Chemical abundances in Seyfert galaxies– VIII. Argon abundance estimates

Chemical Abundances ◽

Line Intensities ◽

Abundance Estimates ◽

Line Region ◽

Sky Survey ◽

First Time

Abstract For the first time, the argon abundance relative to hydrogen abundance (Ar/H) in the narrow line region of a sample of Seyfert 2 nuclei has been derived. In view of this, optical narrow emission line intensities of a sample of 64 local Seyfert 2 nuclei (z < 0.25) taken from Sloan Digital Sky Survey DR7 and measured by the MPA/JHU group were considered. We adopted the Te-method for AGNs, which is based on direct determination of the electron temperature, together with a grid of photoionization model results, built with the Cloudy code, to obtain a method for the derivation of the Ar/H abundance. We find that for a metallicity range of $\rm 0.2 \: \lesssim \: (Z/{\rm Z_{\odot }}) \: \lesssim \: 2.0$, Seyfert 2 nuclei present Ar/H abundance ranging from ∼0.1 to ∼3 times the argon solar value, adopting $\rm log(O/H)_{\odot }=-3.31$ and $\rm log(Ar/H)_{\odot }=-5.60$. These range of values correspond to $\rm 8.0 \: \lesssim \: (12+log(O/H) \: \lesssim \: 9.0$ and $\rm 5.4 \: \lesssim \: (12+log(Ar/H) \: \lesssim \: 6.9$, respectively. The range of Ar/H and Ar/O abundance values obtained from our sample are in consonance with estimations from extrapolations of the radial abundance gradients to the central parts of the disk for four spiral galaxies. We combined our abundance results with estimates obtained from a sample of H ii galaxies, which were taken from the literature, and found that the Ar/O abundance ratio decreases slightly as the O/H abundance increases.

Chemical abundances in Seyfert galaxies – VII. Direct abundance determination of neon based on optical and infrared emission lines

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab2610 ◽

2021 ◽

Vol 508 (1) ◽

pp. 371-391

Author(s):

Mark Armah ◽

O L Dors ◽

C P Aydar ◽

M V Cardaci ◽

G F Hägele ◽

...

Keyword(s):

Electron Temperature ◽

Seyfert Galaxies ◽

Infrared Emission ◽

Emission Lines ◽

Chemical Abundances ◽

Star Forming ◽

Star Forming Regions ◽

Abundance Estimates ◽

Line Region ◽

Semi Empirical

ABSTRACT For the first time, neon abundance has been derived in the narrow line region from a sample of Seyfert 2 nuclei. In view of this, we compiled from the literature fluxes of optical and infrared (IR) narrow emission lines for 35 Seyfert 2 nuclei in the local universe ($z \:\lesssim \:0.06$). The relative intensities of emission lines were used to derive the ionic and total neon and oxygen abundances through electron temperature estimations (Te-method). For the neon, abundance estimates were obtained by using both Te-method and IR-method. Based on photoionization model results, we found a lower electron temperature [$t_{\rm e}({\rm Ne\, \small {III}})$] for the gas phase where the Ne2 + is located in comparison with t3 for the O2 + ion. We find that the differences (D) between Ne2 +/H+ ionic abundances calculated from IR-method and Te-method (assuming t3 in the Ne2 +/H+ derivation) are similar to the derivations in star-forming regions (SFs) and they are reduced by a mean factor of ∼3 when $t_{\rm e}({\rm Ne\, \small {III}})$ is considered. We propose a semi-empirical Ionization Correction Factor (ICF) for the neon, based on [Ne ii]12.81$\rm{\mu m}$, [Ne iii]15.56$\rm{\mu m}$, and oxygen ionic abundance ratios. We find that the average Ne/H abundance for the Seyfert 2s sample is nearly 2 times higher than similar estimate for SFs. Finally, for the very high metallicity regime (i.e. [$\rm 12+log(O/H)\: \gtrsim \: 8.80$]) an increase in Ne/O with O/H is found, which likely indicates secondary stellar production for the neon.

