scholarly journals Optical spectroscopy of type 2 LINERs

2020 ◽  
Vol 635 ◽  
pp. A50
Author(s):  
L. Hermosa Muñoz ◽  
S. Cazzoli ◽  
I. Márquez ◽  
J. Masegosa
Keyword(s):  
Emission Line ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
True Nature ◽  
Star Forming ◽  
Broad Component ◽  
Line Region ◽  
Line Fitting

Context. Type 2 Low-ionization Nuclear Emission-line Regions (LINERs) have been optically classified with the Palomar data as not presenting a broad component in the Balmer emission lines that are associated with the broad-line region (BLR) of the active galactic nuclei (AGN). Aims. We aim to unveil the presence of different kinematic components of emission lines in the nuclear region of a sample of local (z ≤ 0.022) type 2 LINERs. We focus on the analysis of the true nature of LINERs by means of the detection (or nondetection) of a broad component that originated in the BLR of the AGN. Additionally, we search for the possible presence of nonrotational motions such as outflows in these LINERs. Methods. We applied a decomposition of the nuclear emission lines using an spectroscopic analysis of the optical spectra of nine type 2 LINERs of intermediate-resolution spectroscopic data retrieved from the Hubble Space Telescope (HST) archive. The study is completed with archival spectra from the Double Spectrograph from the Palomar Observatory. Results. The emission line fitting reveals the presence of a broad component associated with the BLR in six out of the nine galaxies for the space-based data, and for two out of the eight from the ground-based spectra. The velocity dispersion for two galaxies (NGC 4486 and NGC 4594) measured in HST/STIS data suggest the presence of outflows. Conclusions. The results indicate that the spatial resolution plays a major role in the detection of the BLR, as it appears diluted in the ground-based data (even after removing stellar contribution). This is also true for the emission line diagnostics, as the contaminant light contributes to lower emission line ratios toward the star-forming area of standard BPTs. We propose to reclassify NGC 4594 as a type 1 LINER, since a BLR component is seen in both space- and ground-based spectra. We find ambiguous results for the BLR component of NGC 4486. The modest outflow detection in our sample may indicate that they are not as frequent as seen for type 1 LINERs.

scholarly journals Optical spectroscopy of type-2 LINERs

2019 ◽  
Vol 15 (S356) ◽  
pp. 317-319
Author(s):  
Laura Hermosa Muñoz ◽  
Sara Cazzoli ◽  
Isabel Márquez ◽  
Josefa Masegosa
Keyword(s):  
Active Galactic Nuclei ◽  
Local Population ◽  
Galactic Nuclei ◽  
Broad Component ◽  
Line Region ◽  
Spectral Components ◽  
Liner Galaxies

AbstractLow-Ionisation Nuclear Emission-line Regions (LINERs) are the least luminous and the most numerous among the local population of Active Galactic Nuclei (AGN). They can be classified as type-1 or type-2 if their optical spectra show or do not show, respectively, a broad component. It is associated with the presence of a Broad Line Region (BLR) in these systems. However, recent studies have proven that the classification of type-1 LINERs may be controversial, since space- and ground-based spectroscopy provide contradicting results on the presence of very broad components (Cazzoli et al.2018). We have studied the nuclear spectra of 9 type-2 LINERs with intermediate spectral resolution HST/STIS data. We present the results on our analysis of the different spectral components, and discuss the eventual presence of BLR components in type-2 LINER galaxies, together with the possible presence of outflows, both in comparison with type-1 LINERs. We have found a BLR component in 7 out of the 9 analysed objects within the HST/STIS data.

scholarly journals A bayesian-like approach to derive chemical abundances in type-2 active galactic nuclei based on photoionization models

