Studying The Agn Merger Connection Through Visual Classification Of Candels Galaxies

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Studying the AGN-merger Connection Through Visual Classification of CANDELS Galaxies

Author : Christina T. Magagnoli
Publisher :
ISBN 13 :
Total Pages : 68 pages
Book Rating : 4.:/5 (123 download)

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Book Synopsis Studying the AGN-merger Connection Through Visual Classification of CANDELS Galaxies by : Christina T. Magagnoli

Download or read book Studying the AGN-merger Connection Through Visual Classification of CANDELS Galaxies written by Christina T. Magagnoli and published by . This book was released on 2020 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Mergers play a vital role in galaxy evolution, having the potential to trigger Active Galactic Nucleus (AGN) activity, star formation, or changes in morphology. In this work, we investigate whether galaxy mergers have an effect on AGN activity in the galaxies involved. We used a visual classification scheme to classify the morphologies of nearly 50,000 galaxies and identify galaxy mergers in the CANDELS fields, a Multi-Cycle Treasury Program using the Hubble Space Telescope. We use IR and X-ray selection criteria to identify IR and X-ray AGN, and matched controls to both our AGN subsample and merger subsample. We investigated the fraction of mergers that host AGN, as well as the fraction of AGN that are found in merging systems, to study the AGN-merger connection from multiple angles. We also investigated the properties of mergers, such as the mass ratios of early-stage mergers, and their star forming properties. We find that galaxies involved in a merger or interaction are more likely than non-merging galaxies to host AGN. The fraction of merging systems that host AGN is 0.034±0.002,compared to an AGN fraction of 0.023±0.001 in non-merging systems. We also find that IR AGN are more likely to be found in merging systems, with a merger fraction of 0.353+0.021−0.019, compared to a merger fraction of 0.225+0.007−0.006 in control galaxies without AGN activity. This is likely because these are more dusty and obscured, and are expected to be observed earlier in the merger process, when merger signatures are more visible. The AGN detected in either the X-ray or both the IR and X-ray are even less likely to be found in merging systems, as the merger signatures are expected to fade later in the merging process. These results show that mergers play an important role in driving AGN activity."--Abstract.

Investigating the AGN-merger Connection Using Close Galaxy Pairs in the CANDELS Fields

Author : Sean L. Dougherty
Publisher :
ISBN 13 :
Total Pages : 76 pages
Book Rating : 4.:/5 (126 download)

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Book Synopsis Investigating the AGN-merger Connection Using Close Galaxy Pairs in the CANDELS Fields by : Sean L. Dougherty

Download or read book Investigating the AGN-merger Connection Using Close Galaxy Pairs in the CANDELS Fields written by Sean L. Dougherty and published by . This book was released on 2021 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Galaxy mergers are catastrophic events in that they greatly change the properties of the galaxies involved. Observations of the nearby universe suggest that they may also be able to trigger active galactic nuclei (AGN) even prior to the final coalescence, though there is much controversy surrounding this belief, particularly at high redshifts. In order to address this question, we have assembled a large sample of photometric galaxy pairs within the GDS and EGS fields of the CANDELS survey. We use photometric redshift probability distribution functions and the combined redshift probability function to assign probabilities for each projected pair. We incorporate pair probabilities into a survey of X-ray detected AGN to calculate weighted AGN fractions and AGN enhancements for interacting galaxies. Overall, for both major and minor mergers at 0.5

Galaxy Merger Identification Methods, and Investigations of the Role of Mergers in Galaxy Evolution

Author : Kiyoaki Christopher Omori
Publisher : Springer
ISBN 13 : 9789819787340
Total Pages : 0 pages
Book Rating : 4.7/5 (873 download)

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Book Synopsis Galaxy Merger Identification Methods, and Investigations of the Role of Mergers in Galaxy Evolution by : Kiyoaki Christopher Omori

