems. We review the properties of the highest-$z$ quasars known so far, especially focusing on some of the most recent results obtained in (sub-)millimeter bands. We discuss key observational challenges and open issues in theoretical models and highlight possible new strategies to improve our understanding of the galaxy-black hole formation and evolution in the early Universe., Accepted for publication in PASA

We present preliminary analysis of mid-infrared spectra of M-type and C-type Mira variables. Due to the brightness of this sample, it is straightforward to monitor changes with phase in the infrared spectral features of these regular pulsators. We have spectra of 25 Mira variables, taken with phase, using the Spitzer Infrared Spectrograph (IRS) high-resolution module. Each star has multiple spectra obtained over a one-year period from 2008-09. This is a rich, unique data set due to multiple observations of each star and the high signal-to-noise ratio from quick exposure times to prevent saturation of the IRS instrument. This paper focuses on the 17.6 and 33.2 micron lines shared by M-types and C-types. These are mostly emission lines that change with phase. We discuss preliminary physical diagnostics for the atmospheres based on the lines, as well as possible line identifications such as fluorescence of metal species.

Artículo escrito por un elevado número de autores, solo se referencian el que aparece en primer lugar, el nombre del grupo de colaboración, si le hubiere, y los autores pertenecientes a la UAM, Astronomy and Astrophysics 592 (2016): A121reproduced with permission from Astronomy & Astrophysics, The Sloan Digital Sky Survey IV extended Baryonic Oscillation Spectroscopic Survey (SDSS-IV/eBOSS) will observe 195 000 emission-line galaxies (ELGs) to measure the baryonic acoustic oscillation (BAO) standard ruler at redshift 0.9. To test different ELG selection algorithms, 9000 spectra were observed with the SDSS spectrograph as a pilot survey based on data from several imaging surveys. First, using visual inspection and redshift quality flags, we show that the automated spectroscopic redshifts assigned by the pipeline meet the quality requirements for a reliable BAO measurement. We also show the correlations between sky emission, signal-to-noise ratio in the emission lines, and redshift error. Then we provide a detailed description of each target selection algorithm we tested and compare them with the requirements of the eBOSS experiment. As a result, we provide reliable redshift distributions for the different target selection schemes we tested. Finally, we determine an target selection algorithms that is best suited to be applied on DECam photometry because they fulfill the eBOSS survey efficiency requirements, J.C .and F.P. acknowledge support from the Spanish MICINNs Consolider-Ingenio 2010 Programme under grant MultiDark CSD2009-00064, MINECO Centro de Excelencia Severo Ochoa Programme under the grants SEV-2012-0249, FPA2012-34694, and the projects AYA2014- 60641-C2-1-P and AYA2012-31101. F.P. acknowledges the spanish MEC Salvador de Madariaga program, Ref. PRX14/00444. T.D. and J.P.K. acknowledge support from the LIDA ERC advanced grant. AR acknowledges funding from the P2IO LabEx (ANR-10-LABX-0038) in the framework Investissements d’Avenir (ANR- 11-IDEX-0003-01) managed by the French National Research Agency (ANR). The DES data management system is supported by the National Science Foundation under Grant Number AST-1138766. The DES participants from Spanish institutions are partially supported by MINECO under grants AYA2012-39559, ESP2013- 48274, FPA2013-47986, and Centro de Excelencia Severo Ochoa SEV-2012- 0234. Research leading to these results has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP7/2007−2013) including ERC grant agreements 240672, 291329, and 306478

This is the third installment of the Galactic O-Star Spectroscopic Survey (GOSSS), a massive spectroscopic survey of Galactic O stars, based on new homogeneous, high signal-to-noise ratio, R ∼ 2500 digital observations selected from the Galactic O-Star Catalog. In this paper, we present 142 additional stellar systems with O stars from both hemispheres, bringing the total of O-type systems published within the project to 590. Among the new objects, there are 20 new O stars. We also identify 11 new double-lined spectroscopic binaries, 6 of which are of O+O type and 5 of O+B type, and an additional new tripled-lined spectroscopic binary of O+O+B type. We also revise some of the previous GOSSS classifications, present some egregious examples of stars erroneously classified as O-type in the past, introduce the use of luminosity class IV at spectral types O4-O5.5, and adapt the classification scheme to the work of Arias et al., Instituto de Astrofísica de La Plata, Facultad de Ciencias Astronómicas y Geofísicas

