Jonathan C. Tan - Department of Physics, University of Florida

Jonathan C. Tan
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Name
Jonathan C. Tan
Affiliation
Department of Physics, University of Florida
City
Coral Gables
Country
United States

Pubs By Year

Pub Categories

 
Astrophysics of Galaxies (37)
 
Solar and Stellar Astrophysics (26)
 
Earth and Planetary Astrophysics (6)
 
Instrumentation and Methods for Astrophysics (4)
 
Cosmology and Nongalactic Astrophysics (2)
 
High Energy Astrophysical Phenomena (1)

Publications Authored By Jonathan C. Tan

Star formation from the interstellar medium of galactic disks is a basic process controlling the evolution of galaxies. Understanding the star formation rate in a local patch of a disk with a given gas mass is thus an important challenge for theoretical models. Here we simulate a kiloparsec region of a disk, following the evolution of self-gravitating molecular clouds down to subparsec scales, as they form stars that then inject feedback energy by dissociating and ionizing UV photons and supernova explosions. Read More

We study giant molecular cloud (GMC) collisions and their ability to trigger star cluster formation. We further develop our three dimensional magnetized, turbulent, colliding GMC simulations by implementing star formation sub-grid models. Two such models are explored: (1) "Density-Regulated," i. Read More

2017Feb
Affiliations: 1Department of Astronomy, University of Florida, 2Department of Astronomy, University of Florida, 3Western Washington University, 4University of Oxford, 5Yale, 6Department of Astronomy, University of Florida, 7Leiden Observatory, 8Steward Observatory, 9University of Michigan, 10University of Michigan, 11Vanderbilt University, 12University of Virginia, 13Wesleyan University, 14University of Virginia, 15University of Virginia, 16University of Virginia

The kinematics and dynamics of young stellar populations tests theories of their formation. With this aim, we continue our analysis of the SDSS-III/APOGEE INfrared Spectra of Young Nebulous Clusters (IN-SYNC) survey, a high resolution near infrared spectroscopic survey of young clusters. We focus on the Orion A star-forming region, for which IN-SYNC obtained spectra of ~2700 stars. Read More

2017Jan
Affiliations: 1Dept. of Astronomy, Yale University, USA, 2Dept. of Astronomy, University of Florida, USA, 3Max-Planck-Institute for Extraterrestrial Physics, 4INAF - Osservatorio Astrofisico di Arcetri, Italy, 5European Southern Observatory, 6Max-Planck-Institute for Astronomy, Germany

We present high resolution (0.2", 1000 AU) ALMA observations of massive infrared dark cloud clump, G028.37+00. Read More

2017Jan
Affiliations: 1Dept. of Astronomy, University of Florida, 2Dept. of Astronomy, University of Florida, 3CIERA, Northwestern University

We investigate the formation and early evolution of star clusters assuming that they form from a turbulent starless clump of given mass bounded inside a parent self-gravitating molecular cloud characterized by a particular mass surface density. As a first step we assume instantaneous star cluster formation and gas expulsion. We draw our initial conditions from observed properties of starless clumps. Read More

We study feedback during massive star formation using semi-analytic methods, considering the effects of disk winds, radiation pressure, photoevaporation and stellar winds, while following protostellar evolution in collapsing massive gas cores. We find that disk winds are the dominant feedback mechanism setting star formation efficiencies (SFEs) from initial cores of ~0.3-0. Read More

We present an overview and first results of the {\it SOFIA} Massive (SOMA) Star Formation Survey, which is using the FORCAST instrument to image massive protostars from $\sim10$--$40\:\rm{\mu}\rm{m}$. These wavelengths trace thermal emission from warm dust, which in Core Accretion models mainly emerges from the inner regions of protostellar outflow cavities. Dust in dense core envelopes also imprints characteristic extinction patterns at these wavelengths causing intensity peaks to shift along the outflow axis and profiles to become more symmetric at longer wavelengths. Read More

High levels of deuterium fraction in N$_2$H$^+$ are observed in some pre-stellar cores. Single-zone chemical models find that the timescale required to reach observed values ($D_{\rm frac}^{{\rm N}_2{\rm H}^+} \equiv {\rm N}_2{\rm D}^+/{\rm N}_2{\rm H}^+ \gtrsim 0.1$) is longer than the free-fall time, possibly ten times longer. Read More

2016Sep
Affiliations: 1Dept. of Astronomy, University of Florida, USA, 2Dept. of Astronomy, University of Florida, USA, 3Max-Planck-Institute for Extraterrestrial Physics, 4INAF - Osservatorio Astrofisico di Arcetri, Italy, 5Dept. of Astronomy, University of Florida, USA, 6Max-Planck-Institute for Astronomy, Germany

We carry out an ALMA $\rm N_2D^+$(3-2) and 1.3~mm continuum survey towards 32 high mass surface density regions in seven Infrared Dark Clouds with the aim of finding massive starless cores, which may be the initial conditions for the formation of massive stars. Cores showing strong $\rm N_2D^+$(3-2) emission are expected to be highly deuterated and indicative of early, potentially pre-stellar stages of star formation. Read More

We calculate the cosmic distributions in space and time of the formation sites of the first, "Pop III.1" stars, exploring a model in which these are the progenitors of all supermassive black holes (SMBHs) that are today seen in the centers of most large galaxies. Pop III. Read More

We investigate giant molecular cloud (GMCs) collisions and their ability to induce gravitational instability and thus star formation. This mechanism may be a major driver of star formation activity in galactic disks. We carry out a series of three dimensional, magnetohydrodynamics (MHD), adaptive mesh refinement (AMR) simulations to study how cloud collisions trigger formation of dense filaments and clumps. Read More

We study the probability distribution function (PDF) of mass surface densities, $\Sigma$, of infrared dark cloud (IRDC) G028.37+00.07 and its surrounding giant molecular cloud. Read More

We present ALMA follow-up observations of two massive, early-stage core candidates, C1-N & C1-S, in Infrared Dark Cloud (IRDC) G028.37+00.07, which were previously identified by their N2D+(3-2) emission and show high levels of deuteration of this species. Read More

I review (1) Physics of Star Formation & Open Questions; (2) Structure & Dynamics of Star-Forming Clouds & Young Clusters; (3) Star Formation Rates: Observations & Theoretical Implications. Read More

2015Nov
Affiliations: 1Department of Astronomy, University of Florida, 2Department of Astronomy, University of Florida, 3Western Washington University, 4University of Oxford, 5Yale, 6Department of Astronomy, University of Florida, 7Leiden Observatory, 8Steward Observatory, 9ETH Zurich, 10University of Michigan, 11Vanderbilt University, 12University of Virginia, 13Wesleyan University, 14University of Virginia, 15University of Virginia, 16University of Virginia, 17Apache Point Observatory and New Mexico State University

