Daryl Haggard - University of Washington

Daryl Haggard
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Name
Daryl Haggard
Affiliation
University of Washington
City
Seattle
Country
United States

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Cosmology and Nongalactic Astrophysics (11)
 
High Energy Astrophysical Phenomena (8)
 
Astrophysics (6)
 
Instrumentation and Methods for Astrophysics (5)
 
Astrophysics of Galaxies (5)
 
Solar and Stellar Astrophysics (3)
 
High Energy Physics - Phenomenology (1)
 
Physics - Physics and Society (1)

Publications Authored By Daryl Haggard

If millisecond pulsars (MSPs) are responsible for the excess gamma-ray emission observed from the region surrounding the Galactic Center, the same region should also contain a large population of low-mass X-ray binaries (LMXBs). In this study, we compile and utilize a sizable catalog of LMXBs observed in the the Milky Way's globular cluster system and in the Inner Galaxy, as well as the gamma-ray emission observed from globular clusters, to estimate the flux of gamma rays predicted from MSPs in the Inner Galaxy. From this comparison, we conclude that only up to $\sim$4-23% of the observed gamma-ray excess is likely to originate from MSPs. Read More

2016Oct
Authors: Demitri Muna, Michael Alexander, Alice Allen, Richard Ashley, Daniel Asmus, Ruyman Azzollini, Michele Bannister, Rachael Beaton, Andrew Benson, G. Bruce Berriman, Maciej Bilicki, Peter Boyce, Joanna Bridge, Jan Cami, Eryn Cangi, Xian Chen, Nicholas Christiny, Christopher Clark, Michelle Collins, Johan Comparat, Neil Cook, Darren Croton, Isak Delberth Davids, Éric Depagne, John Donor, Leonardo A. dos Santos, Stephanie Douglas, Alan Du, Meredith Durbin, Dawn Erb, Daniel Faes, J. G. Fernández-Trincado, Anthony Foley, Sotiria Fotopoulou, Søren Frimann, Peter Frinchaboy, Rafael Garcia-Dias, Artur Gawryszczak, Elizabeth George, Sebastian Gonzalez, Karl Gordon, Nicholas Gorgone, Catherine Gosmeyer, Katie Grasha, Perry Greenfield, Rebekka Grellmann, James Guillochon, Mark Gurwell, Marcel Haas, Alex Hagen, Daryl Haggard, Tim Haines, Patrick Hall, Wojciech Hellwing, Edmund Christian Herenz, Samuel Hinton, Renee Hlozek, John Hoffman, Derek Holman, Benne Willem Holwerda, Anthony Horton, Cameron Hummels, Daniel Jacobs, Jens Juel Jensen, David Jones, Arna Karick, Luke Kelley, Matthew Kenworthy, Ben Kitchener, Dominik Klaes, Saul Kohn, Piotr Konorski, Coleman Krawczyk, Kyler Kuehn, Teet Kuutma, Michael T. Lam, Richard Lane, Jochen Liske, Diego Lopez-Camara, Katherine Mack, Sam Mangham, Qingqing Mao, David J. E. Marsh, Cecilia Mateu, Loïc Maurin, James McCormac, Ivelina Momcheva, Hektor Monteiro, Michael Mueller, Roberto Munoz, Rohan Naidu, Nicholas Nelson, Christian Nitschelm, Chris North, Juan Nunez-Iglesias, Sara Ogaz, Russell Owen, John Parejko, Vera Patrício, Joshua Pepper, Marshall Perrin, Timothy Pickering, Jennifer Piscionere, Richard Pogge, Radek Poleski, Alkistis Pourtsidou, Adrian M. Price-Whelan, Meredith L. Rawls, Shaun Read, Glen Rees, Hanno Rein, Thomas Rice, Signe Riemer-Sørensen, Naum Rusomarov, Sebastian F. Sanchez, Miguel Santander-García, Gal Sarid, William Schoenell, Aleks Scholz, Robert L. Schuhmann, William Schuster, Peter Scicluna, Marja Seidel, Lijing Shao, Pranav Sharma, Aleksandar Shulevski, David Shupe, Cristóbal Sifón, Brooke Simmons, Manodeep Sinha, Ian Skillen, Bjoern Soergel, Thomas Spriggs, Sundar Srinivasan, Abigail Stevens, Ole Streicher, Eric Suchyta, Joshua Tan, O. Grace Telford, Romain Thomas, Chiara Tonini, Grant Tremblay, Sarah Tuttle, Tanya Urrutia, Sam Vaughan, Miguel Verdugo, Alexander Wagner, Josh Walawender, Andrew Wetzel, Kyle Willett, Peter K. G. Williams, Guang Yang, Guangtun Zhu, Andrea Zonca

