scholarly journals Constraining photoionization models with a reprojected optical diagnostic diagram

2020 ◽  
Vol 499 (4) ◽  
pp. 5749-5764 ◽  
Author(s):  
Xihan Ji ◽  
Renbin Yan
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Theoretical Models ◽  
Line Ratio ◽  
Star Forming ◽  
Optical Diagnostic ◽  
Diagnostic Diagram ◽  
Upper Limits ◽  
Nitrogen Abundance

ABSTRACT Optical diagnostic diagrams are powerful tools to separate different ionizing sources in galaxies. However, the model-constraining power of the most widely used diagrams is very limited and challenging to visualize. In addition, there have always been classification inconsistencies between diagrams based on different line ratios, and ambiguities between regions purely ionized by active galactic nuclei (AGNs) and composite regions. We present a simple reprojection of the 3D line ratio space composed of [N ii]λ6583/H α, [S ii]λλ6716, 6731/H α, and [O iii]λ5007/H β, which reveals its model-constraining power and removes the ambiguity for the true composite objects. It highlights the discrepancy between many theoretical models and the data loci. With this reprojection, we can put strong constraints on the photoionization models and the secondary nitrogen abundance prescription. We find that a single nitrogen prescription cannot fit both the star-forming locus and AGN locus simultaneously, with the latter requiring higher N/O ratios. The true composite regions stand separately from both models. We can compute the fractional AGN contributions for the composite regions, and define demarcations with specific upper limits on contamination from AGN or star formation. When the discrepancy about nitrogen prescriptions gets resolved in the future, it would also be possible to make robust metallicity measurements for composite regions and AGNs.

scholarly journals The dependence of mass and environment on the secular processes of AGNs in terms of morphology, colour, and specific star-formation rate

2018 ◽  
Vol 620 ◽  
pp. A113 ◽  
Author(s):  
M. Argudo-Fernández ◽  
I. Lacerna ◽  
S. Duarte Puertas
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Galactic Nuclei ◽  
Stellar Mass ◽  
High Mass ◽  
Late Type ◽  
Star Forming ◽  
Isolated Galaxies

Context. Galaxy mass and environment play a major role in the evolution of galaxies. In the transition from star-forming to quenched galaxies, active galactic nuclei (AGNs) also have a principal action therein. However, the connections between these three actors are still uncertain. Aims. In this work we investigate the effects of stellar mass and the large-scale structure (LSS) environment on the fraction of optical nuclear activity in a population of isolated galaxies, where AGN would not be triggered by recent galaxy interactions or mergers. Methods. As a continuation of a previous work, we focus on isolated galaxies to study the effect of stellar mass and the LSS in terms of morphology (early- and late-type), colour (red and blue), and specific star-formation rate (quenched and star-forming). To explore where AGN activity is affected by the LSS, we separate galaxies into two groups, of low- and high mass, respectively, and use the tidal strength parameter to quantify the effects. Results. We found that AGN is strongly affected by stellar mass in “active” galaxies (namely late-type, blue, and star-forming), but that mass has no influence on “quiescent” galaxies (namely early-type, red, and quenched), at least for masses down to 1010 M⊙. In relation to the LSS, we found an increase in the fraction of star-forming nuclei galaxies with denser LSS in low-mass star-forming and red isolated galaxies. Regarding AGN, we find a clear increase in the fraction of AGNs with denser environment in quenched and red isolated galaxies, independently of the stellar mass. Conclusions. Active galactic nuclei activity appears to be “mass triggered” in active isolated galaxies. This means that AGN activity is independent of the intrinsic properties of the galaxies, but is dependent on their stellar mass. On the other hand, AGN activity appears to be “environment triggered” in quiescent isolated galaxies, where the fraction of AGNs as a function of specific star formation rate and colour increases from void regions to denser LSS, independently of stellar mass.

scholarly journals The CO(3–2)/CO(1–0) Luminosity Line Ratio in Nearby Star-forming Galaxies and Active Galactic Nuclei from xCOLD GASS, BASS, and SLUGS

