Physical Sciences and Mathematics Commons^™

How Active Rainwater Harvesting May Help Reduce Nuisance Flooding: Flood Analysis And Social Barriers To Adoption, Isabel Lopez

Open Access Theses & Dissertations

As urbanization continues to expand, fewer pervious surfaces are available to help reduce stormwater runoff from rainfall. The impacts of urbanization are becoming evident through sunny day flooding - flooding that occurs in areas not designated by the Federal Emergency Management Agency (FEMA) as flood zones. Nevertheless, water accumulates in low-lying areas and compromises street intersections and other parts of neighborhoods. Some methods can help alleviate the impacts of unexpected heavy rains, such as passive and active rainwater harvesting. As a pilot study, in a selected area in the northeast of El Paso, the level of adoption (e.g., what percentage …

The Close Agn Reference Survey (Cars): A Parsec-Scale Multi-Phase Outflow In The Super-Eddington Nls1 Mrk 1044, N. Winkel, B. Husemann, M. Singha, V. N. Bennert, F. Combes, T. A. Davis, M. Gaspari, K. Jahnke, R. Mcelroy, C. P. O'Dea, M. A. Pérez-Torres

Physics

Context. The interaction between active galactic nuclei (AGNs) and their host galaxies is scarcely resolved. Narrow-line Seyfert 1 (NLS1) galaxies are believed to represent AGN at early stages of their evolution and to allow one to observe feeding and feedback processes at high black hole accretion rates.

Aims. We aim to constrain the properties of the ionised gas outflow in Mrk 1044, a nearby super-Eddington accreting NLS1. Based on the outflow energetics and the associated timescales, we estimate the outflow’s future impact on the ongoing host galaxy star formation on different spatial scales.

Methods. We applied a spectroastrometric analysis to …

Near-Infrared Emission Line Diagnostics For Agn From The Local Universe To Z ∼ 3*, Mauro Giavalisco, Et. Al.

Astronomy Department Faculty Publication Series

Optical rest-frame spectroscopic diagnostics are usually employed to distinguish between star formation and active galactic nucleus (AGN) powered emission. However, this method is biased against dusty sources, hampering a complete census of the AGN population across cosmic epochs. To mitigate this effect, it is crucial to observe at longer wavelengths in the rest-frame near-infrared (near-IR), which is less affected by dust attenuation and can thus provide a better description of the intrinsic properties of galaxies. AGN diagnostics in this regime have not been fully exploited so far, due to the scarcity of near-IR observations of both AGN and star-forming galaxies, …

A Hybrid (Active-Passive) Vanet Clustering Technique, Garrett Lee Moore

CCE Theses and Dissertations

Clustering serves a vital role in the operation of Vehicular Ad hoc Networks (VANETs) by continually grouping highly mobile vehicles into logical hierarchical structures. These moving clusters support Intelligent Transport Systems (ITS) applications and message routing by establishing a more stable global topology. Clustering increases scalability of the VANET by eliminating broadcast storms caused by packet flooding and facilitate multi-channel operation. Clustering techniques are partitioned in research into two categories: active and passive. Active techniques rely on periodic beacon messages from all vehicles containing location, velocity, and direction information. However, in areas of high vehicle density, congestion may occur on …

General Π-Electron-Assisted Strategy For Single-Atom (Ir, Pt, Ru, Pd, Fe, And Ni) Electrocatalysts With Bi-Functional Active Sites Toward Highly Efficient Water Splitting, Weihong Lai, Li-Fu Zhang, Wei-Bo Hua, Sylvio Indris, Zichao Yan, Zhe Hu, Binwei Zhang, Yani Liu, Li Wang, Min Liu, Rong Liu, Yunxiao Wang, Jiazhao Wang, Zhenpeng Hu, Hua-Kun Liu, Shulei Chou, Shi Xue Dou

