Mostrando recursos 1 - 20 de 38

  1. A study of quasar selection in the supernova fields of the Dark Energy Survey

    Tie, Suk Sien; Martini, Paul; Mudd, Dale; Ostrovski, F.; Reed, Sophie L.; Lidman, Chris; Kochanek, C.S.; Davis, Tamara M.; Sharp, Robert G.; Uddin, Syed; King, Anthea L.; Wester, William Carl; Tucker, Bradley; Tucker, Douglas L.; Buckley-Geer, Elizabeth; Carollo, Daniela; Childress, Michael; Glazebrook, Karl; Hinton, Samuel; Lewis, Geraint F.; Macaulay, Edward; O'Neill, C. R.; Abbott, Timothy M. C.; Abdalla, Filipe B.; Annis, James T.; Benoit-Lévy, Aurélien; Bertin, Emmanuel; Brooks, D.; Carnero Rosell, Aurelio; Carrasco Kind, Matías; Carretero Palacios, Jorge; Cunha, Carlos Eduardo; Costa, Luiz N. da; DePoy, Darren L.; Desai, S.; Doel, Peter; Eifler, Tim; Evrard, August E.; Finley, David A.; Flaugher, Brenna; Fosalba Vela, Pablo; Frieman, Joshua A.; García-Bellido, Juan; Gaztañaga, Enrique; Gerdes, David W.; Goldstein, Daniel Abraham; Gruen, Daniel; Gruendl, Robert A.; Gutierrez, Gaston R.; Honscheid, K.; James, David J.; Kuehn, Kyler; Kuropatkin, Nikolay P.; Lima, Marcos Vinicius Borges Teixeira; Maia, Marcio Antonio Geimba; Marshall, Jennifer L.; Menanteau, Felipe; Miller, Christopher J.; Miquel, Ramon; Nichol, Robert C.; Nord, Brian Dennis; Ogando, Ricardo L.C.; Plazas Malagón, Andrés Alejandro; Romer, Anita K.; Sanchez-Alvaro, Eusebio; Santiago, Basilio Xavier; Scarpine, Victor Emanuel; Schubnell, Michael; Sevilla Noarbe, Ignacio; Smith, Robert Christopher; Soares-Santos, Marcelle; Sobreira, Flávia; Suchyta, Eric; Swanson, Molly E. C.; Tarle, Gregory; Thomas, D.; Walker, Alistair; DES Collaboration
    We present a study of quasar selection using the supernova fields of the Dark Energy Survey (DES). We used a quasar catalog from an overlapping portion of the SDSS Stripe 82 region to quantify the completeness and efficiency of selection methods involving color, probabilistic modeling, variability, and combinations of color/ probabilistic modeling with variability. In all cases, we considered only objects that appear as point sources in the DES images. We examine color selection methods based on the Wide-field Infrared Survey Explorer (WISE) mid- IR W1 - W2 color, a mixture of WISE and DES colors (g − i and...

  2. A study of quasar selection in the supernova fields of the Dark Energy Survey

    Tie, Suk Sien; Martini, Paul; Mudd, Dale; Ostrovski, F.; Reed, Sophie L.; Lidman, Chris; Kochanek, C.S.; Davis, Tamara M.; Sharp, Robert G.; Uddin, Syed; King, Anthea L.; Wester, William Carl; Tucker, Bradley; Tucker, Douglas L.; Buckley-Geer, Elizabeth; Carollo, Daniela; Childress, Michael; Glazebrook, Karl; Hinton, Samuel; Lewis, Geraint F.; Macaulay, Edward; O'Neill, C. R.; Abbott, Timothy M. C.; Abdalla, Filipe B.; Annis, James T.; Benoit-Lévy, Aurélien; Bertin, Emmanuel; Brooks, D.; Carnero Rosell, Aurelio; Carrasco Kind, Matías; Carretero Palacios, Jorge; Cunha, Carlos Eduardo; Costa, Luiz N. da; DePoy, Darren L.; Desai, S.; Doel, Peter; Eifler, Tim; Evrard, August E.; Finley, David A.; Flaugher, Brenna; Fosalba Vela, Pablo; Frieman, Joshua A.; García-Bellido, Juan; Gaztañaga, Enrique; Gerdes, David W.; Goldstein, Daniel Abraham; Gruen, Daniel; Gruendl, Robert A.; Gutierrez, Gaston R.; Honscheid, K.; James, David J.; Kuehn, Kyler; Kuropatkin, Nikolay P.; Lima, Marcos Vinicius Borges Teixeira; Maia, Marcio Antonio Geimba; Marshall, Jennifer L.; Menanteau, Felipe; Miller, Christopher J.; Miquel, Ramon; Nichol, Robert C.; Nord, Brian Dennis; Ogando, Ricardo L.C.; Plazas Malagón, Andrés Alejandro; Romer, Anita K.; Sanchez-Alvaro, Eusebio; Santiago, Basilio Xavier; Scarpine, Victor Emanuel; Schubnell, Michael; Sevilla Noarbe, Ignacio; Smith, Robert Christopher; Soares-Santos, Marcelle; Sobreira, Flávia; Suchyta, Eric; Swanson, Molly E. C.; Tarle, Gregory; Thomas, D.; Walker, Alistair; DES Collaboration
    We present a study of quasar selection using the supernova fields of the Dark Energy Survey (DES). We used a quasar catalog from an overlapping portion of the SDSS Stripe 82 region to quantify the completeness and efficiency of selection methods involving color, probabilistic modeling, variability, and combinations of color/ probabilistic modeling with variability. In all cases, we considered only objects that appear as point sources in the DES images. We examine color selection methods based on the Wide-field Infrared Survey Explorer (WISE) mid- IR W1 - W2 color, a mixture of WISE and DES colors (g − i and...