Download or read book Galaxy Merger Identification Methods, and Investigations of the Role of Mergers in Galaxy Evolution written by Kiyoaki Christopher Omori and published by Springer. This book was released on 2024-11-29 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

The AGN-host Galaxy Connection

Author : Bernd Husemann
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (838 download)

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Book Synopsis The AGN-host Galaxy Connection by : Bernd Husemann

Download or read book The AGN-host Galaxy Connection written by Bernd Husemann and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active Galactic Nuclei (AGN) are powered by gas accretion onto supermassive Black Holes (BH). The luminosity of AGN can exceed the integrated luminosity of their host galaxies by orders of magnitude, which are then classified as Quasi-Stellar Objects (QSOs). Some mechanisms are needed to trigger the nuclear activity in galaxies and to feed the nuclei with gas. Among several possibilities, such as gravitational interactions, bar instabilities, and smooth gas accretion from the environment, the dominant process has yet to be identified. Feedback from AGN may be important an important ingredient of the evolution of galaxies. However, the details of this coupling between AGN and their host galaxies remain unclear. In this work we aim to investigate the connection between the AGN and their host galaxies by studying the properties of the extendend ionised gas around AGN. Our study is based on observations of ~50 luminous, low-redshift (z0.3) QSOs using the novel technique of integral field spectroscopy that combines imaging and spectroscopy. After spatially separating the emission of AGN-ionised gas from HII regions, ionised solely by recently formed massive stars, we demonstrate that the specific star formation rates in several disc-dominated AGN hosts are consistent with those of normal star forming galaxies, while others display no detectable star formation activity. Whether the star formation has been actively suppressed in those particular host galaxies by the AGN, or their gas content is intrinsically low, remains an open question. By studying the kinematics of the ionised gas, we find evidence for non-gravitational motions and outflows on kpc scales only in a few objects. The gas kinematics in the majority of objects however indicate a gravitational origin. It suggests that the importance of AGN feedback may have been overrated in theoretical works, at least at low redshifts. The [OIII] line is the strongest optical emission line for AGN-ionised gas, which can be extended over several kpc scales, usually called the Narrow-Line Region (NLR). We perform a systematic investigation of the NLR size and determine a NLR size-luminosity relation that is consistent with the scenario of a constant ionisation parameter throughout the NLR. We show that previous narrow-band imaging with the Hubble Space Telescope underestimated the NLR size by a factor of 2 and that the continuum AGN luminosity is better correlated with the NLR size than the [OIII] luminosity. These affects may account for the different NLR size-luminosity relations reported in previous studies. On the other hand, we do not detect extended NLRs around all QSOs, and demonstrate that the detection of extended NLRs goes along with radio emission. We employ emission line ratios as a diagnostic for the abundance of heavy elements in the gas, i.e. its metallicity, and find that the radial metallicity gradients are always flatter than in inactive disc-dominated galaxies. This can be interpreted as evidence for radial gas flows from the outskirts of these galaxies to the nucleus. Recent or ongoing galaxy interactions are likely responsible for this effect and may turn out to be a common prerequisite for QSO activity. The metallicity of bulge-dominated hosts are systematically lower than their disc-dominated counterparts, which we interpret as evidence for minor mergers, supported by our detailed study of the bulge-dominated host of the luminous QSO HE 1029-1401, or smooth gas accretion from the environment. In this line another new discovery is that HE 2158-0107 at z=0.218 is the most metal poor luminous QSO ever observed. Together with a large (30kpc) extended structure of low metallicity ionised gas, we propose smooth cold gas accretion as the most likely scenario. Theoretical studies suggested that this process is much more important at earlier epochs of the universe, so that HE 2158-0107 might be an ideal laboratory to study this mechanism of galaxy and BH growth at low redshift more detailed in the furture.

