The WISE AGN Catalog

We present two large catalogs of AGN candidates identified across ~75% of the sky from the Wide-field Infrared Survey Explorer's AllWISE Data Release. Both catalogs, some of the largest such catalogs published to date, are selected purely on the basis of mid-IR photometry in the WISE W1 and W2 bands. The catalogs are designed to be appropriate for a broad range of scientific investigations, with one catalog emphasizing reliability while the other emphasizes completeness. Specifically, the R90 catalog consists of 4,543,530 AGN candidates with 90% reliability, while the C75 catalog consists of 20,907,127 AGN candidates with 75% completeness. We provide a detailed discussion of potential artifacts, and excise portions of the sky close to the Galactic Center, Galactic Plane, nearby galaxies, and other expected contaminating sources. Our final catalogs cover 30,093 deg^2 of extragalactic sky. These catalogs are expected to enable a broad range of science, and we present a few simple illustrative cases. From the R90 sample we identify 45 highly variable AGN lacking radio counterparts in the FIRST survey, implying they are unlikely to be blazars. One of these sources, WISEA J142846.71+172353.1, is a mid-IR-identified changing-look quasar at z=0.104. We characterize our catalogs by comparing them to large, wide-area AGN catalogs in the literature, specifically UV-to-near-IR quasar selections from SDSS and XDQSOz, mid-IR selection from Secrest et al. (2015) and X-ray selection from ROSAT. From the latter work, we identify four ROSAT X-ray sources that each are matched to three WISE-selected AGN in the R90 sample within 30". Palomar spectroscopy reveals one of these systems, 2RXS J150158.6+691029, to consist of a triplet of quasars at z=1.133 +/- 0.004, suggestive of a rich group or forming galaxy cluster.(Abridged)Comment: Accepted for publication in the Astrophysical Journal Supplements. Updated with comments from the referee. 20 pages, 15 figures, 8 tables. The WISE AGN Catalogs can be made available upon request by writing to [email protected]

The Porcupine Survey: A Distributed Survey and WISE Followup

Spitzer post-cryogen observations to perform a moderate depth survey distributed around the sky are proposed. Field centers are chosen to be WISE brown dwarf candidates, which will typically be 160 µJy at 4.7 µm and randomly distributed around the sky. The Spitzer observations will give much higher sensitivity, higher angular resolution, and a time baseline to measure both proper motions and possibly parallaxes. The distance and velocity data obtained on the WISE brown dwarf candidates will greatly improve our knowledge of the mass and age distribution of brown dwarfs. The outer parts of the Spitzer fields surrounding the WISE positions will provide a deep survey in many narrow fields of view distributed around the sky, and the volume of this survey will contain many more distant brown dwarfs, and many extragalactic objects