We present the results of the SDSS APOGEE INfrared Spectroscopy of Young Nebulous Clusters program (IN-SYNC) survey of the Orion A molecular cloud. This survey obtained high resolution near infrared (NIR) spectroscopy of about 2700 young pre-main sequence stars throughout the region, acquired across five distinct fields spanning 6deg field of view (FOV). With these spectra, we have measured accurate stellar parameters (T_eff, log g, v sin i) and extinctions, and placed the sources in the Hertzsprung-Russel Diagram (HRD). Read More

2015Nov
Affiliations: 1Dept. of Astronomy, University of Florida, USA, 2Dept. of Astronomy, University of Florida, USA, 3Max-Planck-Institute for Extraterrestrial Physics, 4INAF - Osservatorio Astrofisico di Arcetri, Italy

To understand massive star formation requires study of its initial conditions. Two massive starless core candidates, C1-N & C1-S, have been detected in IRDC G028.37+00. Read More

I review theoretical models of star formation and how they apply across the stellar mass spectrum. Several distinct theories are under active study for massive star formation, especially Turbulent Core Accretion, Competitive Accretion and Protostellar Mergers, leading to distinct observational predictions. These include the types of initial conditions, the structure of infall envelopes, disks and outflows, and the relation of massive star formation to star cluster formation. Read More

The Kepler-discovered Systems with Tightly-packed Inner Planets (STIPs), typically with several planets of Earth to super-Earth masses on well-aligned, sub-AU orbits may host the most common type of planets, including habitable planets, in the Galaxy. They pose a great challenge for planet formation theories, which fall into two broad classes: (1) formation further out followed by inward migration; (2) formation in situ, in the very inner regions of the protoplanetary disk. We review the pros and cons of these classes, before focusing on a new theory of sequential in situ formation from the inside-out via creation of successive gravitationally unstable rings fed from a continuous stream of small (~cm-m size) "pebbles," drifting inward via gas drag. Read More

IRAS 22134+5834 was observed in the centimeter with (E)VLA, 3~mm with CARMA, 2~mm with PdBI, and 1.3~mm with SMA, to study the continuum emission as well as the molecular lines, that trace different physical conditions of the gas to study the influence of massive YSOs on nearby starless cores, and the possible implications in the clustered star formation process. The multi-wavelength centimeter continuum observations revealed two radio sources within the cluster, VLA1 and VLA2. Read More

2015Sep
Affiliations: 1Dept. of Astronomy, University of Florida, USA, 2Dept. of Astronomy, University of Florida, USA, 3Max-Planck-Institute for Extraterrestrial Physics, 4INAF - Osservatorio Astrofisico di Arcetri, Italy, 5California Institute of Technology, USA, 6Institute for Computational Science, University of Zurich, Switzerland, 7Laboratoire AIM, CEA/DSM-CNRS-Universite Paris Diderot, IRFU/Service d' Astrophysique, France, 8National Astronomical Observatory of Japan, Japan, 9Graduate School of Informatics and Engineering, The University of Electro-Communications, Japan

We study deuterium fractionation in two massive starless/early-stage cores C1-N and C1-S in Infrared Dark Cloud (IRDC) G028.37+00.07, first identified by Tan et al. Read More

2015Sep

We present an evolutionary sequence of models of the photoionized disk-wind outflow around forming massive stars based on the Core Accretion model. The outflow is expected to be the first structure to be ionized by the protostar and can confine the expansion of the HII region, especially in lateral directions in the plane of the accretion disk. The ionizing luminosity increases as Kelvin-Helmholz contraction proceeds, and the HII region is formed when the stellar mass reaches ~10-20Msun depending on the initial cloud core properties. Read More

We present spectroscopic tests of MIR to FIR extinction laws in IRDC G028.36+00.07, a potential site of massive star and star cluster formation. Read More

2015Aug
Affiliations: 1Department of Astronomy, University of Florida, 2Department of Astrophysical Sciences, Princeton University, 3Department of Astronomy, University of Florida, 4Department of Astronomy, University of Florida

The Kepler mission has discovered more than 4000 exoplanet candidates. Many are in systems with tightly packed inner planets. Inside-Out Planet Formation (IOPF) has been proposed to explain these systems. Read More

Most field stars will have encountered the highest stellar density and hence the largest number of interactions in their birth environment. Yet the stellar dynamics during this crucial phase are poorly understood. Here we analyze the radial velocities measured for 152 out of 380 observed stars in the 2-6 Myr old star cluster IC 348 as part of the SDSS-III APOGEE. Read More

2015May
Authors: Warren Skidmore, Ian Dell'Antonio, Misato Fukugawa, Aruna Goswami, Lei Hao, David Jewitt, Greg Laughlin, Charles Steidel, Paul Hickson, Luc Simard, Matthias Schöck, Tommaso Treu, Judith Cohen, G. C. Anupama, Mark Dickinson, Fiona Harrison, Tadayuki Kodama, Jessica R. Lu, Bruce Macintosh, Matt Malkan, Shude Mao, Norio Narita, Tomohiko Sekiguchi, Annapurni Subramaniam, Masaomi Tanaka, Feng Tian, Michael A'Hearn, Masayuki Akiyama, Babar Ali, Wako Aoki, Manjari Bagchi, Aaron Barth, Varun Bhalerao, Marusa Bradac, James Bullock, Adam J. Burgasser, Scott Chapman, Ranga-Ram Chary, Masashi Chiba, Michael Cooper, Asantha Cooray, Ian Crossfield, Thayne Currie, Mousumi Das, G. C. Dewangan, Richard de Grijs, Tuan Do, Subo Dong, Jarah Evslin, Taotao Fang, Xuan Fang, Christopher Fassnacht, Leigh Fletcher, Eric Gaidos, Roy Gal, Andrea Ghez, Mauro Giavalisco, Carol A. Grady, Thomas Greathouse, Rupjyoti Gogoi, Puragra Guhathakurta, Luis Ho, Priya Hasan, Gregory J. Herczeg, Mitsuhiko Honda, Masa Imanishi, Hanae Inami, Masanori Iye, Jason Kalirai, U. S. Kamath, Stephen Kane, Nobunari Kashikawa, Mansi Kasliwal, Vishal Kasliwal, Evan Kirby, Quinn M. Konopacky, Sebastien Lepine, Di Li, Jianyang Li, Junjun Liu, Michael C. Liu, Enrigue Lopez-Rodriguez, Jennifer Lotz, Philip Lubin, Lucas Macri, Keiichi Maeda, Franck Marchis, Christian Marois, Alan Marscher, Crystal Martin, Taro Matsuo, Claire Max, Alan McConnachie, Stacy McGough, Carl Melis, Leo Meyer, Michael Mumma, Takayuki Muto, Tohru Nagao, Joan R. Najita, Julio Navarro, Michael Pierce, Jason X. Prochaska, Masamune Oguri, Devendra K. Ojha, Yoshiko K. Okamoto, Glenn Orton, Angel Otarola, Masami Ouchi, Chris Packham, Deborah L. Padgett, Shashi Bhushan Pandey, Catherine Pilachowsky, Klaus M. Pontoppidan, Joel Primack, Shalima Puthiyaveettil, Enrico Ramirez-Ruiz, Naveen Reddy, Michael Rich, Matthew J. Richter, James Schombert, Anjan Ananda Sen, Jianrong Shi, Kartik Sheth, R. Srianand, Jonathan C. Tan, Masayuki Tanaka, Angelle Tanner, Nozomu Tominaga, David Tytler, Vivian U, Lingzhi Wang, Xiaofeng Wang, Yiping Wang, Gillian Wilson, Shelley Wright, Chao Wu, Xufeng Wu, Renxin Xu, Toru Yamada, Bin Yang, Gongbo Zhao, Hongsheng Zhao