  3. Double-peaked profiles : ubiquitous signatures of disks in the broad emission lines of active galactic nuclei

    Storchi-Bergmann, Thaisa; Schimoia, Jáderson da Silva; Peterson, Bradley M.; Elvis, Martin; Denney, Kelly D.; Eracleous, Michael; Nemmen, Rodrigo S.
    Broad (10,000 km s−1), double-peaked emission-line profiles of Balmer lines emitted by active galactic nuclei (AGN) are thought to originate in the outer parts of an accretion disk surrounding a nuclear supermassive black hole (SMBH), at 1000 gravitational radii, and are most frequently observed in the nuclear spectra of low-luminosity AGN (LLAGN) and radio galaxies. In the present paper we argue that broad double-peaked profiles are present also in the spectra of other type 1 AGN, such as Seyfert 1 galaxies, suggesting that the inner part of the broad-line region (BLR) is also the outer part of the accretion disk....

  4. Double-peaked profiles : ubiquitous signatures of disks in the broad emission lines of active galactic nuclei

    Storchi-Bergmann, Thaisa; Schimoia, Jáderson da Silva; Peterson, Bradley M.; Elvis, Martin; Denney, Kelly D.; Eracleous, Michael; Nemmen, Rodrigo S.
    Broad (10,000 km s−1), double-peaked emission-line profiles of Balmer lines emitted by active galactic nuclei (AGN) are thought to originate in the outer parts of an accretion disk surrounding a nuclear supermassive black hole (SMBH), at 1000 gravitational radii, and are most frequently observed in the nuclear spectra of low-luminosity AGN (LLAGN) and radio galaxies. In the present paper we argue that broad double-peaked profiles are present also in the spectra of other type 1 AGN, such as Seyfert 1 galaxies, suggesting that the inner part of the broad-line region (BLR) is also the outer part of the accretion disk....

  5. Unusual magnetic field-dependence of a possible hidden order phase

    Calegari, Eleonir João; Magalhaes, Sergio Garcia; Riseborough, Peter S.
    URu2Si2 exhibits a second-order phase transition at 17.5 K. Initially it was thought that the transition was to a spin density wave phase, however, subsequent measurements do not support this assignment. Despite the unknown nature of the order parameter, many experimental results can be described in terms of the formation of a generic density wave. Here, we report calculations on an unusual phase of the underscreened Anderson lattice model, the so called spin-dependent inter-orbital density wave that has been proposed as describing the “hidden order” phase of URu2Si2. We determine the effects of an applied magnetic field. Since the order...

  6. Unusual magnetic field-dependence of a possible hidden order phase

    Calegari, Eleonir João; Magalhaes, Sergio Garcia; Riseborough, Peter S.
    URu2Si2 exhibits a second-order phase transition at 17.5 K. Initially it was thought that the transition was to a spin density wave phase, however, subsequent measurements do not support this assignment. Despite the unknown nature of the order parameter, many experimental results can be described in terms of the formation of a generic density wave. Here, we report calculations on an unusual phase of the underscreened Anderson lattice model, the so called spin-dependent inter-orbital density wave that has been proposed as describing the “hidden order” phase of URu2Si2. We determine the effects of an applied magnetic field. Since the order...

  7. Two-site Bose-Hubbard model with nonlinear tunneling : classical and quantum analysis

    Lima, Diefferson Rubeni da Rosa de; Links, Jon; Isaac, Phillip S.; Foerster, Angela
    The extended Bose-Hubbard model for a double-well potential with atom-pair tunneling is studied. Starting with a classical analysis we determine the existence of three quantum phases: self-trapping, phase-locking, and Josephson states. From this analysis we build the parameter space of quantum phase transitions between degenerate and nondegenerate ground states driven by the atom-pair tunneling. Considering only the repulsive case, we confirm the phase transition by the measure of the energy gap between the ground state and the first excited state. We study the structure of the solutions of the Bethe ansatz equations for a small number of atoms. An inspection...

  8. Two-site Bose-Hubbard model with nonlinear tunneling : classical and quantum analysis

    Lima, Diefferson Rubeni da Rosa de; Links, Jon; Isaac, Phillip S.; Foerster, Angela
    The extended Bose-Hubbard model for a double-well potential with atom-pair tunneling is studied. Starting with a classical analysis we determine the existence of three quantum phases: self-trapping, phase-locking, and Josephson states. From this analysis we build the parameter space of quantum phase transitions between degenerate and nondegenerate ground states driven by the atom-pair tunneling. Considering only the repulsive case, we confirm the phase transition by the measure of the energy gap between the ground state and the first excited state. We study the structure of the solutions of the Bethe ansatz equations for a small number of atoms. An inspection...