The Friendship Journey: Developing Global Understanding in the Middle Grades

The goals of developing a global perspective are consistent with the faith-based values of Catholicism. The primary goal is to prepare students academically, morally, and socially to participate in a globalized world that constantly faces new problems. A key component of this is the understanding that other people, who may appear on the surface to be very different from themselves, have differences which have value and similarities which unite us. The purpose of this article is to present one Catholic school’s attempts to prepare its students to meet the challenges of citizenry in an international community and to describe the impact of those efforts. The questions we explored are: (a) Does a student-focused, cultural exchange program enhance American students’ global perspectives? Does a student-focused, cultural exchange opportunity enrich students’ cultural understandings? Findings from this study revealed that students gained an appreciation for diverse cultures through social interaction. While the pre- and post-test survey data revealed some changes in students’ beliefs and attitudes, interviews and observations provided substantial evidence of students’ evolving awareness and respect for other cultures. The tangible connections formed produced young people who have a greater appreciation for our global community. Résumé Les objectifs consistant à développer une perspective mondiale s’accordent avec les valeurs religieuses du catholicisme. Le principal objectif est de préparer les élèves au niveau scolaire, moral et social à prendre part à une mondialisation qui rencontre constamment de nouveaux problèmes. Pour y parvenir, il est essentiel qu’ils comprennent que d’autres personnes qui ne leur ressemblent pas du tout en apparence, présentent des différences que nous apprécions et des ressemblances qui nous unissent. Cet article a pour objet de montrer comment une école catholique a essayé de préparer ses élèves à surmonter les problèmes rencontrés en tant que citoyen d’une communauté internationale et de décrire quel impact ces actions ont eu. Les questions étudiées sont les suivantes : (a) Un programme d’échanges culturels centré sur l’élève renforce-t-il les perspectives mondiales des élèves américains ? Leur compréhension des cultures se trouve-t-elle enrichie par la possibilité d’effectuer un échange culturel centré sur l’élève ? Les conclusions tirées de cette étude ont montré que les élèves ont appris à apprécier des cultures diverses par l’interaction sociale. Alors que les données de l’étude avant et après les tests ont révélé certaines modifications des croyances et attitudes des élèves, les entretiens et observations ont clairement prouvé une évolution de la sensibilisation des élèves et de leur respect vis-à-vis d’autres cultures. Les liens tangibles qui se sont tissés ont amené les jeunes à mieux apprécier notre communauté mondiale. Resumen Los objetivos para desarrollar una perspectiva global son consistentes con los valores basados en la fe del catolicismo. El principal objetivo es preparar a los estudiantes académica, moral y socialmente para participar en un mundo globalizado que se enfrenta constantemente a nuevos problemas. Un componente clave de esto es el entendimiento de que otra gente, que puede aparentar en la superficie ser de una manera muy distinta a ellos, tiene diferencias que resultan valiosas y a su vez similitudes que nos unen. El objetivo de este artículo es presentar la intención de una escuela católica de preparar a sus estudiantes para que logren los desafíos de la ciudadanía en una comunidad internacional y describir el impacto de estos esfuerzos. Las preguntas exploradas son: (a) ¿Puede un programa de intercambio cultural centrado en el alumno ampliar las perspectivas globales de los estudiantes estadounidenses? (b) ¿Puede una oportunidad de intercambio cultural centrado en el alumno enriquecer la comprensión cultural de los estudiantes? Los resultados de este estudio revelaron que los estudiantes ganaron apreciación por las diversas culturas a través de la interacción social. Aunque la información previa y posterior a las encuestas revelaron cambios en las creencias y actitudes de los estudiantes, las entrevistas y las observaciones ofrecieron pruebas sustanciales de evolución en la sensibilización y respeto de los estudiantes hacia otras culturas. Las conexiones tangibles que se formaron produjeron jóvenes con un mayor aprecio por nuestra comunidad global

Spectroscopic confirmation of a galaxy cluster associated with 7C1756+6520 at z=1.416

We present spectroscopic follow-up of an overdensity of galaxies photometrically selected to be at 1.4<z<2.5 found in the vicinity of the radio galaxy 7C1756+6520 at z=1.4156. Using the DEIMOS optical multi-object spectrograph on the Keck 2 telescope, we observed a total of 129 BzK-selected sources, comprising 82 blue, star-forming galaxy candidates (sBzK) and 47 red, passively-evolving galaxy candidates (pBzK*), as well as 11 mid-infrared selected AGN candidates. We obtain robust spectroscopic redshifts for 36 blue galaxies, 7 red galaxies and 9 AGN candidates. Assuming all foreground interlopers were identified, we find that only 16% (9%) of the sBzK (pBzK*) galaxies are at z<1.4. Therefore, the BzK criteria are shown to be relatively robust at identifying galaxies at moderate redshifts. Twenty-one galaxies, including the radio galaxy, four additional AGN candidates and three red galaxy candidates are found with 1.4156 +/- 0.025, forming a large scale structure at the redshift of the radio galaxy. Of these, eight have projected offsets <2Mpc relative to the radio galaxy position and have velocity offsets <1000km/s relative to the radio galaxy redshift. This confirms that 7C1756+6520 is associated with a high-redshift galaxy cluster. A second compact group of four galaxies is found at z~1.437, forming a sub-group offset by Dv~3000km/s and approximately 1.5' east of the radio galaxy.Comment: 9 pages, 6 figures, 2 tables, accepted for publication in A&A

