A5073329735- Galaxies: Formation, Evolution, Phenomena
- Astrophysical Phenomena and Observations
- Astrophysics and Star Formation Studies
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Astro and Planetary Science
- Astronomical Observations and Instrumentation
- Particle Detector Development and Performance
- Adaptive optics and wavefront sensing
- Particle Accelerators and Free-Electron Lasers
- Cosmology and Gravitation Theories
- Spectroscopy and Laser Applications
- Calibration and Measurement Techniques
- Ionosphere and magnetosphere dynamics
- Quantum, superfluid, helium dynamics
- Solar and Space Plasma Dynamics
- Medical Imaging Techniques and Applications
- Heat Transfer Mechanisms
- Phase Equilibria and Thermodynamics
- CCD and CMOS Imaging Sensors
- Magnetic confinement fusion research
University of Waterloo
2016-2025
Perimeter Institute
2016-2025
Tokyo University of Science
2024
Goddard Space Flight Center
2020-2024
Center for Astrophysics Harvard & Smithsonian
2008-2023
University of Manitoba
2019
Regional Municipality of Waterloo
2019
SRON Netherlands Institute for Space Research
2016
Japan Aerospace Exploration Agency
2016
Max Planck Institute for Astrophysics
2009
High resolution X-ray spectroscopy of the hot gas in galaxy clusters has shown that is not cooling to low temperatures at predicted rates hundreds thousands solar masses per year. images have revealed giant cavities and shock fronts provide a direct relatively reliable means measuring energy injected into atmospheres by active galactic nuclei (AGN). Average radio jet powers are near those required offset radiative losses suppress isolated elliptical galaxies, larger systems up richest...
We present 1210 Johnson/Cousins B, V, R, and I photometric observations of 22 recent Type Ia supernovae (SNe Ia): SNe 1993ac, 1993ae, 1994M, 1994S, 1994T, 1994Q, 1994ae, 1995D, 1995E, 1995al, 1995ac, 1995ak, 1995bd, 1996C, 1996X, 1996Z, 1996ab, 1996ai, 1996bk, 1996bl, 1996bo, 1996bv. Most the photometry was obtained at Fred Lawrence Whipple Observatory Harvard-Smithsonian Center for Astrophysics in a cooperative observing plan aimed improving database Ia. The redshifts sample range from cz =...
We present an analysis of 16 galaxy clusters, one group, and drawn from the Chandra Data Archive. These systems possess prominent X-ray surface brightness depressions associated with cavities or bubbles that were created by interactions between powerful radio sources surrounding hot gas. The central galaxies in these harbor luminosities ranging ~2 × 1038 7 1044 ergs s-1. have average radius ~10 kpc, they lie at projected distance ~20 kpc galaxy. minimum energy ranges pV ~ 1055 galaxies,...
We present Chandra X-ray observations of the Hydra A cluster galaxies, and we report discovery structure in central 80 kpc cluster's X-ray-emitting gas. The most remarkable structures are depressions surface brightness, approximately 25-35 diameter, that coincident with A's radio lobes. nearly devoid gas, there is no evidence for shock-heated gas surrounding suggest within brightness was displaced as lobes expanded subsonically, leaving cavities hot atmosphere. temperature declines from 4...
The radiative cooling timescales at the centers of hot atmospheres surrounding elliptical galaxies, groups, and clusters are much shorter than their ages. Therefore, expected to cool form stars. Cold gas star formation observed in central cluster galaxies but levels below those from an unimpeded flow. X-ray observations have shown that wholesale is being offset by mechanical heating radio active galactic nuclei. Feedback widely considered be important perhaps unavoidable consequence...
We present an analysis of the growth black holes through accretion and bulges star formation in 33 galaxies at centers cooling flows. Most these systems show evidence cavities intracluster medium (ICM) inflated by radio jets emanating from their active galactic nuclei (AGN). a new extensive X-ray systems. find that AGN are energetically able to balance radiative losses (cooling) ICM more than half our sample. Using subsample 17 systems, we examine relationship between formation. rates...
We present multiband photometry of 185 type-Ia supernovae (SNe Ia), with over 11,500 observations. These were acquired between 2001 and 2008 at the F. L. Whipple Observatory Harvard-Smithsonian Center for Astrophysics (CfA). This sample contains largest number homogeneously observed reduced nearby SNe Ia (z ≲ 0.08) published to date. It more than doubles sample, bringing SN cosmology point where systematic uncertainties dominate. Our natural system has a precision ≲0.02 mag in BVRIr'i' ≲0.04...
We present UBVRI photometry of 44 Type Ia supernovae (SNe Ia) observed from 1997 to 2001 as part a continuing monitoring campaign at the Fred Lawrence Whipple Observatory Harvard-Smithsonian Center for Astrophysics. The data set comprises 2190 observations and is largest homogeneously reduced sample SNe date, nearly doubling number well-observed, nearby with published multicolor CCD light curves. large U-band unique addition, important connections high redshift. decline rate SN curves...
Using Chandra X-ray and VLA radio data, we investigate the scaling relationship between jet power, P_jet, synchrotron luminosity, P_rad. We expand sample presented in Birzan et al. (2008) to lower power by incorporating measurements for 21 gEs determine if P_jet-P_rad relations are continuous form scatter from giant elliptical galaxies (gEs) up brightest cluster (BCGs). find a mean relation of P_jet approximately 5.8x10^43 (P_rad/10^40)^(0.70) erg/s which is over ~6-8 decades P_rad with 0.7...