  9. Farthest neighbor : the distant Milky Way satellite Eridanus II

    Li, T. S.; Simon, Josh D.; Drlica-Wagner, Alex; Bechtol, Keith; Wang, M.; García-Bellido, Juan; Frieman, Joshua A.; Marshall, Jennifer L.; James, David J.; Strigari, Louis E.; Pace, Andrew B.; Balbinot, Eduardo; Zhang, Y.; Abbott, Timothy M. C.; Allam, Sahar S.; Benoit-Lévy, Aurélien; Bernstein, Gary M.; Bertin, Emmanuel; Brooks, D.; Burke, David Lyle; Carnero Rosell, Aurelio; Carrasco Kind, Matías; Carretero Palacios, Jorge; Cunha, Carlos Eduardo; D'Andrea, Christopher B.; Costa, Luiz N. da; DePoy, Darren L.; Desai, S.; Diehl, H. Thomas; Eifler, Tim; Flaugher, Brenna; Goldstein, Daniel Abraham; Gruen, Daniel; Gruendl, Robert A.; Gschwend, Julia de Figueiredo; Gutierrez, Gaston R.; Krause, Elisabeth; Kuehn, Kyler; Lin, H.; Maia, Marcio Antonio Geimba; March, Marisa Cristina; Menanteau, Felipe; Miquel, Ramon; Plazas Malagón, Andrés Alejandro; Romer, Anita K.; Sanchez-Alvaro, Eusebio; Santiago, Basilio Xavier; Schubnell, Michael; Sevilla Noarbe, Ignacio; Smith, Robert Christopher; Sobreira, Flávia; Suchyta, Eric; Tarle, Gregory; Thomas, D.; Tucker, Douglas L.; Walker, Alistair; Wechsler, Risa H.; Wester, William Carl; Yanny, Brian; DES Collaboration
    We present Magellan/IMACS spectroscopy of the recently discovered Milky Way satellite EridanusII (Eri II). We identify 28 member stars in EriII, from which we measure a systemic radial velocity of vhel = 75.6 1.3 (stat.) 2.0 (sys.) km s-1 and a velocity dispersion of - 6.9+0.9 1.2 km s-1. Assuming that EriII is a dispersion-supported system in dynamical equilibrium, we derive a mass within the half-light radius of - ´ 1.2+ 10 0.3 0.4 7 M, indicating a mass-tolight ratio of - 420+140 210 M/L and confirming that it is a dark matter-dominated dwarf galaxy. From the equivalent width measurements...

  10. Farthest neighbor : the distant Milky Way satellite Eridanus II

    Li, T. S.; Simon, Josh D.; Drlica-Wagner, Alex; Bechtol, Keith; Wang, M.; García-Bellido, Juan; Frieman, Joshua A.; Marshall, Jennifer L.; James, David J.; Strigari, Louis E.; Pace, Andrew B.; Balbinot, Eduardo; Zhang, Y.; Abbott, Timothy M. C.; Allam, Sahar S.; Benoit-Lévy, Aurélien; Bernstein, Gary M.; Bertin, Emmanuel; Brooks, D.; Burke, David Lyle; Carnero Rosell, Aurelio; Carrasco Kind, Matías; Carretero Palacios, Jorge; Cunha, Carlos Eduardo; D'Andrea, Christopher B.; Costa, Luiz N. da; DePoy, Darren L.; Desai, S.; Diehl, H. Thomas; Eifler, Tim; Flaugher, Brenna; Goldstein, Daniel Abraham; Gruen, Daniel; Gruendl, Robert A.; Gschwend, Julia de Figueiredo; Gutierrez, Gaston R.; Krause, Elisabeth; Kuehn, Kyler; Lin, H.; Maia, Marcio Antonio Geimba; March, Marisa Cristina; Menanteau, Felipe; Miquel, Ramon; Plazas Malagón, Andrés Alejandro; Romer, Anita K.; Sanchez-Alvaro, Eusebio; Santiago, Basilio Xavier; Schubnell, Michael; Sevilla Noarbe, Ignacio; Smith, Robert Christopher; Sobreira, Flávia; Suchyta, Eric; Tarle, Gregory; Thomas, D.; Tucker, Douglas L.; Walker, Alistair; Wechsler, Risa H.; Wester, William Carl; Yanny, Brian; DES Collaboration
    We present Magellan/IMACS spectroscopy of the recently discovered Milky Way satellite EridanusII (Eri II). We identify 28 member stars in EriII, from which we measure a systemic radial velocity of vhel = 75.6 1.3 (stat.) 2.0 (sys.) km s-1 and a velocity dispersion of - 6.9+0.9 1.2 km s-1. Assuming that EriII is a dispersion-supported system in dynamical equilibrium, we derive a mass within the half-light radius of - ´ 1.2+ 10 0.3 0.4 7 M, indicating a mass-tolight ratio of - 420+140 210 M/L and confirming that it is a dark matter-dominated dwarf galaxy. From the equivalent width measurements...