Context. All globular clusters (GCs) studied in detail host two or more populations of stars (the multiple population phenomenon). Theoretical models suggest that the second population is formed from gas polluted by processed material produced by massive stars of the first generation. However the nature of the polluters is matter of strong debate. Several candidates have been proposed: massive main-sequence stars (fast rotating or binaries), intermediate-mass AGB stars, or SNeII. Aims: We studied red giant branch (RGB) stars in the GC M4 (NGC 6121) to measure their chemical signature. Our goal is to measure abundances for many key elements (from Li to Eu) in order to derive constraints on the polluters responsible for the multiple populations. Methods: We observed 23 RGB stars below the RGB-bump using the GIRAFFE spectroscopic facility installed on VLT2. Spectra cover a wide range and allowed us to measure light (Li, C, 12C/13C, N, O, Na, Mg, Al), alpha (Si, Ca, Ti), iron-peak (Cr, Fe, Ni), light-s (Y), heavy-s (Ba), and r (Eu) elements. We supplemented this study by analyzing an additional subsample of the UVES spectra in order to gather further clues about light s-elements of different atomic number (Y and Zr). Results: We confirm the presence of a bimodal population. Stars can be easily separated according to their N content. The two groups have different C, 12C/13C, N, O, Na content, but share the same Li, C+N+O, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zr, Ba and Eu abundance. Quite surprisingly the two groups differ also in their Y abundance. This result is strongly supported also by the analysis of the UVES spectra. Conclusions: The absence of a spread in alpha-elements, Eu and Ba makes SNeII and AGB stars unlikely as polluters. On the other hand, massive main-sequence stars can explain the bimodality of Y through the weak s-process. This statement is confirmed independently also by literature data on Rb and Pb. The lack of a Mg/Al spread and the extension of the [O/Na] distribution suggest that the mass of the polluters is between 20 and 30 M&sun;. This implies a formation time scale for the cluster of 10 ÷ 30 Myr. This result is valid for M4. Other clusters such as NGC 1851, M 22, or omega Cen have different chemical signatures and may require other kinds of polluters. Based on observations made with ESO telescopes at La Silla Paranal Observatory under program ID 083.B-0083.Table 6 is available in electronic form at http://www.aanda.org

Recently some pessimism has been expressed about our lack of progress in understanding quasars over the 50+ year since their discovery (Antonucci, 2013). It is worthwhile to look back at some of the progress that has been made—but still lies under the radar—perhaps because few people are working on optical/UV spectroscopy in this field. Great advances in understanding quasar phenomenology have emerged using eigenvector techniques. The 4D eigenvector 1 context provides a surrogate H-R Diagram for quasars with a source main sequence driven by Eddington ratio convolved with line-of-sight orientation. Appreciating the striking differences between quasars at opposite ends of the main sequence (so-called population A and B sources) opens the door toward a unified model of quasar physics, geometry and kinematics. We present a review of some of the progress that has been made over the past 15 years, and point out unsolved issues.

We present the results of a long-term variability campaign of very broad-line AGNs with line widths broader than FWHM > 5000 km s -1 . The main goal of our investigation was to study whether the widths of the optical broad emission lines are correlated with the optical intensity variations on timescales of years. Our AGN sample consisted of 10 objects. We detected a significant correlation between optical continuum variability amplitudes and H β emission line widths ( FWHM ) and, to a lesser degree, between H β line intensity variations and H β equivalent widths. We add the spectroscopic data of variable AGNs from the literature to supplement our sample. The AGNs from other optical variability campaigns with different line-widths helped to improve the statistical significance of our very broad-line AGN sample. After including the data on 35 additional galaxies, the correlation between optical continuum variability amplitudes and H β emission line widths becomes even more significant and the probability that this is a random correlation drops to 0.7 percent.

