Physical Sciences and Mathematics Commons^™

On Outflows Due To Radiation, Randall Cody Dannen

UNLV Theses, Dissertations, Professional Papers, and Capstones

Observations of ionized AGN outflows have provided compelling evidence that the radiation field transfers both momentum and energy to the plasma. At parsec scale distances in AGN, energy transfer can dominate, in which case the only force needed to launch an outflow is due to gas pressure. Much closer to the black hole, gravity dominates thermal energy due to insufficient heating by the radiation and the gas is in the so-called ’cold wind solution’ regime. Only magnetic or radiation forces can lead to outflow, but it is unclear how these forces depend on the spectral energy distribution (SED) and the …

Galaxy And Mass Assembly (Gama): Low-Redshift Quasars And Inactive Galaxies Have Similar Neighbors, Maria B. Stone, Clare F. Wethers, Roberto De Propris, Jari Kotilainen, Nischal Acharya, Benne W. Holwerda, Jonathan Loveday, Steven Phillipps

Faculty Scholarship

We explore the properties of galaxies in the proximity (within a ∼2 Mpc radius sphere) of Type I quasars at 0.1 <z <0.35, to check whether and how an active galaxy influences the properties of its neighbors. We further compare these with the properties of neighbors around inactive galaxies of the same mass and redshift within the same volume of space, using the Galaxy and Mass Assembly spectroscopic survey. Our observations reveal no significant difference in properties such as the number of neighbors, morphologies, stellar mass, star formation rates, and star formation history between the neighbors of quasars and those of the comparison sample. This implies that quasar activity in a host galaxy does not significantly affect its neighbors (e.g., via interactions with the jets). Our results suggest that quasar host galaxies do not strongly differ from the average galaxy within the specified mass and redshift range. Additionally, the implication of the relatively minor importance of the environmental effect on and from quasars is that nuclear activity is more likely triggered by internal and secular processes.

Clear: Spatially Resolved Emission Lines And Active Galactic Nuclei At 0.6 < Z < 1.3, Bren E. Backhaus, Joanna S. Bridge, Jonathan R. Trump, Nikko J. Cleri, Casey Papovich, Raymond C. Simons, Ivelina Momcheva, Benne Holwerda, Zhiyuan Ji, Intae Jung, Jasleen Matharu

Faculty Scholarship

We investigate spatially resolved emission-line ratios in a sample of 219 galaxies (0.6 < z < 1.3) detected using the G102 grism on the Hubble Space Telescope Wide Field Camera 3 taken as part of the CANDELS Lyα Emission at Reionization survey to measure ionization profiles and search for low-luminosity active galactic nuclei (AGN). We analyze [O III] and Hβ emission-line maps, enabling us to spatially resolve the [O III]/Hβ emission-line ratio across the galaxies in the sample. We compare the [O III]/Hβ ratio in galaxy centers and outer annular regions to measure ionization differences and investigate the potential of sources with nuclear ionization to host AGN. We investigate some of the individual galaxies that are candidates to host strong nuclear ionization and find that they often have low stellar mass and are undetected in X-rays, as expected for low-luminosity AGN in low-mass galaxies. We do not find evidence for a significant population of off-nuclear AGN or other clumps of off-nuclear ionization. We model the observed distribution of [O III]/Hβ spatial profiles and find that most galaxies are consistent with a small or zero difference between their nuclear and off-nuclear line ratios, but 6%–16% of galaxies in the sample are likely to host nuclear [O III]/Hβ that is ∼0.5 dex higher than in their outer regions. This study is limited by large uncertainties in most of the measured [O III]/Hβ spatial profiles; therefore, deeper data, e.g., from deeper HST/ WFC3 programs or from JWST/NIRISS, are needed to more reliably measure the spatially resolved emission-line conditions of individual high-redshift galaxies.

