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1. The One-hundred-deg2 DECam Imaging in Narrowbands (ODIN): Survey Design and Science Goals

Author

Lee, Kyoung-Soo, Gawiser, Eric, Park, Changbom, Yang, Yujin, Valdes, Francisco, Lang, Dustin, Ramakrishnan, Vandana, Moon, Byeongha, Firestone, Nicole, Appleby, Stephen, Artale, Maria Celeste, Andrews, Moira, Bauer, Franz, Benda, Barbara, Broussard, Adam, Chiang, Yi-Kuan, Ciardullo, Robin, Dey, Arjun, Farooq, Rameen, Gronwall, Caryl, Guaita, Lucia, Huang, Yun, Hwang, Ho Seong, Im, Sang Hyeok, Jeong, Woong-Seob, Karthikeyan, Shreya, Kim, Hwihyun, Kim, Seongjae, Kumar, Ankit, Nagaraj, Gautam R, Nantais, Julie, Padilla, Nelson, Park, Jaehong, Pope, Alexandra, Popescu, Roxana, Schlegel, David, Seo, Eunsuk, Singh, Akriti, Song, Hyunmi, Troncoso, Paulina, Vivas, A Katherina, Zabludoff, Ann, and Zenteno, Alfredo

Subjects
Astronomical Sciences, Physical Sciences, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics, Astronomical sciences, Particle and high energy physics, Space sciences
Abstract

We describe the survey design and science goals for One-hundred-deg2 DECam Imaging in Narrowbands (ODIN), a NOIRLab survey using the Dark Energy Camera (DECam) to obtain deep (AB ∼ 25.7) narrowband images over an unprecedented area of sky. The three custom-built narrowband filters, N419, N501, and N673, have central wavelengths of 419, 501, and 673 nm and respective FWHM of 7.5, 7.6, and 10.0 nm, corresponding to Lyα at z = 2.4, 3.1, and 4.5 and cosmic times of 2.8, 2.1, and 1.4 Gyr, respectively. When combined with even deeper, public broadband data from the Hyper Suprime-Cam, DECam, and in the future, the Legacy Survey of Space and Time, the ODIN narrowband images will enable the selection of over 100,000 Lyα-emitting (LAE) galaxies at these epochs. ODIN-selected LAEs will identify protoclusters as galaxy overdensities, and the deep narrowband images enable detection of highly extended Lyα blobs (LABs). Primary science goals include measuring the clustering strength and dark matter halo connection of LAEs, LABs, and protoclusters, and their respective relationship to filaments in the cosmic web. The three epochs allow for the redshift evolution of these properties to be determined during the period known as Cosmic Noon, where star formation was at its peak. The narrowband filter wavelengths are designed to enable interloper rejection and further scientific studies by revealing [O ii] and [O iii] at z = 0.34, Lyα and He ii 1640 at z = 3.1, and Lyman continuum plus Lyα at z = 4.5. Ancillary science includes similar studies of the lower-redshift emission-line galaxy samples and investigations of nearby star-forming galaxies resolved into numerous [O iii] and [S ii] emitting regions.

Published
2024

2. DESI Survey Validation Data in the COSMOS/Hyper Suprime-Cam Field: Cool Gas Trace Main-sequence Star-forming Galaxies at the Cosmic Noon

Author

Zou, Siwei, Jiang, Linhua, Cai, Zheng, Moustakas, John, Sun, Zechang, Pan, Zhiwei, Ding, Jiani, Forero-Romero, Jaime E, Zou, Hu, Ting, Yuan-sen, Pieri, Matthew, Ahlen, Steven, Alexander, David, Brooks, David, Dey, Arjun, Font-Ribera, Andreu, Gontcho, Satya Gontcho A, Honscheid, Klaus, Landriau, Martin, de la Macorra, Axel, Magana, Mariana Vargas, Meisner, Aaron, Miquel, Ramon, Schubnell, Michael, Tarlé, Gregory, and Zhou, Zhimin

Subjects
Astronomical Sciences, Physical Sciences, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics, Astronomical sciences, Particle and high energy physics, Space sciences
Abstract

We present the first result in exploring the gaseous halo and galaxy correlation using the Dark Energy Spectroscopic Instrument survey validation data in the Cosmic Evolution Survey (COSMOS) and Hyper Suprime-Cam field. We obtain multiphase gaseous halo properties in the circumgalactic medium by using 115 quasar spectra (signal-to-noise ratio > 3). We detect Mg ii absorption at redshift 0.6 < z < 2.5, C iv absorption at 1.6 < z < 3.6, and H i absorption associated with the Mg ii and C iv. By crossmatching the COSMOS2020 catalog, we identify the Mg ii and C iv host galaxies in 10 quasar fields at 0.9< z < 3.1. We find that within the impact parameter of 250 kpc, a tight correlation is seen between the strong Mg ii equivalent width and the host galaxy star formation rate. The covering fraction f c of the strong Mg ii selected galaxies, which is the ratio of the absorbing galaxy in a certain galaxy population, shows significant evolution in the main-sequence galaxies and marginal evolution in all the galaxy populations within 250 kpc at 0.9 < z < 2.2. The f c increase in the main-sequence galaxies likely suggests the coevolution of strong Mg ii absorbing gas and the main-sequence galaxies at the cosmic noon. Furthermore, Mg ii and C iv absorbing gas is detected out of the galaxy virial radius, tentatively indicating the feedback produced by the star formation and/or the environmental effects.