Detailed line profile variability studies of the narrow line Seyfert 1 galaxy Mrk110 are presented. We obtained the spectra in a variability campaign carried out with the 9.2m Hobby-Eberly Telescope at McDonald Observatory. The integrated Balmer and Helium (HeI,II) emission lines are delayed by 3 to 33 light days to the optical continuum variations respectively. The outer wings of the line profiles respond much faster to continuum variations than the central regions. The comparison of the observed profile variations with model calculations of different velocity fields indicates an accretion disk structure of the broad line emitting region in Mrk110. Comparing the velocity-delay maps of the different emission lines among each other a clear radial stratification in the BLR can be recognized. Furthermore, delays of the red line wings are slightly shorter than those of the blue wings. This indicates an accretion disk wind in the BLR of Mrk110. We determine a central black hole mass of M = $1.8\cdot10^{7} M_{\odot}$. Because of the poorly known inclination angle of the accretion disk this is a lower limit only., 12 pages, 11 figures, Astron & Astrophys, in press

The optical luminous quasar PG0043+039 has not been detected before in deep X-ray observations indicating the most extreme optical-to-X-ray slope index ${\alpha}_{ox}$ of all quasars. This study aims to detect PG0043+039 in a deep X-ray exposure. Furthermore, we wanted to check out whether this object shows specific spectral properties in other frequency bands. We took deep X-ray (XMM-Newton), far-ultraviolet (HST), and optical (HET, SALT telescopes) spectra of PG0043+039 simultaneously in July 2013. We just detected PG0043+039 in our deep X-ray exposure. The steep ${\alpha}_{ox} = -2.37 {\pm} 0.05$ gradient is consistent with an unusual steep gradient $F_{\nu} {\sim} {\nu}^{\alpha}$ with ${\alpha} = -2.67 {\pm} 0.02$ seen in the UV/far-UV continuum. The optical/UV continuum flux has a clear maximum near 2500 {\AA}. The UV spectrum is very peculiar because it shows broad humps in addition to known emission lines. A modeling of these observed humps with cyclotron lines can explain their wavelength positions, their relative distances, and their relative intensities. We derive plasma temperatures of T ${\sim}$ 3keV and magnetic field strengths of B ${\sim}$ 2 ${\times} 10^8$ G for the line-emitting regions close to the black hole., Comment: 4 pages, 3 figures, Astronomy & Astrophysics in press

We present a preliminary analysis of X-ray data of quasars in the context of the 4D eigenvector 1 parameter space (Sulentic et al.2000a, b). 4DE1 serves as a surrogate H-R diagram for representing empirical diversity among quasars and identifying the physical drivers of the diversity. The soft X-ray spectral index (Γ) was adopted as one of the key 4DE1 that correlates contrasting extremes in Type 1 properties. 4DE1 motivated the hypothesis of two quasar populations (A and B) divided by L/L≈0.2. Pop. A is a largely radio-quiet population with FWHM Hβ, This research was supported by the Spanish Ministry of Economy and Competitiveness through projects AYA2010-15169 and AYA2013-42227-P and by the Junta de Andalucia project TIC 114. KS acknowledges financial support from the Ministerio de Economia y Competitividad through the Spanish grant BES-2014-069767. The authors thank the referee for useful suggestions. This research made use of the NASA IPAC extragalactic database (NED), which is operated by the JPL under contract with the National Aeronautics and Space Administration. This research has made use of the NED database which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. We thank the SDSS collaboration for providing the extraordinary database and processing tools that made part of this work possible. The SDSS website is http://www.sdss.org/.

In this work, I study the twofold investigation of the interaction of massive stars with their surroundings: I have analyzed observations of emission lines in H II regions to determine the physical conditions surrounding the formation of massive stars both in the near and far Universe; and I have studied the hydrodynamical evolution of these regions numerically. I developed and tested a radiative transfer code as implemented in the hydrodynamic code FLASH. I used the code to study the hydrodynamical evolution and resulting X-ray emission of a prototypical UltraCompact H II region.