The Astropy Project (http://astropy.org) is, in its own words, "a community effort to develop a single core package for Astronomy in Python and foster interoperability between Python astronomy packages." For five years this project has been managed, written, and operated as a grassroots, self-organized, almost entirely volunteer effort while the software is used by the majority of the astronomical community. Read More

We describe the first data release from the Spitzer-IRAC Equatorial Survey (SpIES); a large-area survey of 115 deg^2 in the Equatorial SDSS Stripe 82 field using Spitzer during its 'warm' mission phase. SpIES was designed to probe sufficient volume to perform measurements of quasar clustering and the luminosity function at z > 3 to test various models for "feedback" from active galactic nuclei (AGN). Additionally, the wide range of available multi-wavelength, multi-epoch ancillary data enables SpIES to identify both high-redshift (z > 5) quasars as well as obscured quasars missed by optical surveys. Read More

We report a sensitive X-ray search for the proposed intermediate mass black hole (IMBH) in the massive Galactic cluster, Omega Centauri (NGC 5139). Combining Chandra X-ray Observatory data from Cycles 1 and 13, we obtain a deep (~291 ks) exposure of the central regions of the cluster. We find no evidence for an X-ray point source near any of the cluster's proposed dynamical centers, and place an upper limit on the X-ray flux from a central source of f_X(0. Read More

Striking similarities have been seen between accretion signatures of Galactic X-ray binary (XRB) systems and active galactic nuclei (AGN). XRB spectral states show a V-shaped correlation between X-ray spectral hardness and Eddington ratio as they vary, and some AGN samples reveal a similar trend, implying analogous processes at vastly larger masses and timescales. To further investigate the analogies, we have matched 617 sources from the Chandra Source Catalog to SDSS spectroscopy, and uniformly measured both X-ray and optical spectral characteristics across a broad range of AGN and galaxy types. Read More

We present results of a search for optical counterparts of X-ray sources in and toward the globular cluster Omega Centauri (NGC 5139) using the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. The ACS data consist of a mosaic of Wide Field Channel (WFC) images obtained using F625W, F435W, and F658N filters; with 9 pointings we cover the central ~10'x10' of the cluster and encompass 109 known Chandra sources. We find promising optical counterparts for 59 of the sources, ~40 of which are likely to be associated with the cluster. Read More