2020 ◽  
Vol 889 (2) ◽  
pp. 103 ◽  
Author(s):  
Isabella Lamperti ◽  
Amélie Saintonge ◽  
Michael Koss ◽  
Serena Viti ◽  
Christine D. Wilson ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Line Ratio ◽  
Nearby Star ◽  
Star Forming

scholarly journals The AGN-Starburst Connection traced by the Nitrogen Abundance

2012 ◽  
Vol 8 (S290) ◽  
pp. 273-274
Author(s):  
Kenta Matsuoka ◽  
Tohru Nagao ◽  
Alessandro Marconi ◽  
Roberto Maiolino ◽  
Yoshiaki Taniguchi
Keyword(s):  
Black Holes ◽  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
Agb Stars ◽  
Line Flux ◽  
Quasar Spectra ◽  
Star Formation Activity ◽  
Nitrogen Abundance

AbstractThe connection between the active galactic nuclei (AGNs) and star formation activity is one of the most important issues in understanding the coevolution of supermassive black holes (SMBHs) and galaxies. In our recent study, by using SDSS quasar spectra we found that the emission-line flux rations involving a nitrogen line correlate with the Eddington ratio. This correlation suggests that the mass accretion in quasars is associated with a post-starburst phase, when AGB stars enrich the interstellar medium with the nitrogen. Moreover, we focused on nitrogen-loud quasars, that have prominent emission lines of the nitrogen, to investigate whether this argument is correct. In this symposium, we present our results regarding the relation between the star formation and feeding to SMBHs traced by the nitrogen abundance.

scholarly journals THE BIASES OF OPTICAL LINE-RATIO SELECTION FOR ACTIVE GALACTIC NUCLEI AND THE INTRINSIC RELATIONSHIP BETWEEN BLACK HOLE ACCRETION AND GALAXY STAR FORMATION

2015 ◽  
Vol 811 (1) ◽  
pp. 26 ◽  
Author(s):  
Jonathan R. Trump ◽  
Mouyuan Sun ◽  
Gregory R. Zeimann ◽  
Cuyler Luck ◽  
Joanna S. Bridge ◽  
...  
Keyword(s):  
Black Hole ◽  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Line Ratio ◽  
Black Hole Accretion ◽  
Optical Line ◽  
Selection For ◽  
Hole Accretion

scholarly journals Close pairs of galaxies with different activity levels

2013 ◽  
Vol 9 (S304) ◽  
pp. 327-330 ◽  
Author(s):  
T. A. Nazaryan ◽  
A. R. Petrosian ◽  
A. A. Hakobyan ◽  
B. J. McLean ◽  
D. Kunth
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Spectral Properties ◽  
Large Scale ◽  
Interaction Strength ◽  
Galactic Nuclei ◽  
Morphological Type ◽  
Activity Levels ◽  
Star Forming ◽  
Interacting Systems

AbstractWe selected and studied 180 pairs with d V < 800 km s−1 and Dp < 60 kpc containing Markarian (MRK) galaxies to investigate the dependence of galaxies integral parameters, star-formation (SF) and active galactic nuclei (AGN) properties on kinematics of pairs, their structure and large-scale environments. Projected radial separation Dp and perturbation level P are better measures of interaction strength than dV. The latter correlates with the density of large-scale environment and with the morphologies of galaxies. Both galaxies in a pair are of the same nature, the only difference is that MRK galaxies are usually brighter than their neighbors. Specific star formation rates (SSFR) of galaxies in pairs with smaller Dp or d V is in average 0.5 dex higher than that of galaxies in pairs with larger Dp or d V. Closeness of a neighbor with the same and later morphological type increases the SSFR, while earlier-type neighbors do not increase SSFR. Major interactions/mergers trigger SF and AGN more effectively than minor ones. The fraction of AGNs is higher in more perturbed pairs and pairs with smaller Dp. AGNs typically are in stronger interacting systems than star-forming and passive galaxies. There are correlations of both SSFRs and spectral properties of nuclei between pair members.