Probing The Inner Structure Of Active Galactic Nuclei Through Reverberation Mapping, Viraja Chandrashekhar Khatu

Electronic Thesis and Dissertation Repository

In the centres of massive galaxies, active galactic nuclei (AGN) are supermassive black holes, surrounded by an accretion disk of ionized gas, that release tremendous energy in the form of electromagnetic radiation. Because AGN are unresolved through telescopes, we employ reverberation mapping (RM) to study their structure. RM capitalizes on the fact that AGN are variable – the continuum emission from the accretion disk varies, and surrounding gas (in the broad-line region, BLR) responds to those variations with a positive time lag. RM translates the measured time lag into a size of the BLR. Combined with gas velocities (measured from …

Galaxy And Mass Assembly (Gama): The Weak Environmental Dependence Of Quasar Activity At 0.1 < Z < 0.35, Clare F. Wethers, Nischal Acharya, Roberto De Propris, Jari Kotilainen, Ivan K. Baldry, Sarah Brough, Simon P. Driver, Alister W. Graham, Benne Holwerda, Andrew M. Hopkins, Angel R. López-Sánchez, Jonathan Loveday, Steven Phillipps, Kevin A. Pimbblet, Edward Taylor, Lingyu Wang, Angus H. Wright

Faculty Scholarship

Understanding the connection between nuclear activity and galaxy environment remains critical in constraining models of galaxy evolution. By exploiting the extensive cataloged data from the Galaxy and Mass Assembly survey, we identify a representative sample of 205 quasars at 0.1 < z < 0.35 and establish a comparison sample of galaxies, closely matched to the quasar sample in terms of both stellar mass and redshift. On scales <1 Mpc, the galaxy number counts and group membership of quasars appear entirely consistent with those of the matched galaxy sample. Despite this, we find that quasars are ∼1.5 times more likely to be classified as the group center, indicating a potential link between quasar activity and cold gas flows or galaxy interactions associated with rich group environments. On scales of ∼a few Mpc, the clustering strengths of both samples are statistically consistent, and beyond 10 Mpc, we find no evidence that quasars trace large-scale structures any more than the galaxy control sample. Both populations are found to prefer intermediate-density sheets and filaments to either very high-density environments or very low-density environments. This weak dependence of quasar activity on galaxy environment supports a paradigm in which quasars represent a phase in the lifetime of all massive galaxies and in which secular processes and a group-centric location are the dominant triggers of quasars at low redshift.

Space Telescope And Optical Reverberation Mapping Project. Xi. Disk-Wind Characteristics And Contributions To The Very Broad Emission Lines Of Ngc 5548, Maryam Dehghanian, Gary J. Ferland, G. A. Kriss, B. M. Peterson, K. T. Korista, M. R. Goad, Marios Chatzikos, Francisco Guzmán, G. De Rosa, M. Mehdipour, J. Kaastra, S. Mathur, M. Vestergaard, D. Proga, T. Waters, M. C. Bentz, S. Bisogni, W. N. Brandt, E. Dalla Bontà, M. M. Fausnaugh, J. M. Gelbord, Keith Horne, I. M. Mchardy, R. W. Pogge, D. A. Starkey

Physics and Astronomy Faculty Publications

In 2014 the NGC 5548 Space Telescope and Optical Reverberation Mapping campaign discovered a two-month anomaly when variations in the absorption and emission lines decorrelated from continuum variations. During this time the soft X-ray part of the intrinsic spectrum had been strongly absorbed by a line-of-sight (LOS) obscurer, which was interpreted as the upper part of a disk wind. Our first paper showed that changes in the LOS obscurer produces the decorrelation between the absorption lines and the continuum. A second study showed that the base of the wind shields the broad emission-line region (BLR), leading to the emission-line decorrelation. …

The Nature Of Deeply Buried Ultraluminous Infrared Galaxies: A Unified Model For Highly Obscured Dusty Galaxy Emission, J. A. Marshall, Moshe Elitzur, L. Armus, T. Diaz-Santos, V. Charmandaris