2012Jul
Authors: Kyle S. Dawson, David J. Schlegel, Christopher P. Ahn, Scott F. Anderson, Éric Aubourg, Stephen Bailey, Robert H. Barkhouser, Julian E. Bautista, Alessandra Beifiori, Andreas A. Berlind, Vaishali Bhardwaj, Dmitry Bizyaev, Cullen H. Blake, Michael R. Blanton, Michael Blomqvist, Adam S. Bolton, Arnaud Borde, Jo Bovy, W. N. Brandt, Howard Brewington, Jon Brinkmann, Peter J. Brown, Joel R. Brownstein, Kevin Bundy, N. G. Busca, William Carithers, Aurelio R. Carnero, Michael A. Carr, Yanmei Chen, Johan Comparat, Natalia Connolly, Frances Cope, Rupert A. C. Croft, Antonio J. Cuesta, Luiz N. da Costa, James R. A. Davenport, Timothée Delubac, Roland de Putter, Saurav Dhital, Anne Ealet, Garrett L. Ebelke, Daniel J. Eisenstein, S. Escoffier, Xiaohui Fan, N. Filiz Ak, Hayley Finley, Andreu Font-Ribera, R. Génova-Santos, James E. Gunn, Hong Guo, Daryl Haggard, Patrick B. Hall, Jean-Christophe Hamilton, Ben Harris, David W. Harris, Shirley Ho, David W. Hogg, Diana Holder, Klaus Honscheid, Joe Huehnerhoff, Beatrice Jordan, Wendell P. Jordan, Guinevere Kauffmann, Eyal A. Kazin, David Kirkby, Mark A. Klaene, Jean-Paul Kneib, Jean-Marc Le Goff, Khee-Gan Lee, Daniel C. Long, Craig P. Loomis, Britt Lundgren, Robert H. Lupton, Marcio A. G. Maia, Martin Makler, Elena Malanushenko, Viktor Malanushenko, Rachel Mandelbaum, Marc Manera, Claudia Maraston, Daniel Margala, Karen L. Masters, Cameron K. McBride, Patrick McDonald, Ian D. McGreer, Richard McMahon, Olga Mena, Jordi Miralda-Escudé, Antonio D. Montero-Dorta, Francesco Montesano, Demitri Muna, Adam D. Myers, Tracy Naugle, Robert C. Nichol, Pasquier Noterdaeme, Sebastián E. Nuza, Matthew D. Olmstead, Audrey Oravetz, Daniel J. Oravetz, Russell Owen, Nikhil Padmanabhan, Nathalie Palanque-Delabrouille, Kaike Pan, John K. Parejko, Isabelle Pâris, Will J. Percival, Ismael Pérez-Fournon, Ignasi Pérez-Ràfols, Patrick Petitjean, Robert Pfaffenberger, Janine Pforr, Matthew M. Pieri, Francisco Prada, Adrian M. Price-Whelan, M. Jordan Raddick, Rafael Rebolo, James Rich, Gordon T. Richards, Constance M. Rockosi, Natalie A. Roe, Ashley J. Ross, Nicholas P. Ross, Graziano Rossi, J. A. Rubiño-Martin, Lado Samushia, Ariel G. Sánchez, Conor Sayres, Sarah J. Schmidt, Donald P. Schneider, C. G. Scóccola, Hee-Jong Seo, Alaina Shelden, Erin Sheldon, Yue Shen, Yiping Shu, Anže Slosar, Stephen A. Smee, Stephanie A. Snedden, Fritz Stauffer, Oliver Steele, Michael A. Strauss, Alina Streblyanska, Nao Suzuki, Molly E. C. Swanson, Tomer Tal, Masayuki Tanaka, Daniel Thomas, Jeremy L. Tinker, Rita Tojeiro, Christy A. Tremonti, M. Vargas Magana, Licia Verde, Matteo Viel, David A. Wake, Mike Watson, Benjamin A. Weaver, David H. Weinberg, Benjamin J. Weiner, Andrew A. West, Martin White, W. M. Wood-Vasey, Christophe Yeche, Idit Zehavi, Gong-Bo Zhao, Zheng Zheng

The Baryon Oscillation Spectroscopic Survey (BOSS) is designed to measure the scale of baryon acoustic oscillations (BAO) in the clustering of matter over a larger volume than the combined efforts of all previous spectroscopic surveys of large scale structure. BOSS uses 1.5 million luminous galaxies as faint as i=19. Read More

