scholarly journals Active galactic nucleus feedback in an elliptical galaxy with the most updated AGN physics: Parameter explorations

2020 ◽  
Vol 501 (1) ◽  
pp. 398-410
Author(s):  
Zhiyuan Yao ◽  
Feng Yuan ◽  
Jeremiah P Ostriker
Keyword(s):  
Star Formation ◽  
Active Galactic Nucleus ◽  
Accretion Rate ◽  
State Of The Art ◽  
Elliptical Galaxy ◽  
Model Parameters ◽  
Mass Growth ◽  
Radiative Efficiency ◽  
The Galaxy ◽  
Parameter Values

ABSTRACT In a previous work, we have proposed a sub-grid model of active galactic nucleus (AGN) feedback by taking into account the state-of-the-art AGN physics, and used that model to study the effect of AGN feedback on the evolution of an isolated elliptical galaxy by performing 2D high-resolution (i.e. the Bondi radius is well resolved) simulations. In that work, typical values of model parameters were adopted. In this work, we extend that study by exploring the effects of uncertainties of parameter values. Such a study is also useful for us to understand the respective roles of various components of the model. These parameters include the mass flux and velocity of AGN wind and radiative efficiency in both the hot and cold feedback modes, and the initial black hole (BH) mass. We find that the velocity of AGN wind in the hot mode is the most important quantity to control the typical accretion rate and luminosity of AGN, and the mass growth of the BH. The effect of the wind on star formation is less sensitive. Within the limited parameter range explored in this work, a stronger AGN wind suppresses star formation within ∼100 pc but enhances star formation beyond this radius, while the star formation integrated over the evolution time and the whole galaxy roughly remain unchanged. AGN radiation suppresses the BH accretion in a mild way, but dust is not considered here. Finally, a smaller initial BH mass results in a more violent evolution of the BH accretion rate. The corresponding AGN spends more time in the high-luminosity state and the percentage of BH mass growth is higher. Our results indicate the robustness of AGN feedback in keeping the galaxy quenched.

Numerical study of active galactic nucleus feedback in an elliptical galaxy with MACER

2018 ◽  
Vol 14 (S342) ◽  
pp. 101-107
Author(s):  
Feng Yuan ◽  
Jeremiah P. Ostriker ◽  
DooSoo Yoon ◽  
Ya-Ping Li ◽  
Luca Ciotti ◽  
...  
Keyword(s):  
Star Formation ◽  
Light Curve ◽  
Accretion Rate ◽  
Numerical Study ◽  
Dominant Role ◽  
Elliptical Galaxy ◽  
Formation Rate ◽  
Host Galaxy ◽  
Physical Processes ◽  
The Galaxy

AbstractThis paper summarizes our recent works of studying AGN feedback in an isolated elliptical galaxy by performing high-resolution hydrodynamical numerical simulations. Bondi radius is resolved and the mass accretion rate of the black hole is calculated. The most updated AGN physics, namely the discrimination of cold and hot accretion modes and the exact descriptions of the AGN radiation and wind for a given accretion rate are adopted and their interaction with the gas in the host galaxy is calculated. Physical processes such as star formation and SNe feedback are taken into account. Consistent with observation, we find the AGN spends most of the time in the low-luminosity regime. AGN feedback overall suppresses the star formation; but depending on location in the galaxy and time, it can also enhance it. The light curve of specific star formation rate is not synchronous with the AGN light curve. These results put a serious challenge to the observational test of the relation between AGN activity and star formation. We find that wind usually plays a dominant role in controlling the AGN luminosity and star formation, but radiation also cannot be neglected.

scholarly journals The Origin of the Colour Bimodality in the Scatter of the Stellar-to-Halo Mass Relation

2020 ◽  
Author(s):  
Weiguang Cui ◽  
Romeel Dave ◽  
John Peacock ◽  
Daniel Anglés-Alcázar ◽  
Xiaohu Yang
Keyword(s):  
Star Formation ◽  
Stellar Mass ◽  
Transition Time ◽  
Mass Relation ◽  
Mass Growth ◽  
The Galaxy ◽  
Blue Galaxies ◽  
Late Transition ◽  
Early Transition ◽  
Cold Gas