The TMT Detailed Science Case describes the transformational science that the Thirty Meter Telescope will enable. Planned to begin science operations in 2024, TMT will open up opportunities for revolutionary discoveries in essentially every field of astronomy, astrophysics and cosmology, seeing much fainter objects much more clearly than existing telescopes. Per this capability, TMT's science agenda fills all of space and time, from nearby comets and asteroids, to exoplanets, to the most distant galaxies, and all the way back to the very first sources of light in the Universe. Read More

2015Mar
Affiliations: 1Department of Physics, University of Florida, 2School of Physics and Astronomy, University of Leeds, 3Department of Physics, University of Florida, 4Max Planck Institute for Extraterrestrial Physics

We utilize magnetohydrodynamic (MHD) simulations to develop a numerical model for GMC-GMC collisions between nearly magnetically critical clouds. The goal is to determine if, and under what circumstances, cloud collisions can cause pre-existing magnetically subcritical clumps to become supercritical and undergo gravitational collapse. We first develop and implement new photodissociation region (PDR) based heating and cooling functions that span the atomic to molecular transition, creating a multiphase ISM and allowing modeling of non-equilibrium temperature structures. Read More

We study Giant Molecular Cloud (GMC) environments surrounding 10 Infrared Dark Clouds (IRDCs), using $^{13}$CO(1-0) emission from the Galactic Ring Survey. We measure physical properties of these IRDCs/GMCs on a range of scales extending to radii, R, of 30 pc. By comparing different methods for defining cloud boundaries and for deriving mass surface densities and velocity dispersions, we settle on a preferred "CE,$\tau$,G" method of "Connected Extraction" in position-velocity space plus Gaussian fitting to opacity-corrected line profiles for velocity dispersion and mass estimation. Read More