Chemical abundances of Seyfert 2 AGNs – I. Comparing oxygen abundances from distinct methods using SDSS

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz3492 ◽

2019 ◽

Vol 492 (1) ◽

pp. 468-479 ◽

Author(s):

O L Dors ◽

P Freitas-Lemes ◽

E B Amôres ◽

E Pérez-Montero ◽

M V Cardaci ◽

...

Keyword(s):

Strong Line ◽

Host Galaxies ◽

Chemical Abundances ◽

Oxygen Abundance ◽

Line Intensities ◽

Sky Survey ◽

Direct Measurements ◽

Low Metallicity ◽

Semi Empirical

ABSTRACT We compare the oxygen abundance (O/H) of the narrow-line regions (NLRs) of Seyfert 2 AGNs obtained through strong-line methods and from direct measurements of the electron temperature (Te-method). The aim of this study is to explore the effects of the use of distinct methods on the range of metallicity and on the mass–metallicity relation of active galactic nuclei (AGNs) at low redshifts (z ≲ 0.4). We used the Sloan Digital Sky Survey (SDSS) and NASA/IPAC Extragalactic Database (NED) to selected optical (3000 < λ(Å) < 7000) emission line intensities of 463 confirmed Seyfert 2 AGNs. The oxygen abundances of the NLRs were estimated using the theoretical Storchi-Bergmann et al. calibrations, the semi-empirical N2O2 calibration, the Bayesian H ii-Chi-mistry code and the Te-method. We found that the oxygen abundance estimations via the strong-line methods differ from each other up to ∼0.8 dex, with the largest discrepancies in the low-metallicity regime ($\rm 12+\log (O/H) \: \lesssim \: 8.5$). We confirmed that the Te-method underestimates the oxygen abundance in NLRs, producing unreal subsolar values. We did not find any correlation between the stellar mass of the host galaxies and the metallicity of their AGNs. This result is independent of the method used to estimate Z.

Spitzer IRS Observations of Low-Mass Seyfert Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310006459 ◽

2009 ◽

Vol 5 (S267) ◽

pp. 268-268

Author(s):

Carol E. Thornton ◽

Aaron J. Barth ◽

Luis C. Ho ◽

Jenny E. Greene

Keyword(s):

Dust Emission ◽

Seyfert Galaxies ◽

Physical Conditions ◽

Sky Survey ◽

Low Mass ◽

Ngc 4395 ◽

Black Hole Masses

The Sloan Digital Sky Survey has made it possible to identify the first samples of active galaxies with estimated black hole masses below ~ 106M⊙. We have obtained Spitzer IRS low-resolution spectra, covering 5–38 μm, of a sample of 41 Seyfert galaxies with low-mass black holes. Our sample includes SDSS-selected objects from the low-mass Seyfert 1 sample of Greene & Ho (2004) and the low-mass Seyfert 2 sample of Barth et al. (2008), as well as NGC 4395 and POX 52. The goals of this work are to examine the dust emission properties of these objects and investigate the relationship between type 1 and type 2 AGNs at low luminosities and low masses, to search for evidence of star formation, and to use emission-line diagnostics to constrain physical conditions within the narrow-line regions. Here we present preliminary results from this project.

Fundamental differences in the radio properties of red and blue quasars: insight from the LOFAR Two-metre Sky Survey (LoTSS)

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa866 ◽

2020 ◽

Vol 494 (3) ◽

pp. 3061-3079 ◽

Author(s):

D J Rosario ◽

V A Fawcett ◽

L Klindt ◽

D M Alexander ◽

L K Morabito ◽

...

Keyword(s):