Published
2024

3. GTC Follow-up Observations of Very Metal-poor Star Candidates from DESI

Author

Prieto, Carlos Allende, Aguado, David S, Hernández, Jonay I González, Rebolo, Rafael, Najita, Joan, Manser, Christopher J, Rockosi, Constance, Slepian, Zachary, Mezcua, Mar, Valluri, Monica, Ezzeddine, Rana, Koposov, Sergey E, Cooper, Andrew P, Dey, Arjun, Gänsicke, Boris T, Li, Ting S, Cunha, Katia, Zou, Siwei, Aguilar, Jessica Nicole, Ahlen, Steven, Brooks, David, Claybaugh, Todd, Cole, Shaun, Eftekharzadeh, Sarah, Fanning, Kevin, Forero-Romero, Jaime, Gontcho, Satya Gontcho A, Honscheid, Klaus, Jablonka, Pascale, Kehoe, Robert, Kisner, Theodore, Landriau, Martin, de la Macorra, Axel, Meisner, Aaron, Miquel, Ramón, Moustakas, John, Nie, Jundan, Poppett, Claire, Prada, Francisco, Rezaie, Mehdi, Rossi, Graziano, Sánchez, Eusebio, Schubnell, Michael, Sharples, Ray, Siudek, Malgorzata, Smith, Verne V, Tarlé, Gregory, Vincenzo, Fiorenzo, Weaver, Benjamin Alan, Zhou, Zhimin, and Zou, Hu

Subjects
Astronomical Sciences, Physical Sciences, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics, Astronomical sciences, Particle and high energy physics, Space sciences
Abstract

The observations from the Dark Energy Spectroscopic Instrument (DESI) will significantly increase the numbers of known extremely metal-poor stars by a factor of ∼10, improving the sample statistics to study the early chemical evolution of the Milky Way and the nature of the first stars. In this paper we report follow-up observations with high signal-to-noise ratio of nine metal-poor stars identified during the DESI commissioning with the Optical System for Imaging and Low-Resolution Integrated Spectroscopy (OSIRIS) instrument on the 10.4 m Gran Telescopio Canarias. The analysis of the data using a well-vetted methodology confirms the quality of the DESI spectra and the performance of the pipelines developed for the data reduction and analysis of DESI data.

Published
2023

4. Target Selection and Validation of DESI Quasars

Author

Chaussidon, Edmond, Yèche, Christophe, Palanque-Delabrouille, Nathalie, Alexander, David M, Yang, Jinyi, Ahlen, Steven, Bailey, Stephen, Brooks, David, Cai, Zheng, Chabanier, Solène, Davis, Tamara M, Dawson, Kyle, de laMacorra, Axel, Dey, Arjun, Dey, Biprateep, Eftekharzadeh, Sarah, Eisenstein, Daniel J, Fanning, Kevin, Font-Ribera, Andreu, Gaztañaga, Enrique, Gontcho, Satya Gontcho A, Gonzalez-Morales, Alma X, Guy, Julien, Herrera-Alcantar, Hiram K, Honscheid, Klaus, Ishak, Mustapha, Jiang, Linhua, Juneau, Stephanie, Kehoe, Robert, Kisner, Theodore, Kovács, Andras, Kremin, Anthony, Lan, Ting-Wen, Landriau, Martin, Le Guillou, Laurent, Levi, Michael E, Magneville, Christophe, Martini, Paul, Meisner, Aaron M, Moustakas, John, Muñoz-Gutiérrez, Andrea, Myers, Adam D, Newman, Jeffrey A, Nie, Jundan, Percival, Will J, Poppett, Claire, Prada, Francisco, Raichoor, Anand, Ravoux, Corentin, Ross, Ashley J, Schlafly, Edward, Schlegel, David, Tan, Ting, Tarlé, Gregory, Zhou, Rongpu, Zhou, Zhimin, and Zou, Hu

Subjects
Space Sciences, Physical Sciences, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics, Astronomical sciences, Particle and high energy physics, Space sciences
Abstract

The Dark Energy Spectroscopic Instrument (DESI) survey will measure large-scale structures using quasars as direct tracers of dark matter in the redshift range 0.9 < z < 2.1 and using Lyα forests in quasar spectra at z > 2.1. We present several methods to select candidate quasars for DESI, using input photometric imaging in three optical bands (g, r, z) from the DESI Legacy Imaging Surveys and two infrared bands (W1, W2) from the Wide-field Infrared Survey Explorer. These methods were extensively tested during the Survey Validation of DESI. In this paper, we report on the results obtained with the different methods and present the selection we optimized for the DESI main survey. The final quasar target selection is based on a random forest algorithm and selects quasars in the magnitude range of 16.5 < r < 23. Visual selection of ultra-deep observations indicates that the main selection consists of 71% quasars, 16% galaxies, 6% stars, and 7% inconclusive spectra. Using the spectra based on this selection, we build an automated quasar catalog that achieves a fraction of true QSOs higher than 99% for a nominal effective exposure time of ∼1000 s. With a 310 deg−2 target density, the main selection allows DESI to select more than 200 deg−2 quasars (including 60 deg−2 quasars with z > 2.1), exceeding the project requirements by 20%. The redshift distribution of the selected quasars is in excellent agreement with quasar luminosity function predictions.