2015Jan
Authors: Shadab Alam1, Franco D. Albareti2, Carlos Allende Prieto3, F. Anders4, Scott F. Anderson5, Brett H. Andrews6, Eric Armengaud7, Éric Aubourg8, Stephen Bailey9, Julian E. Bautista10, Rachael L. Beaton11, Timothy C. Beers12, Chad F. Bender13, Andreas A. Berlind14, Florian Beutler15, Vaishali Bhardwaj16, Jonathan C. Bird17, Dmitry Bizyaev18, Cullen H. Blake19, Michael R. Blanton20, Michael Blomqvist21, John J. Bochanski22, Adam S. Bolton23, Jo Bovy24, A. Shelden Bradley25, W. N. Brandt26, D. E. Brauer27, J. Brinkmann28, Peter J. Brown29, Joel R. Brownstein30, Angela Burden31, Etienne Burtin32, Nicolás G. Busca33, Zheng Cai34, Diego Capozzi35, Aurelio Carnero Rosell36, Ricardo Carrera37, Yen-Chi Chen38, Cristina Chiappini39, S. Drew Chojnowski40, Chia-Hsun Chuang41, Nicolas Clerc42, Johan Comparat43, Kevin Covey44, Rupert A. C. Croft45, Antonio J. Cuesta46, Katia Cunha47, Luiz N. da Costa48, Nicola Da Rio49, James R. A. Davenport50, Kyle S. Dawson51, Nathan De Lee52, Timothée Delubac53, Rohit Deshpande54, Letícia Dutra-Ferreira55, Tom Dwelly56, Anne Ealet57, Garrett L. Ebelke58, Edward M. Edmondson59, Daniel J. Eisenstein60, Stephanie Escoffier61, Massimiliano Esposito62, Xiaohui Fan63, Emma Fernández-Alvar64, Diane Feuillet65, Nurten Filiz Ak66, Hayley Finley67, Alexis Finoguenov68, Kevin Flaherty69, Scott W. Fleming70, Andreu Font-Ribera71, Jonathan Foster72, Peter M. Frinchaboy73, J. G. Galbraith-Frew74, D. A. García-Hernández75, Ana E. García Pérez76, Patrick Gaulme77, Jian Ge78, R. Génova-Santos79, Luan Ghezzi80, Bruce A. Gillespie81, Léo Girardi82, Daniel Goddard83, Satya Gontcho A Gontcho84, Jonay I. González Hernández85, Eva K. Grebel86, Jan Niklas Grieb87, Nolan Grieves88, James E. Gunn89, Hong Guo90, Paul Harding91, Sten Hasselquist92, Suzanne L. Hawley93, Michael Hayden94, Fred R. Hearty95, Shirley Ho96, David W. Hogg97, Kelly Holley-Bockelmann98, Jon A. Holtzman99, Klaus Honscheid100, Joseph Huehnerhoff101, Linhua Jiang102, Jennifer A. Johnson103, Karen Kinemuchi104, David Kirkby105, Francisco Kitaura106, Mark A. Klaene107, Jean-Paul Kneib108, Xavier P. Koenig109, Charles R. Lam110, Ting-Wen Lan111, Dustin Lang112, Pierre Laurent113, Jean-Marc Le Goff114, Alexie Leauthaud115, Khee-Gan Lee116, Young Sun Lee117, Timothy C. Licquia118, Jian Liu119, Daniel C. Long120, Martín López-Corredoira121, Diego Lorenzo-Oliveira122, Sara Lucatello123, Britt Lundgren124, Robert H. Lupton125, Claude E. Mack III126, Suvrath Mahadevan127, Marcio A. G. Maia128, Steven R. Majewski129, Elena Malanushenko130, Viktor Malanushenko131, A. Manchado132, Marc Manera133, Qingqing Mao134, Claudia Maraston135, Robert C. Marchwinski136, Daniel Margala137, Sarah L. Martell138, Marie Martig139, Karen L. Masters140, Cameron K. McBride141, Peregrine M. McGehee142, Ian D. McGreer143, Richard G. McMahon144, Brice Ménard145, Marie-Luise Menzel146, Andrea Merloni147, Szabolcs Mészáros148, Adam A. Miller149, Jordi Miralda-Escudé150, Hironao Miyatake151, Antonio D. Montero-Dorta152, Surhud More153, Xan Morice-Atkinson154, Heather L. Morrison155, Demitri Muna156, Adam D. Myers157, Jeffrey A. Newman158, Mark Neyrinck159, Duy Cuong Nguyen160, Robert C. Nichol161, David L. Nidever162, Pasquier Noterdaeme163, Sebastián E. Nuza164, Julia E. O'Connell165, Robert W. O'Connell166, Ross O'Connell167, Ricardo L. C. Ogando168, Matthew D. Olmstead169, Audrey E. Oravetz170, Daniel J. Oravetz171, Keisuke Osumi172, Russell Owen173, Deborah L. Padgett174, Nikhil Padmanabhan175, Martin Paegert176, Nathalie Palanque-Delabrouille177, Kaike Pan178, John K. Parejko179, Changbom Park180, Isabelle Pâris181, Petchara Pattarakijwanich182, M. Pellejero-Ibanez183, Joshua Pepper184, Will J. Percival185, Ismael Pérez-Fournon186, Ignasi Pérez-Ràfols187, Patrick Petitjean188, Matthew M. Pieri189, Marc H. Pinsonneault190, Gustavo F. Porto de Mello191, Francisco Prada192, Abhishek Prakash193, Adrian M. Price-Whelan194, M. Jordan Raddick195, Mubdi Rahman196, Beth A. Reid197, James Rich198, Hans-Walter Rix199, Annie C. Robin200, Constance M. Rockosi201, Thaíse S. Rodrigues202, Sergio Rodríguez-Rottes203, Natalie A. Roe204, Ashley J. Ross205, Nicholas P. Ross206, Graziano Rossi207, John J. Ruan208, J. A. Rubiño-Martín209, Eli S. Rykoff210, Salvador Salazar-Albornoz211, Mara Salvato212, Lado Samushia213, Ariel G. Sánchez214, Basílio Santiago215, Conor Sayres216, Ricardo P. Schiavon217, David J. Schlegel218, Sarah J. Schmidt219, Donald P. Schneider220, Mathias Schultheis221, Axel D. Schwope222, C. G. Scóccola223, Kris Sellgren224, Hee-Jong Seo225, Neville Shane226, Yue Shen227, Matthew Shetrone228, Yiping Shu229, Thirupathi Sivarani230, M. F. Skrutskie231, Anže Slosar232, Verne V. Smith233, Flávia Sobreira234, Keivan G. Stassun235, Matthias Steinmetz236, Michael A. Strauss237, Alina Streblyanska238, Molly E. C. Swanson239, Jonathan C. Tan240, Jamie Tayar241, Ryan C. Terrien242, Aniruddha R. Thakar243, Daniel Thomas244, Benjamin A. Thompson245, Jeremy L. Tinker246, Rita Tojeiro247, Nicholas W. Troup248, Mariana Vargas-Magaña249, Jose A. Vazquez250, Licia Verde251, Matteo Viel252, Nicole P. Vogt253, David A. Wake254, Ji Wang255, Benjamin A. Weaver256, David H. Weinberg257, Benjamin J. Weiner258, Martin White259, John C. Wilson260, John P. Wisniewski261, W. M. Wood-Vasey262, Christophe Yèche263, Donald G. York264, Nadia L. Zakamska265, O. Zamora266, Gail Zasowski267, Idit Zehavi268, Gong-Bo Zhao269, Zheng Zheng270, Xu Zhou271, Zhimin Zhou272, Guangtun Zhu273, Hu Zou274
Affiliations: 1Bruce and Astrid McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, USA, 2Instituto de Física Teórica, 3Instituto de Astrofísica de Canarias, 4Leibniz-Institut für Astrophysik Potsdam, 5Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA, 6Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA, 7CEA, Centre de Saclay, Irfu/SPP, F-91191 Gif-sur-Yvette, France, 8APC, University of Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cité, F-75205 Paris, France, 9Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA, 10APC, University of Paris Diderot, CNRS/IN2P3, CEA/IRFU, Observatoire de Paris, Sorbonne Paris Cité, F-75205 Paris, France, 11Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325, USA, 12Department of Physics and JINA Center for the Evolution of the Elements, University of Notre Dame, Notre Dame, IN 46556 USA, 13Department of Astronomy and Astrophysics, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802, USA, 14Department of Physics and Astronomy, Vanderbilt University, VU Station 1807, Nashville, TN 37235, USA, 15Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA, 16Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA, 17Department of Physics and Astronomy, Vanderbilt University, VU Station 1807, Nashville, TN 37235, USA, 18Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA, 19University of Pennsylvania, Department of Physics and Astronomy, 219 S. 33rd St., Philadelphia, PA 19104, USA, 20Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003, USA, 21Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA, 22Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA, 23Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA, 24Institute for Advanced Study, Einstein Drive, Princeton, NJ 08540, USA, 25Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA, 26Department of Astronomy and Astrophysics, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802, USA, 27Leibniz-Institut für Astrophysik Potsdam, 28Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA, 29George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A. and M. University, Department of Physics and Astronomy, 4242 TAMU, College Station, TX 77843, USA, 30Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA, 31Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK, 32CEA, Centre de Saclay, Irfu/SPP, F-91191 Gif-sur-Yvette, France, 33Observatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil, 34Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721, USA, 35Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK, 36Observatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil, 37Instituto de Astrofísica de Canarias, 38Department of Statistics, Bruce and Astrid McWilliams Center for Cosmology, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, USA, 39Leibniz-Institut für Astrophysik Potsdam, 40Department of Astronomy, MSC 4500, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003, USA, 41Instituto de Física Teórica, 42Max-Planck-Institut für Extraterrestrische Physik, Postfach 1312, Giessenbachstr. D-85741 Garching, Germany, 43Instituto de Física Teórica, 44Lowell Observatory, 1400 W. Mars Hill Road, Flagstaff AZ 86001, 45Bruce and Astrid McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, USA, 46Institut de Ciències del Cosmos, Universitat de Barcelona/IEEC, Barcelona