Using WISE to Find Obscured AGN Activity in SDSS Mergers and Interactions

Author : Madalyn Elizabeth Weston
Publisher :
ISBN 13 :
Total Pages : 73 pages
Book Rating : 4.:/5 (957 download)

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Book Synopsis Using WISE to Find Obscured AGN Activity in SDSS Mergers and Interactions by : Madalyn Elizabeth Weston

Download or read book Using WISE to Find Obscured AGN Activity in SDSS Mergers and Interactions written by Madalyn Elizabeth Weston and published by . This book was released on 2015 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: In simulations, major encounters between gas-rich galaxies are predicted to drive gas to the centers of interacting and merging systems triggering new star formation (SF) and fueling an active galactic nucleus (AGN). Depending on the rate of SF, large amounts of obscuring dust can make detection of merger-induced activity difficult and may be at the heart of the ongoing merger-AGN connection debate. To provide better constraints on the importance of obscured AGNs, we use data from the Wide-field Infrared Survey Explorer (WISE) for a comprehensive sample of over 1000 major galaxy interactions and ongoing mergers visually selected from the SDSS with 1010 M¤ and 0.01

A Multi-Wavelength Study of Post-Merger Remnants

Author : Wenhao Li
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (139 download)

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Book Synopsis A Multi-Wavelength Study of Post-Merger Remnants by : Wenhao Li

Download or read book A Multi-Wavelength Study of Post-Merger Remnants written by Wenhao Li and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Post-merger galaxies are late-stage coalesced merger remnants which are highly disturbed and characterized by shells and tidal structures. Theoretically, the supermassive black holes (SMBHs) in the centers of post-merger systems are expected to be triggered as active galactic nuclei (AGN). These AGN can shut off star formation by ionizing or expelling gas out of the host galaxies. The goal of my dissertation research is to observationally test the relationship between mergers, AGN, and star formation quenching using a large sample of nearby post-merger remnant galaxies. The specific questions I address are: First, do galaxy mergers trigger active SMBHs as expected from theory? Second, can we constrain the SMBH occupation fraction in galaxies to distinguish between different formation models of seed black holes? Third, do AGN regulate star formation in their host galaxies? Using multi-waveband data, I found a significant enhancement of AGN in post-merger galaxies compared to non-merging control galaxies, proving a tight correlation between mergers and AGN. I also found that the AGN fractions in post-mergers are independent of stellar mass at logM*/M⊙ >9.7 while future work is needed to constrain the black hole occupation fraction. I investigated the resolved star formation history using MaNGA integral-field-unit spectroscopy and studied the atomic hydrogen gas fraction in post-mergers compared to non-merging control galaxies with data from the GBT. I found that the gas consumption or expulsion is the cause of star formation quenching in mergers while the merger-driven AGN is not the main cause. Overall, I have shown that post-mergers are an excellent tracer to study the relationship between mergers, AGN, and star formation quenching

Multiwavelength AGN Surveys and Studies (IAU S304)

Author : Areg M. Mickaelian
Publisher : Cambridge University Press
ISBN 13 : 9781107045248
Total Pages : 0 pages
Book Rating : 4.0/5 (452 download)

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Book Synopsis Multiwavelength AGN Surveys and Studies (IAU S304) by : Areg M. Mickaelian

Download or read book Multiwavelength AGN Surveys and Studies (IAU S304) written by Areg M. Mickaelian and published by Cambridge University Press. This book was released on 2014-08-21 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active galactic nuclei (AGN) are among the most interesting astrophysical objects in the Universe. IAU Symposium 304, dedicated to marking the centenary of B. E. Markarian's birth, addresses the most important questions in this area: understanding the possible evolutionary and/or physical connections between the different classes of AGN; the relation of AGN to their host galaxies; and understanding the true fraction of heavily obscured AGN in order to determine the true AGN luminosity function and its variation with redshift. This volume's topics include: historical spectral and colorimetric surveys, multiwavelength AGN surveys, AGN statistics, unification and other models of AGN, AGN feedback in galaxies and clusters, their host galaxies and environments, binary AGN and merging supermassive black holes, AGN variability, and future large projects. This fresh summary of AGN surveys is especially useful for researchers engaged in this exciting field and helping them plan for future surveys and observations.