A new four-image gravitational lens system, B0712+472, has been discovered during the Cosmic Lens All-Sky Survey. This system consists of four flat-spectrum radio images that are also seen on a Hubble Space Telescope (HST) image, together with the lensing galaxy. We present MERLIN, VLA and VLBA maps and WHT spectra of the system as well as the HST images. The light distribution of the tensing galaxy is highly elongated and so too is the mass distribution deduced from modelling. We suggest a redshift of similar to 1.33 for the lensed object the lens redshift will require further investigation. The discovery of this new system further increases the ratio of four-image to two-image lens systems currently known, exacerbating problems of required ellipticity of matter distributions in lensing galaxies.

Broad emission lines originate in the surroundings of supermassive black holes in the centers of active galactic nuclei (AGN). One method to investigate the extent, structure, and kinematics of the BLR is to study the continuum and line profile variability in AGN. We selected the radio-loud Seyfert 1 galaxy 3C 120 as a target for this study. We took spectra with a high signal-to-noise ratio of 3C 120 with the 9.2m Hobby-Eberly Telescope between Sept. 2008 and March 2009. In parallel, we photometrically monitored the continuum flux at the Wise observatory. We analyzed the continuum and line profile variations in detail (1D and 2D reverberation mapping) and modeled the geometry of the line-emitting regions based on the line profiles. We show that the BLR in 3C 120 is stratified with respect to the distance of the line-emitting regions from the center with respect to the line widths (FWHM) of the rms profiles and with respect to the variability amplitude of the emission lines. The emission line wings of H{\alpha} and H{\beta} respond much faster than their central region. This is explained by accretion disk models. In addition, these lines show a stronger response in the red wings. However, the velocity-delay maps of the helium lines show a stronger response in the blue wing. Furthermore, the HeII{\lambda}4686 line responds faster in the blue wing in contradiction to observations made one and a half years later when the galaxy was in a lower state. The faster response in the blue wing is an indication for central outflow motions when this galaxy was in a bright state during our observations. The vertical BLR structure in 3C 120 coincides with that of other AGN. We confirm the general trend: the emission lines of narrow line AGN originate at larger distances from the midplane than AGN with broader emission lines., Comment: 18 pages, 25 figures, Astronomy & Astrophysics in press

We consider photometric reverberation mapping, where the nuclear continuum variations are monitored via a broad-band filter and the echo of emission line clouds of the broad line region (BLR) is measured with a suitable narrow-band (NB) filter. We investigate how an incomplete emission-line coverage by the NB filter influences the BLR size determination. This includes two basic cases: 1) a symmetric cut of the blue and red part of the line wings, and 2) the filter positioned asymmetrically to the line centre so that essentially a complete half of the emission line is contained in the NB filter. Under the assumption that the BLR size is dominated by circular Keplerian orbits, we find that symmetric cutting of line wings may lead to overestimating the BLR size by less than 5%. The case of asymmetric half-line coverage, similar as for our data of the Seyfert 1 galaxy 3C120, yields the BLR size with a bias of less than 1%. Our results suggest that any BLR size bias due to narrow-band line cut in photometric reverberation mapping is small and in most cases negligible. We used well sampled photometric reverberation mapping light curves with sharp variation features in both the continuum and the Hbeta light curves to determine the geometry type of the Hbeta BLR for 3C120. Modelling of the light curve, under the assumption that the BLR is essentially virialised, argues against a spherical geometry and favours a nearly face-on disk-like geometry with inclination i = 10 +/- 4 deg and extension from 22 to 28 light days. The low inclination may lead to a larger black hole mass than the derived when using the average geometry scaling factor f=5.5. We discuss deviations of Seyfert 1 galaxies from the M_BH - sigma relation., 9 pages, 11 figures, accepted for publication in Astronomy and Astrophysics