Abstract Recent observations reveal that there is a strong bimodality in the scatter around the galaxy stellar-to-halo mass relation (SHMR): at a given halo mass, galaxies with a higher stellar mass tend to be blue indicating a higher specific star formation rate, while galaxies having a lower stellar mass tend to be red and quiescent; or at a given stellar mass, blue galaxies tend to live in halos with lower mass while red galaxies tend to have massive host halo. This has important implications for abundance matching and halo occupancy models commonly used in cosmological studies, but its physical origin remains debated. The SIMBA cosmological galaxy formation simulation successfully reproduces these observations, enabling us to investigate the physical driver behind this phenomenon. We show that the offset from the mean SHMR is strongly correlated with both halo formation time when half the halo mass assembled, as well as galaxy transition time defined as when the stellar doubling time becomes longer than 10 Gyr. Moreover, these two quantities are anti-correlated: early formed halos tend to host late transition galaxies corresponding to blue galaxies today, and vice versa, particularly for halo masses 11.5 ≲ log Mhalo ≲ 12.8M⊙ and galaxy stellar masses log M∗ ≥ 10M⊙. Prior to their transition time, galaxies lie on the SHMR for blue galaxies. Early transition galaxies, hosted by late formed halos, have their stellar mass growth almost ceased owing to AGN feedback even though their host halos continue to accrete mass, which moves these galaxies off the blue SHMR towards the red one creating the SHMR bimodality. We then investigate why early formed halos tend to host late transition galaxies. We find two key interconnected times: the gas-to-stellar domination time when the galaxy’s cold gas mass becomes smaller than its stellar mass, and the black hole (BH) jet ignition time governed by the BH Eddington ratio. Both show strong linear correlations with the galaxy transition time. Early formed halos have higher cold gas fractions (defined by cold gas mass in central galaxy with respect to the host halo mass) with a lower stellar-to-halo mass growth ratio before the transition time compared to the median or late forming halos; this allows them to sustain their stellar growth longer. Eventually, the continued growth fed by the cold gas reservoir allows them to surpass the galaxies with early transition times. Conversely, galaxies hosted by late formed halos have less cold gas with high stellar-to-halo mass growth ratios. Hence the Eddington rate be-comes low earlier on, which triggers AGN into an energetic jet mode that heats gas, rapidly truncates further accretion and also stops star formation. These processes thus conspire to create the SHMR bimodality. In SIMBA, the cold gas evolution occurs naturally owing to the interplay of accretion and star formation feedback, while the AGN feedback transitions from a radiative mode at high Eddington ratios that is ineffective at quenching, to a jet mode at low Eddington ratios that suppresses star formation. SIMBA further includes X-ray feedback that drives the last remaining cold gas out, completing the quenching and strengthening the SHMR bimodality.

scholarly journals Hard X-Ray Irradiation Potentially Drives Negative AGN Feedback by Altering Molecular Gas Properties

2021 ◽  
Vol 257 (2) ◽  
pp. 64
Author(s):  
Taiki Kawamuro ◽  
Claudio Ricci ◽  
Takuma Izumi ◽  
Masatoshi Imanishi ◽  
Shunsuke Baba ◽  
...  
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Active Galactic Nucleus ◽  
Accretion Rate ◽  
Spatial Separation ◽  
Molecular Gas ◽  
X Ray ◽  
Mass Accretion Rate ◽  
Nuclear Regions

Abstract To investigate the role of active galactic nucleus (AGN) X-ray irradiation on the interstellar medium (ISM), we systematically analyzed Chandra and Atacama Large Millimeter/submillimeter Array CO (J = 2–1) data for 26 hard X-ray (>10 keV) selected AGNs at redshifts below 0.05. While Chandra unveils the distribution of X-ray-irradiated gas via Fe-Kα emission, the CO (J = 2–1) observations reveal that of cold molecular gas. At high resolutions ≲1″, we derive Fe-Kα and CO (J = 2–1) maps for the nuclear 2″ region and for the external annular region of 2″–4″, where 2″ is ∼100–600 pc for most of our AGNs. First, focusing on the external regions, we find the Fe-Kα emission for six AGNs above 2σ. Their large equivalent widths (≳1 keV) suggest a fluorescent process as their origin. Moreover, by comparing the 6–7 keV/3–6 keV ratio, as a proxy of Fe-Kα, and CO (J = 2–1) images for three AGNs with the highest significant Fe-Kα detections, we find a possible spatial separation. These suggest the presence of X-ray-irradiated ISM and the change in the ISM properties. Next, examining the nuclear regions, we find that (1) the 20–50 keV luminosity increases with the CO (J = 2–1) luminosity; (2) the ratio of CO (J = 2–1)/HCN (J = 1–0) luminosities increases with 20–50 keV luminosity, suggesting a decrease in the dense gas fraction with X-ray luminosity; and (3) the Fe-Kα-to-X-ray continuum luminosity ratio decreases with the molecular gas mass. This may be explained by a negative AGN feedback scenario: the mass accretion rate increases with gas mass, and simultaneously, the AGN evaporates a portion of the gas, which possibly affects star formation.