2012Jul
Authors: SDSS-III Collaboration, :, Christopher P. Ahn, Rachael Alexandroff, Carlos Allende Prieto, Scott F. Anderson, Timothy Anderton, Brett H. Andrews, Éric Aubourg Stephen Bailey, Rory Barnes, Julian Bautista, Timothy C. Beers, Alessandra Beifiori, Andreas A. Berlind, Vaishali Bhardwaj, Dmitry Bizyaev, Cullen H. Blake, Michael R. Blanton, Michael Blomqvist, John J. Bochanski, Adam S. Bolton, Arnaud Borde, Jo Bovy, W. N. Brandt, J. Brinkmann, Peter J. Brown, Joel R. Brownstein, Kevin Bundy, N. G. Busca, William Carithers, Aurelio R. Carnero, Michael A. Carr, Dana I. Casetti-Dinescu, Yanmei Chen, Cristina Chiappini, Johan Comparat, Natalia Connolly, Justin R. Crepp, Stefano Cristiani, Rupert A. C. Croft, Antonio J. Cuesta, Luiz N. da Costa, James R. A. Davenport, Kyle S. Dawson, Roland de Putter, Nathan De Lee, Timothée Delubac, Saurav Dhital, Anne Ealet, Garrett L. Ebelke, Edward M. Edmondson, Daniel J. Eisenstein, S. Escoffier, Massimiliano Esposito, Michael L. Evans, Xiaohui Fan, Bruno Femení a Castellá, Emma Fernández Alvar, Leticia D. Ferreira, N. Filiz Ak, Hayley Finley, Scott W. Fleming, Andreu Font-Ribera, Peter M. Frinchaboy, D. A. García-Hernández, A. E. García Pérez, Jian Ge, R. Génova-Santos, Bruce A. Gillespie, Léo Girardi, Jonay I. González Hernández, Eva K. Grebel, James E. Gunn, Daryl Haggard, Jean-Christophe Hamilton, David W. Harris, Suzanne L. Hawley, Frederick R. Hearty, Shirley Ho, David W. Hogg, Jon A. Holtzman, Klaus Honscheid, J. Huehnerhoff, Inese I. Ivans, Zeljko Ivezić, Heather R. Jacobson, Linhua Jiang, Jonas Johansson, Jennifer A. Johnson, Guinevere Kauffmann, David Kirkby, Jessica A. Kirkpatrick, Mark A. Klaene, Gillian R. Knapp, Jean-Paul Kneib, Jean-Marc Le Goff, Alexie Leauthaud, Khee-Gan Lee, Young Sun Lee, Daniel C. Long, Craig P. Loomis, Sara Lucatello, Britt Lundgren, Robert H. Lupton, Bo Ma, Zhibo Ma, Nicholas MacDonald, Suvrath Mahadevan, Marcio A. G. Maia, Steven R. Majewski, Martin Makler, Elena Malanushenko, Viktor Malanushenko, A. Manchado, Rachel Mandelbaum, Marc Manera, Claudia Maraston, Daniel Margala, Sarah L. Martell, Cameron K. McBride, Ian D. McGreer, Richard G. McMahon, Brice Ménard, Sz. Meszaros, Jordi Miralda-Escudé, Antonio D. Montero-Dorta, Francesco Montesano, Heather L. Morrison, Demitri Muna, Jeffrey A. Munn, Hitoshi Murayama, Adam D. Myers, A. F. Neto, Duy Cuong Nguyen, Robert C. Nichol, David L. Nidever, Pasquier Noterdaeme, Ricardo L. C. Ogando, Matthew D. Olmstead, Daniel J. Oravetz, Russell Owen, Nikhil Padmanabhan, Nathalie Palanque-Delabrouille, Kaike Pan, John K. Parejko, Prachi Parihar, Isabelle Pâris, Petchara Pattarakijwanich, Joshua Pepper, Will J. Percival, Ismael Pérez-Fournon, Ignasi Pérez-Ráfols, Patrick Petitjean, Janine Pforr, Matthew M. Pieri, Marc H. Pinsonneault, G. F. Porto de Mello, Francisco Prada, Adrian M. Price-Whelan, M. Jordan Raddick, Rafael Rebolo, James Rich, Gordon T. Richards, Annie C. Robin, Helio J. Rocha-Pinto, Constance M. Rockosi, Natalie A. Roe, Ashley J. Ross, Nicholas P. Ross, J. A. Rubiño-Martin, Lado Samushia, J. Sanchez Almeida, Ariel G. Sánchez, Basílio Santiago, Conor Sayres, David J. Schlegel, Katharine J. Schlesinger, Sarah J. Schmidt, Donald P. Schneider, Axel D. Schwope, C. G. Scóccola, Uros Seljak, Erin Sheldon, Yue Shen, Yiping Shu, Jennifer Simmerer, Audrey E. Simmons, Ramin A. Skibba, A. Slosar, Flavia Sobreira, Jennifer S. Sobeck, Keivan G. Stassun, Oliver Steele, Matthias Steinmetz, Michael A. Strauss, Molly E. C. Swanson, Tomer Tal, Aniruddha R. Thakar, Daniel Thomas, Benjamin A. Thompson, Jeremy L. Tinker, Rita Tojeiro, Christy A. Tremonti, M. Vargas Magaña, Licia Verde, Matteo Viel, Shailendra K. Vikas, Nicole P. Vogt, David A. Wake, Ji Wang, Benjamin A. Weaver, David H. Weinberg, Benjamin J. Weiner, Andrew A. West, Martin White, John C. Wilson, John P. Wisniewski, W. M. Wood-Vasey, Brian Yanny, Christophe Yèche, Donald G. York, O. Zamora, Gail Zasowski, Idit Zehavi, Gong-Bo Zhao, Zheng Zheng, Guangtun Zhu, Joel C. Zinn