Published
2023

5. Variations in the Width, Density, and Direction of the Palomar 5 Tidal Tails

Author

Bonaca, Ana, Pearson, Sarah, Price-Whelan, Adrian M, Dey, Arjun, Geha, Marla, Kallivayalil, Nitya, Moustakas, John, Muñoz, Ricardo, Myers, Adam D, Schlegel, David J, and Valdes, Francisco

Subjects
Astronomical Sciences, Physical Sciences, Globular star clusters, Milky Way dynamics, Milky Way stellar halo, Milky Way dark matter halo, Tidal tails, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics, Astronomical sciences, Particle and high energy physics, Space sciences
Abstract

Stars that escape globular clusters form tidal tails that are predominantly shaped by the global distribution of mass in the Galaxy, but also preserve a historical record of small-scale perturbations. Using deep grz photometry from DECaLS, we present highly probable members of the tidal tails associated with the evaporating globular cluster Palomar 5. These data yield the cleanest view of a stellar stream beyond ≈20 kpc and reveal: (1) a wide, low surface-brightness extension of the leading tail; (2) significant density variations along the stream; and (3) sharp changes in the direction of both the leading and the trailing tail. In the fiducial Milky Way model, a rotating bar perturbs the Palomar 5 tails and can produce streams with similar width and density profiles to those observed. However, the deviations of the stream track in this simple model do not match those observed in the Palomar 5 trailing tail, indicating the need for an additional source of perturbation. These discoveries open up the possibility of measuring the population of perturbers in the Milky Way, including dark-matter subhalos, with an ensemble of stellar streams and deep photometry alone.

Published
2020

6. A Census of Galaxy Constituents in a Coma Progenitor Observed at z > 3

Author

Shi, Ke, Lee, Kyoung-Soo, Dey, Arjun, Huang, Yun, Malavasi, Nicola, Hung, Chao-Ling, Inami, Hanae, Ashby, Matthew, Duncan, Kenneth, Xue, Rui, Reddy, Naveen, Hong, Sungryong, Jannuzi, Buell T, Cooper, Michael C, Gonzalez, Anthony H, Röttgering, Huub JA, Best, Phillip N, and Tasse, Cyril

Subjects
cosmology: observations, galaxies: clusters: general, galaxies: evolution, galaxies: formation, galaxies: high-redshift, astro-ph.GA, astro-ph.CO, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics
Abstract

We present a detailed census of galaxies in and around PC 217.96+32.3, a spectroscopically confirmed Coma analog at z = 3.78. Diverse galaxy types identified in the field include Lyα emitters (LAEs), massive star-forming galaxies, and ultramassive galaxies (≳ 10 11 M o ) which may have already halted their star formation. The sky distribution of the star-forming galaxies suggests the presence of a significant overdensity (δ SFG ≈ 8 ±2), which is spatially offset from the previously confirmed members by 3-4 Mpc to the west. Candidate quiescent and post-starburst galaxies are also found in large excess (a factor of ∼8-15 higher surface density than the field's), although their redshifts are less certain. We estimate that the total enclosed mass traced by the candidate star-forming galaxies is roughly comparable to that of PC 217.96+32.3 traced by the LAEs. We speculate that the true extent of PC 217.96+32.3 may be larger than previously known, half of which is missed by our LAE selection. Alternatively, the newly discovered overdensity may belong to another Coma progenitor not associated with PC 217.96+32.3. Expectations from theory suggest that both scenarios are equally unlikely (

Published
2019

7. First Discoveries of z > 6 Quasars with the DECam Legacy Survey and UKIRT Hemisphere Survey

Author

Wang, Feige, Fan, Xiaohui, Yang, Jinyi, Wu, Xue-Bing, Yang, Qian, Bian, Fuyan, McGreer, Ian D, Li, Jiang-Tao, Li, Zefeng, Ding, Jiani, Dey, Arjun, Dye, Simon, Findlay, Joseph R, Green, Richard, James, David, Jiang, Linhua, Lang, Dustin, Lawrence, Andy, Myers, Adam D, Ross, Nicholas P, Schlegel, David J, and Shanks, Tom

Subjects
galaxies: active, galaxies: high-redshift, quasars: emission lines, quasars: general, astro-ph.GA, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics
Abstract

We present the first discoveries from a survey of z ≳ 6 quasars using imaging data from the DECam Legacy Survey (DECaLS) in the optical, the UKIRT Deep Infrared Sky Survey (UKIDSS) and a preliminary version of the UKIRT Hemisphere Survey (UHS) in the near-IR, and ALLWISE in the mid-IR. DECaLS will image 9000 deg2 of sky down to z AB ∼ 23.0, and UKIDSS and UHS will map the northern sky at 0 < decl. < +607deg;, reaching J VEGA ∼ 19.6 (5-σ). The combination of these data sets allows us to discover quasars at redshift z ≳ 7 and to conduct a complete census of the faint quasar population at z ≳ 6. In this paper, we report on the selection method of our search, and on the initial discoveries of two new, faint z ≳ 6 quasars and one new z = 6.63 quasar in our pilot spectroscopic observations. The two new z ∼ 6 quasars are at z = 6.07 and z = 6.17 with absolute magnitudes at rest-frame wavelength 1450 Å being M 1450 = -25.83 and M 1450 = -25.76, respectively. These discoveries suggest that we can find quasars close to or fainter than the break magnitude of the Quasar Luminosity Function (QLF) at z ≳ 6. The new z = 6.63 quasar has an absolute magnitude of M 1450 = -25.95. This demonstrates the potential of using the combined DECaLS and UKIDSS/UHS data sets to find z ≳ 7 quasars. Extrapolating from previous QLF measurements, we predict that these combined data sets will yield ∼200 z ∼ 6 quasars to z AB < 21.5, ∼1000 z ∼ 6 quasars to z AB < 23, and ∼30 quasars at z > 6.5 to J VEGA < 19.5.