2019 ◽  
Vol 489 (2) ◽  
pp. 2652-2668 ◽  
Author(s):  
E Pérez-Montero ◽  
O L Dors ◽  
J M Vílchez ◽  
R García-Benito ◽  
M V Cardaci ◽  
...  
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Chemical Properties ◽  
Galactic Nuclei ◽  
Optical Emission ◽  
Emission Lines ◽  
Chemical Abundances ◽  
Star Forming ◽  
Large Dispersion

Abstract We present a new methodology for the analysis of the emission lines of the interstellar medium in the narrow-line regions around type-2 active galactic nuclei. Our aim is to provide a recipe that can be used for large samples of objects in a consistent way using different sets of optical emission lines that takes into the account possible variations from the O/H–N/O relation to use [N ii] lines. Our approach consists of a bayesian-like comparison between certain observed emission-line ratios sensitive to total oxygen abundance, nitrogen-to-oxygen ratio, and ionization parameter with the predictions from a large grid of photoionization models calculated under the most usual conditions in this environment. We applied our method to a sample of Seyfert 2 galaxies with optical emission-line fluxes and determinations of their chemical properties from detailed models in the literature. Our results agree within the errors with other results and confirm the high metallicity of the objects of the sample, with N/O values consistent with a large secondary production of N, but with a large dispersion. The obtained ionization parameters for this sample are much larger than those for star-forming object at the same metallicity.

scholarly journals A new tool to derive chemical abundances in type-2 active galactic nuclei

2019 ◽  
Vol 15 (S356) ◽  
pp. 61-65
Author(s):  
Rubén García-Benito ◽  
Enrique Pérez-Montero ◽  
Oli L. Dors ◽  
José M. Vlchez ◽  
Monica V. Cardaci ◽  
...  
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Direct Method ◽  
Galactic Nuclei ◽  
Optical Emission ◽  
Emission Lines ◽  
Chemical Abundances ◽  
Line Region ◽  
Oxygen Ratio

AbstarctWe present a new tool for the analysis of the optical emission lines of the gas in the Narrow Line Region (NLR) around Active Galactic Nuclei (AGNs). This new tool can be used in large samples of objects in a consistent way using different sets of optical emission-lines taking into the account possible variations from the O/H - N/O relation. The code compares certain observed emission-line ratios with the predictions from a large grid of photoionization models calculated under the most usual conditions in the NLR of AGNs to calculate the total oxygen abundance, nitrogen-to-oxygen ratio and ionization parameter. We applied our method to a sample of Seyfert 2 galaxies with optical emission-line fluxes from the literature. Our results confirm the high metallicity of the objects of the sample and provide consistent values with the direct method. The usage of models to calculate precise ICFs is mandatory when only optical emission lines are available to derive chemical abundances using the direct method in NLRs of AGN.

scholarly journals Constraints on the production and escape of ionizing radiation from the emission-lines of metal-poor star-forming galaxies

2019 ◽  
Vol 15 (S352) ◽  
pp. 121-122
Author(s):  
A. Plat ◽  
S. Charlot ◽  
G. Bruzual ◽  
A. Feltre ◽  
A. Vidal-Garca ◽  
...  
Keyword(s):  
Ionizing Radiation ◽  
Emission Line ◽  
Active Galactic Nuclei ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
High Redshift Galaxies ◽  
Star Forming ◽  
Radiative Shocks ◽  
Metal Poor Star

AbstractTo understand how the nature of the ionizing sources and the leakage of ionizing photons in high-redshift galaxies can be constrained from their emission-line spectra, we compare emission-line models of star-forming galaxies including leakage of ionizing radiation, active galactic nuclei (AGN) and radiative shocks, with observations of galaxies at various redshifts with properties expected to approach those of primeval galaxies.

scholarly journals Molecular hydrogen and [Fe ii] in active galactic nuclei – III. Low-ionization nuclear emission-line region and star-forming galaxies