  11. Sloan Digital Sky Survey IV : mapping the Milky Way, nearby galaxies, and the distant universe

    Blanton, M.R.; Bershady, Matthew A.; Abolfathi, Bela; Albareti, Franco D.; Allende Prieto, Carlos; Almeida, Andres; Alonso Garcia, Javier; Anders, Friedrich; Anderson, Scott F.; Andrews, Brett H.; Aquino-Ortíz, Erik; Aragón-Salamanca, Alfonso; Argudo-Fernández, Maria; Armengaud, Eric; Aubourg, Éric; Avila-Reese, Vladimir; Badenes, Carles; Bailey, Stephen; Barger, Kathleen A.; Barrera-Ballesteros, Jorge; Bartosz, Curtis; Bates, Dominic; Baumgarten, Falk; Bautista, Julian; Beaton, Rachael Lynn; Beers, T.C.; Belfiore, Francesco; Bender, Chad Frederick; Berlind, Andreas A.; Bernardi, Mariangela; Beutler, Florian; Bird, Jonathan C.; Bizyaev, D.; Blanc, Guillermo A.; Blomqvist, Michael C.; Bolton, Adam S.; Boquien, Médéric; Borissova, Jura; Bosch, Remco van den; Bovy, Jo; Brandt, W.N.; Brinkmann, Jon; Brownstein, Joel R.; Bundy, Kevin; Burgasser, Adam J.; Burtin, Etienne; Busca, Nicolas G.; Cappellari, Michele; Carigi, Leticia; Carlberg, J.K.; Carnero Rosell, Aurelio; Carrera, Ricardo; Chanover, Nancy J.; Cherinka, Brian; Cheung, Edmond; Chew, Yilen Gómez Maqueo; Chiappini, C.C.M.; Choi, Peter Doohyun; Chojnowski, Stephen Drew; Chuang, Chia-Hsun; Chung, Haeun; Cirolini, Rafael Fernando; Clerc, Nicolas; Cohen, Roger; Comparat, Johan; Costa, Luiz N. da; Cousinou, Marie-Claude; Covey, Kevin; Crane, Jeffrey D.; Croft, Rupert A.C.; Cruz-Gonzalez, Irene; Cuadra, Daniel Garrido; Cunha, Katia; Damke, Guillermo J.; Darling, Jeremy; Davies, Roger L.; Dawson, K.S.; Macorra, Axel de la; Dell'Agli, Flavia; De Lee, Nathan M.; Delubac, Timothée; Di Mille, Francesco; Diamond-Stanic, Aleksandar M.; Cano-Díaz, Mariana; Donor, John; Downes Wallace, Juan Jose; Drory, Niv; Du Mas Des Bourboux, Hélion; Duckworth, Christopher; Dwelly, Tom; Dyer, Jamie Christine; Ebelke, Garrett L.; Eigenbrot, Arthur D.; Eisenstein, Daniel, J.; Emsellem, Eric; Eracleous, Michael; Escoffier, Stephanie; Evans, Michael L.; Fan, Xiaohui; Fernández Alvar, Emma; Fernández-Trincado, José Gregorio; Feuillet, Diane; Finoguenov, Alexis; Fleming, S.W.; Font-Ribera, A.; Fredrickson, Alexander; Freischlad, Gordon; Frinchaboy, P.M.; Fuentes, Carla E.; Galbany, Lluís; Dias, Rafael Augusto Garcia; García-Hernández, D. A.; Gaulme, Patrick; Geisler, Doug; Gelfand, Joseph D.; Gil-Marín, Héctor; Gillespie, Bruce A.; Goddard, Daniel; Gonzalez-Perez, Violeta; Grabowski, Kathleen; Green, Paul J.; Grier, Catherine J.; Gunn, James E.; Guo, Hong; Guy, Julien; Hagen, Alex; Hahn, ChangHoon; Hall, Matthew; Harding, Paul; Hasselquist, Sten; Hawley, Suzanne L.; Hearty, Frederick R.; González Hernández, Jonay I.; Ho, Shirley; Hogg, D.W.; Holley-Bockelmann, Kelly; Holtzman, J.A.; Holzer, Parker H.; Huehnerhoff, Joseph; Hutchinson, Timothy A.; Hwang, Ho Seong; Ibarra Medel, Hector Javier; Ilha, Gabriele da Silva; Ivans, Inese I.; Ivory, KeShawn; Jackson, Kelly M.; Jensen, Trey W.; Johnson, Jennifer A.; Jones, Amy P.; Jönsson, Henrik; Jullo, Eric; Kamble, Vikrant Anand; Kinemuchi, Karen; Kirkby, David; Kitaura, Francisco-Shu; Klaene, Mark A.; Knapp, G. R.; Kneib, J.P.; Kollmeier, Juna A.; Lacerna, Ivan; Lane, Richard R.; Lang, Dustin; Law, David R.; Lazarz, Daniel; Lee, Youngbae; Le Goff, Jean-Marc; Liang, Fu-Heng; Li, Cheng; Li, Hongyu; Lian, Jianhui; Lima, Marcos Vinicius Borges Teixeira; Lin, Lihwai; Lin, Y.-T.; Lis, Sara Bertran de; Lizaola, Miguel Angel C. de Icaza; Long, Daniel C.; Lucatello, Sara; Lundgren, B.; Macdonald, Nicholas; Machado, Alice Deconto; MacLeod, Chelsea L.; Mahadevan, Suvrath; Maia, Marcio Antonio Geimba; Maiolino, Roberto; Majewski, Steven Raymond; Malanushenko, E.; Malanushenko, V.; Manchado, Arturo; Mao, Shude; Maraston, Claudia; Marques-Chaves, Rui; Masseron, Thomas; Masters, K.L.; McBride, Cameron K.; McDermid, Richard; McGrath, Brianne; McGreer, Ian D.; Medina Peña, Nicolás; Melendez, Matthew; Merloni, Andrea; Merrifield, Michael; Mészáros, S.; Meza, Andres; Minchev, Ivan; Minniti, Dante; Miyaji, Takamitsu; More, Surhud Shrikant; Mulchaey, John Scott; Muller-Sanchez, Francisco; Muna, Demitri; Mũñoz, Ricardo R.; Myers, A.D.; Nair, Preethi B.; Nandra, Kirpal; Nascimento, Janaina Correa do; Negrete, Alenka; Ness, Melissa; Newman, Jeffrey A.; Nichol, Robert C.; Nidever, D.L.; Nitschelm, Christian; Ntelis, Pierros; O'Connell, Julia E.; Oelkers, Ryan J.; Oravetz, Audrey; Oravetz, Daniel J.; Pace, Zach; Padilla, Nelson; Palanque-Delabrouille, Nathalie; Alonso Palicio, Pedro; Pan, K.; Parejko, J.K.; Parikh, Taniya; Pâris, Isabelle; Park, Changbom; Patten, Alim Y.; Peirani, Sébastien; Pellejero-Ibanez, Marcos; Penny, Samantha J.; Percival, Will J.; Pérez-Fournon, Ismael; Petitjean, P.; Pieri, Matthew M.; Pinsonneault, Marc H.; Pisani, Alice; Poleski, Radosław; Prada, Francisco; Prakash, Abhishek; Queiroz, Anna Bárbara de Andrade; Raddick, M. Jordan; Raichoor, Anand; Rembold, Sandro Barboza; Richstein, Hannah; Riffel, Rogemar André; Riffel, Rogério; Rix, H.-W.; Robin, Annie C.; Rockosi, C.M.; Rodríguez-Torres, Sergio; Roman-Lopes, Alexandre; Román-Zñiga, Carlos Gerardo; Rosado, Margarita; Ross, Ashley Jacob; Rossi, Graziano; Ruan, John J.; Ruggeri, Rossana; Rykoff, Eli; Salazar-Albornoz, Salvador; Salvato, Mara; Sánchez, Ariel G.; Sánchez Aguado, David; Sánchez-Gallego, José Ramón; Santana, Felipe A.; Santiago, Basilio Xavier; Sayres, Conor; Schiavon, Ricardo P.; Schimoia, Jáderson da Silva; Schlafly, Edward F.; Schlegel, David J.; Schneider, D.P.; Schultheis, Mathias; Schuster, William J.; Schwope, Axel D.; Seo, Hee-Jong; Shao, Zhengyi; Shen, Shiyin; Shetrone, M.; Shull, John Michael; Simon, Josh D.; Skinner, Danielle; Skrutskie, M.F.; Slosar, A.; Smith, Verne V.; Sobeck, Jennifer S.; Sobreira, Flávia; Somers, Garrett; Souto, Diogo Martins; Stark, David V.; Stassun, Keivan G.; Stauffer, Fritz; Steinmetz, M.; Storchi-Bergmann, Thaisa; Streblyanska, Alina; Stringfellow, Guy S.; Suárez, Genaro; Sun, Jing; Suzuki, Nao; Szigeti, Laszlo; Taghizadeh-Popp, Manuchehr; Tang, Baitian; Tao, Charling; Tayar, Jamie; Tembe, Mita; Teske, Johanna K.; Thakar, Aniruddha R.; Thomas, Daniel B.; Thompson, Benjamin A.; Tinker, Jeremy; Tissera, Patricia Beatriz; Tojeiro, R.; Hernandez-Toledo, Hector M.; Torre, Sylvain De La; Tremonti, Christy A.; Troup, Nicholas W.; Valenzuela, Octavio; Valpuesta, Inma Martinez; Vargas-González, Jaime; Vargas Magaña, Mariana; Vazquez, Jose Alberto; Villanova , Sandro; Vivek, M.; Vogt, N.P.; Wake, D.A.; Walterbos, Rene A. M.; Wang, Yuting; Weaver, Benjamin A.; Weijmans, Anne Marie; Weinberg, D.H.; Westfall, Kyle B.; Whelan, David G.; Wild, Vivienne; Wilson, John C.; Wood-Vasey, W.M.; Wylezalek, Dominika; Xiao, Ting; Yan, Renbin; Yang, Meng; Ybarra, Jason E.; Yèche, Christophe; Zakamska, Nadia L.; Zamora, Olga; Zarrouk, Pauline; Zasowski, G.; Zhang, Kai; Zhao, Gong-Bo; Zheng, Zheng; Zhou, Xu; Zhou, Zhimin; Zhu, Guangtun; Zoccali, Manuela; Zou, Hu
    We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z ~ 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z ~ 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions,...