Characterizing the Mid-IR Extragalactic Sky with WISE and SDSS

The Wide-field Infrared Survey Explorer (WISE) has completed its all-sky survey at 3.4-22 micron. We merge the WISE data with optical SDSS data and provide a phenomenological characterization of mid-IR, extragalactic sources. WISE is most sensitive at 3.4micron(W1) and least at 22micron(W4). The W1 band probes massive early-type galaxies out to z\gtrsim1. This is more distant than SDSS identified early-type galaxies, consistent with the fact that 28% of 3.4micron sources have faint or no r-band counterparts (r>22.2). In contrast, 92-95% of 12 and 22micron sources have SDSS optical counterparts with r<22.2. WISE 3.4micron detects 89.8% of the entire SDSS QSO catalog at SNR(W1)>7, but only 18.9% at 22micron with SNR(W4)>5. We show that WISE colors alone are effective in isolating stars (or local early-type galaxies), star-forming galaxies and strong AGN/QSOs at z<3. We highlight three major applications of WISE colors: (1) Selection of strong AGN/QSOs at z0.8 and W2<15.2 criteria, producing a census of this population. The surface density of these strong AGN/QSO candidates is 67.5+-0.14/deg^2. (2) Selection of dust-obscured, type-2 AGN/QSO candidates. We show that WISE W1-W2>0.8, W2<15.2 combined with r-W2>6 (Vega) colors can be used to identify type-2 AGN candidates. The fraction of these type-2 AGN candidates is 1/3rd of all WISE color-selected AGNs. (3) Selection of ULIRGs at z\sim2 with extremely red colors, r-W4>14 or well-detected 22micron sources lacking detections in the 3.4 and 4.6micron bands. The surface density of z~2 r-W4>14 ULIRGs is 0.9+-0.07/deg^2 at SNR(W4)>5 (flux(W4)>=2.5mJy), which is consistent with that inferred from smaller area Spitzer surveys. Optical spectroscopy of a small number of these high-redshift ULIRGs confirms our selection, and reveals a possible trend that optically fainter or r-W4 redder candidates are at higher redshifts.Comment: 41 pages, 20 figures, Accepted for publication by the Astronomical Journa

The Cluster and Field Galaxy AGN Fraction at z = 1 to 1.5: Evidence for a Reversal of the Local Anticorrelation Between Environment and AGN Fraction

The fraction of cluster galaxies that host luminous AGN is an important probe of AGN fueling processes, the cold ISM at the centers of galaxies, and how tightly black holes and galaxies co-evolve. We present a new measurement of the AGN fraction in a sample of 13 clusters of galaxies (M >= 10^{14} Msun) at 1<z<1.5 selected from the Spitzer/IRAC Shallow Cluster Survey, as well as the field fraction in the immediate vicinity of these clusters, and combine these data with measurements from the literature to quantify the relative evolution of cluster and field AGN from the present to z~3. We estimate that the cluster AGN fraction at 1<z<1.5 is f_A = 3.0^{+2.4}_{-1.4}% for AGN with a rest-frame, hard X-ray luminosity greater than L_{X,H} >= 10^{44} erg/s. This fraction is measured relative to all cluster galaxies more luminous than M*_{3.6}(z)+1, where M*_{3.6}(z) is the absolute magnitude of the break in the galaxy luminosity function at the cluster redshift in the IRAC 3.6um bandpass. The cluster AGN fraction is 30 times greater than the 3sigma upper limit on the value for AGN of similar luminosity at z~0.25, as well as more than an order of magnitude greater than the AGN fraction at z~0.75. AGN with L_{X,H} >= 10^{43} erg/s exhibit similarly pronounced evolution with redshift. In contrast with the local universe, where the luminous AGN fraction is higher in the field than in clusters, the X-ray and MIR-selected AGN fractions in the field and clusters are consistent at 1<z<1.5. This is evidence that the cluster AGN population has evolved more rapidly than the field population from z~1.5 to the present. This environment-dependent AGN evolution mimics the more rapid evolution of star-forming galaxies in clusters relative to the field.Comment: ApJ Accepted. 16 pages, 8 figures in emulateapj forma

Galaxy Cluster Correlation Function to z ~ 1.5 in the IRAC Shallow Cluster Survey