2013 ◽  
Vol 430 (3) ◽  
pp. 2002-2017 ◽  
Author(s):  
R. Riffel ◽  
A. Rodríguez-Ardila ◽  
I. Aleman ◽  
M. S. Brotherton ◽  
M. G. Pastoriza ◽  
...  
Keyword(s):  
Emission Line ◽  
Active Galactic Nuclei ◽  
Molecular Hydrogen ◽  
Galactic Nuclei ◽  
Star Forming ◽  
Line Region

scholarly journals Black hole mass estimation for active galactic nuclei from a new angle

2019 ◽  
Vol 487 (3) ◽  
pp. 3404-3418 ◽  
Author(s):  
Dalya Baron ◽  
Brice Ménard
Keyword(s):  
Black Hole ◽  
Active Galactic Nuclei ◽  
Cosmic Time ◽  
Galactic Nuclei ◽  
Host Galaxy ◽  
Black Hole Mass ◽  
Mass Estimation ◽  
Line Region

Abstract The scaling relations between supermassive black holes and their host galaxy properties are of fundamental importance in the context black hole-host galaxy co-evolution throughout cosmic time. In this work, we use a novel algorithm that identifies smooth trends in complex data sets and apply it to a sample of 2000 type 1 active galactic nuclei (AGNs) spectra. We detect a sequence in emission line shapes and strengths which reveals a correlation between the narrow L([O iii])/L(H β) line ratio and the width of the broad H α. This scaling relation ties the kinematics of the gas clouds in the broad line region to the ionization state of the narrow line region, connecting the properties of gas clouds kiloparsecs away from the black hole to material gravitationally bound to it on sub-parsec scales. This relation can be used to estimate black hole masses from narrow emission lines only. It therefore enables black hole mass estimation for obscured type 2 AGNs and allows us to explore the connection between black holes and host galaxy properties for thousands of objects, well beyond the local Universe. Using this technique, we present the MBH–σ and MBH–M* scaling relations for a sample of about 10 000 type 2 AGNs from Sloan Digital Sky Survey. These relations are remarkably consistent with those observed for type 1 AGNs, suggesting that this new method may perform as reliably as the classical estimate used in non-obscured type 1 AGNs. These findings open a new window for studies of black hole-host galaxy co-evolution throughout cosmic time.

scholarly journals AGN types and unification model

2019 ◽  
Vol 15 (S356) ◽  
pp. 29-43
Author(s):  
Luigi Spinoglio ◽  
Juan Antonio Fernández-Ontiveros
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Seyfert Galaxies ◽  
Physical Object ◽  
Host Galaxy ◽  
Star Forming ◽  
Star Formation Activity ◽  
Frequency Monitoring

AbstractThe motivation of the “unified model” is to explain the main properties of the large zoo of active galactic nuclei with a single physical object. The discovery of broad permitted lines in the polarized spectrum of type 2 Seyfert galaxies in the mid 80’s led to the idea of an obscuring torus, whose orientation with respect to our line of sight was the reason of the different optical spectra. However, after many years of observations with different techniques, including IR and mm interferometry, the resulting properties of the observed dust structures differ from the torus model that would be needed to explain the type 1 vs type 2 dichotomy. Moreover, in the last years, multi-frequency monitoring of active galactic nuclei has shown an increasing number of transitions from one type to the other one, which cannot be explained in terms of the simple orientation of the dusty structure surrounding the active galactic nucleus (AGN). The interrelations between the AGN and the host galaxy, as also shown in the Magorrian relation, suggest that the evolution of the host galaxy may also have an important role in the observed manifestation of the nuclei. As an example, the observed delay between the maximum star formation activity and the onset of the AGN activity, and the higher occurrence of type 2 nuclei in star forming galaxies, have suggested the possible evolutionary path from, e.g., H II → AGN2 → AGN1. In the next years the models of unification need to also consider this observational framework and not only simple orientation effects.