Advanced Lectures On The Starburst-agn Connection

Author : Itziar Aretxaga
Publisher : World Scientific
ISBN 13 : 981449108X
Total Pages : 387 pages
Book Rating : 4.8/5 (144 download)

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Book Synopsis Advanced Lectures On The Starburst-agn Connection by : Itziar Aretxaga

Download or read book Advanced Lectures On The Starburst-agn Connection written by Itziar Aretxaga and published by World Scientific. This book was released on 2001-04-24 with total page 387 pages. Available in PDF, EPUB and Kindle. Book excerpt: A group of leading experts in the field of starbursts and active galactic nuclei have joined hands to produce this review volume which covers the starburst-AGN connection, and the tests to be carried out with the upcoming new astronomical facilities to ascertain the relevance of both components to the formation and evolution of galaxies.The book is addressed to advanced graduate students and researchers in the fields of active galactic nuclei and young galaxies.

Far-UV to Mid-IR Spectral Energy Distributions of Nearby Merging Galaxies

Author : Madalyn Elizabeth Weston
Publisher :
ISBN 13 :
Total Pages : 138 pages
Book Rating : 4.:/5 (133 download)

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Book Synopsis Far-UV to Mid-IR Spectral Energy Distributions of Nearby Merging Galaxies by : Madalyn Elizabeth Weston

Download or read book Far-UV to Mid-IR Spectral Energy Distributions of Nearby Merging Galaxies written by Madalyn Elizabeth Weston and published by . This book was released on 2022 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: Simulations of gas-rich, major galaxy mergers predict elevated amounts of star formation (SF) and nuclear black hole growth (active galactic nuclei, or AGN). This model is supported by observations that find enhanced SF in mergers, but support for the AGN-merger connection remains uncertain. Interstellar dust, a bi-product of SF, can block much of the light from an AGN and re-radiate that energy at infrared (IR) wavelengths. Therefore, quantifying the amount of buried AGN activity in the IR is key to understanding the role of major mergers in galaxy evolution. Spectral energy distributions (SEDs) allow Astrophysicists to disentangle AGN activity from SF. I hypothesize that applying SED analysis to a sample of merging galaxies will show an enhancement in AGN activity over control galaxies. I perform SED analysis from the far-ultraviolet (FUV) to the mid-IR on a sample of 49 merging galaxies and 49 statistically-matched control galaxies in the nearby universe. I find that the SED AGN luminosity correlates with the [OIII] luminosity, a common indicator of AGN power. I find that galaxies previously identified as Seyfert or WISE AGNs generally have a higher SED AGN luminosity. I do not find an increased occurrence of SED-detected AGNs in merging over control galaxies, rejecting our study hypothesis. To meet the interdisciplinary requirements of this degree, I also design a new graduate-level course in Multicultural Education for STEM (science, technology, engineering and mathematics) fields. “Diversity and Inclusion” have become buzz words in STEM, as research continues to show achievement and participation gaps for women, people of color, disabled persons, those of low socio-economic status, and members of the LGBTQIA+ community. Research about the STEM gaps has existed for decades, particularly with respect to teaching practices that contribute to under-representation. Yet little change has occurred in STEM classrooms. Graduate students (i.e., future STEM professors and industry leaders) stand in a unique position to impact diversity and inclusion efforts. Through targeted education centered on diversity and inclusion in teaching methods, we can produce a new generation of STEM educators who are aware and mindful of their unique role in fighting inequality in STEM.