Published
2017

8. A Large Sample of Extremely Metal-poor Galaxies at z < 1 Identified from the DESI Early Data

Author

Zou, Hu, primary, Sui, Jipeng, additional, Saintonge, Amélie, additional, Scholte, Dirk, additional, Moustakas, John, additional, Siudek, Malgorzata, additional, Dey, Arjun, additional, Juneau, Stephanie, additional, Guo, Weijian, additional, Canning, Rebecca, additional, Aguilar, J., additional, Ahlen, S., additional, Brooks, D., additional, Claybaugh, T., additional, Dawson, K., additional, de la Macorra, A., additional, Doel, P., additional, Forero-Romero, J. E., additional, Gontcho A Gontcho, S., additional, Honscheid, K., additional, Landriau, M., additional, Le Guillou, L., additional, Manera, M., additional, Meisner, A., additional, Miquel, R., additional, Nie, Jundan, additional, Poppett, C., additional, Rezaie, M., additional, Rossi, G., additional, Sanchez, E., additional, Schubnell, M., additional, Seo, H., additional, Tarlé, G., additional, Zhou, Zhimin, additional, and Zou, Siwei, additional

Published
2024
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9. SPECTROSCOPIC CONFIRMATION OF A PROTOCLUSTER AT z ≈ 3.786

Author

Dey, Arjun, Lee, Kyoung-Soo, Reddy, Naveen, Cooper, Michael, Inami, Hanae, Hong, Sungryong, Gonzalez, Anthony H, and Jannuzi, Buell T

Subjects
cosmology: observations, galaxies: clusters: individual, galaxies: distances and redshifts, galaxies: evolution, galaxies: formation, galaxies: high-redshift, astro-ph.GA, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics
Abstract

We present new observations of the field containing the z = 3.786 protocluster PC 217.96+32.3. We confirm that it is one of the largest known and most overdense high-redshift structures. Such structures are rare even in the largest cosmological simulations. We used the Mayall/MOSAIC1.1 imaging camera to image a 1.°2 0.°6 area (≈150 75 comoving Mpc) surrounding the protocluster's core and discovered 165 candidate Lyα emitting galaxies (LAEs) and 788 candidate Lyman Break galaxies (LBGs). There are at least two overdense regions traced by the LAEs, the largest of which shows an areal overdensity in its core (i.e., within a radius of 2.5 comoving Mpc) of 14 ± 7 relative to the average LAE spatial density () in the imaged field. Further, is twice that derived by other field LAE surveys. Spectroscopy with Keck/DEIMOS yielded redshifts for 164 galaxies (79 LAEs and 85 LBGs); 65 lie at a redshift of 3.785 ± 0.010. The velocity dispersion of galaxies near the core is σ = 350 ± 40 km s-1, a value robust to selection effects. The overdensities are likely to collapse into systems with present-day masses of >1015 M o and >6 1014 M o. The low velocity dispersion may suggest a dynamically young protocluster. We find a weak trend between narrow-band (Lyα) luminosity and environmental density: the Lyα luminosity is enhanced on average by 1.35 within the protocluster core. There is no evidence that the Lyα equivalent width depends on environment. These suggest that star formation and/or active galactic nucleus (AGN) activity is enhanced in the higher-density regions of the structure. PC 217.96+32.3 is a Coma cluster analog, witnessed in the process of formation.

Published
2016

10. SPATIALLY RESOLVED GAS KINEMATICS WITHIN A Lyα NEBULA: EVIDENCE FOR LARGE-SCALE ROTATION

Author

Prescott, Moire KM, Martin, Crystal L, and Dey, Arjun

Subjects
galaxies: evolution, galaxies: formation, galaxies: high-redshift, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics
Abstract

We use spatially extended measurements of Lyα as well as less optically thick emission lines from an 80 kpc Lyα nebula at z 1.67 to assess the role of resonant scattering and to disentangle kinematic signatures from Lyα radiative transfer effects. We find that the Lyα, C IV, He II, and C III] emission lines all tell a similar story in this system, and that the kinematics are broadly consistent with large-scale rotation. First, the observed surface brightness profiles are similar in extent in all four lines, strongly favoring a picture in which the Lyα photons are produced in situ instead of being resonantly scattered from a central source. Second, we see low kinematic offsets between Lyα and the less optically thick He II line (100-200 km s-1), providing further support for the argument that the Lyα and other emission lines are all being produced within the spatially extended gas. Finally, the full velocity field of the system shows coherent velocity shear in all emission lines: 500 km s-1 over the central 50 kpc of the nebula. The kinematic profiles are broadly consistent with large-scale rotation in a gas disk that is at least partially stable against collapse. These observations suggest that the Lyα nebula represents accreting material that is illuminated by an offset, hidden active galactic nucleus or distributed star formation, and that is undergoing rotation in a clumpy and turbulent gas disk. With an implied mass of M(