  12. Sloan Digital Sky Survey IV : mapping the Milky Way, nearby galaxies, and the distant universe

    Blanton, M.R.; Bershady, Matthew A.; Abolfathi, Bela; Albareti, Franco D.; Allende Prieto, Carlos; Almeida, Andres; Alonso Garcia, Javier; Anders, Friedrich; Anderson, Scott F.; Andrews, Brett H.; Aquino-Ortíz, Erik; Aragón-Salamanca, Alfonso; Argudo-Fernández, Maria; Armengaud, Eric; Aubourg, Éric; Avila-Reese, Vladimir; Badenes, Carles; Bailey, Stephen; Barger, Kathleen A.; Barrera-Ballesteros, Jorge; Bartosz, Curtis; Bates, Dominic; Baumgarten, Falk; Bautista, Julian; Beaton, Rachael Lynn; Beers, T.C.; Belfiore, Francesco; Bender, Chad Frederick; Berlind, Andreas A.; Bernardi, Mariangela; Beutler, Florian; Bird, Jonathan C.; Bizyaev, D.; Blanc, Guillermo A.; Blomqvist, Michael C.; Bolton, Adam S.; Boquien, Médéric; Borissova, Jura; Bosch, Remco van den; Bovy, Jo; Brandt, W.N.; Brinkmann, Jon; Brownstein, Joel R.; Bundy, Kevin; Burgasser, Adam J.; Burtin, Etienne; Busca, Nicolas G.; Cappellari, Michele; Carigi, Leticia; Carlberg, J.K.; Carnero Rosell, Aurelio; Carrera, Ricardo; Chanover, Nancy J.; Cherinka, Brian; Cheung, Edmond; Chew, Yilen Gómez Maqueo; Chiappini, C.C.M.; Choi, Peter Doohyun; Chojnowski, Stephen Drew; Chuang, Chia-Hsun; Chung, Haeun; Cirolini, Rafael Fernando; Clerc, Nicolas; Cohen, Roger; Comparat, Johan; Costa, Luiz N. da; Cousinou, Marie-Claude; Covey, Kevin; Crane, Jeffrey D.; Croft, Rupert A.C.; Cruz-Gonzalez, Irene; Cuadra, Daniel Garrido; Cunha, Katia; Damke, Guillermo J.; Darling, Jeremy; Davies, Roger L.; Dawson, K.S.; Macorra, Axel de la; Dell'Agli, Flavia; De Lee, Nathan M.; Delubac, Timothée; Di Mille, Francesco; Diamond-Stanic, Aleksandar M.; Cano-Díaz, Mariana; Donor, John; Downes Wallace, Juan Jose; Drory, Niv; Du Mas Des Bourboux, Hélion; Duckworth, Christopher; Dwelly, Tom; Dyer, Jamie Christine; Ebelke, Garrett L.; Eigenbrot, Arthur D.; Eisenstein, Daniel, J.; Emsellem, Eric; Eracleous, Michael; Escoffier, Stephanie; Evans, Michael L.; Fan, Xiaohui; Fernández Alvar, Emma; Fernández-Trincado, José Gregorio; Feuillet, Diane; Finoguenov, Alexis; Fleming, S.W.; Font-Ribera, A.; Fredrickson, Alexander; Freischlad, Gordon; Frinchaboy, P.M.; Fuentes, Carla E.; Galbany, Lluís; Dias, Rafael Augusto Garcia; García-Hernández, D. A.; Gaulme, Patrick; Geisler, Doug; Gelfand, Joseph D.; Gil-Marín, Héctor; Gillespie, Bruce A.; Goddard, Daniel; Gonzalez-Perez, Violeta; Grabowski, Kathleen; Green, Paul J.; Grier, Catherine J.; Gunn, James E.; Guo, Hong; Guy, Julien; Hagen, Alex; Hahn, ChangHoon; Hall, Matthew; Harding, Paul; Hasselquist, Sten; Hawley, Suzanne L.; Hearty, Frederick R.; González Hernández, Jonay I.; Ho, Shirley; Hogg, D.W.; Holley-Bockelmann, Kelly; Holtzman, J.A.; Holzer, Parker H.; Huehnerhoff, Joseph; Hutchinson, Timothy A.; Hwang, Ho Seong; Ibarra Medel, Hector Javier; Ilha, Gabriele da Silva; Ivans, Inese I.; Ivory, KeShawn; Jackson, Kelly M.; Jensen, Trey W.; Johnson, Jennifer A.; Jones, Amy P.; Jönsson, Henrik; Jullo, Eric; Kamble, Vikrant Anand; Kinemuchi, Karen; Kirkby, David; Kitaura, Francisco-Shu; Klaene, Mark A.; Knapp, G. R.; Kneib, J.P.; Kollmeier, Juna A.; Lacerna, Ivan; Lane, Richard R.; Lang, Dustin; Law, David R.; Lazarz, Daniel; Lee, Youngbae; Le Goff, Jean-Marc; Liang, Fu-Heng; Li, Cheng; Li, Hongyu; Lian, Jianhui; Lima, Marcos Vinicius Borges Teixeira; Lin, Lihwai; Lin, Y.