Australian Institute for Innovative Materials - Papers

Both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) are crucial to water splitting, but require alternative active sites. Now, a general pelectron- assisted strategy to anchor single-atom sites (M=Ir, Pt, Ru, Pd, Fe, Ni) on a heterogeneous support is reported. The Matoms can simultaneously anchor on two distinct domains of the hybrid support, four-fold N/C atoms (M@NC), and centers of Co octahedra (M@Co), which are expected to serve as bifunctional electrocatalysts towards the HER and the OER. The Ir catalyst exhibits the best water-splitting performance, showing a low applied potential of 1.603V to achieve 10 mAcm@2 …

Rheology And Collective Behavior In Living Tissue, Michael David Czajkowski

Dissertations - ALL

Recent experiments and simulations have indicated that confluent epithelial layers, where there are no gaps or overlaps between the cells, can transition from a soft fluid-like state to a solid-like state, with dynamics that share many features with glass transitions. While a coherent picture has begun to form connecting the microscopic mechanisms that drive this transition with macroscopic observables, much less is known of its consequences in biological processes. Do tissues tune themselves to a fluid state in order to promote collective motion? Has evolution made use of the ability of tissues to tune themselves between fluid and solid states …

An Active Galactic Nucleus Caught In The Act Of Turning Off And On, Julia M. Comerford, R Scott Barrows, Francisco Müller Sánchez, Rebecca Nevin, Jenny E. Greene, David Pooley, Daniel Stern, Fiona A. Harrison

Physics and Astronomy Faculty Research

We present the discovery of an active galactic nucleus (AGN) that is turning off and then on again in the z = 0.06 galaxy SDSS J1354+1327. This episodic nuclear activity is the result of discrete accretion events that could have been triggered by a past interaction with the companion galaxy that is currently located 12.5 kpc away. We originally targeted SDSS J1354+1327 because its Sloan Digital Sky Survey spectrum has narrow AGN emission lines that exhibit a velocity offset of 69 km s⁻¹ relative to systemic. To determine the nature of the galaxy and its velocity-offset emission lines, we …

Spatially Offset Active Galactic Nuclei. Ii. Triggering In Galaxy Mergers, R Scott Barrows, Julia M. Comerford, Jenny E. Greene, David Pooley

Physics and Astronomy Faculty Research

Galaxy mergers are likely to play a role in triggering active galactic nuclei (AGNs), but the conditions under which this process occurs are poorly understood. In Paper I, we constructed a sample of spatially offset X-ray AGNs that represent galaxy mergers hosting a single AGN. In this paper, we use our offset AGN sample to constrain the parameters that affect AGN observability in galaxy mergers. We also construct dual-AGN samples with similar selection properties for comparison. We find that the offset AGN fraction shows no evidence for a dependence on AGN luminosity, while the dual-AGN fractions show stronger evidence for …

Field Investigation Of An Active Landslide In Kentucky: A Framework To Correlate Electrical Data And Shear Strength, Matthew M. Crawford, L. Sebastian Bryson

Report of Investigations--KGS

Landslide hazard assessments are best accomplished by a multidisciplinary approach that connects geologic processes with geotechnical behavior. Tools to accomplish this in the field include geologic characterization, hydrologic monitoring, and geophysical surveys, and in the laboratory, soil-strength testing. Volumetric water content, soil-water potential (suction), local rainfall, and in situ electrical conductivity were measured at a shallow colluvial landslide in Kentucky. Surface electrical-resistivity surveys were also conducted to support interpretations of depth to failure, lithologic differences, and changes in moisture content over time. Correlations of hydrologic data with electrical measurements and shear strength indicate that observed changes in the degree of …

Mid-Infrared Luminous Quasars In The Goods–Herschel Fields: A Large Population Of Heavily Obscured, Compton-Thick Quasars At Z ≈ 2, A. Del Moro, D. M. Alexander, F. E. Bauer, E. Daddi, Dale D. Kocevski, Daniel H. Mcintosh, F. Stanley, W. N. Brandt, D. Elbaz, C. M. Harrison, B. Luo, J. R. Mullaney, Y. Q. Xue