Supermassive black holes in the centers of active galactic nuclei (AGN) are surrounded by broad-line regions (BLRs). The broad emission lines seen in the AGN spectra are emitted in this spatially unresolved region. We intend to obtain information on the structure and geometry of this BLR based on observed line profiles. We modeled the rotational and turbulent velocities in the line-emitting region on the basis of the line-width FWHM and line dispersion sigma_line of the variable broad emission lines in NGC5548. Based on these velocities we estimated the height of the line-emitting regions above the midplane in the context of their distances from the center. The broad emission lines originate at distances of 2 to 27 light days from the center. Higher ionized lines originate in the inner region (lesser equal 13 light days) in specific filamentary structures 1 to 14 light days above the midplane. In contrast, the Hbeta line is emitted in an outer (6 - 26 light days), more flattened configuration at heights of 0.7 to 4 light days only above the midplane. The derived geometry of the line-emitting region in NGC5548 is consistent with an outflowing wind launched from an accretion disk., 4 pages, 5 figures, Astron. & Astrophys. Letter, in press

We present an analysis of broad emission lines observed in moderate-luminosity active galactic nuclei (AGNs), typical of those found in X-ray surveys of deep fields, with the aim to test the validity of single-epoch virial black hole mass estimates. We have acquired near-infrared (NIR) spectra of AGNs up to z ~ 1.8 in the COSMOS and Extended Chandra Deep Field-South Survey, with the Fiber Multi-Object Spectrograph (FMOS) mounted on the Subaru Telescope. These low-resolution NIR spectra provide a significant detection of the broad Halpha line that has been shown to be a reliable probe of black hole mass at low redshift. Our sample has existing optical spectroscopy which provides a detection of MgII, a broad emission line typically used for black hole mass estimation at z > 1. We carry out a spectral-line fitting procedure using both Halpha and MgII to determine the virial velocity of gas in the broad line region, the monochromatic continuum luminosity at 3000 A, and the total Halpha line luminosity. With a sample of 43 AGNs spanning a range of two decades in luminosity (i.e., L ~ 10^44-46 ergs/s), we find a tight correlation between the continuum and line luminosity with a distribution characterized by = 1.52 and a dispersion sigma = 0.16. There is also a close one-to-one relationship between the FWHM of Halpha and of MgII up to 10000 km/s with a dispersion of 0.14 in the distribution of the logarithm of their ratios. Both of these then lead to there being very good agreement between Halpha- and MgII-based masses over a wide range in black hole mass (i.e., M_BH ~ 10^7-9 M_sun). We do find a small offset in MgII-based masses, relative to those based on Halpha, of +0.17 dex and a dispersion sigma = 0.32. In general, these results demonstrate that local scaling relations, using MgII or Halpha, are applicable for AGN at moderate luminosities and up to z ~ 2., Comment: Submitted to ApJ, 9 pages, 7 figures

Broad emission lines are emitted in the surroundings of supermassive black holes in the centers of active galactic nuclei (AGN). This region is spatially not resolved. We intend to get information on the structure and geometry of this broad emitting line region (BLR) based on line profile observations. We model the rotational and turbulent velocities in the line-emitting regions based on observed full-width at half maximum line values (FWHM) and {\sigma}_{line} of the variable broad emission lines in four nearby AGN: NGC 3783, NGC 7469, NGC 5548, and 3C 390.3. On the basis of these velocities, we estimate the height of the line-emitting regions above the midplane in context with their distances from the center. The H{\beta} lines are emitted in a more flattened configuration above the midplane in comparison to the highly ionized lines. The H{\beta} lines originate at heights of 0.7 to 1.6 light-days and at distances of 1.4 to 24 light-days with height/distance (H/R) ratios of only 0.07 to 0.5. The highly ionized lines originate at smaller radii than the H{\beta} lines and/or at greater distances above the midplane with H/R values of 0.2 to 1.7. In total, the emission lines do not originate in a thin atmosphere of an accretion disk but rather at very extended regions above an accretion disk. The observed geometries of the line-emitting regions resemble the geometries of accretion disk wind models. Furthermore, the angle of the central opening cone (generated by the emitting regions of the highly ionized lines) is small for those galaxies with slow rotational velocities and increases with the rotation velocity of the central region. The derived geometries of the line-emitting regions of all four AGN are consistent with the geometries that are predicted in outflowing disk wind models., Comment: 12 pages, 18 figures, Astronomy & Astrophysics in press