-T.; Lis, Sara Bertran de; Lizaola, Miguel Angel C. de Icaza; Long, Daniel C.; Lucatello, Sara; Lundgren, B.; Macdonald, Nicholas; Machado, Alice Deconto; MacLeod, Chelsea L.; Mahadevan, Suvrath; Maia, Marcio Antonio Geimba; Maiolino, Roberto; Majewski, Steven Raymond; Malanushenko, E.; Malanushenko, V.; Manchado, Arturo; Mao, Shude; Maraston, Claudia; Marques-Chaves, Rui; Masseron, Thomas; Masters, K.L.; McBride, Cameron K.; McDermid, Richard; McGrath, Brianne; McGreer, Ian D.; Medina Peña, Nicolás; Melendez, Matthew; Merloni, Andrea; Merrifield, Michael; Mészáros, S.; Meza, Andres; Minchev, Ivan; Minniti, Dante; Miyaji, Takamitsu; More, Surhud Shrikant; Mulchaey, John Scott; Muller-Sanchez, Francisco; Muna, Demitri; Mũñoz, Ricardo R.; Myers, A.D.; Nair, Preethi B.; Nandra, Kirpal; Nascimento, Janaina Correa do; Negrete, Alenka; Ness, Melissa; Newman, Jeffrey A.; Nichol, Robert C.; Nidever, D.L.; Nitschelm, Christian; Ntelis, Pierros; O'Connell, Julia E.; Oelkers, Ryan J.; Oravetz, Audrey; Oravetz, Daniel J.; Pace, Zach; Padilla, Nelson; Palanque-Delabrouille, Nathalie; Alonso Palicio, Pedro; Pan, K.; Parejko, J.K.; Parikh, Taniya; Pâris, Isabelle; Park, Changbom; Patten, Alim Y.; Peirani, Sébastien; Pellejero-Ibanez, Marcos; Penny, Samantha J.; Percival, Will J.; Pérez-Fournon, Ismael; Petitjean, P.; Pieri, Matthew M.; Pinsonneault, Marc H.; Pisani, Alice; Poleski, Radosław; Prada, Francisco; Prakash, Abhishek; Queiroz, Anna Bárbara de Andrade; Raddick, M. Jordan; Raichoor, Anand; Rembold, Sandro Barboza; Richstein, Hannah; Riffel, Rogemar André; Riffel, Rogério; Rix, H.-W.; Robin, Annie C.; Rockosi, C.M.; Rodríguez-Torres, Sergio; Roman-Lopes, Alexandre; Román-Zñiga, Carlos Gerardo; Rosado, Margarita; Ross, Ashley Jacob; Rossi, Graziano; Ruan, John J.; Ruggeri, Rossana; Rykoff, Eli; Salazar-Albornoz, Salvador; Salvato, Mara; Sánchez, Ariel G.; Sánchez Aguado, David; Sánchez-Gallego, José Ramón; Santana, Felipe A.; Santiago, Basilio Xavier; Sayres, Conor; Schiavon, Ricardo P.; Schimoia, Jáderson da Silva; Schlafly, Edward F.; Schlegel, David J.; Schneider, D.P.; Schultheis, Mathias; Schuster, William J.; Schwope, Axel D.; Seo, Hee-Jong; Shao, Zhengyi; Shen, Shiyin; Shetrone, M.; Shull, John Michael; Simon, Josh D.; Skinner, Danielle; Skrutskie, M.F.; Slosar, A.; Smith, Verne V.; Sobeck, Jennifer S.; Sobreira, Flávia; Somers, Garrett; Souto, Diogo Martins; Stark, David V.; Stassun, Keivan G.; Stauffer, Fritz; Steinmetz, M.; Storchi-Bergmann, Thaisa; Streblyanska, Alina; Stringfellow, Guy S.; Suárez, Genaro; Sun, Jing; Suzuki, Nao; Szigeti, Laszlo; Taghizadeh-Popp, Manuchehr; Tang, Baitian; Tao, Charling; Tayar, Jamie; Tembe, Mita; Teske, Johanna K.; Thakar, Aniruddha R.; Thomas, Daniel B.; Thompson, Benjamin A.; Tinker, Jeremy; Tissera, Patricia Beatriz; Tojeiro, R.; Hernandez-Toledo, Hector M.; Torre, Sylvain De La; Tremonti, Christy A.; Troup, Nicholas W.; Valenzuela, Octavio; Valpuesta, Inma Martinez; Vargas-González, Jaime; Vargas Magaña, Mariana; Vazquez, Jose Alberto; Villanova , Sandro; Vivek, M.; Vogt, N.P.; Wake, D.A.; Walterbos, Rene A. M.; Wang, Yuting; Weaver, Benjamin A.; Weijmans, Anne Marie; Weinberg, D.H.; Westfall, Kyle B.; Whelan, David G.; Wild, Vivienne; Wilson, John C.; Wood-Vasey, W.M.; Wylezalek, Dominika; Xiao, Ting; Yan, Renbin; Yang, Meng; Ybarra, Jason E.; Yèche, Christophe; Zakamska, Nadia L.; Zamora, Olga; Zarrouk, Pauline; Zasowski, G.; Zhang, Kai; Zhao, Gong-Bo; Zheng, Zheng; Zhou, Xu; Zhou, Zhimin; Zhu, Guangtun; Zoccali, Manuela; Zou, Hu
    We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z ~ 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z ~ 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions,...