Physics and Astronomy Faculty Publications

We present the infrared (IR) and X-ray properties of a sample of 33 mid-IR luminous quasars (νL_6 μm ≥ 6 × 10⁴⁴ erg s⁻¹) at redshift z ≈ 1–3, identified through detailed spectral energy distribution analyses of distant star-forming galaxies, using the deepest IR data from Spitzer and Herschel in the GOODS–Herschel fields. The aim is to constrain the fraction of obscured, and Compton-thick (CT, N_H > 1.5 × 10²⁴ cm⁻²) quasars at the peak era of nuclear and star formation activities. Despite being very bright in the mid-IR band, ≈30 …

Electrochemically Active, Novel Layered M-Znv2o6 Nanobelts For Highly Rechargeable Na-Ion Energy Storage, Yan Sun, Chun-Sheng Li, Qiuran Yang, Shulei Chou, Hua-Kun Liu

Australian Institute for Innovative Materials - Papers

Electrode materials with a three-dimensional (3D) layered framework and excellent electrochemical stability can provide a new avenue for enhancing the overall performance of promising sodium ion batteries. Here, we show that layered monoclinic (m) - ZnV2O6 nanobelts with high chemical activity for Na-ion energy storage have been effectively fabricated via a rapid microwave irradiation method over the reaction time of 8 h, in which the fabricating efficiency is 24.5 times greater in comparison with the traditional hydrothermal method. The morphology and phase evolutions were verified by means of X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. This study also …

Improved Cycling Stability Of Lithium-Sulphur Batteries By Enhancing The Retention Of Active Material With A Sandwiched Hydrothermally Treated Graphite Film, Yuede Pan, Shulei Chou, Hua-Kun Liu, S X. Dou

Australian Institute for Innovative Materials - Papers

A new lithium-sulphur battery with a hydrothermally treated graphite film sandwiched between the separator and the sulphur cathode shows increased capacity, enhanced cycling stability and improved coulombic efficiency. After 50 cycles, a high capacity of 631 mA h g-1 is maintained, compared to 203 mA h g-1 for the Li-S battery with conventional configuration. Moreover, the coulombic efficiency is increased to near 100% from around 94%. This improved electrochemical performance could be attributed to the new cell configuration, because the graphite film greatly retains the active material by alleviating the polysulphide shuttling problem and providing extra reaction sites for sulphur …

A Methodical Approach For Fabrication Of Binder-Free Li2s-C Composite Cathode With High Loading Of Active Material For Li-S Battery, Mohammad Kaiser, Xin Liang, Hua-Kun Liu, S X. Dou, Jiazhao Wang

Australian Institute for Innovative Materials - Papers

Lithium sulfide (Li2S), which has a theoretical capacity of 1166 mA h/g, is considered as a promising cathode material for the Li-S battery. The electrochemical performance of microsized Li2S is impaired, however, by its low electrical conductivity as well as first cycle high activation potential problem. In this work, microsized Li2S powder had been ball-milled with different carbon sources to synthesize Li2S-C composites as well as to find the suitable carbon sources, which were then capillary-deposited in three-dimensional multi-layered Ni foam from a dioxolane-containing mixture to fabricate a binder-free Li2S-C composite cathode. A large amount of active material (∼5 mg/cm2) …

A Deep Look At The Nuclear Region Of Ugc 5101 Through High Angular Resolution Mid-Ir Data With Gtc/Canaricam, M. Martínez-Paredes, Almudena Alonso-Herrero, Itziar Aretxaga, C. Ramos Almeida, A. Hernán-Caballero, O. González-Martín, M. Pereira-Santaella, Christopher Packham, A. Asensio Ramos, T. Díaz-Santos, Moshe Elitzur, P. Esquej, I. García-Bernete, Masatoshi Imanishi, Nancy A. Levenson, José Miguel Rodríguez Espinosa