Star Formation ◽

Control Sample ◽

Low Frequency ◽

Galactic Nuclei ◽

Stellar Objects ◽

Radio Detection ◽

Sky Survey ◽

Quasi Stellar Objects ◽

First Time

ABSTRACT Red quasi-stellar objects (QSOs) are a subset of the luminous end of the cosmic population of active galactic nuclei (AGNs), most of which are reddened by intervening dust along the line of sight towards their central engines. In recent work from our team, we developed a systematic technique to select red QSOs from the Sloan Digital Sky Survey, and demonstrated that they have distinctive radio properties using the Faint Images of the Radio Sky at Twenty centimetres radio survey. Here we expand our study using low-frequency radio data from the LOFAR Two-metre Sky Survey (LoTSS). With the improvement in depth that LoTSS offers, we confirm key results: Compared to a control sample of normal ‘blue’ QSOs matched in redshift and accretion power, red QSOs have a higher radio detection rate and a higher incidence of compact radio morphologies. For the first time, we also demonstrate that these differences arise primarily in sources of intermediate radio loudness: Radio-intermediate red QSOs are × 3 more common than typical QSOs, but the excess diminishes among the most radio-loud systems and the most radio-quiet systems in our study. We develop Monte Carlo simulations to explore whether differences in star formation could explain these results, and conclude that, while star formation is an important source of low-frequency emission among radio-quiet QSOs, a population of AGN-driven compact radio sources is the most likely cause for the distinct low-frequency radio properties of red QSOs. Our study substantiates the conclusion that fundamental differences must exist between the red and normal blue QSO populations.

Chemical abundances of Seyfert 2 AGNs – II. N2 metallicity calibration based on SDSS

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa193 ◽

2020 ◽

Vol 492 (4) ◽

pp. 5675-5683 ◽

Author(s):

S P Carvalho ◽

O L Dors ◽

M V Cardaci ◽

G F Hägele ◽

A C Krabbe ◽

...

Keyword(s):

Spectral Energy Distribution ◽

Spectral Energy ◽

Chemical Abundances ◽

Data Set ◽

Line Intensity Ratio ◽

Sky Survey ◽

Empirical Calibration ◽

Semi Empirical ◽

Photoionization Model

ABSTRACT We present a semi-empirical calibration between the metallicity (Z) of Seyfert 2 active galactic nuclei and the N2 = log([N ii]λ6584/H α) emission-line intensity ratio. This calibration was derived through the [O iii]λ5007/[O ii]λ3727 versus N2 diagram containing observational data and photoionization model results obtained with the cloudy code. The observational sample consists of 463 confirmed Seyfert 2 nuclei (redshift $z \: \lesssim 0.4$) taken from the Sloan Digital Sky Survey DR7 data set. The obtained Z–N2 relation is valid for the range $0.3 \: \lesssim \: (Z/{\rm Z}_{\odot }) \: \lesssim \: 2.0$ that corresponds to $-0.7 \: \lesssim \: ({\rm N}2) \: \lesssim \: 0.6$. The effects of varying the ionization parameter (U), electron density and the slope of the spectral energy distribution on the Z estimations are of the order of the uncertainty produced by the error measurements of N2. This result indicates the large reliability of our Z –N2 calibration. A relation between U and the [O iii]/[O ii] line ratio, almost independent of other nebular parameter, was obtained.

Carbon-loud SDSS BOSS type II quasars at z > 2: high-density gas or secondary production of carbon?

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa1409 ◽

2020 ◽

Vol 495 (4) ◽

pp. 4707-4746

Author(s):

M Silva ◽

A Humphrey ◽

P Lagos ◽

S G Morais

Keyword(s):

Abundance Ratio ◽

Systematic Difference ◽

Type Ii ◽

Narrow Line ◽

Chemical Abundances ◽

Gas Density ◽

Chemical Enrichment ◽

Order Of Magnitude ◽

Nitrogen Abundance

ABSTRACT We study the ultraviolet (UV) emission-line ratios of a sample of 145 type II quasars (QSO2s) from Sloan Digital Sky Survey iii Baryon Oscillation Spectroscopic Survey, and compare against a grid of active galactic nucleus (AGN) photoionization models with a range in gas density, gas chemical abundances, and ionization parameter. Most of the quasars are ‘carbon-loud’, with C iv/He ii ratios that are unusually high for the narrow-line region, implying higher than expected gas density (>106 cm−3) and/or significantly supersolar-relative carbon abundance. We also find that solar or supersolar nitrogen abundance and metallicity are required in the majority of our sample, with potentially significant variation between objects. Compared to radio galaxies at similar redshifts (HzRGs; z > 2), the QSO2s are offset to higher N v/He ii, C iv/He ii, and C iii]/He ii, suggesting systematically higher gas density and/or systematically higher C and N abundances. We find no evidence for a systematic difference in the N/C abundance ratio between the two types of objects. Scatter in the N iv]/C iv ratio implies a significant scatter in the N/C abundance ratio among the QSO2s and HzRGs, consistent with differences in the chemical enrichment histories between objects. Interestingly, we find that adopting secondary behaviour for both N and C alleviates the long-standing ‘N iv] problem’. A subset of the QSO2s and HzRGs also appear to be ‘silicon-loud’, with Si iii] relative fluxes suggesting Si/C and Si/O are an order of magnitude above their solar values. Finally, we propose new UV-line criteria to select genuine QSO2s with low-density narrow-line regions.