scholarly journals AGN feedback and star formation in ETGs: negative and positive feedback

2015 ◽  
Vol 11 (S315) ◽  
pp. 224-227 ◽  
Author(s):  
Luca Ciotti ◽  
Jeremiah P. Ostriker ◽  
Andrea Negri ◽  
Silvia Pellegrini ◽  
Silvia Posacki ◽  
...  
Keyword(s):  
Black Holes ◽  
Star Formation ◽  
Stellar Population ◽  
State Of The Art ◽  
Host Galaxy ◽  
Early Type ◽  
Spatial And Temporal Scales ◽  
Cooling Flows ◽  
The Galaxy ◽  
Hydrodynamical Simulations

AbstractAGN feedback from supermassive black holes (SMBHs) at the center of early type galaxies is commonly invoked as the explanation for the quenching of star formation in these systems. The situation is complicated by the significant amount of mass injected in the galaxy by the evolving stellar population over cosmological times. In absence of feedback, this mass would lead to unobserved galactic cooling flows, and to SMBHs two orders of magnitude more massive than observed. By using high-resolution 2D hydrodynamical simulations with radiative transport and star formation in state-of-the-art galaxy models, we show how the intermittent AGN feedback is highly structured on spatial and temporal scales, and how its effects are not only negative (shutting down the recurrent cooling episodes of the ISM), but also positive, inducing star formation in the inner regions of the host galaxy.

A population synthesis study of the local white dwarf population

2017 ◽  
Vol 13 (S334) ◽  
pp. 374-375
Author(s):  
Santiago Torres ◽  
Florian Nutten ◽  
Georgy Skorobogatov ◽  
Enrique García-Berro
Keyword(s):  
Monte Carlo ◽  
Star Formation ◽  
White Dwarf ◽  
Star Formation Rate ◽  
State Of The Art ◽  
Formation Rate ◽  
The Sun ◽  
Population Synthesis ◽  
Monte Carlo Techniques ◽  
The Galaxy

AbstractWhite dwarfs are natural cosmochronometers, and this allows us to use them to study relevant properties of the Galaxy, such as its age or its star formation rate history. Here we present a population synthesis study of the white dwarf population within 40 pc from the Sun, and compare the results of this study with the properties of the observed sample. We use a state-of-the-art population synthesis code based on Monte Carlo techniques that incorporates the most recent and reliable white dwarf cooling sequences, an accurate description of the Galactic neighborhood, and a realistic treatment of all the known observational biases.

scholarly journals Signatures of Cool Gas Fueling a Star-Forming Galaxy at Redshift 2.3

Science ◽  
2013 ◽  
Vol 341 (6141) ◽  
pp. 50-53 ◽  
Author(s):  
N. Bouché ◽  
M. T. Murphy ◽  
G. G. Kacprzak ◽  
C. Péroux ◽  
T. Contini ◽  
...  
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Accretion Rate ◽  
Formation Rate ◽  
Observational Evidence ◽  
Intergalactic Gas ◽  
Star Forming ◽  
The Galaxy ◽  
Cool Gas ◽  
Gas Accretion

Galaxies are thought to be fed by the continuous accretion of intergalactic gas, but direct observational evidence has been elusive. The accreted gas is expected to orbit about the galaxy’s halo, delivering not just fuel for star formation but also angular momentum to the galaxy, leading to distinct kinematic signatures. We report observations showing these distinct signatures near a typical distant star-forming galaxy, where the gas is detected using a background quasar passing 26 kiloparsecs from the host. Our observations indicate that gas accretion plays a major role in galaxy growth because the estimated accretion rate is comparable to the star-formation rate.

scholarly journals Estimation of Galactic Model Parameters by Interval Method

1996 ◽  
Vol 169 ◽  
pp. 713-714
Author(s):  
S. A. Kutuzov
Keyword(s):  
Mutual Interaction ◽  
Component Model ◽  
Model Parameters ◽  
Interval Method ◽  
Two Component ◽  
The Galaxy ◽  
Galactic Model