Physics and Astronomy Faculty Publications

We present an analysis of the nuclear infrared (IR, 1.6–18 μm) emission of the ultraluminous IR galaxy UGC 5101 to derive the properties of its active galactic nucleus (AGN) and its obscuring material. We use new mid-IR high angular resolution (0.3–0.5 arcsec) imaging using the Si-2 filter (λ_C = 8.7 μm) and 7.5–13 μm spectroscopy taken with CanariCam (CC) on the 10.4 m Gran Telescopio CANARIAS. We also use archival Hubble Space Telescope/NICMOS and Subaru/COMICS imaging and Spitzer/IRS spectroscopy. We estimate the near- and mid-IR unresolved nuclear emission by modelling the imaging data with GALFIT. We decompose …

The Nustar Extragalactic Survey: First Direct Measurements Of The Greater Than Or Similar To 10 Kev X-Ray Luminosity Function For Active Galactic Nuclei At Z > 0.1, J. Aird, D. M. Alexander, D. R. Ballantyne, R. C. Hickox, A. Del-Moro, R. C. Hickox, G. B. Lansbury, J. R. Mullaney, F. E. Bauer, W. N. Brandt

Dartmouth Scholarship

We present the first direct measurements of the rest-frame 10–40 keV X-ray luminosity function (XLF) of active galactic nuclei (AGNs) based on a sample of 94 sources at 0.1 < z < 3, selected at 8–24 keV energies from sources in the Nuclear Spectroscopic Telescope Array (NuSTAR) extragalactic survey program. Our results are consistent with the strong evolution of the AGN population seen in prior, lower-energy studies of the XLF. However, different models of the intrinsic distribution of absorption, which are used to correct for selection biases, give significantly different predictions for the total number of sources in our sample, leading to small, systematic differences in our binned estimates of …

P-Manga Galaxies: Emission-Lines Properties – Gas Ionization And Chemical Abundances From Prototype Observations, F. Belfiore, R. Maiolino, K. Bundy, D. Thomas, C. Maraston, D. Wilkinson, S. F. Sánchez, M. Bershady, G. A. Blanc, M. Bothwell, S. L. Cales, L. Coccato, N. Drory, E. Emsellem, H. Fu, J. Gelfand, D. Law, K. Masters, J. Parejko, C. Tremonti, D. Wake, A. Weijmans, Renbin Yan, T. Xiao, K. Zhang, T. Zheng, K. Bizyaev, K. Kinemuchi, D. Oravetz, A. Simmons

Physics and Astronomy Faculty Publications

MaNGA (Mapping Nearby Galaxies at Apache Point Observatory) is a 6-yr Sloan Digital Sky Survey (SDSS-IV) survey that will obtain spatially resolved spectroscopy from 3600 to 10 300 Å for a representative sample of over 10 000 nearby galaxies. In this paper, we present the analysis of nebular emission-line properties using observations of 14 galaxies obtained with P-MaNGA, a prototype of the MaNGA instrument. By using spatially resolved diagnostic diagrams, we find extended star formation in galaxies that are centrally dominated by Seyfert/LINER-like emission, which illustrates that galaxy characterizations based on single fibre spectra are necessarily incomplete. We observe extended …

The Nuclear Near-Infrared Spectral Properties Of Nearby Galaxies, Rachel E. Mason, Eric S. Perlman

Aerospace, Physics, and Space Science Faculty Publications

We present spectra of the nuclear regions of 50 nearby (D = 1-92 Mpc, median = 20 Mpc) galaxies of morphological types E to Sm. The spectra, obtained with the Gemini Near-IR Spectrograph on the Gemini North telescope, cover a wavelength range of approximately 0.85-2.5 μm at R ∼ 1300-1800. There is evidence that most of the galaxies host an active galactic nucleus (AGN), but the range of AGN luminosities (log (L2 - 10 kev [erg s-1]) = 37.0-43.2) in the sample means that the spectra display a wide variety of features. Some nuclei, especially the Seyferts, exhibit a rich …

The Host Galaxies Of X-Ray Selected Active Galactic Nuclei To Z = 2.5: Structure, Star Formation, And Their Relationships From Candels And Herschel/Pacs, Dale D. Kocevski, D. J. Rosario, D. H. Mcintosh, A. Van Der Wel, J. Kartaltepe, P. Lang, P. Santini, S. Wuyts, D. Lutz, M. Rafelski, C. Villforth