scholarly journals X-ray absorption in INTEGRAL active galactic nuclei

2020 ◽  
Vol 639 ◽  
pp. A5
Author(s):  
A. Malizia ◽  
L. Bassani ◽  
J. B. Stephen ◽  
A. Bazzano ◽  
P. Ubertini
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Axial Ratio ◽  
Host Galaxy ◽  
Host Galaxies ◽  
X Ray ◽  
Line Region ◽  
Absorbing Material

In this work the INTEGRAL hard X-ray selected sample of active galactic nuclei (AGN) has been used to investigate the possible contribution of absorbing material distributed within the host galaxies to the total amount of NH measured in the X-ray band. We collected all the available axial ratio measurements of the galaxies hosting our AGN together with their morphological information and found that for our hard X-ray selected sample as well there is a deficit of edge-on galaxies hosting type 1 AGN. We estimate that in our hard X-ray selected sample there is a deficit of 24% (±5%) of type 1 AGN. Possible bias in redshift has been excluded, as we found the same effect in a well-determined range of z where the number and the distributions of the two classes are statistically the same. Our findings clearly indicate that material located in the host galaxy on scales of hundreds of parsecs and not aligned with the putative absorbing torus of the AGN can contribute to the total amount of column density. This galactic absorber could be large enough to hide the broad line region of some type 1 AGN, thus causing their classification as type 2 objects and giving rise to the deficiency of type 1 objects in edge-on galaxies.

X-ray galaxies

1979 ◽  
Vol 366 (1726) ◽  
pp. 461-489 ◽  
Keyword(s):  
Radio Emission ◽  
Line Width ◽  
Emission Lines ◽  
Radio Sources ◽  
X Rays ◽  
X Ray ◽  
Line Region ◽  
Radio Power

The currently identified classes of compact extragalactic X-ray sources comprise type 1 Seyfert galaxies, galaxies with active nuclei and relatively sharp emission lines, BL Lac objects and quasars. The known members of these categories are listed. In this paper, the properties of the first two classes are reviewed and discussed, with particular emphasis on their radio and optical properties and the relation between the various nuclear components. Electromagnetic spectra from radio to X-rays are presented for those galaxies detected in more than two wavebands. Optical observations of type 1 Seyferts indicate a wide range of scales for the emitting material. The continuum source and the broad wings on the Balmer lines probably originate in a region less than about 0.1 pc in extent, while the forbidden line region may occupy several hundred parsecs. From the point of view of their radio properties, galaxies with Seyfert or Seyfert-like spectra may be divided into four general categories, namely: (1) powerful (more than 10 25 W Hz -1 sr -1 at 1.4 GHz), very extended, double radio sources with steep spectra; (2) powerful (more than 10 24 W Hz -1 sr -1 at 1.4 GHz) compact radio sources with flat or inverted spectra, the radio emission originating from a small region in the nucleus; (3) weaker (10 20 -10 23 W Hz -1 sr -1 at 1.4 GHz) emission from the nucleus, usually with a steep non-thermal radio spectrum and occasionally an extended ( ca . 50 kpc) radio halo; and (4) no detected radio emission. The distinction between (3) and (4) is probably only a matter of observational selection and almost all Seyferts fall into these last two categories. When spatially resolved, the radio emitting region of category (3) galaxies usually has an approximately similar scale to the forbidden line region. The radio power is correlated with Seyfert type and forbidden line power, which may be interpreted in terms of a pressure balance between the filaments of thermal gas radiating the forbidden lines and the relativistic gas emitting the non-thermal radio radiation. The radio power is, however, uncorrelated with the thermal pressure, suggesting that the differences in radio and forbidden line power from galaxy to galaxy are dominated by variations in overall size or filling factor. Recent discussions of the infrared radiation have proposed a non thermal origin in type 1 Seyferts but a thermal mechanism in type 2 Seyferts. The infrared and radio powers seem to be correlated in both types. The X-rays originate in a region not more than 10 -2 pc in extent, and possibly much smaller. Type 1 Seyferts are intrinsically more powerful X-ray sources than type 2 Seyferts. The X-ray power appears to be correlated with the optical and infrared continuum luminosities and possibly with the Balmer line width. Studies of highly ionized species in the optical emission line spectrum are described with a view to their possible relation to the X-rays. Both [Fe x] λ 6374 Å and [Fe xi] λ 7892 Å are blue-shifted with respect to lines of lower ionization species by an amount ranging up to 300km s -1 . At least in NGC 3783, the line width is correlated with the ionization potential necessary to create the species in the sense that the higher the ionization, the greater the line width. This result fits into the scheme of a systematic decrease in density ( N e > 10 8 -10 3 cm -3 ) and decrease in velocity dispersion(< v > = 10 4 -3 x 10 2 km s -1 ) with increasing distance from the central object ( r ≾ 0.1-5 x 10 2 pc). It is proposed that the highly ionized species occur in a region of intermediate velocity spread (<v> ≈ 1.5 x 10 3 km s -1 ) and distance ( r ≈ 2 pc). X-ray emitting galaxies with active nuclei but relatively sharp emission lines have X-ray luminosities in the range 10 41 -10 43 ergs -1 (1 erg s -1 = 10 -7 W), weaker than type 1 Seyferts (10 43 -10 45 ergs -1 ) but stronger than relatively normal galaxies ( ca .10 39 ergs -1 ). Lines from species of both high and low ionization are found in the optical spectra, implying ionization by a non-thermal continuum or by hot stars. These galaxies have very strong infrared excesses and are often detected as radio sources. They contain appreciable quantities of dust and, presumably, neutral gas and are either a member of an interacting pair or lie in a small group. Possibly the gas has been accreted from the neighbour(s), triggering the X-ray activity.