Broad-line region structure and line profile variations in the changing look AGN HE 1136-2304

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833727 ◽

2018 ◽

Vol 619 ◽

pp. A168 ◽

Cited By ~ 6

Author(s):

W. Kollatschny ◽

M. W. Ochmann ◽

M. Zetzl ◽

M. Haas ◽

D. Chelouche ◽

...

Keyword(s):

Seyfert Galaxies ◽

Spectroscopic Properties ◽

Emission Lines ◽

Broad Line ◽

Spectral Variability ◽

Continuum Source ◽

Line Intensities ◽

Broad Line Region ◽

Line Region ◽

Optical Continuum

Aims. A strong X-ray outburst was detected in HE 1136-2304 in 2014. Accompanying optical spectra revealed that the spectral type has changed from a nearly Seyfert 2 type (1.95), classified by spectra taken 10 and 20 years ago, to a Seyfert 1.5 in our most recent observations. We seek to investigate a detailed spectroscopic campaign on the spectroscopic properties and spectral variability behavior of this changing look AGN and compare this to other variable Seyfert galaxies. Methods. We carried out a detailed spectroscopic variability campaign of HE 1136-2304 with the 10 m Southern African Large Telescope (SALT) between 2014 December and 2015 July. Results. The broad-line region (BLR) of HE 1136-2304 is stratified with respect to the distance of the line-emitting regions. The integrated emission line intensities of Hα, Hβ, He I λ5876, and He II λ4686 originate at distances of 15.0−3.8+4.2, 7.5−5.7+4.6, 7.3−4.4+2.8, and 3.0−3.7+5.3 light days with respect to the optical continuum at 4570 Å. The variability amplitudes of the integrated emission lines are a function of distance to the ionizing continuum source as well. We derived a central black hole mass of 3.8 ± 3.1 × 107 M⊙ based on the linewidths and distances of the BLR. The outer line wings of all BLR lines respond much faster to continuum variations indicating a Keplerian disk component for the BLR. The response in the outer wings is about two light days shorter than the response of the adjacent continuum flux with respect to the ionizing continuum flux. The vertical BLR structure in HE 1136-2304 confirms a general trend that the emission lines of narrow line active galactic nuclei (AGNs) originate at larger distances from the midplane in comparison to AGNs showing broader emission lines. Otherwise, the variability behavior of this changing look AGN is similar to that of other AGN.

Barlenses in the CALIFA survey: Combining photometric and stellar population analyses

Astronomy and Astrophysics ◽

10.1051/0004-6361/201833138 ◽

2018 ◽

Vol 618 ◽

pp. A34 ◽

Author(s):

E. Laurikainen ◽

H. Salo ◽

J. Laine ◽

J. Janz

Keyword(s):