Physics and Astronomy Faculty Publications

We study the relationship between the structure and star formation rate (SFR) of X-ray selected low and moderate luminosity active galactic nuclei (AGNs) in the two Chandra Deep Fields, using Hubble Space Telescope imaging from the Cosmic Assembly Near Infrared Extragalactic Legacy Survey (CANDELS) and deep far-infrared maps from the PEP+GOODS-Herschel survey. We derive detailed distributions of structural parameters and FIR luminosities from carefully constructed control samples of galaxies, which we then compare to those of the AGNs. At z ~ 1, AGNs show slightly diskier light profiles than massive inactive (non-AGN) galaxies, as well as modestly higher levels …

Vimos Ultra-Deep Survey (Vuds): Witnessing The Assembly Of A Massive Cluster At Z ~ 3.3, B. C. Lemaux, O. Cucciati, L. A. M. Tasca, O. Le Fèvre, G. Zamorani, P. Cassata, B. Garilli, V. Le Brun, D. Maccagni, L. Pentericci, R. Thomas, E. Vanzella, R. Amorín, S. Bardelli, P. Capak, L. P. Cassarà, M. Castellano, A. Cimatti, J. G. Cuby, S. De La Torre, A. Durkalec, A. Fontana, M. Giavalisco, A. Grazian, N. P. Hathi, O. Ilbert, C. Moreau, S. Paltani, B. Ribeiro, M. Salvato, D. Schaerer, M. Scodeggio, V. Sommariva, M. Talia, Y. Taniguchi, L. Tresse, D. Vergani, P. W. Wang, S. Charlot, T. Contini, S. Fotopoulou, R. R. Gal, Dale D. Kocevski, C. López-Sanjuan, L. M. Lubin, Y. Mellier, T. Sadibekova, N. Scoville

Physics and Astronomy Faculty Publications

Using new spectroscopic observations obtained as part of the VIMOS Ultra-Deep Survey (VUDS), we performed a systematic search for overdense environments in the early universe (z> 2) and report here on the discovery of Cl J0227-0421, a massive protocluster at z = 3.29. This protocluster is characterized by both the large overdensity of spectroscopically confirmed members, δ_gal = 10.5 ± 2.8, and a significant overdensity in photometric redshift members. The halo mass of this protocluster is estimated by a variety of methods to be ~3 × 10¹⁴ℳ_⊙ at z ~ 3.3, which, evolved to z …

Hidden Starbursts And Active Galactic Nuclei At 0 < Z < 4 From The Herschel-Vvds-Cfhtls-D1 Field: Inferences On Coevolution And Feedback, B. C. Lemaux, E. Le Foc'h, O. Le Fèvre, O. Ilbert, L. Tresse, L. M. Lubin, G. Zamorani, R. R. Gal, P. Ciliegi, P. Cassata, Dale D. Kocevski, E. J. Mcgrath, S. Bardelli, E. Zucca, G. K. Squires

Physics and Astronomy Faculty Publications

We investigate of the properties of ~2000 Herschel/SPIRE far-infrared-selected galaxies from 0 < z < 4 in the CFHTLS-D1 field. Using a combination of extensive spectroscopy from the VVDS and ORELSE surveys, deep multiwavelength imaging from CFHT, VLA, Spitzer, XMM-Newton, and Herschel, and well-calibrated spectral energy distribution fitting, Herschel-bright galaxies are compared to optically-selected galaxies at a variety of redshifts. Herschel-selected galaxies are observed to span a range of stellar masses, colors, and absolute magnitudes equivalent to galaxies undetected in SPIRE. Though many Herschel galaxies appear to be in transition, such galaxies are largely consistent with normal star-forming galaxies when rest-frame colors are utilized. The nature of the star-forming “main sequence” is studied and we warn against adopting this …

Line-Driven Radiative Outflows In Luminous Quasars, Rebecca A. A. Bowler, Paul C. Hewett, James T. Allen, Gary J. Ferland