Optical long-slit spectroscopy in the cluster Abell S0805

2019 ◽  
Vol 488 (3) ◽  
pp. 3685-3715
Author(s):  
P C da Rocha-Poppe ◽  
V A Fernandes-Martin ◽  
M Faúndez-Abans ◽  
M de Oliveira-Abans ◽  
G A Silva ◽  
...  
Keyword(s):  
Emission Line ◽  
Stellar Population ◽  
Spectral Synthesis ◽  
Emission Lines ◽  
Cluster Galaxy ◽  
Nuclear Activity ◽  
Star Forming ◽  
Line Region ◽  
Nitrogen Emission ◽  
First Time

ABSTRACT This contribution aims to study the nature (kinematic, nuclear activity, and stellar population) of a sample of 10 galaxies in the poor cluster Abell S0805. As no detailed optical spectroscopy for some members has been published yet, the selected sample makes this study ideal for investigating the properties of the following objects: ESO 104- G(002, 006, 007, 008, 009, 010, 013), Fairall 0187, and PGC (062384, 062391). Our main results were obtained after subtraction of the underlying stellar population with the spectral synthesis code starlight. The residual spectra reveal seven galaxies with only absorption lines [ESO 104- G(002, 007, 008, 009), Fairall 0187 and PGC (062384, 062391)], and three galaxies with emission lines [ESO 104- G(006, 010, 013)]. According to the boundaries in the diagnostic diagrams, the intensities of H α and the low-ionization lines ([N ii] λ6584 Å and [S ii] λλ6716,6731 Å) suggest the following results: (i) the brightest cluster galaxy (ESO 104- G006, an elliptical cD galaxy) shows low-ionization nuclear emission-line region (LINER)-like excitation, quite common in ‘cool core clusters’; (ii) the ESO 104- G010 (‘X-Galaxy’ or ‘Crystal Frog’) shows an excess of the nitrogen emission-line [N ii] λ6584 Å not yet reported. We also suggest this object as a LINER; (iii) the spiral ESO 104- G013 is a star-forming galaxy with typical emission lines. No obvious signs of interaction were observed in this study. The heliocentric velocities agree within 1σ with the most recent values. The stellar population, rotation curves, and velocity dispersions are also discussed for the first time for some objects.

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