Active Galactic Nuclei

Author : Volker Beckmann
Publisher : John Wiley & Sons
ISBN 13 : 3527410783
Total Pages : 390 pages
Book Rating : 4.5/5 (274 download)

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Book Synopsis Active Galactic Nuclei by : Volker Beckmann

Download or read book Active Galactic Nuclei written by Volker Beckmann and published by John Wiley & Sons. This book was released on 2012-09-24 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt: Active Galactic Nuclei This AGN textbook gives an overview on the current knowledge of the Active Galacitc Nuclei phenomenon. The spectral energy distribution will be discussed, pointing out what can be observed in different wavebands. The different physical models are presented together with formula important for the understanding of AGN physics. Furthermore, the authors discuss the AGN with respect to its environment, host galaxy, feedback in galaxies and in clusters of galaxies, variability, etc. and finally the cosmological evolution of the AGN phenomenon. This book includes phenomena based on new results in the X-Ray and gamma-ray domain from new telescopes such as Chandra, XMM-Newton, the Fermi Gamma-Ray Space Telescope, and the VHE regime not mentioned so far in AGN books. Those and other new developments as well as simulations of AGN merging events and formations, enabled through latest super-computing capabilities. From the contents: The observational picture of AGN Radiative processes The central engine AGN types and unification AGN through the electromagnetic spectrum AGN variability Environment Quasars and cosmology Formation, evolution and the ultimate fate of AGN What we do not know (yet)

The Star Formation and Merger Evolution of Interacting Galaxies

Author : Carrie Ruth Bridge
Publisher :
ISBN 13 : 9780494393765
Total Pages : 270 pages
Book Rating : 4.3/5 (937 download)

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Book Synopsis The Star Formation and Merger Evolution of Interacting Galaxies by : Carrie Ruth Bridge

Download or read book The Star Formation and Merger Evolution of Interacting Galaxies written by Carrie Ruth Bridge and published by . This book was released on 2007 with total page 270 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hierarchical models and observations show that galaxy mergers and interactions play a key role in galaxy assembly and star formation, but to what extent is still unclear. This thesis attempts to quantify their contribution to galaxy evolution by probing the number of interactions and mergers, along with their star forming properties as a function of redshift. The presence of long tidal tails and bridges are robust signatures of recent merger activity. This completely dynamical phenomenon was used to develop a new classification scheme to identify interacting galaxies and probe the interaction fraction and merger rate. We applied this new technique to large area, multi-band imaging obtained via the Canada France Hawaii Telescope Legacy Survey (CFHTLS-Deep), yielding the first statistically secure, lower limit of the galaxy interaction fraction between 0.1 z 1.0. Optically, the fraction of galaxies undergoing an interaction evolves moderately with redshift as (1 + z)2.24+/-0.24The Spitzer 24mum coverage of both the Extragalactic First Look Survey (XFLS) and CFHTLSDeep Survey were used to carry out one of the first and largest merger studies of IR bright galaxies. Within the ACS component of the XFLS, interactions were identified over the full merger sequence using traditional techniques, finding a merger rate increase for 24microm galaxies of (1 + z) & sim;2. This result implies that merging is an increasingly important process in the evolution of luminous IR galaxies (LIRGs), contributing 40--60% of the IR luminosity density and at least 30--40% of the star formation rate density at z & sim; 1. Galaxy interactions at all stages are found to have elevated star formation rates greater than a factor of two-four (on average) and a higher incidence of AGN activity compared to non-interacting field galaxies. This result supports a causal connection between galaxy merging, induced star formation, and AGN activity. Ultimately, major mergers provide a moderate contribution to the evolution of the cosmic star formation rate density and IR luminosity density to z & sim; 1, with an increasing trend suggesting that merging plays a larger role at higher redshifts (z 1). It is also clear that merging plays a significant role in triggering the processes that power the IR emission of LIRG galaxies at z 0.5.