E-08028, Spain, 47Observatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil, 48Observatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil, 49Department of Astronomy, University of Florida, Bryant Space Science Center, Gainesville, FL 32611-2055, USA, 50Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA, 51Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA, 52Department of Physics and Geology, Northern Kentucky University, Highland Heights, KY 41099, USA, 53Laboratoire d'Astrophysique, École Polytechnique Fédérale de Lausanne, 54Department of Astronomy and Astrophysics, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802, USA, 55Universidade Federal do Rio de Janeiro, Observatório do Valongo, Ladeira do Pedro Antônio 43, 20080-090 Rio de Janeiro, Brazil, 56Max-Planck-Institut für Extraterrestrische Physik, Postfach 1312, Giessenbachstr. D-85741 Garching, Germany, 57Centre de Physique des Particules de Marseille, Aix-Marseille Université, CNRS/IN2P3, E-13288 Marseille, France, 58Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325, USA, 59Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK, 60Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138, USA, 61Centre de Physique des Particules de Marseille, Aix-Marseille Université, CNRS/IN2P3, E-13288 Marseille, France, 62Instituto de Astrofísica de Canarias, 63Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721, USA, 64Instituto de Astrofísica de Canarias, 65Department of Astronomy, MSC 4500, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003, USA, 66Department of Astronomy and Astrophysics, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802, USA, 67Institut d'Astrophysique de Paris, UPMC-CNRS, UMR7095, 98 bis Boulevard Arago, F-75014, Paris, France, 68Department of Physics, University of Helsinki, Gustaf Hällströmin katu 2, Helsinki FI-00140, Finland, 69Department of Astronomy, Van Vleck Observatory, Wesleyan University, Middletown, CT 06459, 70Space Telescope Science Institute, 3700 San Martin Dr, Baltimore, MD 21218, USA, 71Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA, 72Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT, 06520, USA, 73Department of Physics and Astronomy, Texas Christian University, 2800 South University Drive, Fort Worth, TX 76129, USA, 74Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA, 75Instituto de Astrofísica de Canarias, 76Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325, USA, 77Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA, 78Department of Astronomy, University of Florida, Bryant Space Science Center, Gainesville, FL 32611-2055, USA, 79Instituto de Astrofísica de Canarias, 80Observatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil, 81Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA, 82INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy, 83Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK, 84Institut de Ciències del Cosmos, Universitat de Barcelona/IEEC, Barcelona E-08028, Spain, 85Instituto de Astrofísica de Canarias, 86Astronomisches Rechen-Institut, Zentrum für Astronomie der Universität Heidelberg, Mönchhofstr. 12--14, D-69120 Heidelberg, Germany, 87Max-Planck-Institut für Extraterrestrische Physik, Postfach 1312, Giessenbachstr. D-85741 Garching, Germany, 88Department of Astronomy, University of Florida, Bryant Space Science Center, Gainesville, FL 32611-2055, USA, 89Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA, 90Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA, 91Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106, USA, 92Department of Astronomy, MSC 4500, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003, USA, 93Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA, 94Department of Astronomy, MSC 4500, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003, USA, 95Department of Astronomy and Astrophysics, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802, USA, 96Bruce and Astrid McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, USA, 97Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003, USA, 98Department of Physics and Astronomy, Vanderbilt University, VU Station 1807, Nashville, TN 37235, USA, 99Department of Astronomy, MSC 4500, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003, USA, 100Department of Physics, Ohio State University, Columbus, OH 43210, USA, 101Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA, 102Kavli Institute for Astronomy and Astrophysics, Peking University, Beijing 100871, China, 103Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA, 104Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA, 105Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA, 106Leibniz-Institut für Astrophysik Potsdam, 107Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA, 108Laboratoire d'Astrophysique, École Polytechnique Fédérale de Lausanne, 109Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101, USA, 110Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325, USA, 111Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA, 112Bruce and Astrid McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, USA, 113CEA, Centre de Saclay, Irfu/SPP, F-91191 Gif-sur-Yvette, France, 114CEA, Centre de Saclay, Irfu/SPP, F-91191 Gif-sur-Yvette, France, 115Kavli Institute for the Physics and Mathematics of the Universe, 116Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany, 117Department of Astronomy and Space Science Chungnam National University Daejeon 305-764, Repulic of Korea, 118PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260, USA, 119Department of Astronomy, University of Florida, Bryant Space Science Center, Gainesville, FL 32611-2055, USA, 120Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA, 121Instituto de Astrofísica de Canarias, 122Universidade Federal do Rio de Janeiro, Observatório do Valongo, Ladeira do Pedro Antônio 43, 20080-090 Rio de Janeiro, Brazil, 123INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy, 124Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison WI 53703, USA, 125Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA, 126Department of Physics and Astronomy, Vanderbilt University, VU Station 1807, Nashville, TN 37235, USA, 127Department of Astronomy and Astrophysics, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802, USA, 128Observatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil, 129Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325, USA, 130Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA, 131Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA, 132Instituto de Astrofísica de Canarias, 133Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK, 134Department of Physics and Astronomy, Vanderbilt University, VU Station 1807, Nashville, TN 37235, USA, 135Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK, 136Department of Astronomy and Astrophysics, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802, USA, 137Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA, 138School of Physics, University of New South Wales, Sydney, NSW 2052, Australia, 139Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany, 140Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK, 141Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138, USA, 142IPAC, MS 220-6, California Institute of Technology, Pasadena, CA 91125, USA, 143Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721, USA, 144Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK, 145Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA, 146Max-Planck-Institut für Extraterrestrische Physik, Postfach 1312, Giessenbachstr. D-85741 Garching, Germany, 147Max-Planck-Institut für Extraterrestrische Physik, Postfach 1312, Giessenbachstr. D-85741 Garching, Germany, 148ELTE Gothard Astrophysical Observatory, H-9704 Szombathely, Szent Imre herceg st. 112, Hungary, 149Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA, 150Institució Catalana de Recerca i Estudis Avançats, Barcelona E-08010, Spain, 151Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA, 152Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA, 153Kavli Institute for the Physics and Mathematics of the Universe, 154Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK, 155Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106, USA, 156Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA, 157Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071, USA, 158PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260, USA, 159Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA, 160Dunlap Institute for Astronomy and Astrophysics, University of Toronto, Toronto, ON, M5S 3H4, Canada, 161Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK, 162Dept. of Astronomy, University of Michigan, Ann Arbor, MI, 48104, USA, 163Institut d'Astrophysique