  13. Evidence from K2 for Rapid Rotation in the Descendant of an Intermediate-mass Star

    Hermes, James J.; Kawaler, Steven D.; Romero, Alejandra Daniela; Kepler, Souza Oliveira; Tremblay, Pier-Emmanuel; Bell, Keaton; Dunlap, Bart; Montgomery, Michael Houston; Gänsicke, Boris; Clemens, J. Christopher; Dennihy, Erik D.; Redfield, Seth
    Using patterns in the oscillation frequencies of a white dwarf observed by K2, we have measured the fastest rotation rate (1.13 ± 0.02 hr) of any isolated pulsating white dwarf known to date. Balmer-line fits to follow-up spectroscopy from the SOAR telescope show that the star (SDSSJ0837+1856, EPIC 211914185) is a 13,590 340 K, 0.87±0.03Me white dwarf. This is the highest mass measured for any pulsating white dwarf with known rotation, suggesting a possible link between high mass and fast rotation. If it is the product of single-star evolution, its progenitor was a roughly 4.0Me main-sequence B star; we know...

  14. Evidence from K2 for Rapid Rotation in the Descendant of an Intermediate-mass Star

    Hermes, James J.; Kawaler, Steven D.; Romero, Alejandra Daniela; Kepler, Souza Oliveira; Tremblay, Pier-Emmanuel; Bell, Keaton; Dunlap, Bart; Montgomery, Michael Houston; Gänsicke, Boris; Clemens, J. Christopher; Dennihy, Erik D.; Redfield, Seth
    Using patterns in the oscillation frequencies of a white dwarf observed by K2, we have measured the fastest rotation rate (1.13 ± 0.02 hr) of any isolated pulsating white dwarf known to date. Balmer-line fits to follow-up spectroscopy from the SOAR telescope show that the star (SDSSJ0837+1856, EPIC 211914185) is a 13,590 340 K, 0.87±0.03Me white dwarf. This is the highest mass measured for any pulsating white dwarf with known rotation, suggesting a possible link between high mass and fast rotation. If it is the product of single-star evolution, its progenitor was a roughly 4.0Me main-sequence B star; we know...