Published
2015

11. GTC Follow-up Observations of Very Metal-poor Star Candidates from DESI

Author

Allende Prieto, Carlos, primary, Aguado, David S., additional, González Hernández, Jonay I., additional, Rebolo, Rafael, additional, Najita, Joan, additional, Manser, Christopher J., additional, Rockosi, Constance, additional, Slepian, Zachary, additional, Mezcua, Mar, additional, Valluri, Monica, additional, Ezzeddine, Rana, additional, Koposov, Sergey E., additional, Cooper, Andrew P., additional, Dey, Arjun, additional, Gänsicke, Boris T., additional, Li, Ting S., additional, Cunha, Katia, additional, Zou, Siwei, additional, Aguilar, Jessica Nicole, additional, Ahlen, Steven, additional, Brooks, David, additional, Claybaugh, Todd, additional, Cole, Shaun, additional, Eftekharzadeh, Sarah, additional, Fanning, Kevin, additional, Forero-Romero, Jaime, additional, Gontcho A Gontcho, Satya, additional, Honscheid, Klaus, additional, Jablonka, Pascale, additional, Kehoe, Robert, additional, Kisner, Theodore, additional, Landriau, Martin, additional, de la Macorra, Axel, additional, Meisner, Aaron, additional, Miquel, Ramón, additional, Moustakas, John, additional, Nie, Jundan, additional, Poppett, Claire, additional, Prada, Francisco, additional, Rezaie, Mehdi, additional, Rossi, Graziano, additional, Sánchez, Eusebio, additional, Schubnell, Michael, additional, Sharples, Ray, additional, Siudek, Malgorzata, additional, Smith, Verne V., additional, Tarlé, Gregory, additional, Vincenzo, Fiorenzo, additional, Weaver, Benjamin Alan, additional, Zhou, Zhimin, additional, and Zou, Hu, additional

Published
2023
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12. MID-INFRARED VARIABILITY FROM THE SPITZER DEEP WIDE-FIELD SURVEY

Author

Kozłowski, Szymon, Kochanek, Christopher S, Stern, Daniel, Ashby, Matthew LN, Assef, Roberto J, Bock, JJ, Borys, C, Brand, K, Brodwin, M, Brown, MJI, Cool, R, Cooray, A, Croft, S, Dey, Arjun, Eisenhardt, PR, Gonzalez, A, Gorjian, V, Griffith, R, Grogin, N, Ivison, R, Jacob, J, Jannuzi, BT, Mainzer, A, Moustakas, L, Röttgering, H, Seymour, N, Smith, HA, Stanford, SA, Stauffer, JR, Sullivan, IS, van Breugel, W, Willner, SP, and Wright, EL

Subjects
cosmology: observations, galaxies: active, infrared: galaxies, quasars: general, astro-ph.CO, Astronomical and Space Sciences, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Astronomy & Astrophysics
Abstract

We use the multi-epoch, mid-infrared Spitzer Deep Wide-Field Survey to investigate the variability of objects in 8.1 deg2 of the NOAO Deep Wide Field Survey Boötes field. We perform a Difference Image Analysis of the four available epochs between 2004 and 2008, focusing on the deeper 3.6 and 4.5 μm bands. Out of 474, 179 analyzed sources, 1.1% meet our standard variability selection criteria that the two light curves are strongly correlated (r>0.8) and that their joint variance (σ12) exceeds that for all sources with the same magnitude by 2σ. We then examine the mid-IR colors of the variable sources and match them with X-ray sources from the XBoötes survey, radio catalogs, 24 μm selected active galactic nucleus (AGN) candidates, and spectroscopically identified AGNs from the AGN and Galaxy Evolution Survey (AGES). Based on their mid-IR colors, most of the variable sources are AGNs (76%), with smaller contributions from stars (11%), galaxies (6%), and unclassified objects, although most of the stellar, galaxy, and unclassified sources are false positives. For our standard selection criteria, 11%-12% of the mid-IR counterparts to X-ray sources, 24 μm AGN candidates, and spectroscopically identified AGNs show variability. The exact fractions depend on both the search depth and the selection criteria. For example, 12% of the 1131 known z>1 AGNs in the field and 14%-17% of the known AGNs with well-measured fluxes in all four Infrared Array Camera bands meet our standard selection criteria. The mid-IR AGN variability can be well described by a single power-law structure function with an index of γ ≈ 0.5 at both 3.6 and 4.5 μm, and an amplitude of S 0 ≃ 0.1 mag on rest-frame timescales of 2 yr. The variability amplitude is higher for shorter rest-frame wavelengths and lower luminosities. © 2010. The American Astronomical Society. All rights reserved.