We present a catalog of 203 clusters galaxies serendipitously detected in 647 ROSAT PSPC high Galactic latitude pointings covering 158 deg2. This is one the largest X-ray-selected cluster samples, comparable size only to All-Sky Survey sample nearby (Ebeling et al. 1997). detect inner 175 field view using spatial extent their X-ray emission. Fluxes range from 1.6 × 10-14 8 10-12 ergs s-1 cm-2 0.5-2 keV energy band. luminosities 1042 s-1, corresponding very poor groups, ~5 1044 rich clusters....
The cooling flow cluster Hydra A was observed during the orbital activation and calibration phase of Chandra Observatory. While X-ray image exhibits complex structure in central region as reported McNamara et al., large-scale morphology is fairly smooth. spectroscopic analysis ACIS data shows that gas temperature increases outward, reaches a maximum 4 keV at 200 kpc, then decreases slightly larger radii. distribution heavy elements nonuniform, with factor 2 increase Fe Si abundances within...
We present an analysis of the energetics and particle content lobes 24 radio galaxies at cores cooling clusters. The in these systems have created visible cavities surrounding hot, X-ray-emitting gas, which allow direct measurement mechanical jet power sources over six decades luminosity, independently properties themselves. find that (cavity) increases with synchrotron approximately as Pjet ∼ Lβradio, where 0.35 ⩽ β 0.70 depending on bandpass state source. However, scatter about relations...
Using broadband optical imaging and Chandra X-ray data for a sample of 46 cluster central dominant galaxies (CDGs), we investigate the connection between star formation, intracluster medium (ICM), active galactic nucleus (AGN). We report discovery remarkably sharp threshold onset formation that occurs when cooling time hot atmosphere falls below ~5 × 108 yr, or equivalently entropy ~30 keV cm2. In addition to this criterion, in flows also appears require galaxy centroids lie within ~20 kpc...
Quillen et al. presented an imaging survey with the Spitzer Space Telescope of 62 brightest cluster galaxies optical line emission located in cores X-ray-luminous clusters. They found that at least half these sources have signs excess IR emission. Here we discuss nature and its implications for cool core The strength mid-IR correlates luminosity lines. Excluding four systems dominated by AGN, remaining is likely related to star formation. mass molecular gas (estimated from CO observations)...
A Chandra image of the central 100 kpc Abell 2597 cluster galaxies shows bright irregular X-ray emission within dominant galaxy (CDG) and two low surface brightness cavities located 30 from nucleus CDG. Unlike commonly seen in other clusters, "ghost" are not coincident with radio source. Instead, they appear to be associated faint extended a deep Very Large Array map. We interpret ghost as buoyantly rising relics outburst that occurred between 50 Myr ago. The demography few clusters studied...
Deep Chandra observations of the Hydra A Cluster reveal a feature in X-ray surface brightness that surrounds 330 MHz radio lobes AGN at cluster center. Surface profiles this and its close association with argue strongly it is shock front driven by expanding lobes. The image also reveals other new structure on smaller scales associated source, including large cavity filament. extends 200 - 300 kpc from center strength varies along front, Mach numbers range ~ 1.2 1.4. It stronger where more...
A 227 ksec Chandra Observatory X-ray image of the hot plasma in Hydra cluster has revealed an extensive cavity system. The system was created by a continuous outflow or series bursts from nucleus central galaxy over past 200-500 Myr. cavities have displaced 10% within 300 kpc radius galaxy, creating swiss-cheese-like topology gas. surface brightness decrements are consistent with empty oriented 40 degrees plane sky. deposited upward 10^61 erg into gas, most which propelled beyond inner ~100...
Observation shows that nebular emission, molecular gas, and young stars in giant galaxies are associated with rising X-ray bubbles inflated by radio jets launched from nuclear black holes. We propose a model where clouds condense low entropy gas caught the updraft of bubbles. The becomes thermally unstable when it is lifted to an altitude its cooling time shorter than required fall equilibrium location galaxy i.e., t_c/t_I < 1. infall speed cloud bounded lesser free-fall terminal speeds,...
We examine unresolved nuclear X-ray sources in 57 brightest cluster galaxies to study the relationship between emission and accretion onto supermassive black holes (SMBHs). The majority of clusters our sample have prominent cavities embedded surrounding hot atmospheres, which we use estimate mean jet power average rate SMBHs over past several hundred Myr. find that ~50% detectable emission. luminosity is correlated with determined using cavities, consistent hypothesis traces ongoing...
We present first results from a very deep (~650 ksec) Chandra X-ray observation of Abell 2052, as well archival VLA radio observations. The data reveal detailed structure in the inner parts cluster, including bubbles evacuated by AGN's lobes, compressed bubble rims, filaments, and loops. Two concentric shocks are seen, temperature rise is measured for innermost one. On larger scales, we report detection an excess surface brightness spiral feature. has cooler temperatures, lower entropies,...
We report ALMA Early Science observations of the Abell 1835 brightest cluster galaxy (BCG) in CO (3-2) and (1-0) emission lines. detect 5E10 solar masses molecular gas within 10 kpc BCG. Its velocity width ~130 km/s FWHM is too narrow to be supported by dynamical pressure. The may instead a rotating, turbulent disk oriented nearly face-on. forming stars at rate 100-180 per year. Roughly 1E10 projected 3-10 north-west east nucleus with line sight velocities lying between -250 +480 respect...
Chandra X-ray observations of the nearby brightest cluster galaxy M87 resolve hot gas structure across Bondi accretion radius central supermassive black hole (SMBH), a measurement possible in only handful systems but complicated by bright nucleus and jet emission. By stacking short frame-time to limit pileup, after subtracting nuclear point spread function, we analysed properties within at 0.12-0.22 kpc (1.5-2.8 arcsec), depending on mass. Within 2 radius, detect two significant temperature...