Physics and Astronomy Faculty Publications

An analysis of ≃19 500 narrow ( ≲ 200 km s⁻¹) C iv λλ1548.2,1550.8 absorbers in ≃34 000 Sloan Digital Sky Survey quasar spectra is presented. The statistics of the number of absorbers as a function of outflow velocity shows that in approximately two-thirds of outflows, with multiple C iv absorbers present, absorbers are line-locked at the 500 km s⁻¹ velocity separation of the C iv absorber doublet; appearing as ‘triplets’ in the quasar spectra. Line-locking is an observational signature of radiative line-driving in outflowing material, where the successive shielding of ‘clouds’ of material in the outflow …

A Framework For Creating Active And Healthy Communities: A Case Study Of The Gold Coast, Bhishna Bajracharya, Linda Too, Isara Khanjanasthiti

Linda Too

Poor modern lifestyle choices have led to a burgeoning health concern for various government agencies prompting urgent review and action. Whilst the health sector has the primary role in addressing health issues, town planning can also contribute to better health by providing supportive environments for an active and healthy lifestyle. Local councils and other decision makers have a fundamental role in promoting healthy lifestyles among local community members through city planning and implementing physical activity and health programs. This research paper has two primary objectives. First, it develops an integrated 3-P (Place, Program and Partnership) framework for promoting active and …

A Framework For Creating Active And Healthy Communities: A Case Study Of The Gold Coast, Bhishna Bajracharya, Linda Too, Isara Khanjanasthiti

Bhishna Bajracharya

Poor modern lifestyle choices have led to a burgeoning health concern for various government agencies prompting urgent review and action. Whilst the health sector has the primary role in addressing health issues, town planning can also contribute to better health by providing supportive environments for an active and healthy lifestyle. Local councils and other decision makers have a fundamental role in promoting healthy lifestyles among local community members through city planning and implementing physical activity and health programs. This research paper has two primary objectives. First, it develops an integrated 3-P (Place, Program and Partnership) framework for promoting active and …

Polypyrrole Doped With Redox-Active Poly(2-Methoxyaniline-5-Sulfonic Acid) For Lithium Secondary Batteries, Yang Yang, Caiyun Wang, Syed A. Ashraf, Gordon G. Wallace

Gordon Wallace

Polypyrrole is a promising electrode material for flexible/bendable energy storage devices due to its inherent fast redox switching, mechanical flexibility, easy processability and being environmentally benign. However, its low attainable capacity limits its practical applications. Here, we synthesise a polypyrrole/poly(2-methoxyaniline-5-sulfonic acid) (PPy/PMAS) composite by incorporating redox-active PMAS into a PPy matrix via an electropolymerization method. For comparison, polypyrrole containing the electrochemically inert dopant p-toluenesulfonate (PPy-pTS) was prepared under the same conditions. The resultant PPy/PMAS film shows greatly improved electrochemical properties by harnessing the contribution from PMAS, i.e. higher specific capacity, better rate capability and improved cycling stability when used as …

Hard X-Ray Lags In Active Galactic Nuclei: Testing The Distant Reverberation Hypothesis With Ngc 6814, D. J. Walton, A. Zoghbi, E. M. Cackett, P. Uttley, F. A. Harrison, A. C. Fabian, E. Kara, J. M. Miller, R. C. Reis, C. S. Reynolds

Physics and Astronomy Faculty Research Publications

We present an X-ray spectral and temporal analysis of the variable active galaxy NGC 6814, observed with Suzaku during 2011 November. Remarkably, the X-ray spectrum shows no evidence for the soft excess commonly observed amongst other active galaxies, despite its relatively low level of obscuration, and is dominated across the whole Suzaku bandpass by the intrinsic powerlaw-like continuum. Despite this, we clearly detect the presence of a low-frequency hard lag of ~1600 s between the 0.5-2.0 and 2.0-5.0 keV energy bands at greater than 6σ significance, similar to those reported in the literature for a variety of other active galactic …