Published
2010

13. Overview of the DESI Milky Way Survey

Author

Cooper, Andrew P., primary, Koposov, Sergey E., additional, Allende Prieto, Carlos, additional, Manser, Christopher J., additional, Kizhuprakkat, Namitha, additional, Myers, Adam D., additional, Dey, Arjun, additional, Gänsicke, Boris T., additional, Li, Ting S., additional, Rockosi, Constance, additional, Valluri, Monica, additional, Najita, Joan, additional, Deason, Alis, additional, Raichoor, Anand, additional, Wang, M.-Y., additional, Ting, Y.-S., additional, Kim, Bokyoung, additional, Carrillo, Andreia, additional, Wang, Wenting, additional, Beraldo e Silva, Leandro, additional, Han, Jiwon Jesse, additional, Ding, Jiani, additional, Sánchez-Conde, Miguel, additional, Aguilar, Jessica N., additional, Ahlen, Steven, additional, Bailey, Stephen, additional, Belokurov, Vasily, additional, Brooks, David, additional, Cunha, Katia, additional, Dawson, Kyle, additional, de la Macorra, Axel, additional, Doel, Peter, additional, Eisenstein, Daniel J., additional, Fagrelius, Parker, additional, Fanning, Kevin, additional, Font-Ribera, Andreu, additional, Forero-Romero, Jaime E., additional, Gaztañaga, Enrique, additional, A Gontcho, Satya Gontcho, additional, Guy, Julien, additional, Honscheid, Klaus, additional, Kehoe, Robert, additional, Kisner, Theodore, additional, Kremin, Anthony, additional, Landriau, Martin, additional, Levi, Michael E., additional, Martini, Paul, additional, Meisner, Aaron M., additional, Miquel, Ramon, additional, Moustakas, John, additional, Nie, Jundan J. D., additional, Palanque-Delabrouille, Nathalie, additional, Percival, Will J., additional, Poppett, Claire, additional, Prada, Francisco, additional, Rehemtulla, Nabeel, additional, Schlafly, Edward, additional, Schlegel, David, additional, Schubnell, Michael, additional, Sharples, Ray M., additional, Tarlé, Gregory, additional, Wechsler, Risa H., additional, Weinberg, David H., additional, Zhou, Zhimin, additional, and Zou, Hu, additional

Published
2023
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14. DESI Observations of the Andromeda Galaxy: Revealing the Immigration History of Our Nearest Neighbor

Author

Dey, Arjun, primary, Najita, Joan R., additional, Koposov, Sergey E., additional, Josephy-Zack, J., additional, Maxemin, Gabriel, additional, Bell, Eric F., additional, Poppett, C., additional, Patel, E., additional, Beraldo e Silva, L., additional, Raichoor, A., additional, Schlegel, D., additional, Lang, D., additional, Meisner, A., additional, Myers, Adam D., additional, Aguilar, J., additional, Ahlen, S., additional, Allende Prieto, C., additional, Brooks, D., additional, Cooper, A. P., additional, Dawson, K. S., additional, Macorra, A. de la, additional, Doel, P., additional, Font-Ribera, A., additional, García-Bellido, Juan, additional, Gontcho A Gontcho, S., additional, Guy, J., additional, Honscheid, K., additional, Kehoe, R., additional, Kisner, T., additional, Kremin, A., additional, Landriau, M., additional, Le Guillou, L., additional, Levi, Michael E., additional, Li, T. S., additional, Martini, Paul, additional, Miquel, R., additional, Moustakas, J., additional, Nie, Jundan, additional, Palanque-Delabrouille, N., additional, Prada, F., additional, Schlafly, E. F., additional, Sharples, Ray M., additional, Tarlé, Gregory, additional, Ting, Yuan-Sen, additional, Tyas, L., additional, Valluri, M., additional, Wechsler, Risa H., additional, and Zou, H., additional

Published
2023
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15. Evaluating Lyα Emission as a Tracer of the Largest Cosmic Structure at z ∼ 2.47

Author

Huang, Yun, primary, Lee, Kyoung-Soo, additional, Cucciati, Olga, additional, Lemaux, Brian C., additional, Sawicki, Marcin, additional, Malavasi, Nicola, additional, Ramakrishnan, Vandana, additional, Xue, Rui, additional, Cassara, Letizia P., additional, Chiang, Yi-Kuan, additional, Dey, Arjun, additional, Gwyn, Stephen D. J., additional, Hathi, Nimish, additional, Pentericci, Laura, additional, Prescott, Moire K. M., additional, and Zamorani, Gianni, additional

Published
2022
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19. A Luminosity Function of Ly(alpha)-Emitting Galaxies at Z [Approx. Equal to] 4.5(Sup 1),(Sup 2)

Author

Dawson, Steve, Rhoads, James E, Malhotra, Sangeeta, Stern, Daniel, Wang, JunXian, Dey, Arjun, Spinrad, Hyron, and Jannuzi, Buell T