Physics and Astronomy Faculty Publications

We present models of deeply buried ultraluminous infrared galaxy (ULIRG) spectral energy distributions (SEDs) and use them to construct a three-dimensional diagram for diagnosing the nature of observed ULIRGs. Our goal is to construct a suite of SEDs for a very simple model ULIRG structure, and to explore how well this simple model can (by itself) explain the full range of observed ULIRG properties. We use our diagnostic to analyze archival Spitzer Space Telescope Infrared Spectrograph data of ULIRGs and find that: (1) in general, our model does provide a comprehensive explanation of the distribution of mid-IR ULIRG properties; (2) …

Intermediate-Line Emission In Agns: The Effect Of Prescription Of The Gas Density, T. P. Adhikari, K. Hryniewicz, A. Różańska, B. Czerny, Gary J. Ferland

Physics and Astronomy Faculty Publications

The requirement of an intermediate-line component in the recently observed spectra of several active galactic nuclei (AGNs) points to the possible existence of a physically separate region between the broad-line region (BLR) and narrow-line region (NLR). In this paper we explore the emission from the intermediate-line region (ILR) by using photoionization simulations of the gas clouds distributed radially from the center of the AGN. The gas clouds span distances typical for the BLR, ILR, and NLR, and the appearance of dust at the sublimation radius is fully taken into account in our model. The structure of a single cloud is …

Luminous And Obscured Quasars And Their Host Galaxies, Agnese Del Moro, David M. Alexander, Franz E. Bauer, Emanuele Daddi, Dale D. Kocevski, Flora Stanley, Daniel H. Mcintosh

Physics and Astronomy Faculty Publications

The most heavily-obscured, luminous quasars might represent a specific phase of the evolution of the actively accreting supermassive black holes and their host galaxies, possibly related to mergers. We investigated a sample of the most luminous quasars at z ≈ 1 − 3 in the GOODS fields, selected in the mid-infrared band through detailed spectral energy distribution (SED) decomposition. The vast majority of these quasars (~80%) are obscured in the X-ray band and ~30% of them to such an extent, that they are undetected in some of the deepest (2 and 4 Ms) Chandra X-ray data. Although no clear relation …

The Carbon And Nitrogen Abundance Ratio In The Broad Line Region Of Tidal Disruption Events, Chenwei Yang, Tinggui Wang, Gary J. Ferland, Liming Dou, Hongyan Zhou, Ning Jiang, Zhenfeng Sheng

Physics and Astronomy Faculty Publications

The rest-frame UV spectra of three recent tidal disruption events (TDEs), ASASSN-14li, PTF15af, and iPTF16fnl, display strong nitrogen emission lines but weak or undetectable carbon lines. In these three objects, the upper limits of the C III] λ1908/N III] λ1750 ratio are about two orders of magnitude lower than those of quasars, suggesting a high abundance ratio of [N/C]. With detailed photoionization simulations, we demonstrate that C²⁺ and N²⁺ are formed in the same zone, so the CIII]/N III] ratio depends only moderately on the physical conditions in the gas and weakly on the shape of …

Space Telescope And Optical Reverberation Mapping Project. Vii. Understanding The Ultraviolet Anomaly In Ngc 5548 With X-Ray Spectroscopy, S. Mathur, A. Gupta, K. Page, R. W. Pogge, Y. Krongold, M. R. Goad, S. M. Adams, M. D. Anderson, P. Arévalo, A. J. Barth, C. Bazhaw, T. G. Beatty, M. C. Bentz, A. Bigley, S. Bisogni, G. A. Borman, T. A. Boroson, M. C. Bottorff, W. N. Brandt, A. A. Breeveld, J. E. Brown, J. S. Brown, E. M. Cackett, G. Canalizo, M. T. Carini, K. I. Clubb, J. M. Comerford, C. T. Coker, E. M. Corsini, D. M. Crenshaw, Gary J. Ferland