We present NuSTAR hard X-ray observations of two X-ray weak broad absorption line (BAL) quasars, PG 1004+130 (radio loud) and PG 1700+518 (radio quiet). Many BAL quasars appear X-ray weak, probably due to absorption by the shielding gas between the nucleus and the accretion-disk wind. The two targets are among the optically brightest BAL quasars, yet they are known to be significantly X-ray weak at rest-frame 2-10 keV (16-120 times fainter than typical quasars). We would expect to obtain ~400-600 hard X-ray (>10 keV) photons with NuSTAR, provided that these photons are not significantly absorbed (NH, 18 pages, 9 figures. ApJ in press

We present photometry and spectroscopy of the A0IVe star 68 Ophiuchi, for which Vidal-Madjar et al. (1993) suspected the presence of a circumstellar disc of material similar to that found around beta Pic. The UV and optical continuum agrees well with a Kurucz model with parameters that are consistent with the spectral type. 68 Oph is detected at 12 and 25 mu m by IRAS, but the data show no strong evidence for thermal emission from cool circumstellar dust grains. Observations at 450 mu m and 800 mu m also indicate that there is no strong dust component. Intermediate and high resolution optical and near-IR spectra of 68 Oph confirm that the star is surrounded by a gaseous disc, seen in H alpha and Br alpha. The Ca II lambda 3933.7 line shows a broad photospheric absorption line with two narrow, blue-shifted absorption lines near line centre, one of which is also found in Na I. These absorption lines are probably of interstellar origin. We conclude that 68 Oph does not show properties observed in other proto-planetary sytems, such as red-shifted absorption features in spectral lines and a strong dust continuum.

We report the discovery of a new gravitational lens system associated with the flat-spectrum radio source 1600+434. The system has been found in a new large survey of such radio sources. It consists of a 1.4-arcsec double radio source with an associated optical double at the same position and orientation, and with an almost identical flux density ratio to that in the radio. Spectra of the light from two optical images show broad emission lines with a redshift of 1.61. The spectral data are not of sufficient quality to show that both images have identical spectra. Nevertheless, we argue that the probability that 1600+434 is indeed a lensed system is very high.

Galaxies grow by accreting gas, which they need to form stars, from their surrounding haloes. These haloes, in turn, accrete gas from the diffuse intergalactic medium. Feedback from stars and black holes returns gas from the galaxy to the halo and can even expel it from the halo. This cycle of gas inflow and outflow, its impact on star formation, and the detectability of the gas outside of galaxies are discussed in this thesis. The growth of galaxies and their gaseous haloes depends strongly on their mass, the age of the Universe, and the inclusion of feedback processes, as do their physical and observational properties.

We present an optical spectroscopic atlas for 123 core-dominated radio-loud active galactic nuclei with relativistic jets, drawn from the MOJAVE/2cm sampleat 15 GHz. It is the first time that spectroscopic and photometric parameters for a large sample of such type of AGN are presented. The atlas includes spectralparameters for the emission lines H, [O III]/5007, Mg II/2798 and/or C IV/ 1549 and corresponding data for the continuum, as well as the luminosities and equivalentwidths of the Fe II UV/optical. It also contains homogeneous photometric information in the B-band for 242 sources of the sample, with a distribution peak at BJ = 18.0 and a magnitude interval of 11.1 BJ 23.7.

From low and high resolution spectroscopic observations of IRAS 10215 - 5916 we have discovered the presence of nebular emission lines in this G-type supergiant star in the post-AGB stage. From its high resolution spectrum we derived an expansion velocity of 17 km s-1 for the shell, similar to the values usually observed in planetary and proto-planetary nebulae. The images taken in the near infrared show that IRAS 10215-5916 is slightly extended and asymmetric. Although we cannot rule out a possible binary nature for the central star of this IRAS source, in which a hot component could be the responsible for the observed nebular emission, no indications of binarity have been found so far. We suggest that the observed spectrum and morphology could be produced by the asymmetric mass loss of a single star in the post-AGB phase. Post-AGB mass loss can play a fundamental role on shortening the transition time towards the planetary nebula stage and favour the formation of the bipolar structures commonly observed in evolved planetary nebulae. In this sense, it is shown that this mass loss is more intense and frequent for massive progenitors of PNe.