The Effect of Galaxy Interactions on Star Formation and AGN Activity at 0:5

Author : Ekta Arjunkumar Shah
Publisher :
ISBN 13 :
Total Pages : 180 pages
Book Rating : 4.:/5 (129 download)

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Book Synopsis The Effect of Galaxy Interactions on Star Formation and AGN Activity at 0:5 by : Ekta Arjunkumar Shah

Download or read book The Effect of Galaxy Interactions on Star Formation and AGN Activity at 0:5 written by Ekta Arjunkumar Shah and published by . This book was released on 2021 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Galaxy interactions and mergers play an important role in the hierarchical formation and evolution of galaxies. Studies in the nearby universe show a higher star formation rate (SFR) and active galactic nuclei (AGN) fraction in interacting and merging galaxies than in their isolated counterparts, indicating that such interactions are important contributors to star formation and black hole growth. A large fraction of massive galaxies is thought to be affected by galaxy mergers at high redshifts because the galaxy merger rate increases with redshift. We use deep observations and cosmological simulations to study the role of galaxy mergers and interactions in enhancing SFR and AGN activity in galaxies at $0.5 z 3.0$, covering the peak of cosmic star formation and AGN activity ($z\sim2$). For the observational study, we use deep CANDELS and COSMOS observations to compile the largest known sample of major spectroscopic galaxy pairs (2381 with $V

Optical Surveys of AGN and Their Host Galaxies

Author : Daria Dubinovska
Publisher :
ISBN 13 :
Total Pages : 143 pages
Book Rating : 4.:/5 (865 download)

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Book Synopsis Optical Surveys of AGN and Their Host Galaxies by : Daria Dubinovska

Download or read book Optical Surveys of AGN and Their Host Galaxies written by Daria Dubinovska and published by . This book was released on 2012 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Investigating AGN Contribution to Galaxy Merger Infrared Luminosity

Author : Lee Rosenthal
Publisher :
ISBN 13 :
Total Pages : 13 pages
Book Rating : 4.:/5 (18 download)

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Book Synopsis Investigating AGN Contribution to Galaxy Merger Infrared Luminosity by : Lee Rosenthal

Download or read book Investigating AGN Contribution to Galaxy Merger Infrared Luminosity written by Lee Rosenthal and published by . This book was released on 2014 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Using GMOS Spectroscopy to Study Star Formation and AGN in the CANDELS COSMOS and UDS Fields

Author : Isabella G. Cox
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (137 download)

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Book Synopsis Using GMOS Spectroscopy to Study Star Formation and AGN in the CANDELS COSMOS and UDS Fields by : Isabella G. Cox

Download or read book Using GMOS Spectroscopy to Study Star Formation and AGN in the CANDELS COSMOS and UDS Fields written by Isabella G. Cox and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Spectroscopic measurements of galaxies can help us to better understand their properties. Spectroscopy allows for the measurement of spectroscopic redshifts, which have better precision than redshifts derived from photometry. Precise redshifts are needed to eliminate distance un- certainties when deriving distance-dependent properties of galaxies. Additionally, spectroscopy provides insight into the physical state and processes within a galaxy, such as its rate of on- going star formation, its chemical abundance, and the properties of the interstellar medium within the galaxy. Spectroscopy is particularly powerful when coupled with broad, multiwavelength photometric data. The five extragalactic fields from the Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey (CANDELS) have excellent multiwavelength photometric coverage. Two of the fields however, were lacking in spectroscopic coverage. To rectify this, spectroscopic observations were taken for sources in those particular fields in 2014, 2016, and 2019 with the Gemini Multi-Object Spectrometer on the twin Gemini Telescopes. We reduced the spectroscopic observations, which were taken in a configuration not compatible with existing reduction pipelines. We were able to extract spectra for 196 sources and measured their spectroscopic redshifts. We also measured emission fluxes from the spectra. We used the Halpha and [OII]3727 emission lines as star formation rate indicators to measure the star formation rates of our galaxies, and compared these results to star formation rates obtained from other techniques. We also used Hbeta, [OIII]5007, Halpha, and [NII]6583 to construct diagnostics to detect AGN in our sample, and compared those classifications to sources in our sample detected as an AGN with other methods (e.g., mid-infrared colors, X-ray flux). Using the spectroscopic data, we identified seven possible AGN sources not identified with X-ray or infrared data that could be followed up."--Abstract.