Physics and Astronomy Faculty Publications

During the Space Telescope and Optical Reverberation Mapping Project observations of NGC 5548, the continuum and emission-line variability became decorrelated during the second half of the six-month-long observing campaign. Here we present Swift and Chandra X-ray spectra of NGC 5548 obtained as part of the campaign. The Swift spectra show that excess flux (relative to a power-law continuum) in the soft X-ray band appears before the start of the anomalous emission-line behavior, peaks during the period of the anomaly, and then declines. This is a model-independent result suggesting that the soft excess is related to the anomaly. We divide the …

The Formation And Dynamics Of Clouds In The Environment Of Active Galactic Nuclei, Timothy Waters

UNLV Theses, Dissertations, Professional Papers, and Capstones

Active galactic nuclei (AGN) are among the most luminous objects in the universe and are known to be powered by accretion onto supermassive black holes in the centers of galaxies. AGN clouds are prominent components of successful models that attempt to unify the diversity of AGN. These clouds are often hypothesized to be the source of the broad and narrow line emission features seen in AGN spectra. Moreover, the high column densities of gas needed to account for broad absorption lines has been attributed to the same population of clouds, while the motion of AGN clouds has been invoked to …

Swift Monitoring Of Ngc 4151: Evidence For A Second X-Ray/Uv Reprocessing, R. Edelson, J. Gelbord, E. Cackett, S. Connolly, C. Done, M. Fausnaugh, E. Gardner, N. Gehrels, M. Goad, K. Horne, I. Mchardy, B. M. Peterson, S. Vaughan, M. Vestergaard, A. Breeveld, A. J. Barth, M. Bentz, M. Bottorff, W. N. Brandt, S. M. Crawford, E. Dalla Bontà, D. Emmanoulopoulos, P. Evans, R. Figuera Jaimes, A. V. Filippenko, Gary J. Ferland, D. Grupe, M. Joner, J. Kennea, K. T. Korista

Physics and Astronomy Faculty Publications

Swift monitoring of NGC 4151 with an ~6 hr sampling over a total of 69 days in early 2016 is used to construct light curves covering five bands in the X-rays (0.3–50 keV) and six in the ultraviolet (UV)/optical (1900–5500 Å). The three hardest X-ray bands (> 2.5 keV) are all strongly correlated with no measurable interband lag, while the two softer bands show lower variability and weaker correlations. The UV/optical bands are significantly correlated with the X-rays, lagging ~3–4 days behind the hard X-rays. The variability within the UV/optical bands is also strongly correlated, with the UV appearing to …

Space Telescope And Optical Reverberation Mapping Project. V. Optical Spectroscopic Campaign And Emission-Line Analysis For Ngc 5548, L. Pei, M. M. Fausnaugh, A. J. Barth, B. M. Peterson, M. C. Bentz, G. De Rosa, K. D. Denney, M. R. Goad, C. S. Kochanek, K. T. Korista, G. A. Kriss, R. W. Pogge, V. N. Bennert, M. Brotherton, K. I. Clubb, E. Dalla Bontà, A. V. Filippenko, J. E. Greene, C. J. Grier, M. Vestergaard, W. Zheng, Scott M. Adams, Thomas G. Beatty, A. Bigley, Jacob E. Brown, Jonathan S. Brown, G. Canalizo, J. M. Comerford, Carl T. Coker, E. M. Corsini, Gary J. Ferland, S. A. Klimanov

Physics and Astronomy Faculty Publications

We present the results of an optical spectroscopic monitoring program targeting NGC 5548 as part of a larger multiwavelength reverberation mapping campaign. The campaign spanned 6 months and achieved an almost daily cadence with observations from five ground-based telescopes. The Hβ and He ii λ4686 broad emission-line light curves lag that of the 5100 Å optical continuum by 4.17^+0.36 _-0.36 days and 0.79^+0.35_-0.34 days respectively. The Hβ lag relative to the 1158 Å ultraviolet continuum light curve measured by the Hubble Space Telescope is ~50% longer than that measured against the optical continuum, and …