Subjects
Astronomy
Abstract

We present a catalog of 59 z [approx. equal to] 4:5 Ly(alpha)-emitting galaxies spectroscopically confirmed in a campaign of Keck DEIMOS follow-up observations to candidates selected in the Large Are (LALA) narrowband imaging survey.We targeted 97 candidates for spectroscopic follow-up; by accounting for the variety of conditions under which we performed spectroscopy, we estimate a selection reliability of approx.76%. Together with our previous sample of Keck LRIS confirmations, the 59 sources confirmed herein bring the total catalog to 73 spectroscopically confirmed z [approx. equal to] 4:5 Ly(alpha)- emitting galaxies in the [approx. equal to] 0.7 deg(exp 2) covered by the LALA imaging. As with the Keck LRIS sample, we find that a nonnegligible fraction of the co rest-frame equivalent widths (W(sub lambda)(sup rest)) that exceed the maximum predicted for normal stellar populations: 17%-31%(93%confidence) of the detected galaxies show (W(sub lambda)(sup rest)) 12%-27% (90% confidence) show (W(sub lambda)(sup rest)) > 240 A. We construct a luminosity function of z [approx. equal to] 4.5 Ly(alpha) emission lines for comparison to Ly(alpha) luminosity function < 6.6. We find no significant evidence for Ly(alpha) luminosity function evolution from z [approx. equal to] 3 to z [approx. equal to] 6. This result supports the conclusion that the intergalactic me largely reionized from the local universe out to z [approx. equal to] 6.5. It is somewhat at odds with the pronounced drop in the cosmic star formation rate density recently measured between z approx. 3 an z approx. 6 in continuum-selected Lyman-break galaxies, and therefore potentially sheds light on the relationship between the two populations.

Published
2007

21. A Mid-IR Selected Changing-look Quasar and Physical Scenarios for Abrupt AGN Fading

Author

Stern, Daniel, primary, McKernan, Barry, additional, Graham, Matthew J., additional, Ford, K. E. S., additional, Ross, Nicholas P., additional, Meisner, Aaron M., additional, Assef, Roberto J., additional, Baloković, Mislav, additional, Brightman, Murray, additional, Dey, Arjun, additional, Drake, Andrew, additional, Djorgovski, S. G., additional, Eisenhardt, Peter, additional, and Jun, Hyunsung D., additional

Published
2018
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22. Discovery of a Very Large (≈20 kpc) Galaxy at z = 3.72

Author

Lee, Kyoung-Soo, primary, Dey, Arjun, additional, Matheson, Thomas, additional, Shi, Ke, additional, Hung, Chao-Ling, additional, Xue, Rui, additional, Inami, Hanae, additional, Huang, Yun, additional, Lee, Khee-Gan, additional, Ashby, Matthew L. N., additional, Jannuzi, Buell, additional, Reddy, Naveen, additional, Hong, Sungryong, additional, Mo, Wenli, additional, and Malavasi, Nicola, additional

Published
2018
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23. First Discoveries ofz> 6 Quasars with the DECam Legacy Survey and UKIRT Hemisphere Survey

Author

Wang, Feige, primary, Fan, Xiaohui, additional, Yang, Jinyi, additional, Wu, Xue-Bing, additional, Yang, Qian, additional, Bian, Fuyan, additional, McGreer, Ian D., additional, Li, Jiang-Tao, additional, Li, Zefeng, additional, Ding, Jiani, additional, Dey, Arjun, additional, Dye, Simon, additional, Findlay, Joseph R., additional, Green, Richard, additional, James, David, additional, Jiang, Linhua, additional, Lang, Dustin, additional, Lawrence, Andy, additional, Myers, Adam D., additional, Ross, Nicholas P., additional, Schlegel, David J., additional, and Shanks, Tom, additional

Published
2017
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25. STAR FORMATION AND AGN ACTIVITY IN GALAXY CLUSTERS FROMz= 1–2: A MULTI-WAVELENGTH ANALYSIS FEATURINGHERSCHEL/PACS

Author

Alberts, Stacey, primary, Pope, Alexandra, additional, Brodwin, Mark, additional, Chung, Sun Mi, additional, Cybulski, Ryan, additional, Dey, Arjun, additional, Eisenhardt, Peter R. M., additional, Galametz, Audrey, additional, Gonzalez, Anthony H., additional, Jannuzi, Buell T., additional, Stanford, S. Adam, additional, Snyder, Gregory F., additional, Stern, Daniel, additional, and Zeimann, Gregory R., additional

Published
2016
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28. PROBING THE PHYSICAL PROPERTIES OFz= 4.5 LyαEMITTERS WITHSPITZER

Author

Finkelstein, Keely D., primary, Finkelstein, Steven L., additional, Tilvi, Vithal, additional, Malhotra, Sangeeta, additional, Rhoads, James E., additional, Grogin, Norman A., additional, Pirzkal, Norbert, additional, Dey, Arjun, additional, Jannuzi, Buell T., additional, Mobasher, Bahram, additional, Pakzad, Sabrina, additional, Salmon, Brett, additional, and Wang, Junxian, additional

Published
2015
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29. STAR FORMATION IN HIGH-REDSHIFT CLUSTER ELLIPTICALS

Author

Wagner, Cory R., primary, Brodwin, Mark, additional, Snyder, Gregory F., additional, Gonzalez, Anthony H., additional, Stanford, S. A., additional, Alberts, Stacey, additional, Pope, Alexandra, additional, Stern, Daniel, additional, Zeimann, Gregory R., additional, Chary, Ranga-Ram, additional, Dey, Arjun, additional, Eisenhardt, Peter R. M., additional, Mancone, Conor L., additional, and Moustakas, John, additional

Published
2015
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30. THE CLUSTERING AND HALO MASSES OF STAR-FORMING GALAXIES ATz< 1