Physics of Active Galactic Nuclei at all Scales

Author : Danielle Alloin
Publisher : Springer
ISBN 13 : 354034621X
Total Pages : 243 pages
Book Rating : 4.5/5 (43 download)

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Book Synopsis Physics of Active Galactic Nuclei at all Scales by : Danielle Alloin

Download or read book Physics of Active Galactic Nuclei at all Scales written by Danielle Alloin and published by Springer. This book was released on 2006-09-07 with total page 243 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains a collection of lecture notes written by recognized experts in the field of Active Galactic Nuclei (AGN). The collection is aimed at providing both an introduction and at the same time an overview of the state-of-the-art of AGN research. This book also addresses the still not entirely understood link of an AGN with its host galaxy and also the related question of the birth and growth of massive black holes in the Universe.

Properties and Impact of Active Galactic Nuclei-driven Outflows Through Cosmic Time

Author : Gene Chun Kwan Leung
Publisher :
ISBN 13 :
Total Pages : 193 pages
Book Rating : 4.:/5 (119 download)

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Book Synopsis Properties and Impact of Active Galactic Nuclei-driven Outflows Through Cosmic Time by : Gene Chun Kwan Leung

Download or read book Properties and Impact of Active Galactic Nuclei-driven Outflows Through Cosmic Time written by Gene Chun Kwan Leung and published by . This book was released on 2020 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation studies the properties of outflows driven by active galactic nuclei (AGNs) and their impact on the evolution of galaxies. AGNs are predicted by theoretical models of galaxy formation to provide the necessary feedback to produce realistic galaxies. In theoretical models, AGNs provide feedback by driving outflows that remove gas from the host galaxy, thereby quenching star formation in massive galaxies and producing scaling relations between supermassive black holes and galaxies. Despite being indispensable in theory, critical open questions remain for AGN-driven outflows from an observational perspective. This dissertation first presents two studies using data from the MOSDEF survey, a large spectroscopic survey of galaxies when the Universe was about 3.5 billions years old (z~2). The first study focuses on the incidence and physical properties of AGN-driven outflows at z~2. We show that AGN-drive outflows are at least as prevalent at z~2 as they are in the local Universe. They are fast and extend to distances comparable to the size of the host galaxy. Using emission line ratio diagnostics, we find our data consistent with the picture of negative AGN feedback, where AGN-driven outflows suppress star formation, and find no evidence of galaxy-wide positive AGN feedback. The second study focuses on the demographics of galaxies hosting AGN-driven outflows and the relation between outflow properties and the galaxy and AGN population at z~2. We show that AGN-driven outflows are a ubiquitous phenomenon occurring across the galaxy population and in different phases of galaxy evolution, both before and after quenching. By measuring the energetics and correlations of AGN-driven outflows, we find that the outflows are more energetic at z~2 than in the local Universe, where AGNs are more powerful on average. We find that the outflows remove gas at a rate comparable to or faster than gas is being converted into stars. This shows that AGN-driven outflows at z~2 are capable of regulating star formation in the host galaxy. The third study in this dissertation presents integral field spectroscopy of a nearby ultraluminous infrared galaxy (ULIRG) and AGN Mrk 273. The study focuses on the extended ionized gas on scales of ~20 kpc. We detect for the first time highly ionized gas in one of the extended nebula surrounding the galaxy. From this, we show that shocks contribute significantly to the ionization of the gas in the extended nebulae, mixed with AGN photoionization. Our data is compatible with theoretical models in which AGNs drive a multiphase outflow, and slower-moving extended cold gas filaments form out of a more spatially confined but faster warm outflow. Our data suggests that AGNs play an important role in ejecting gas in the ULIRG phase of galaxy evolution.