A Multiwavelength Continuum Characterization Of High-Redshift Broad Absorption Line Quasars, D. Tuccillo, G. Bruni, M. A. Dipompeo, M. S. Brotherton

Dartmouth Scholarship

We present the results of a multiwavelength study of a sample of high-redshift radio-loud (RL) broad absorption line (BAL) quasars. This way, we extend to higher redshift previous studies on the radio properties and broad-band optical colours of these objects. We have selected a sample of 22 RL BAL quasars with 3.6 ≤ z ≤ 4.8 cross-correlating the FIRST radio survey with the Sloan Digital Sky Survey (SDSS). Flux densities between 1.25 and 9.5 GHz have been collected with the Jansky Very Large Array and Effelsberg-100 m telescopes for 15 BAL and 14 non-BAL quasars used as a comparison sample. …

The Dusty Tori Of Nearby Qsos As Constrained By High-Resolution Mid-Ir Observations, M. Martínez-Paredes, I. Aretxaga, A. Alonso-Herrero, O. González-Martín, E. Lopéz-Rodríguez, C. Ramos Almeida, A. Asensio Ramos, T. Diaz Santos, Moshe Elitzur, P. Esquej, A. Hernán-Caballero, K. Ichikawa, R. Nikutta, C. Packham, M. Pereira-Santaella, C. Telesco

Physics and Astronomy Faculty Publications

We present mid-infrared (MIR; 7.5–13.5 μm) imaging and spectroscopy observations obtained with the CanariCam (CC) instrument on the 10.4-m Gran Telescopio CANARIAS for a sample of 20 nearby, MIR bright and X-ray luminous quasi-stellar objects (QSOs). We find that for the majority of QSOs the MIR emission is unresolved at angular scales ∼0.3 arcsec, corresponding to physical scales ≲ 600 pc. We find that the higher-spatial resolution CC spectra have similar shapes to those obtained with Spitzer/IRS, and hence we can assume that the spectra are not heavily contaminated by extended emission in the host galaxy. We thus take …

Sdss-Iv Manga: The Impact Of Diffuse Ionized Gas On Emission-Line Ratios, Interpretation Of Diagnostic Diagrams And Gas Metallicity Measurements, Kai Zhang, Renbin Yan, Kevin Bundy, Matthew Bershady, L. Matthew Haffner, René Walterbos, Roberto Maiolino, Christy Tremonti, Daniel Thomas, Niv Drory, Amy Jones, Francesco Belfiore, Sebastian F. Sánchez, Aleksandar M. Diamond-Stanic, Dmitry Bizyaev, Christian Nitschelm, Brett Andrews, Jon Brinkmann, Joel R. Brownstein, Edmond Cheung, Cheng Li, David R. Law, Alexandre Roman Lopes, Daniel Oravetz, Kaike Pan, Thaisa Storchi Bergmann, Audrey Simmons

Physics and Astronomy Faculty Publications

Diffuse ionized gas (DIG) is prevalent in star-forming galaxies. Using a sample of 365 nearly face-on star-forming galaxies observed by Mapping Nearby Galaxies at APO, we demonstrate how DIG in star-forming galaxies impacts the measurements of emission-line ratios, hence the interpretation of diagnostic diagrams and gas-phase metallicity measurements. At fixed metallicity, DIG-dominated low Σ_Hα regions display enhanced [S II]/Hα, [N II]/Hα, [O II]/Hβ and [O I]/Hα. The gradients in these line ratios are determined by metallicity gradients and Σ_Hα. In line ratio diagnostic diagrams, contamination by DIG moves H II …

The Mid-Infrared Luminosity Evolution And Luminosity Function Of Quasars With Wise And Sdss, Jack Singal