Calculating Time Lags From Unevenly Sampled Light Curves, A. Zoghbi, C. Reynolds, E. M. Cackett

Physics and Astronomy Faculty Research Publications

Timing techniques are powerful tools to study dynamical astrophysical phenomena. In the X-ray band, they offer the potential of probing accretion physics down to the event horizon. Recent work has used frequency- and energy-dependent time lags as tools for studying relativistic reverberation around the black holes in several Seyfert galaxies. This was achieved due to the evenly sampled light curves obtained using XMM-Newton. Continuously sampled data are, however, not always available and standard Fourier techniques are not applicable. Here, building on the work of Miller et al., we discuss and use a maximum likelihood method to obtain frequency-dependent lags that …

Discovery Of High-Frequency Iron K Lags In Ark 564 And Mrk 335, E. Kara, A. C. Fabian, E. M. Cackett, P. Uttley, D. R. Wilkins, A. Zoghbi

Physics and Astronomy Faculty Research Publications

We use archival XMM-Newton observations of Ark 564 and Mrk 335 to calculate the frequency-dependent time lags for these two well-studied sources. We discover high-frequency Fe K lags in both sources, indicating that the red wing of the line precedes the rest-frame energy by roughly 100 and 150 s for Ark 564 and Mrk 335, respectively. Including these two new sources, Fe K reverberation lags have been observed in seven Seyfert galaxies. We examine the low-frequency lag-energy spectrum, which is smooth, and shows no feature of reverberation, as would be expected if the low-frequency lags were produced by distant reflection …

Discovery Of A Relation Between Black Hole Mass And Soft X-Ray Time Lags In Active Galactic Nuclei, B. De Marco, G. Ponti, M. Cappi, M. Dadina, P. Uttley, E. M. Cackett, A. C. Fabian, G. Miniutti

Physics and Astronomy Faculty Research Publications

We carried out a systematic analysis of time lags between X-ray energy bands in a large sample (32 sources) of unabsorbed, radio quiet active galactic nuclei (AGN), observed by XMM-Newton. The analysis of X-ray lags (up to the highest/shortest frequencies/time-scales), is performed in the Fourier-frequency domain, between energy bands where the soft excess (soft band) and the primary power law (hard band) dominate the emission. We report a total of 15 out of 32 sources displaying a high-frequency soft lag in their light curves. All 15 are at a significance level exceeding 97 per cent and 11 are at a …

Discovery Of Fe Kα X-Ray Reverberation Around The Black Holes In Mcg-5-23-16 And Ngc 7314, A. Zoghbi, C. Reynolds, E. M. Cackett, G. Miniutti, E. Kara, A. C. Fabian

Physics and Astronomy Faculty Research Publications

Several X-ray observations have recently revealed the presence of reverberation time delays between spectral components in active galactic nuclei. Most of the observed lags are between the power-law Comptonization component, seen directly, and the soft excess produced by reflection in the vicinity of the black hole. NGC 4151 was the first object to show these lags in the iron K band. Here, we report the discovery of reverberation lags in the Fe K band in two other sources: MCG-5-23-16 and NGC 7314. In both objects, the 6-7 keV band, where the Fe Kα line peaks, lags the bands at lower …

Revealing The X-Ray Source In Iras 13224-3809 Through Flux-Dependent Reverberation Lags, E. Kara, A. C. Fabian, E. M. Cackett, G. Miniutti, P. Uttley

Physics and Astronomy Faculty Research Publications

IRAS 13224-3809 was observed in 2011 for 500 ks with the XMM-Newton observatory. We detect highly significant X-ray lags between soft (0.3-1 keV) and hard (1.2-5 keV) energies. The hard band lags the soft at low frequencies (i.e. hard lag), while the opposite (i.e. soft lag) is observed at high frequencies. In this paper, we study the lag during flaring and quiescent periods. We find that the frequency and absolute amplitude of the soft lag are different during high-flux and low-flux periods. During the low-flux intervals, the soft lag is detected at higher frequencies and with smaller amplitude. Assuming that …