de Paris, UPMC-CNRS, UMR7095, 98 bis Boulevard Arago, F-75014, Paris, France, 164Leibniz-Institut für Astrophysik Potsdam, 165Department of Physics and Astronomy, Texas Christian University, 2800 South University Drive, Fort Worth, TX 76129, USA, 166Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325, USA, 167Bruce and Astrid McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, USA, 168Observatório Nacional, Rua Gal. José Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil, 169Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA, 170Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA, 171Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA, 172Bruce and Astrid McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, USA, 173Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA, 174NASA/GSFC, Code 665, Greenbelt, MC 20770, USA, 175Yale Center for Astronomy and Astrophysics, Yale University, New Haven, CT, 06520, USA, 176Department of Physics and Astronomy, Vanderbilt University, VU Station 1807, Nashville, TN 37235, USA, 177CEA, Centre de Saclay, Irfu/SPP, F-91191 Gif-sur-Yvette, France, 178Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349, USA, 179Department of Physics, Yale University, 260 Whitney Ave, New Haven, CT, 06520, USA, 180School of Physics, Korea Institute for Advanced Study, 85 Hoegiro, Dongdaemun-gu, Seoul 130-722, Republic of Korea, 181INAF, Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, I-34131 Trieste, Italy, 182Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA, 183Instituto de Astrofísica de Canarias, 184Department of Physics, Lehigh University, 16 Memorial Drive East, Bethlehem, PA 18015, USA, 185Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK, 186Instituto de Astrofísica de Canarias, 187Institut de Ciències del Cosmos, Universitat de Barcelona/IEEC, Barcelona E-08028, Spain, 188Institut d'Astrophysique de Paris, UPMC-CNRS, UMR7095, 98 bis Boulevard Arago, F-75014, Paris, France, 189A*MIDEX, Aix Marseille Université, CNRS, LAM, 190Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA, 191Universidade Federal do Rio de Janeiro, Observatório do Valongo, Ladeira do Pedro Antônio 43, 20080-090 Rio de Janeiro, Brazil, 192Instituto de Física Teórica, 193PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260, USA, 194Department of Astronomy, Columbia University, New York, NY 10027, USA, 195Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA, 196Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA, 197Department of Physics, University of California, Berkeley, CA 94720, USA, 198CEA, Centre de Saclay, Irfu/SPP, F-91191 Gif-sur-Yvette, France, 199Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany, 200Université de Franche-Comté, Institut Utinam, UMR CNRS 6213, OSU Theta, Besançon, F-25010, France, 201Department of Astronomy and Astrophysics, University of California, Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA, 202INAF, Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, I-35122 Padova, Italy, 203Instituto de Física Teórica, 204Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA, 205Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK, 206Department of Physics, Drexel University, 3141 Chestnut Street, Philadelphia, PA 19104, USA, 207Department of Astronomy and Space Science, Sejong University, Seoul, 143-747, Korea, 208Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA, 209Instituto de Astrofísica de Canarias, 210SLAC National Accelerator Laboratory, Menlo Park, CA 94025, 211Universitäts-Sternwarte München, Scheinerstrasse 1, D-81679 Munich, Germany, 212Max-Planck-Institut für Extraterrestrische Physik, Postfach 1312, Giessenbachstr. D-85741 Garching, Germany, 213Department of Physics, Kansas State University, 116 Cardwell Hall, Manhattan, KS 66506, USA, 214Max-Planck-Institut für Extraterrestrische Physik, Postfach 1312, Giessenbachstr. D-85741 Garching, Germany, 215Instituto de Física, UFRGS, Caixa Postal 15051, Porto Alegre, RS - 91501-970, Brazil, 216Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195, USA, 217Gemini Observatory, 670 N. A'Ohoku Place, Hilo, HI 96720, USA, 218Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA, 219Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA, 220Department of Astronomy and Astrophysics, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802, USA, 221Université de Nice Sophia-Antipolis, CNRS, Observatoire de Côte d'Azur, Laboratoire Lagrange, BP 4229, F-06304 Nice Cedex 4, France, 222Leibniz-Institut für Astrophysik Potsdam, 223Instituto de Astrofísica de Canarias, 224Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA, 225Department of Physics and Astronomy, Ohio University, 251B Clippinger Labs, Athens, OH 45701, USA, 226Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325, USA, 227Observatories of the Carnegie Institution of Washington, 813 Santa Barbara Street, Pasadena, CA 91101, USA, 228University of Texas at Austin, Hobby-Eberly Telescope, 32 Fowlkes Rd, McDonald Observatory, TX 79734-3005, USA, 229Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA, 230Indian Institute of Astrophysics, II Block, Koramangala, Bangalore 560 034, India, 231Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325, USA, 232Brookhaven National Laboratory, Bldg 510, Upton, NY 11973, USA, 233National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ, 85719, USA, 234Laboratório Interinstitucional de e-Astronomia, - LIneA, Rua Gal.José Cristino 77, Rio de Janeiro, RJ - 20921-400, Brazil, 235Department of Physics and Astronomy, Vanderbilt University, VU Station 1807, Nashville, TN 37235, USA, 236Leibniz-Institut für Astrophysik Potsdam, 237Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA, 238Instituto de Astrofísica de Canarias, 239Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138, USA, 240Department of Astronomy, University of Florida, Bryant Space Science Center, Gainesville, FL 32611-2055, USA, 241Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA, 242Department of Astronomy and Astrophysics, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16802, USA, 243Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA, 244Institute of Cosmology and Gravitation, Dennis Sciama Building, University of Portsmouth, Portsmouth, PO1 3FX, UK, 245Department of Physics and Astronomy, Texas Christian University, 2800 South University Drive, Fort Worth, TX 76129, USA, 246Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003, USA, 247School of Physics and Astronomy, University of St Andrews, St Andrews, Fife, KY16 9SS, UK, 248Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325, USA, 249Bruce and Astrid McWilliams Center for Cosmology, Department of Physics, Carnegie Mellon University, 5000 Forbes Ave, Pittsburgh, PA 15213, USA, 250Brookhaven National Laboratory, Bldg 510, Upton, NY 11973, USA, 251Institució Catalana de Recerca i Estudis Avançats, Barcelona E-08010, Spain, 252INAF, Osservatorio Astronomico di Trieste, Via G. B. Tiepolo 11, I-34131 Trieste, Italy, 253Department of Astronomy, MSC 4500, New Mexico State University, P.O. Box 30001, Las Cruces, NM 88003, USA, 254Department of Astronomy, University of Wisconsin-Madison, 475 North Charter Street, Madison WI 53703, USA, 255Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101, USA, 256Center for Cosmology and Particle Physics, Department of Physics, New York University, 4 Washington Place, New York, NY 10003, USA, 257Department of Astronomy, Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA, 258Steward Observatory, 933 North Cherry Avenue, Tucson, AZ 85721, USA, 259Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, CA 94720, USA, 260Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904-4325, USA, 261H.L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019, USA, 262PITT PACC, Department of Physics and Astronomy, University of Pittsburgh, 3941 O'Hara Street, Pittsburgh, PA 15260, USA, 263CEA, Centre de Saclay, Irfu/SPP, F-91191 Gif-sur-Yvette, France, 264Department of Astronomy and Astrophysics and the Enrico Fermi Institute, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA, 265Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA, 266Instituto de Astrofísica de Canarias, 267Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA, 268Department of Astronomy, Case Western Reserve University, Cleveland, OH 44106, USA, 269National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012, China, 270Department of Physics and Astronomy, University of Utah, Salt Lake City, UT 84112, USA, 271Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012, China, 272Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012, China, 273Center for Astrophysical Sciences, Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA, 274Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012, China