scholarly journals An IFU View of the Active Galactic Nuclei in MaNGA Galaxy Pairs

2021 ◽  
Vol 923 (1) ◽  
pp. 6
Author(s):  
Gaoxiang Jin ◽  
Y. Sophia Dai ◽  
Hsi-An Pan ◽  
Lihwai Lin ◽  
Cheng Li ◽  
...  
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Formation Rate ◽  
Galactic Nuclei ◽  
Central Star ◽  
Mass Star ◽  
Star Forming ◽  
Isolated Galaxies ◽  
Radial Profiles ◽  
Significant Difference

Abstract The role of active galactic nuclei (AGNs) during galaxy interactions and how they influence the star formation in the system are still under debate. We use a sample of 1156 galaxies in galaxy pairs or mergers (hereafter “pairs”) from the MaNGA survey. This pair sample is selected by the velocity offset, projected separation, and morphology, and is further classified into four cases along the merger sequence based on morphological signatures. We then identify a total of 61 (5.5%) AGNs in pairs based on the emission-line diagnostics. No evolution of the AGN fraction is found, either along the merger sequence or compared to isolated galaxies (5.0%). We observe a higher fraction of passive galaxies in galaxy pairs, especially in the pre-merging cases, and associate the higher fraction to their environmental dependence. The isolated AGN and AGNs in pairs show similar distributions in their global stellar mass, star-formation rate (SFR), and central [O iii] surface brightness. AGNs in pairs show radial profiles of increasing specific SFR and declining Dn4000 from center to outskirts, and no significant difference from the isolated AGNs. This is clearly different from star-forming galaxies (SFGs) in our pair sample, which show enhanced central star formation, as reported before. AGNs in pairs have lower Balmer decrements at outer regions, possibly indicating less dust attenuation. Our findings suggest that AGNs are likely follow an inside-out quenching and the merger impact on the star formation in AGNs is less prominent than in SFGs.

Role of environment on AGN activity

2019 ◽  
Vol 15 (S356) ◽  
pp. 171-171
Author(s):  
Amirnezam Amiri
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galaxy Clusters ◽  
Galactic Nuclei ◽  
Stellar Mass ◽  
Local Universe ◽  
Nuclear Activity ◽  
Star Forming ◽  
Star Formation Activity

AbstractMotivated by the apparently conflicting results reported in the literature on the effect of environment on nuclear activity, we have carried out a new analysis by comparing the fraction of galaxies hosting active galactic nuclei (AGNs) in the most overdense regions (rich galaxy clusters) and the most underdense ones (voids) in the local universe. Exploiting the classical BPT diagnostics, we have extracted volume limited samples of star forming and AGN galaxies. We find that, at variance with star-forming galaxies, AGN galaxies have similar distributions of specific star formation rates and of galactic ages (as indicated by the Dn4000 parameter) both in clusters and in voids. In both environments galaxies hosting AGNs are generally old, with low star formation activity. The AGN fraction increases faster with stellar mass in clusters than in voids, especially above 1010.2 M⊙. Our results indicate that, in the local universe, the nuclear activity correlates with stellar mass and galaxy morphology and is weakly, if at all, affected by the local galaxy density.

scholarly journals X-rays from Green Pea analogues

2017 ◽  
Vol 470 (1) ◽  
pp. 606-611 ◽  
Author(s):  
M. Brorby ◽  
P. Kaaret
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Formation Rate ◽  
Galactic Nuclei ◽  
High Mass ◽  
X Rays ◽  
X Ray ◽  
Star Forming ◽  
Green Pea ◽  
X Ray Binaries