We report on a multifrequency radio study of the supernova remnant (SNR) G338.3-0.0, in positional coincidence with the TeV source HESS J1640-465. To carry out this research we observed the SNR G338.3-0.0 using the Giant Metrewave Radio Telescope (GMRT) at 235, 610, and 1280 MHz. We also reprocessed archival data from the Australia Telescope Compact Array (ATCA) at 1290 and 2300 MHz. Also we conducted a search for radio pulsations towards a central point-like source, using the GMRT antennas at 610 and 1280 MHz. The molecular material in the region of the SNR was investigated based on observations made with the NANTEN telescope in the 12^CO (J=1-0) emission line. The new radio observations revealed a remnant with a bilateral morphology, which at 235 MHz has the western wing completely attenuated because of absorption due to foreground ionized gas. The quality of the new images allows us to provide accurate estimates for the total radio flux density of the whole SNR at different radio frequencies. From the new and existing flux density estimates between 235 and 5000 MHz we derived for the whole remnant a spectral index alpha=-0.51 +/-0.06 with a local free-free continuum optical depth at 235 MHz tau_{235}=0.9+/-0.3. No radio pulsations were detected towards the only radio point-like source within the HESS error circle. We derived upper limits of 2.0 and 1.0 mJy at 610 and 1280 MHz, respectively, for the pulsed flux towards this source. No radio counterpart was found for the pulsar wind nebula discovered in X-rays. The inspection of the interstellar molecular gas towards G338.3-0.0 and surroundings revealed that there is not any associated dense cloud that might explain a hadronic origin for the TeV detection., 7 pages, 4 figures. Accepted for publication in A&A

Determining the masses of the central compact object believed to power all active galactic nuclei is relevant to our understanding of their evolution and of their inner workings. Keys to present-day mass estimates are: (1) the assumption of line broadening due to virial motion of the emitting gas, (2) an estimate of the distance of broad-line emitting gas from the central compact object, and (3) a measure of the AGN luminosity. We discuss the merits and the limitations of an alternative method based on estimates of physical conditions in the broad line emitting region derived from an appropriate multi-component analysis of emission line profiles. This ‘photo-ionization method’, applied to UV intermediate-ionization lines appears to be promising for at least a sizable population of high-z quasars.

Broad emission line regions in AGN are connected with the outer layers of accretion disks. This has been shown by means of line variability studies of individual AGN as well as line profile studies of AGN samples. We could model the broad-line profiles in AGN in a simple way only through rotational broadening of Lorentzian profiles. To individual emission lines belongs one typical Lorentz profile only with a fixed turbulence velocity: e.g., 500 km/s for Hβ, 3000 km/s for CIV λ1550. The rotation velocities in the broad line regions of the AGN range from 1000 to 7000 km/s.

I describe some of the outstanding “big picture” questions in quasar research and how the development of the plasma simulation code Cloudy is being guided to answer them. QSO spectra are complex and challenge even the most sophisticated spectral codes. Particular emphasis is given to a central question - how do the properties of the central black hole and the accretion disk are manifested in the observed spectrum.

SAO 244567 (Hen 1357 = CPD -59(0)6926 = IRAS 17119-5926) is an IRAS source with far infrared colours and flux distribution similar to those of planetary nebulae. The IUE ultraviolet spectra obtained in July, 1988 and April 1992 show nebular emission fines and also the changes in the spectra suggest the formation of the planetary nebula and the rapid evolution of the central star. The optical spectrum of this star obtained by Henize around 1950 shows only the Halpha line in emission, while the most recent one, obtained in 1990 shows strong forbidden emission lines corresponding to a low excitation and young planetary nebula. The IUE ultraviolet spectra show evidence for the presence of stellar wind and mass loss. The stellar lines show P-Cygni type profiles and the terminal velocity of the stellar wind is approximately -3000 km s-1. The spectral type of the central star is approximately 08 V. The presence of a detached cold dust shell (125 K), high galactic latitude and abundances suggest that SAO 244567 has recently evolved from a low or intermediate mass progenitor star which has ejected its outer envelope during the AGB stage of evolution and is rapidly evolving towards hotter spectral types.