The third generation of the Sloan Digital Sky Survey (SDSS-III) took data from 2008 to 2014 using the original SDSS wide-field imager, the original and an upgraded multi-object fiber-fed optical spectrograph, a new near-infrared high-resolution spectrograph, and a novel optical interferometer. All the data from SDSS-III are now made public. In particular, this paper describes Data Release 11 (DR11) including all data acquired through 2013 July, and Data Release 12 (DR12) adding data acquired through 2014 July (including all data included in previous data releases), marking the end of SDSS-III observing. Read More

The regulation of galactic-scale star formation rates (SFRs) is a basic problem for theories of galaxy formation and evolution: which processes are responsible for making observed star formation rates so inefficient compared to maximal rates of gas content divided by dynamical timescale? Here we study the effect of magnetic fields of different strengths on the evolution of giant molecular clouds (GMCs) within a kiloparsec patch of a disk galaxy and resolving scales down to $\simeq0.5\:{\rm{pc}}$. Including an empirically motivated prescription for star formation from dense gas ($n_{\rm{H}}>10^5\:{\rm{cm}^{-3}}$) at an efficiency of 2\% per local free-fall time, we derive the amount of suppression of star formation by magnetic fields compared to the nonmagnetized case. Read More

The compact multi-transiting systems discovered by Kepler challenge traditional planet formation theories. These fall into two broad classes: (1) formation further out followed by migration; (2) formation in situ from a disk of gas and planetesimals. In the former, an abundance of resonant chains is expected, which the Kepler data do not support. Read More

2014Nov
Affiliations: 1Departamento de Astronomia, Universidad de Chile, 2Department of Astronomy, University of Florida

Even today in our Galaxy, stars form from gas cores in a variety of environments, which may affect the properties of resulting star and planetary systems. Here we study the role of pressure, parameterized via ambient clump mass surface density, on protostellar evolution and appearance, focussing on low-mass, Sun-like stars and considering a range of conditions from relatively low pressure filaments in Taurus, to intermediate pressures of cluster-forming clumps like the Orion Nebula Cluster (ONC), to very high pressures that may be found in the densest Infrared Dark Clouds (IRDCs) or in the Galactic Center (GC). We present unified analytic and numerical models for collapse of prestellar cores, accretion disks, protostellar evolution and bipolar outflows, coupled to radiative transfer (RT) calculations and a simple astrochemical model to predict CO gas phase abundances. Read More

High-mass Stars are cosmic engines known to dominate the energetics in the Milky Way and other galaxies. However, their formation is still not well understood. Massive, cold, dense clouds, often appearing as Infrared Dark Clouds (IRDCs), are the nurseries of massive stars. Read More

We present hydrodynamic simulations of self-gravitating dense gas in a galactic disk, exploring scales ranging from 1 kpc down to $\sim 0.1$~pc. Our primary goal is to understand how dense filaments form in Giant Molecular Clouds (GMCs). Read More

2014Oct
Affiliations: 1Dept. of Astronomy, University of Florida, 2Dept. of Astronomy, University of Florida, 3CIERA, Dept. of Physics and Astronomy, Northwestern University

Inside-Out Planet Formation (IOPF; Chatterjee & Tan 2014, hereafter CT14) is a scenario for sequential in situ planet formation at the pressure traps of retreating dead zone inner boundaries (DZIBs) motivated to explain the many systems with tightly packed inner planets (STIPs) discovered by Kepler. The scenario involves build-up of a pebble-dominated protoplanetary ring, supplied by radial drift of pebbles from the outer disk. It may also involve further build-up of planetary masses to gap-opening scales via continued pebble accretion. Read More

2014Oct
Affiliations: 1University of Florida, 2University of Florida, 3University of Florida

We study the degree of angular substructure in the stellar position distribution of young members of Galactic star-forming regions, looking for correlations with distance from cluster center, surface number density of stars, and local dynamical age. To this end we adopt the catalog of members in 18 young ($\sim$1-3 Myr) clusters from the Massive Young Star-Forming Complex Study in Infrared and X-ray (MYStIX) Survey and the statistical analysis of the Angular Dispersion Parameter, $\delta_{\rm ADP}$. We find statistically significant correlation between $\delta_{\rm ADP}$ and physical projected distance from the center of the clusters, with the centers appearing smoother than the outskirts, consistent with more rapid dynamical processing on local dynamical, free-fall or orbital timescales. Read More

2014Sep
Affiliations: 1Dept. of Astronomy, University of Florida, 2Dept. of Astronomy, University of Florida, 3Dept. of Astronomy, University of Florida

The spatial morphology and dynamical status of a young, still-forming stellar cluster provide valuable clues on the conditions during the star formation event and the processes that regulated it. We analyze the Orion Nebula Cluster (ONC), utilizing the latest censuses of its stellar content and membership estimates over a large wavelength range. We determine the center of mass of the ONC, and study the radial dependence of angular substructure. Read More

Over two years 8,859 high-resolution H-band spectra of 3,493 young (1 - 10 Myr) stars were gathered by the multi-object spectrograph of the APOGEE project as part of the IN-SYNC ancillary program of that SDSS-III survey. Here we present the forward modeling approach used to derive effective temperatures, surface gravities, radial velocities, rotational velocities, and H-band veiling from these near-infrared spectra. We discuss in detail the statistical and systematic uncertainties in these stellar parameters. Read More

