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 xGASS: the role of bulges along and across the local star-forming main sequence

2020 ◽  
Vol 493 (4) ◽  
pp. 5596-5605 ◽  
Author(s):  
Robin H W Cook ◽  
Luca Cortese ◽  
Barbara Catinella ◽  
Aaron Robotham
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Formation Rate ◽  
Stellar Mass ◽  
Local Universe ◽  
Star Forming ◽  
Star Formation Activity ◽  
The Galaxy ◽  
Stellar Masses

ABSTRACT We use our catalogue of structural decomposition measurements for the extended GALEX Arecibo SDSS Survey (xGASS) to study the role of bulges both along and across the galaxy star-forming main sequence (SFMS). We show that the slope in the sSFR–M⋆ relation flattens by ∼0.1 dex per decade in M⋆ when re-normalizing specifice star formation rate (sSFR) by disc stellar mass instead of total stellar mass. However, recasting the sSFR–M⋆ relation into the framework of only disc-specific quantities shows that a residual trend remains against disc stellar mass with equivalent slope and comparable scatter to that of the total galaxy relation. This suggests that the residual declining slope of the SFMS is intrinsic to the disc components of galaxies. We further investigate the distribution of bulge-to-total ratios (B/T) as a function of distance from the SFMS (ΔSFRMS). At all stellar masses, the average B/T of local galaxies decreases monotonically with increasing ΔSFRMS. Contrary to previous works, we find that the upper envelope of the SFMS is not dominated by objects with a significant bulge component. This rules out a scenario in which, in the local Universe, objects with increased star formation activity are simultaneously experiencing a significant bulge growth. We suggest that much of the discrepancies between different works studying the role of bulges originate from differences in the methodology of structurally decomposing galaxies.

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 Starburst – AGN Connection: a Critical Review

2011 ◽  
Vol 20 (3) ◽  
Author(s):  
P. Rafanelli ◽  
G. La Mura ◽  
D. Bindoni ◽  
S. Ciroi ◽  
V. Cracco ◽  
...  
Keyword(s):  
Star Formation ◽  
Active Galaxies ◽  
Host Galaxy ◽  
Nuclear Activity ◽  
Massive Black Holes ◽  
Star Forming ◽  
Spectral Signatures ◽  
Star Formation Activity ◽  
Nuclear Regions

AbstractNuclear activity and star formation processes represent two key elements in the evolution of galaxies across the cosmic ages. In spite of very different physical backgrounds, several arguments suggest that they should be closely connected. On the basis of simple theoretical considerations, the transport of appreciable amounts of fuel to the AGN scale is very likely to trigger star formation in the gas. Young stellar populations, in their turn, are expected to affect the properties of the interstellar medium, leading to a complex balance of interactions among nuclear activity and star formation. This scenario is also supported by the observation of super-massive black holes and host galaxy properties, which strongly suggest a common evolutionary track. However, despite several years of extensive investigation, the relationship among the two processes still has to be properly explained. Here we provide a review of some of the most important observations, which are relevant to the issue of the connection among AGN and starburst events. Based on a wide sample of observations, we present an analysis of the spectral signatures connected with AGN and star formation activity. Expanding the concept of the distinction among star forming galaxies and the true active nuclei, we provide systematic evidence for a role of recent starburst events in the circum-nuclear regions of active galaxies and discuss the possibility of its influence onto the AGN environment. We also analyze the age, mass and metallicity properties of star-forming and active galaxies, illustrating that they are arranged in a sequence that is consistent with the identified relation.

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 SDSS-IV MaNGA: effects of morphology in the global and local star formation main sequences

2019 ◽  
Vol 488 (3) ◽  
pp. 3929-3948 ◽  
Author(s):  
M Cano-Díaz ◽  
V Ávila-Reese ◽  
S F Sánchez ◽  
H M Hernández-Toledo ◽  
A Rodríguez-Puebla ◽  
...  
Keyword(s):  
Star Formation ◽  
Surface Density ◽  
Main Sequence ◽  
Formation Rate ◽  
Stellar Mass ◽  
Star Forming ◽  
Spatially Resolved ◽  
Star Formation Activity ◽  
Global And Local ◽  
Universal Mechanism

ABSTRACT We study the global star formation rate (SFR) versus stellar mass (M*) correlation, and the spatially resolved SFR surface density (ΣSFR) versus stellar mass surface density (Σ*) correlation, in a sample of ∼2000 galaxies from the MaNGA MPL-5 survey. We classify galaxies and spatially resolved areas into star forming and retired according to their ionization processes. We confirm the existence of a star-forming main sequence (SFMS) for galaxies and spatially resolved areas, and show that they have the same nature, with the global as a consequence of the local one. The latter presents a bend below a limit Σ* value, ≈3 × 107 M$\odot$ kpc−2, which is not physical. Using only star-forming areas (SFAs) above this limit, a slope and a scatter of ≈1 and ≈0.27 dex are determined. The retired galaxies/areas strongly segregate from their respective SFMSs, by ∼−1.5 dex on average. We explore how the global/local SFMSs depend on galaxy morphology, finding that for star-forming galaxies and SFAs, there is a trend to lower values of star formation activity with earlier morphological types, which is more pronounced for the local SFMS. The morphology not only affects the global SFR due to the diminish of SFAs with earlier types, but also affects the local SF process. Our results suggest that the local SF at all radii is established by some universal mechanism partially modulated by morphology. Morphology seems to be connected to the slow aging and sharp decline of the SF process, and on its own it may depend on other properties as the environment.