Physics Faculty Publications

We determine the 22 μm luminosity evolution and luminosity function for quasars from a data set of over 20,000 objects obtained by combining flux-limited Sloan Digital Sky Survey optical and Wide field Infrared Survey Explorer mid-infrared data. We apply methods developed in previous works to access the intrinsic population distributions non-parametrically, taking into account the truncations and correlations inherent in the data. We find that the population of quasars exhibits positive luminosity evolution with redshift in the mid-infrared, but with considerably less mid-infrared evolution than in the optical or radio bands. With the luminosity evolutions accounted for, we determine …

The Intermediate-Line Region In Active Galactic Nuclei, T. P. Adhikari, A. Różańska, B. Czerny, K. Hryniewicz, Gary J. Ferland

Physics and Astronomy Faculty Publications

We show that the recently observed suppression of the gap between the broad-line region (BLR) and the narrow-line region (NLR) in some active galactic nuclei (AGNs) can be fully explained by an increase of the gas density in the emitting region. Our model predicts the formation of the intermediate-line region (ILR) that is observed in some Seyfert galaxies by the detection of emission lines with intermediate-velocity FWHM ~ 700–1200 km s⁻¹. These lines are believed to be originating from an ILR located somewhere between the BLR and NLR. As was previously proved, the apparent gap is assumed to …

The Abundance Discrepancy Factor And T2 In Nebulae: Are Non-Thermal Electrons The Culprits?, Gary J. Ferland, W. J. Henney, C. R. O'Dell, M. Peimbert

Physics and Astronomy Faculty Publications

We discuss recent claims that the free electrons in ionized nebulae may not have a significantly Maxwellian velocity distribution. Supra-thermal electrons, electrons with much more energy than is encountered at electron temperatures found in nebulae, may solve the t²/ADF puzzle, the observations that abundances obtained from recombination and collisionally excited lines do not agree, and that different temperature indicators give different results. These non-Maxwellian electrons can be designated by the kappa formalism. We show that the distance over which heating rates change are much longer than the distance supra-thermal electrons can travel, and that the timescale to thermalize …

High-Velocity Bipolar Molecular Emission From An Agn Torus, Jack F. Gallimore, Moshe Elitzur, Robert Maiolino, Alessandro Marconi, Christopher P. O'Dea, Dieter Lutz, Stefi A. Baum, Robert Nikutta, C. M. V. Impellizzeri, Richard Davies, Amy E. Kimball, Eleonora Sani

Physics and Astronomy Faculty Publications

We have detected in ALMA observations CO J = 6 → 5 emission from the nucleus of the Seyfert galaxy NGC 1068. The low-velocity (up to ±70 km s⁻¹ relative to systemic) CO emission resolves into a 12 × 7 pc structure, roughly aligned with the nuclear radio source. Higher-velocity emission (up to ±400 km s⁻¹) is consistent with a bipolar outflow in a direction nearly perpendicular (≃80°) to the nuclear disk. The position–velocity diagram shows that in addition to the outflow, the velocity field may also contain rotation about the disk axis. These observations provide compelling …

Space Telescope And Optical Reverberation Mapping Project. Iv. Anomalous Behavior Of The Broad Ultraviolet Emission Lines In Ngc 5548, M. R. Goad, K. T. Korista, G. De Grosa, G. A. Kriss, R. Edelson, A. J. Barth, Gary J. Ferland, C. S. Kochanek, H. Netzer, B. M. Peterson, M. C. Bentz, S. Bisogni, D. M. Crenshaw, K. D. Denney, J. Ely, M. M. Fausnaugh, C. J. Grier, A. Gupta, K. D. Horne, J. Kaastra, A. Pancoast, L. Pei, R. W. Pogge, A. Skielboe, D. Starkey, M. Vestergaard, Y. Zu, M. D. Anderson, P. Arévalo, C. Bazhaw

Physics and Astronomy Faculty Publications

During an intensive Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) UV monitoring campaign of the Seyfert 1 galaxy NGC 5548 performed from 2014 February to July, the normally highly correlated far UV continuum and broad emission line variations decorrelated for ~60–70 days, starting ~75 days after the first HST/COS observation. Following this anomalous state, the flux and variability of the broad emission lines returned to a more normal state. This transient behavior, characterized by significant deficits in flux and equivalent width of the strong broad UV emission lines, is the first of its kind to be unambiguously identified …