The interval method of estimating model parameters (MPs) for the Galaxy was suggested earlier (Kutuzov 1988). Intervals are proposed to be used both for observational estimates of galactic parameters (GPs) and for the values of MPs. In this work we consider a model as a tool for studying mutual interaction of GPs. Two-component model is considered (Kutuzov, Ossipkov 1989). We have to estimate the array P of eight MPs.

scholarly journals GASTON: Galactic Star Formation with NIKA2. Evidence for the mass growth of star-forming clumps

2021 ◽  
Author(s):  
A J Rigby ◽  
N Peretto ◽  
R Adam ◽  
P Ade ◽  
M Anderson ◽  
...  
Keyword(s):  
Star Formation ◽  
Large Scale ◽  
Galactic Plane ◽  
High Sensitivity ◽  
High Mass ◽  
Evolutionary Stage ◽  
Mass Star ◽  
Mass Growth ◽  
Star Forming ◽  
Compact Source

Abstract Determining the mechanism by which high-mass stars are formed is essential for our understanding of the energy budget and chemical evolution of galaxies. By using the New IRAM KIDs Array 2 (NIKA2) camera on the Institut de Radio Astronomie Millimétrique (IRAM) 30-m telescope, we have conducted high-sensitivity and large-scale mapping of a fraction of the Galactic plane in order to search for signatures of the transition between the high- and low-mass star-forming modes. Here, we present the first results from the Galactic Star Formation with NIKA2 (GASTON) project, a Large Programme at the IRAM 30-m telescope which is mapping ≈2 deg2 of the inner Galactic plane (GP), centred on ℓ = 23${_{.}^{\circ}}$9, b = 0${_{.}^{\circ}}$05, as well as targets in Taurus and Ophiuchus in 1.15 and 2.00 mm continuum wavebands. In this paper we present the first of the GASTON GP data taken, and present initial science results. We conduct an extraction of structures from the 1.15 mm maps using a dendrogram analysis and, by comparison to the compact source catalogues from Herschel survey data, we identify a population of 321 previously-undetected clumps. Approximately 80 per cent of these new clumps are 70 μm-quiet, and may be considered as starless candidates. We find that this new population of clumps are less massive and cooler, on average, than clumps that have already been identified. Further, by classifying the full sample of clumps based upon their infrared-bright fraction – an indicator of evolutionary stage – we find evidence for clump mass growth, supporting models of clump-fed high-mass star formation.

scholarly journals On the emergent system mass function: the contest between accretion and fragmentation

2020 ◽  
Vol 500 (2) ◽  
pp. 1697-1707
Author(s):  
Paul C Clark ◽  
Anthony P Whitworth
Keyword(s):  
Star Formation ◽  
Standard Deviation ◽  
Mass Distribution ◽  
Power Law ◽  
Accretion Rate ◽  
Mass Function ◽  
High Mass ◽  
New Model ◽  
System Formation ◽  
Low Mass

ABSTRACT We propose a new model for the evolution of a star cluster’s system mass function (SMF). The model involves both turbulent fragmentation and competitive accretion. Turbulent fragmentation creates low-mass seed proto-systems (i.e. single and multiple protostars). Some of these low-mass seed proto-systems then grow by competitive accretion to produce the high-mass power-law tail of the SMF. Turbulent fragmentation is relatively inefficient, in the sense that the creation of low-mass seed proto-systems only consumes a fraction, ${\sim }23{{\ \rm per\ cent}}$ (at most ${\sim }50{{\ \rm per\ cent}}$), of the mass available for star formation. The remaining mass is consumed by competitive accretion. Provided the accretion rate on to a proto-system is approximately proportional to its mass (dm/dt ∝ m), the SMF develops a power-law tail at high masses with the Salpeter slope (∼−2.3). If the rate of supply of mass accelerates, the rate of proto-system formation also accelerates, as appears to be observed in many clusters. However, even if the rate of supply of mass decreases, or ceases and then resumes, the SMF evolves homologously, retaining the same overall shape, and the high-mass power-law tail simply extends to ever higher masses until the supply of gas runs out completely. The Chabrier SMF can be reproduced very accurately if the seed proto-systems have an approximately lognormal mass distribution with median mass ${\sim } 0.11 \, {\rm M}_{\odot }$ and logarithmic standard deviation $\sigma _{\log _{10}({M/M}_\odot)}\sim 0.47$).

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