The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median z=0.52), 102,100 new quasar spectra (median z=2. Read More

From optical spectroscopy of X-ray sources observed as part of ChaMP, we present redshifts and classifications for a total of 1569 Chandra sources from our targeted spectroscopic follow up using the FLWO, SAAO, WIYN, CTIO, KPNO, Magellan, MMT and Gemini telescopes, and from archival SDSS spectroscopy. We classify the optical counterparts as 50% BLAGN, 16% NELG, 14% ALG, and 20% stars. We detect QSOs out to z~5. Read More

2012Jan
Affiliations: 1CIERA/Northwestern U, 2New Mexico State U, 3Harvard-Smithsonian CfA, 4Harvard-Smithsonian CfA, 5U. of Washington

Broad absorption line (BAL) quasars probe the high velocity gas ejected by luminous accreting black holes. BAL variability timescales place constraints on the size, location, and dynamics of the emitting and absorbing gas near the supermassive black hole. We present multi-epoch spectroscopy of seventeen BAL QSOs from the Sloan Digital Sky Survey (SDSS) using the Fred Lawrence Whipple Observatory's 1. Read More

2012Jan
Affiliations: 1CIERA/Northwestern University, 2University of Alberta

Modern X-ray observatories yield unique insight into the astrophysical time domain. Each X-ray photon can be assigned an arrival time, an energy and a sky position, yielding sensitive, energy-dependent light curves and enabling time-resolved spectra down to millisecond time-scales. Combining those with multiple views of the same patch of sky (e. Read More

2010Dec
Affiliations: 1Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University, 2San Francisco State University, 3San Francisco State University, 4San Francisco State University, 5Space Telescope Science Institute, 6Lund Observatory

We summarize results of a search for X-ray-emitting binary stars in the massive globular cluster Omega Centauri (NGC 5139) using Chandra and HST. ACIS-I imaging reveals 180 X-ray sources, of which we estimate that 45-70 are associated with the cluster. We present 40 identifications, most of which we have obtained using ACS/WFC imaging with HST that covers the central 10'x10' of the cluster. Read More

Quasars that allow the study of IGM He II are very rare, since they must be at high redshift along sightlines free of substantial hydrogen absorption, but recent work has dramatically expanded the number of such quasars known. We analyze two dozen higher-redshift (z=3.1-3. Read More

We employ the Chandra Multiwavelength Project (ChaMP) and the Sloan Digital Sky Survey (SDSS) to study the fraction of X-ray-active galaxies in the field out to z = 0.7. We utilize spectroscopic redshifts from SDSS and ChaMP, as well as photometric redshifts from several SDSS catalogs, to compile a parent sample of more than 100,000 SDSS galaxies and nearly 1,600 Chandra X-ray detections. Read More

2009Sep
Affiliations: 1Univ. of Washington, 2Univ. of Washington, 3Johns Hopkins, 4Univ. of Washington, 5Univ. of Edinburgh, 6Pennsylvania State Univ, 7Univ. of Chicago

Absorption along quasar sightlines remains among the most sensitive direct measures of HeII reionization in much of the intergalactic medium (IGM). Until recently, fewer than a half-dozen unobscured quasar sightlines suitable for the HeII Gunn-Peterson test were known; although these handful demonstrated great promise, the small sample size limited confidence in cosmological inferences. We have recently added nine more such clean HeII quasars, exploiting SDSS quasar samples, broadband UV imaging from GALEX, and high-yield UV spectroscopic confirmations from HST. Read More

2009Sep
Affiliations: 1Harvard-Smithsonian CfA, 2Harvard-Smithsonian CfA, 3Harvard-Smithsonian CfA, 4Harvard-Smithsonian CfA, 5Univ. of Washington, 6Univ. of North Dakota, 7Univ. of Washington