Disc Outflows And High-Luminosity True Type 2 Agn, Moshe Elitzur, Hagai Netzer

Physics and Astronomy Faculty Publications

The absence of intrinsic broad-line emission has been reported in a number of active galactic nuclei (AGN), including some with high Eddington ratios. Such ‘true type 2 AGN’ are inherent to the disc-wind scenario for the broad-line region: broad-line emission requires a minimal column density, implying a minimal outflow rate and thus a minimal accretion rate. Here we perform a detailed analysis of the consequences of mass conservation in the process of accretion through a central disc. The resulting constraints on luminosity are consistent with all the cases where claimed detections of true type 2 AGN pass stringent criteria, and …

Scale Invariant Jet Suppression Across The Black Hole Mass Scale, David Garofalo, Chandra B. Singh

Faculty and Research Publications

We provide a schematic framework for understanding observations of jet suppression in soft state black hole X-ray binaries based on the Blandford-Payne process and the net magnetic flux threading the black hole. Due to the geometrical thinness of soft state disks, mass-loading of field lines is ineffective compared to both geometrically thick disks as well as thin disks with greater black hole threading flux, a simple physical picture that allows us to understand the weakness of jets in radiatively efficient thin disks accreting in the prograde direction around high-spinning black holes. Despite a simplicity that forbids insights into the complexity …

The Impact Of The Dusty Torus On Obscured Quasar Halo Mass Measurements, M. A. Dipompeo, J. C. Runnoe, R. C. Hickox, A. D. Myers, J. E. Geach

Dartmouth Scholarship

Recent studies have found that obscured quasars cluster more strongly and are thus hosted by dark matter haloes of larger mass than their unobscured counterparts. These results pose a challenge for the simplest unification models, in which obscured objects are intrinsically the same as unobscured sources but seen through a dusty line of sight. There is general consensus that a structure like a "dusty torus" exists, meaning that this intrinsic similarity is likely the case for at least some subset of obscured quasars. However, the larger host halo masses of obscured quasars implies that there is a second obscured population …

The Young Radio Lobe Of 3c 84: Inferred Gas Properties In The Central 10 Pc, Yutaka Fujita, Nozomu Kawakatu, Isaac Shlosman, Hirotaka Ito

Physics and Astronomy Faculty Publications

We analyse the environment of the supermassive black hole (SMBH) in the centre of a massive elliptical galaxy NGC 1275 in the Perseus cluster, hosting the radio source 3C 84. We focus on the young radio lobe observed inside the estimated Bondi accretion radius, and discusss the momentum balance between the jet associated with the lobe and the surrounding gas. The results are compared with the proper motion of the radio lobe obtained with the very long baseline interferometry. We find that under assumption of a high-density environment ( ≳ 100 cm⁻³), the jet power must be comparable …

Deep Chandra, Hst-Cos, And Megacam Observations Of The Phoenix Cluster: Extreme Star Formation And Agn Feedback On Hundred Kiloparsec Scales, Michael Mcdonald, B. R. Mcnamara, Reinout J. Van Weeren, Douglas E. Applegate, Matthew Bayliss, Marshall W. Bautz, Bradford A. Benson, John E. Carlstrom, Lindsey E. Bleem, Marios Chatzikos, A. C. Edge, A. C. Fabian, Gordon P. Garmire, Julie Hlavacek-Larrondo, Christine Jones-Forman, Adam B. Mantz, Eric D. Miller, Brian Stalder, Sylvain Veilleux, John A. Zuhone