scholarly journals The build-up of the outskirts of distant star-forming galaxies at z ~ 2

2016 ◽  
Vol 11 (S321) ◽  
pp. 327-329 ◽  
Author(s):  
Sandro Tacchella ◽  
C. Marcella Carollo ◽  
Avishai Dekel ◽  
Natascha Förster Schreiber ◽  
Alvio Renzini ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Stellar Mass ◽  
Mass Star ◽  
Intermediate Mass ◽  
Massive Galaxies ◽  
Star Forming ◽  
Star Formation Activity ◽  
Dust Attenuation ◽  
Inside Out

AbstractIn order to constrain – and understand – the growth of galaxies, we present a sample of ~ 30 galaxies at z ~ 2 with resolved distribution of stellar mass, star-formation rate, and dust attenuation on scales of ~ 1 kpc. We find that low- and intermediate-mass galaxies grow self-similarly, doubling their stellar mass in the centers and outskirts with the same pace. More massive galaxies (~ 1011 M⊙) have a reduced star-formation activity in their center: they grow mostly in the outskirts (inside-out quenching / formation). Similar trends are find in cosmological zoom-in simulations, highlighting that high stellar mass densities are formed in a gas-rich compaction phase. This nuclear ‘starburst’ phase is followed by a suppressed star-formation activity in the center, resulting in growth of the outskirts. All in all, we put forward that we witness at z ~ 2 the dissipative formation of z = 0 M* early-type galaxies.

scholarly journals Mid-IR Spectroscopy of Submm Galaxies: Extended Star Formation in High-z Galaxies

2009 ◽  
Vol 5 (H15) ◽  
pp. 423-424
Author(s):  
K. Menéndez-Delmestre ◽  
A. W. Blain ◽  
I. Smail ◽  
D. M. Alexander ◽  
S. C. Chapman ◽  
...  
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
Dust Emission ◽  
Infrared Galaxies ◽  
Local Universe ◽  
Star Forming ◽  
Luminous Infrared Galaxies ◽  
Star Formation Activity ◽  
Polycyclic Aromatic ◽  
Intense Star Formation

AbstractUltra-luminous infrared galaxies (ULIRGs; L > 1012 L⊙) are quite rare in the local universe, but seem to dominate the co-moving energy density at z > 2. Many are optically-faint, dust-obscured galaxies that have been identified only relatively recently by the detection of their thermal dust emission redshifted into the sub-mm wavelengths. These submm galaxies (SMGs) have been shown to be a massive objects (M* ~ 1011 M⊙) undergoing intense star-formation(SFRs ~ 102 − 103 M⊙ yr−1) and the likely progenitors of massive ellipticals today. However, the AGN contribution to the far-IR luminosity had for years remained a caveat to these results. We used the Spitzer Infrared Spectrograph (IRS) to investigate the energetics of 24 radio-identified and spectroscopically-confirmed SMGs in the redshift range of 0.6 < z < 3.2. We find emission from Polycyclic Aromatic Hydrocarbons (PAHs) – which are associated with intense star-formation activity – in >80% of our sample and find that the median mid-IR spectrum is well described by a starburst component with an additional power-law continuum representing < 32% AGN contribution to the far-IR luminosity. We also find evidence for a more extended distribution of warm dust in SMGs compared to the more compact nuclear bursts in local ULIRGs and starbursts, suggesting that SMGs are not simple high-redshift analogs of local ULIRGs or nuclear starbursts, but have star formation which resembles that seen in less-extreme star-forming environments at z ~ 0.

Probing the building blocks of galaxies: Sub-galactic scaling relations between X-ray luminosity, SFR and stellar mass

2019 ◽  
Vol 15 (S341) ◽  
pp. 162-166
Author(s):  
K. Kouroumpatzakis ◽  
A. Zezas ◽  
P. H. Sell ◽  
P. Bonfini ◽  
M. L. N. Ashby ◽  
...  
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Building Blocks ◽  
Stellar Mass ◽  
High Mass ◽  
Scaling Relations ◽  
Local Universe ◽  
X Ray ◽  
Star Formation Activity ◽  
X Ray Binaries

AbstractIt is well known that X-ray luminosity (Lx) originating from high mass X-ray binaries (HMXBs) is tightly correlated with the host galaxy’s star formation rate (SFR). We explore this connection using a sample representative of the star-formation activity in the local Universe (Star-Formation Reference Survey; SFRS) along with a comprehensive set of star-formation (radio, FIR, 24μm, 8 μm, Hα, UV, SED fitting) and stellar mass (K-band, 3.6 μm, SED fitting) indicators, and Chandra observations. We investigate the Lx–SFR and Lx– stellar mass (M*) scaling relations down to sub-galactic scales of ∼lkpc2. This way we extend these relations to extremely low SFR (∼10−6M⊙.yr−1) and M* (∼104M⊙). We also quantify their scatter and their dependence on the age of the local stellar populations as inferred from the different age sensitive SFR indicators. These results are particularly important for setting the benchmark for the formation of X-ray binaries in vigorous, but low SFR objects such as galaxies in the early Universe.

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