The combination of the SDSS and the Chandra Multiwavelength Project (ChaMP) currently offers the largest and most homogeneously selected sample of nearby galaxies for investigating the relation between X-ray nuclear emission, nebular line-emission, black hole masses, and properties of the associated stellar populations. We present here novel constraints that both X-ray luminosity Lx and X-ray spectral energy distribution bring to the galaxy evolutionary sequence H II -> Seyfert/Transition Object -> LINER -> Passive suggested by optical data. In particular, we show that both Lx and Gamma, the slope of the power-law that best fits the 0. Read More

2009Mar
Affiliations: 1NOAO, 2AAS, 3Columbia University, 4Columbia University, 5University of Washington, 6Rutgers University, 7Caltech, 8Caltech, 9Vanderbilt University, Pres. of the Nat. Soc. of Hispanic Physicists, 10Rutgers University, 11University ofMaryland, College Park, 12Washington State University, 13NOAO, 14Western Kentucky University, 15University of Notre Dame, 16Spitzer Science Center, 17STScI, 18Princeton University, 19South Carolina State University, 20MIT, 21Faculty Project Leader, 22University of Washington, 23University of Washington, 24University of Washington, 25University of Washington, 26University of Washington, 27University of Washington, 28University of Washington, 29University of Washington, 30University of Washington, 31University of Washington, 32University of Washington, 33University of Washington

Promoting racial and ethnic diversity is critically important to the future success and growth of the field of astronomy. The raw ability, drive and interest required to excel in the field is distributed without regard to race, gender, or socioeconomic background. By not actively promoting diversity in our field we risk losing talented people to other professions (or losing them entirely), which means that there will be astronomical discoveries that simply won't get made. Read More

2009Mar
Affiliations: 1NOAO, 2AAS, 3Columbia University, 4Columbia University, 5University of Washington, 6Rutgers University, 7Caltech, 8Caltech, 9Vanderbilt University, Pres. of the Nat. Soc. of Hispanic Physicists, 10Rutgers University, 11University of Maryland, College Park, 12Washington State University, 13NOAO, 14Western Kentucky University, 15University of Notre Dame, 16Spitzer Science Center, 17STScI, 18Princeton University, 19South Carolina State University, 20MIT, 21Faculty Project Leader, 22University of Washington, 23University of Washington, 24University of Washington, 25University of Washington, 26University of Washington, 27University of Washington, 28University of Washington, 29University of Washington, 30University of Washington, 31University of Washington, 32University of Washington, 33University of Washington

If the ethnic makeup of the astronomy profession is to achieve parity with the general population within one generation (~30 years), the number of underrepresented minorities earning graduate degrees in astronomy and astrophysics must increase in the coming decade by a factor of 5 to 10. To accomplish this, the profession must develop and invest in mechanisms to more effectively move individuals across critical educational junctures to the PhD and beyond. Early and continuous research engagement starting in the undergraduate years is critical to this vision, in which the federally funded research internship programs (e. Read More

2009Mar
Affiliations: 1NOAO, 2AAS, 3Columbia University, 4Columbia University, 5University of Washington, 6Rutgers University, 7Caltech, 8Caltech, 9Vanderbilt University, Pres. of the Nat. Soc. of Hispanic Physicists, 10Rutgers University, 11University of Maryland, College Park, 12Washington State University, 13NOAO, 14Western Kentucky University, 15University of Notre Dame, 16Spitzer Science Center, 17STScI, 18Princeton University, 19South Carolina State University, 20MIT, 21Faculty Project Leader, 22University of Washington, 23University of Washington, 24University of Washington, 25University of Washington, 26University of Washington, 27University of Washington, 28University of Washington, 29University of Washington, 30University of Washington, 31University of Washington, 32University of Washington, 33University of Washington

In order to attract, recruit and retain underrepresented minority students to pursue Astronomy and related fields, we must ensure that there continues to be a well qualified pool of graduate and undergraduate students from which to recruit. This required pool of people are today's elementary, middle and high school students. The Astronomy community must be proactive in demonstrating the importance of pursing scientific study and careers to these students and their parents. Read More