Physics and Astronomy Faculty Publications

We present new ultraviolet, optical, and X-ray data on the Phoenix galaxy cluster (SPT-CLJ2344-4243). Deep optical imaging reveals previously undetected filaments of star formation, extending to radii of ~50–100 kpc in multiple directions. Combined UV-optical spectroscopy of the central galaxy reveals a massive (2 x 10⁹ M_⊙), young (~4.5 Myr) population of stars, consistent with a time-averaged star formation rate of 610 ± 50 M_⊙ yr⁻¹. We report a strong detection of O ᴠɪ λλ1032,1038, which appears to originate primarily in shock-heated gas, but may contain a substantial contribution (>1000 M_{⊙ …}

The Nustar Extragalactic Surveys: Initial Results And Catalog From The Extended Chandra Deep Field South, J. R. Mullaney, A. Del-Moro, J. Aird, D. M. Alexander, F. M. Civano, R. C. Hickox

Dartmouth Scholarship

We present initial results and the source catalog from the NuSTAR survey of the Extended Chandra Deep Field South (hereafter, ECDFS) - currently the deepest contiguous component of the NuSTAR extragalactic survey program. The survey covers the full ~30 arcmin x 30 arcmin area of this field to a maximum depth of ~360 ks (~220 ks when corrected for vignetting at 3-24 keV), reaching sensitivity limits of ~1.3 x 10^-14 erg/cm2/s (3-8 keV), ~3.4 x 10^-14 erg/cm2/s (8-24 keV) and ~3.0 x 10^-14 erg/cm2/s (3-24 keV). Fifty four (54) sources are detected over the full field, although five of these …

A Remarkably Flat Relationship Between The Average Star Formation Rate And Agn Luminosity For Distant X-Ray Agn, F. Stanley, C. M. Harrison, D. M. Alexander, A. M. Swinbank, J. A. Aird, A. Del Moro, R. C. Hickox, J. R. Mullaney

Dartmouth Scholarship

In this study we investigate the relationship between the star formation rate, SFR, and AGN luminosity, L(AGN), for ~2000 X-ray detected AGN. The AGN span over three orders of magnitude in X-ray luminosity (10^(42) < L(2-8keV) < 10^(45.5) erg/s) and are in the redshift range z = 0.2 - 2.5. Using infrared (IR) photometry (8 - 500um), including deblended Spitzer and Herschel images and taking into account photometric upper limits, we decompose the IR spectral energy distributions into AGN and star formation components. Using the IR luminosities due to star formation, we investigate the average SFRs as a function of redshift and AGN luminosity. In agreement with previous studies, we find a strong evolution of the average SFR with redshift, tracking the observed evolution of the overall star forming galaxy population. However, we find that the relationship between the average SFR and AGN luminosity is flat at all redshifts and across all the AGN luminosities investigated; in comparison to previous studies, we find less scatter amongst the average SFRs across the wide range of AGN luminosities investigated. By comparing to empirical models, we argue that the observed flat relationship is due to short timescale variations in AGN luminosity, driven by changes in the mass accretion rate, which wash out any underlying correlations between SFR and L(AGN). Furthermore, we show that the exact form of the predicted relationship between SFR and AGN luminosity (and it's normalisation) is highly sensitive to the assumed intrinsic Eddington ratio distribution.

Galaxy Pairs In The Sloan Digital Sky Survey - Xii. The Fuelling Mechanism Of Low-Excitation Radio-Loud Agn, Sara L. Ellison, David R. Patton, Ryan C. Hickox

Dartmouth Scholarship

We investigate whether the fuelling of low-excitation radio galaxies (LERGs) is linked to major galaxy interactions. Our study utilizes a sample of 10 800 spectroscopic galaxy pairs and 97 post-mergers selected from the Sloan Digital Sky Survey with matches to multiwavelength data sets. The LERG fraction amongst interacting galaxies is a factor of 3.5 higher than that of a control sample matched in local galaxy density, redshift and stellar mass. However, the LERG excess in pairs does not depend on projected separation and remains elevated out to at least 500 h70−1" role="presentation">h−170

kpc, suggesting that major mergers are not …