2014Jul
Affiliations: 1and IRIS team, 2and IRIS team, 3and IRIS team, 4and IRIS team, 5and IRIS team, 6and IRIS team, 7and IRIS team, 8and IRIS team, 9and IRIS team, 10and IRIS team, 11and IRIS team, 12and IRIS team, 13and IRIS team, 14and IRIS team, 15and IRIS team, 16and IRIS team, 17and IRIS team, 18and IRIS team, 19and IRIS team, 20and IRIS team, 21and IRIS team, 22and IRIS team, 23and IRIS team, 24and IRIS team, 25and IRIS team

IRIS (InfraRed Imaging Spectrograph) is a first light near-infrared diffraction limited imager and integral field spectrograph being designed for the future Thirty Meter Telescope (TMT). IRIS is optimized to perform astronomical studies across a significant fraction of cosmic time, from our Solar System to distant newly formed galaxies (Barton et al. [1]). Read More

2014Apr
Affiliations: 1Dept. of Astronomy, University of Florida, 2Dept. of Astronomy, University of Florida, 3National Radio Astronomy Observatory

We use observed radial profiles of mass surface densities of total, $\Sigma_g$, & molecular, $\Sigma_{\rm H2}$, gas, rotation velocity & star formation rate (SFR) surface density, $\Sigma_{\rm sfr}$, of the molecular-rich ($\Sigma_{\rm H2}\ge\Sigma_{\rm HI}/2$) regions of 16 nearby disk galaxies to test several star formation laws: a Kennicutt-Schmidt law, $\Sigma_{\rm sfr}=A_g\Sigma_{g,2}^{1.5}$; a Constant Molecular law, $\Sigma_{\rm sfr}=A_{\rm H2}\Sigma_{\rm H2,2}$; the turbulence-regulated laws of Krumholz & McKee (KM05) and Krumholz et al. (KMT09), a Gas-$\Omega$ law, $\Sigma_{\rm sfr}=B_\Omega\Sigma_g\Omega$; and a shear-driven GMC Collision law, $\Sigma_{\rm sfr}=B_{\rm CC}\Sigma_g\Omega(1-0. Read More

Infrared Dark Clouds (IRDCs) are unique laboratories to study the initial conditions of high-mass star and star cluster formation. We present high-sensitivity and high-angular resolution IRAM PdBI observations of N2H+ (1-0) towards IRDC G035.39-00. Read More

The enormous radiative and mechanical luminosities of massive stars impact a vast range of scales and processes, from the reionization of the universe, to the evolution of galaxies, to the regulation of the interstellar medium, to the formation of star clusters, and even to the formation of planets around stars in such clusters. Two main classes of massive star formation theory are under active study, Core Accretion and Competitive Accretion. In Core Accretion, the initial conditions are self-gravitating, centrally concentrated cores that condense with a range of masses from the surrounding, fragmenting clump environment. Read More

We use deep $8\:\mu m$ Spitzer-IRAC imaging of a massive Infrared Dark Cloud (IRDC) G028.37+00.07 to construct a Mid-Infrared (MIR) extinction map that probes mass surface densities up to $\Sigma\:\sim 1\:\rm{g~cm^{-2}}$ ($A_V\sim200\:$mag), amongst the highest values yet probed by extinction mapping. Read More

2013Dec
Affiliations: 1Dept. of Astronomy, Yale University, 2Dept. of Astronomy, University of Florida, 3Dept. of Physics, University of Tokyo

We present radiation transfer (RT) simulations of evolutionary sequences of massive protostars forming from massive dense cores in environments of high surface densities. The protostellar evolution is calculated with a detailed multi-zone model, with the accretion rate regulated by feedback from an evolving disk-wind outflow cavity. Disk and envelope evolutions are calculated self-consistently. Read More

Progress in understanding star formation requires detailed observational constraints on the initial conditions, i.e. dense clumps and cores in giant molecular clouds that are on the verge of gravitational instability. Read More

2013Dec
Affiliations: 1Dept. of Astronomy, University of Florida, 2Max-Planck-Institute for Extraterrestrial Physics, 3Dept. of Astronomy, University of Florida, 4University of Bordeaux, LAB, Floirac, France, 5Max-Planck-Institute for Extraterrestrial Physics

The deuterium fraction [N$_2$D$^+$]/[N$_2$H$^+$], may provide information about the ages of dense, cold gas structures, important to compare with dynamical models of cloud core formation and evolution. Here we introduce a complete chemical network with species containing up to three atoms, with the exception of the Oxygen chemistry, where reactions involving H$_3$O$^+$ and its deuterated forms have been added, significantly improving the consistency with comprehensive chemical networks. Deuterium chemistry and spin states of H$_2$ and H$_3^+$ isotopologues are included in this primarily gas-phase chemical model. Read More

2013Jun
Affiliations: 1Dept. of Astronomy, University of Florida, 2Dept. of Astronomy, University of Florida

The compact multi-transiting planet systems discovered by Kepler challenge planet formation theories. Formation in situ from disks with radial mass surface density, $\Sigma$, profiles similar to the minimum mass solar nebula (MMSN) but boosted in normalization by factors $\gtrsim 10$ has been suggested. We propose that a more natural way to create these planets in the inner disk is formation sequentially from the inside-out via creation of successive gravitationally unstable rings fed from a continuous stream of small (~cm--m size) "pebbles", drifting inwards via gas drag. Read More

We report new near-infrared and mm-wave observational data on a selection of massive Galactic molecular clumps (part of the CHaMP sample) and their associated young star clusters. The clumps show, for the first time in a "dense gas tracer", a significant correlation between HCO+ line emission from cold molecular gas and Br{\gamma} line emission of associated nebulae. This correlation arises in the HCO+ line's brightness, not its linewidth. Read More

2013Apr
Affiliations: 1Osservatorio Astrofisico di Arcetri - INAF, Italy, 2Institut Ciencies de l'Espai - CSIC, Spain, 3Osservatorio Astrofisico di Arcetri - INAF, Italy, 4INAF - IAPS, Italy, 5Institut Ciencies de l'Espai - CSIC, Spain, 6Dpt Astronomia i Meteorologia - UB, Spain, 7Dpts of Astronomy and Physics - University of Florida, USA, 8Dpt Astronomia i Meteorologia - UB, Spain, 9Institue of Astronomy and Astrophysics, Academia Sinica, Taiwan, 10CfA, USA, 11CRyA - UNAM, Mexico

We aim at characterising dense cores in the clustered environments associated with massive star-forming regions. For this, we present an uniform analysis of VLA NH3(1,1) and (2,2) observations towards a sample of 15 massive star-forming regions, where we identify a total of 73 cores, classify them as protostellar, quiescent starless, or perturbed starless, and derive some physical properties. The average sizes and ammonia column densities are 0. Read More