  15. Neutrino-driven electrostatic instabilities in a magnetized plasma

    Haas, Fernando; Pascoal, Kellen Alves; Mendonça, José Tito
    The destabilizing role of neutrino beams on the Trivelpiece-Gould modes is considered, assuming electrostatic perturbations in a magnetized plasma composed by electrons in a neutralizing ionic background, coupled to a neutrino species by means of an effective neutrino force arising from the electroweak interaction. The magnetic field is found to significantly improve the linear instability growth rate, as calculated for supernova type II environments. On the formal level, for wave vectors parallel or perpendicular to the magnetic field, the instability growth rate is found from the unmagnetized case replacing the plasma frequency by the appropriated Trivelpiece-Gould frequency. The growth rate...

  16. Neutrino-driven electrostatic instabilities in a magnetized plasma

    Haas, Fernando; Pascoal, Kellen Alves; Mendonça, José Tito
    The destabilizing role of neutrino beams on the Trivelpiece-Gould modes is considered, assuming electrostatic perturbations in a magnetized plasma composed by electrons in a neutralizing ionic background, coupled to a neutrino species by means of an effective neutrino force arising from the electroweak interaction. The magnetic field is found to significantly improve the linear instability growth rate, as calculated for supernova type II environments. On the formal level, for wave vectors parallel or perpendicular to the magnetic field, the instability growth rate is found from the unmagnetized case replacing the plasma frequency by the appropriated Trivelpiece-Gould frequency. The growth rate...

  17. Low-mass variable stars in the globular cluster NGC 6397

    Martinazzi, Elizandra; Kepler, Souza Oliveira; Costa, Jose Eduardo da Silveira
    We have conducted a photometric survey of the globular cluster NGC 6397 in a search for variable stars. We obtained ∼11 h of time-resolved photometric images with one European Southern Observatory-Very Large Telescope using the FOcal Reducer and low dispersion Spectrograph imager distributed over two consecutive nights. We analysed 8391 light curves of stars brighter than magnitude 23 with the 465-nm filter, and we identified 412 variable stars, reaching ∼4.8 ± 0.2 per cent of variability with time-scales between 0.004 and 2 d, with amplitudes variation greater than ±0.2 mag.

  18. Low-mass variable stars in the globular cluster NGC 6397

    Martinazzi, Elizandra; Kepler, Souza Oliveira; Costa, Jose Eduardo da Silveira
    We have conducted a photometric survey of the globular cluster NGC 6397 in a search for variable stars. We obtained ∼11 h of time-resolved photometric images with one European Southern Observatory-Very Large Telescope using the FOcal Reducer and low dispersion Spectrograph imager distributed over two consecutive nights. We analysed 8391 light curves of stars brighter than magnitude 23 with the 465-nm filter, and we identified 412 variable stars, reaching ∼4.8 ± 0.2 per cent of variability with time-scales between 0.004 and 2 d, with amplitudes variation greater than ±0.2 mag.

  19. Gel-combustion-synthesized ZnO nanoparticles for visible light-assisted photocatalytic hydrogen generation

    Ramasami, Alamelu Kannan; Ravishankar, Thammadihalli Nanjundaiah; Nagaraju, Ganganagappa; Ramakrishnappa, Thippeswamy; Teixeira, Sergio Ribeiro; Balakrishna, R. Geetha
    Zinc oxide nanoparticles (ZnO NPs) synthesized by the gel combustion technique using a bio-fuel, cassava starch (root tubers of Manihot esculenta), have been characterized by various techniques. The X-ray diffraction pattern reveals hexagonal wurtzite structure. The particle size averaged around 45nm with an excellent band gap of 2.5 eV. The scanning electron and transmission electron microscopic images confirm the ZnO NPs to be agglomerated with loop- and chain-like morphology. The ZnO NPs prepared by this method is a promising candidate for photocatalytic hydrogen generation (41 μmol h−1 g−1) under UV light illumination and (140 μmol h−1 g−1) under visible light...

  20. Gel-combustion-synthesized ZnO nanoparticles for visible light-assisted photocatalytic hydrogen generation

    Ramasami, Alamelu Kannan; Ravishankar, Thammadihalli Nanjundaiah; Nagaraju, Ganganagappa; Ramakrishnappa, Thippeswamy; Teixeira, Sergio Ribeiro; Balakrishna, R. Geetha
    Zinc oxide nanoparticles (ZnO NPs) synthesized by the gel combustion technique using a bio-fuel, cassava starch (root tubers of Manihot esculenta), have been characterized by various techniques. The X-ray diffraction pattern reveals hexagonal wurtzite structure. The particle size averaged around 45nm with an excellent band gap of 2.5 eV. The scanning electron and transmission electron microscopic images confirm the ZnO NPs to be agglomerated with loop- and chain-like morphology. The ZnO NPs prepared by this method is a promising candidate for photocatalytic hydrogen generation (41 μmol h−1 g−1) under UV light illumination and (140 μmol h−1 g−1) under visible light...

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