Stellar Population ◽

Population Analysis ◽

Central Component ◽

Time Period ◽

Stellar Ages ◽

Sky Survey ◽

First Time ◽

Field Area ◽

Integral Field

Aims: It is theoretically predicted that, at low galaxy inclinations, boxy/peanut bar components have a barlens appearance of a round central component embedded in the narrow bar. We investigate barlenses in the Calar Alto Legacy Integral Field Area (CALIFA) survey galaxies, studying their morphologies, stellar populations, and metallicities. We show that, when present, barlenses account for a significant portion of light of photometric bulges, i.e., the excess light on top of the disks, which highlights the importance of bars in accumulating central galaxy mass concentrations in the cosmic timescale. Methods: We made multi-component decompositions for a sample of 46 barlens galaxies drawn from the CALIFA survey, where M⋆/M⊙ = 109.7 − 1011.4 and z = 0.005 − 0.03. Unsharp masks of the Sloan Digital Sky Survey (SDSS) r′-band mosaics were used to identify the boxy/peanut or X-shaped features. Barlenses are identified in the images using our simulation snapshots as an additional guide. Our decompositions with GALFIT include bulges, disks, and bars as well as barlenses as a separate component. For 26 of the decomposed galaxies the CALIFA DR2 V500 grating data cubes were used to explore stellar ages and metallicities at the regions of various structure components. Results: We find that 25 ± 2% of the 1064 galaxies in the whole CALIFA sample show either X-shaped or barlens features. In the decomposed galaxies with barlenses, on average 13% ± 2% of the total galaxy light belongs to this component, leaving less than 10% for possible separate bulge components. Most importantly, bars and barlenses are found to have similar cumulative stellar age and metallicity distributions. The metallicities in barlenses are on average near solar, but exhibit a large range. In some of the galaxies barlenses and X-shaped features appear simultaneously, in which case the bar origin of the barlens is unambiguous. Conclusion: This is the first time that a combined morphological and stellar population analysis is used to study barlenses. We show that their stars are accumulated in a prolonged time period concurrently with the evolution of the narrow bar.

Baryon acoustic oscillations at z = 2.34 from the correlations of Lyα absorption in eBOSS DR14

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935638 ◽

2019 ◽

Vol 629 ◽

pp. A85 ◽

Cited By ~ 47

Author(s):

Victoria de Sainte Agathe ◽

Christophe Balland ◽

Hélion du Mas des Bourboux ◽

Nicolás G. Busca ◽

Michael Blomqvist ◽

...

Keyword(s):

Correlation Function ◽

Cross Correlation ◽

Companion Paper ◽

Acoustic Oscillations ◽

Angular Diameter Distance ◽

Quasar Spectra ◽

Sky Survey ◽

Baryon Acoustic Oscillations ◽

First Time

We measure the imprint of primordial baryon acoustic oscillations (BAOs) in the correlation function of Lyα absorption in quasar spectra from the Baryon Oscillation Spectroscopic Survey (BOSS) and the extended BOSS (eBOSS) in Data Release 14 (DR14) of the Sloan Digital Sky Survey (SDSS)-IV. In addition to 179 965 spectra with absorption in the Lyman-α (Lyα) region, we use Lyα absorption in the Lyman-β region of 56 154 spectra for the first time. We measure the Hubble distance, DH, and the comoving angular diameter distance, DM, relative to the sound horizon at the drag epoch rd at an effective redshift z = 2.34. Using a physical model of the correlation function outside the BAO peak, we find DH(2.34)/rd = 8.86 ± 0.29 and DM(2.34)/rd = 37.41 ± 1.86, within 1σ from the flat-ΛCDM model consistent with CMB anisotropy measurements. With the addition of polynomial “broadband” terms, the results remain within one standard deviation of the CMB-inspired model. Combined with the quasar-Lyα cross-correlation measurement presented in a companion paper, the BAO measurements at z = 2.35 are within 1.7σ of the predictions of this model.

The relation between the properties of the NLR in narrow-line Seyfert 1 galaxies and the accretion rate

Proceedings of the International Astronomical Union ◽

10.1017/s1743921307006011 ◽

2006 ◽

Vol 2 (S238) ◽

pp. 473-474

Author(s):

Dawei Xu ◽

Stefanie Komossa

Keyword(s):

Accretion Rate ◽

Physical Parameters ◽

Broad Line ◽

Narrow Line ◽

Black Hole Mass ◽

Line Region ◽

Sky Survey ◽

Narrow Line Region ◽

The Relationship

AbstractWe present a systematic study of the properties of the narrow-line region (NLR) of narrow-line Seyfert 1 galaxies (NLS1s) using Sloan Digital Sky Survey (SDSS) spectroscopy. Various correlations between the observed parameters and physical properties of NLS1s and broad-line Seyfert 1 galaxies (BLS1s) are detected. We search for possible origins of these trends by employing correlation analyses. We further investigate the relationship between black hole mass, Eddington ratio (L/LEdd) and physical parameters of the NLR.