Author

Dolley, Tim, primary, Brown, Michael J. I., additional, Weiner, Benjamin J., additional, Brodwin, Mark, additional, Kochanek, C. S., additional, Pimbblet, Kevin A., additional, Palamara, David P., additional, Jannuzi, Buell T., additional, Dey, Arjun, additional, Atlee, David W., additional, and Beare, Richard, additional

Published
2014
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31. DISCOVERY OF A VERY LARGE STRUCTURE ATZ= 3.78

Author

Lee, Kyoung-Soo, primary, Dey, Arjun, additional, Hong, Sungryong, additional, Reddy, Naveen, additional, Wilson, Christian, additional, Jannuzi, Buell T., additional, Inami, Hanae, additional, and Gonzalez, Anthony H., additional

Published
2014
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33. THE ERA OF STAR FORMATION IN GALAXY CLUSTERS

Author

Brodwin, M., primary, Stanford, S. A., additional, Gonzalez, Anthony H., additional, Zeimann, G. R., additional, Snyder, G. F., additional, Mancone, C. L., additional, Pope, A., additional, Eisenhardt, P. R., additional, Stern, D., additional, Alberts, S., additional, Ashby, M. L. N., additional, Brown, M. J. I., additional, Chary, R.-R., additional, Dey, Arjun, additional, Galametz, A., additional, Gettings, D. P., additional, Jannuzi, B. T., additional, Miller, E. D., additional, Moustakas, J., additional, and Moustakas, L. A., additional

Published
2013
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36. A CORRELATION BETWEEN STAR FORMATION RATE AND AVERAGE BLACK HOLE ACCRETION IN STAR-FORMING GALAXIES

Author

Chen, Chien-Ting J., primary, Hickox, Ryan C., additional, Alberts, Stacey, additional, Brodwin, Mark, additional, Jones, Christine, additional, Murray, Stephen S., additional, Alexander, David M., additional, Assef, Roberto J., additional, Brown, Michael J. I., additional, Dey, Arjun, additional, Forman, William R., additional, Gorjian, Varoujan, additional, Goulding, Andrew D., additional, Le Floc'h, Emeric, additional, Jannuzi, Buell T., additional, Mullaney, James R., additional, and Pope, Alexandra, additional

Published
2013
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39. THE CLUSTERING OF EXTREMELY RED OBJECTS

Author

Palamara, David P., primary, Brown, Michael J. I., additional, Jannuzi, Buell T., additional, Dey, Arjun, additional, Stern, Daniel, additional, Pimbblet, Kevin A., additional, Weiner, Benjamin J., additional, Ashby, Matthew L. N., additional, Kochanek, C. S., additional, Gonzalez, Anthony, additional, Brodwin, Mark, additional, Le Floc'h, Emeric, additional, and Rieke, Marcia, additional

Published
2013
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41. EVIDENCE FOR A WIDE RANGE OF ULTRAVIOLET OBSCURATION INz∼ 2 DUSTY GALAXIES FROM THE GOODS-HERSCHELSURVEY

Author

Penner, Kyle, primary, Dickinson, Mark, additional, Pope, Alexandra, additional, Dey, Arjun, additional, Magnelli, Benjamin, additional, Pannella, Maurilio, additional, Altieri, Bruno, additional, Aussel, Herve, additional, Buat, Veronique, additional, Bussmann, Shane, additional, Charmandaris, Vassilis, additional, Coia, Daniela, additional, Daddi, Emanuele, additional, Dannerbauer, Helmut, additional, Elbaz, David, additional, Hwang, Ho Seong, additional, Kartaltepe, Jeyhan, additional, Lin, Lihwai, additional, Magdis, Georgios, additional, Morrison, Glenn, additional, Popesso, Paola, additional, Scott, Douglas, additional, and Valtchanov, Ivan, additional

Published
2012
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45. ASSEMBLY OF THE RED SEQUENCE IN INFRARED-SELECTED GALAXY CLUSTERS FROM THE IRAC SHALLOW CLUSTER SURVEY

Author

Snyder, Gregory F., primary, Brodwin, Mark, additional, Mancone, Conor M., additional, Zeimann, Gregory R., additional, Stanford, S. A., additional, Gonzalez, Anthony H., additional, Stern, Daniel, additional, Eisenhardt, Peter R. M., additional, Brown, Michael J. I., additional, Dey, Arjun, additional, Jannuzi, Buell, additional, and Perlmutter, Saul, additional

Published
2012
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48. MID-INFRARED SELECTION OF ACTIVE GALACTIC NUCLEI WITH THEWIDE-FIELD INFRARED SURVEY EXPLORER. I. CHARACTERIZINGWISE-SELECTED ACTIVE GALACTIC NUCLEI IN COSMOS

Author

Stern, Daniel, primary, Assef, Roberto J., additional, Benford, Dominic J., additional, Blain, Andrew, additional, Cutri, Roc, additional, Dey, Arjun, additional, Eisenhardt, Peter, additional, Griffith, Roger L., additional, Jarrett, T. H., additional, Lake, Sean, additional, Masci, Frank, additional, Petty, Sara, additional, Stanford, S. A., additional, Tsai, Chao-Wei, additional, Wright, E. L., additional, Yan, Lin, additional, Harrison, Fiona, additional, and Madsen, Kristin, additional

Published
2012
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