Abstract X-ray observations of two metal-deficient luminous compact galaxies (LCG; SHOC 486 and SDSS J084220.94+115000.2) with properties similar to the so-called Green Pea galaxies were obtained using the Chandra X-ray Observatory. Green Pea galaxies are relatively small, compact (a few kpc across) galaxies that get their green colour from strong [O iii] λ5007 Å emission, an indicator of intense, recent star formation. These two galaxies were predicted to have the highest observed count rates, using the X-ray luminosity–star formation rate (LX–SFR) relation for X-ray binaries, from a statistically complete sample drawn from optical criteria. We determine the X-ray luminosity relative to SFR and metallicity for these two galaxies. Neither exhibits any evidence of active galactic nuclei, and we suspect that the X-ray emission originates from unresolved populations of high-mass X-ray binaries. We discuss the LX–SFR–metallicity plane for star-forming galaxies and show that the two LCGs are consistent with the prediction of this relation. This is the first detection of Green Pea analogues in X-rays.

scholarly journals Obtaining the (dust-obscured) star formation history using the VLA-COSMOS survey

2006 ◽  
Vol 2 (S235) ◽  
pp. 428-428
Author(s):  
V. Smolčić ◽  
E. Schinnerer ◽  
M. Scodeggio ◽  
C.L. Carilli ◽  
P. Franzetti ◽  
...  
Keyword(s):  
Star Formation ◽  
Active Galactic Nuclei ◽  
Galactic Nuclei ◽  
Photometric Data ◽  
Star Formation History ◽  
Star Forming ◽  
Radio Data ◽  
Formation History ◽  
First Results ◽  
Multi Wavelength

AbstractUsing the multi-wavelength COSMOS survey (Scoville et al. 2006), we develop a method based on purely photometric data to separate the faint VLA-COSMOS radio population into star-forming (SF) galaxies and active-galactic nuclei (AGN). Based on this classification method we select SF galaxies within our sample and present first results on the cosmic (dust-obscured) star-formation history based on VLA-COSMOS (Schinnerer et al. 2006) radio data.

scholarly journals Subaru narrow-band imaging search for Lyman continuum from galaxies at z > 3 in the GOODS-N field

2019 ◽  
Vol 488 (4) ◽  
pp. 5671-5689 ◽  
Author(s):  
Ikuru Iwata ◽  
Akio K Inoue ◽  
Genoveva Micheva ◽  
Yuichi Matsuda ◽  
Toru Yamada
Keyword(s):  
Active Galactic Nuclei ◽  
Narrow Band ◽  
Narrow Band Imaging ◽  
Density Ratio ◽  
Galactic Nuclei ◽  
Star Forming ◽  
Lyman Continuum ◽  
Band Filter ◽  
Upper Limits ◽  
Narrow Band Filter

Abstract We report results of a search for galaxies at z &gt; 3 with Lyman continuum (LyC) emission using a narrow-band filter NB359  with Subaru/Suprime-Cam in an ∼800 arcmin2 blank field around the GOODS-N. We use 103 star-forming galaxies (SFGs) and 8 active galactic nuclei (AGNs) with spectroscopic redshifts in a range between 3.06 and 3.5 and 157 photometrically selected z = 3.1 Lyman α emitter (LAE) candidates as the targets. After removing galaxies spectroscopically confirmed to be contaminated by foreground sources, we found two SFGs and one AGN as candidate LyC-emitting sources among the targets with spectroscopic redshifts. Among LAE candidates, five sources are detected in the NB359 image, and three among them may be contaminated by foreground sources. We compare the sample galaxies in the GOODS-N with those in the SSA22, where a prominent protocluster at z = 3.1 is known and an LyC search using the same NB359 filter has been made. The frequency of galaxies with LyC leakage in the SSA22 field may be about two times higher than that of galaxies in the GOODS-N with the sample ultraviolet (UV) magnitude range, although the numbers of LyC detections in these fields are too small to make a statistically significant conclusion. By combining the sample galaxies in these fields, we place the 3σ upper limits of the observed LyC-to-UV flux density ratio and LyC escape fraction for galaxies at z = 3.1 with absolute UV magnitude MUV &lt; −18.8 as (fLyC/fUV)obs &lt; 0.036 and $f_\mathrm{esc}^\mathrm{abs}\,\lt\, 8$ per cent, respectively.

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