2009Feb
Affiliations: 1University of Washington, 2San Francisco State University, 3Lund Observatory

We analyze a ~70 ksec Chandra ACIS-I exposure of the globular cluster Omega Centauri (NGC 5139). The ~17 amin x 17 amin field of view fully encompasses three core radii and almost twice the half-mass radius. We detect 180 sources to a limiting flux of ~4. Read More

2008Sep
Affiliations: 1University of Washington, 2University of Washington, 3Johns Hopkins, 4University of Washington, 5University of Edinburgh, 6Anglo-Australian Observatory, 7University of Washington, 8Pennsylvania State University, 9University of Chicago
Category: Astrophysics

Investigations of He II Ly-alpha (304 A rest) absorption toward a half-dozen quasars at z~3-4 have demonstrated the great potential of helium studies of the IGM, but the current critically small sample size of clean sightlines for the He II Gunn-Peterson test limits confidence in cosmological inferences, and a larger sample is required. Although the unobscured quasar sightlines to high redshift are extremely rare, SDSS DR6 provides thousands of z>2.8 quasars. Read More

2007Jul
Affiliations: 1Harvard Smithsonian Center for Astrophysics, 2University of Washington, 3Lawrence Berkeley National Laboratory, 4Harvard Smithsonian Center for Astrophysics, 5Lawrence Berkeley National Laboratory, 6Princeton University Observatory, 7Columbia University, 8University of Washington, 9University of Washington, 10Univeristy of California Berkeley, 11Harvard Smithsonian Center for Astrophysics, 12University of Washington, 13University of Washington, 14University of Washington, 15University of Washington, 16University of Washington, 17Penn State, 18University of Washington
Category: Astrophysics

The Sloan Digital Sky Survey (SDSS) and Two Micron All Sky Survey (2MASS) are rich resources for studying stellar astrophysics and the structure and formation history of the Galaxy. As new surveys and instruments adopt similar filter sets, it is increasingly important to understand the properties of the ugrizJHKs stellar locus, both to inform studies of `normal' main sequence stars as well as for robust searches for point sources with unusual colors. Using a sample of ~600,000 point sources detected by SDSS and 2MASS, we tabulate the position and width of the ugrizJHKs stellar locus as a function of g-i color, and provide accurate polynomial fits. Read More

We describe further results of a program aimed to yield ~10^4 fully characterized optical identifications of ROSAT X-ray sources. Our program employs X-ray data from the ROSAT All-Sky Survey (RASS), and both optical imaging and spectroscopic data from the Sloan Digital Sky Survey (SDSS). RASS/SDSS data from 5740 deg^2 of sky spectroscopically covered in SDSS Data Release 5 (DR5) provide an expanded catalog of 7000 confirmed quasars and other AGN that are probable RASS identifications. Read More

2005Jun

AM CVn systems are a rare (about a dozen previously known) class of cataclysmic variables, arguably encompassing the shortest orbital periods (down to about 10 minutes) of any known binaries. Both binary components are thought to be degenerate (or partially so), likely with mass-transfer from a helium-rich donor onto a white dwarf, driven by gravitational radiation. Although rare, AM CVn systems are of high interest as possible SN Ia progenitors, and because they are predicted to be common sources of gravity waves in upcoming experiments such as LISA. Read More

2005May
Affiliations: 1Univ. of Washington, 2Univ. of Washington, 3Univ. of Washington, 4Kapteyn Institute, 5Cornell Univ, 6Univ. of Washington, 7Univ. of Washington, 8Univ. of Pittsburgh, 9Princeton Univ, 10Princeton Univ, 11Princeton Univ, 12Princeton Univ, 13Univ. of Washington, 14Univ. of Washington, 15Univ. of Washington, 16Univ. of Washington, 17Univ. of Washington, 18Univ. of Washington, 19Univ. of Washington, 20Univ. of Washington, 21Univ. of Washington
Category: Astrophysics

We discuss the UV, optical, and IR properties of the SDSS sources detected by GALEX as part of its All-sky Imaging Survey Early Release Observations. Virtually all of the GALEX sources in the overlap region are detected by SDSS. GALEX sources represent ~2. Read More