We present the galaxy cluster autocorrelation function of 277 galaxy cluster candidates with 0.25 \le z \le 1.5 in a 7 deg^2 area of the IRAC Shallow Cluster Survey. We find strong clustering throughout our galaxy cluster sample, as expected for these massive structures. Specifically, at = 0.5 we find a correlation length of r_0 = 17.40^{+3.98}_{-3.10} h^-1 Mpc, in excellent agreement with the Las Campanas Distant Cluster Survey, the only other non-local measurement. At higher redshift, = 1, we find that strong clustering persists, with a correlation length of r_0=19.14^{+5.65}_{-4.56} h^-1 Mpc. A comparison with high resolution cosmological simulations indicates these are clusters with halo masses of \sim 10^{14} Msun, a result supported by estimates of dynamical mass for a subset of the sample. In a stable clustering picture, these clusters will evolve into massive (10^{15} Msun) clusters by the present day.Comment: 4 pages, 4 figures, 1 table. ApJ Letters, in pres

A z=5.34 Galaxy Pair in the Hubble Deep Field

We present spectrograms of the faint V-drop (V(606) = 28.1, I(814) = 25.6) galaxy pair HDF3-951.1 and HDF3-951.2 obtained at the Keck II Telescope. Fernandez-Soto, Lanzetta, & Yahil (1998) derive a photometric redshift of z(ph) = 5.28 (+0.34,-0.41; 2 sigma) for these galaxies; our integrated spectrograms show a large and abrupt discontinuity near 7710 (+- 5) Angstroms. This break is almost certainly due to the Lyman alpha forest as its amplitude (1 - fnu(short) / fnu(long) > 0.87; 95% confidence limit) exceeds any discontinuities observed in stellar or galaxian rest-frame optical spectra. The resulting absorption-break redshift is z=5.34 (+- 0.01). Optical/near-IR photometry from the HDF yields an exceptionally red (V(606)-I(814)) color, consistent with this large break. A more accurate measure of the continuum depression blueward of Lyman alpha utilizing the imaging photometry yields D(A) = 0.88. The system as a whole is slightly brighter than L*(1500) relative to the z~3 Lyman break population and the total star formation rate inferred from the UV continuum is ~22 h(50)^-2 M(sun) yr^-1 (q(0) = 0.5) assuming the absence of dust extinction. The two individual galaxies are quite small (size scales < 1 h(50)^-1 kpc). Thus these galaxies superficially resemble the Pascarelle etal (1996) ``building blocks''; if they comprise a gravitationally bound system, the pair will likely merge in a time scale ~100 Myr.Comment: 18 pages, 4 figures; accepted to A

Heavy X-ray obscuration in the most-luminous galaxies discovered by WISE

Hot Dust-Obscured Galaxies (Hot DOGs) are hyperluminous ($L_{\mathrm{8-1000\,\mu m}}>10^{13}\,\mathrm{L_\odot}$) infrared galaxies with extremely high (up to hundreds of K) dust temperatures. The sources powering both their extremely high luminosities and dust temperatures are thought to be deeply buried and rapidly accreting supermassive black holes (SMBHs). Hot DOGs could therefore represent a key evolutionary phase in which the SMBH growth peaks. X-ray observations can be used to study their obscuration levels and luminosities. In this work, we present the X-ray properties of the 20 most-luminous ($L_{\mathrm{bol}}\gtrsim10^{14}\, L_\odot$) known Hot DOGs at $z=2-4.6$. Five of them are covered by long-exposure ($10-70$ ks) Chandra and XMM-Newton observations, with three being X-ray detected, and we study their individual properties. One of these sources (W0116$-$0505) is a Compton-thick candidate, with column density $N_H=(1.0-1.5)\times10^{24}\,\mathrm{cm^{-2}}$ derived from X-ray spectral fitting. The remaining 15 Hot DOGs have been targeted by a Chandra snapshot (3.1 ks) survey. None of these 15 is individually detected; therefore we applied a stacking analysis to investigate their average emission. From hardness-ratio analysis, we constrained the average obscuring column density and intrinsic luminosity to be log$N_H\,\mathrm{[cm^{-2}]}>23.5$ and $L_X\gtrsim10^{44}\,\mathrm{erg\,cm^{-2}\,s^{-1}}$, which are consistent with results for individually detected sources. We also investigated the $L_X-L_{6\mu\mathrm{m}}$ and $L_X-L_{bol}$ relations, finding hints that Hot DOGs are typically X-ray weaker than expected, although larger samples of luminous obscured QSOs are needed to derive solid conclusions.Comment: MNRAS, accepted 2017 November 29 . Received 2017 November 29 ; in original form 2017 October 11. 15 pages, 6 figure