scholarly journals A Wide-Field View of Leo II: A Structural Analysis Using the Sloan Digital Sky Survey

2007 ◽  
Vol 134 (5) ◽  
pp. 1938-1951 ◽  
Author(s):  
Matthew G. Coleman ◽  
Katrin Jordi ◽  
Hans-Walter Rix ◽  
Eva K. Grebel ◽  
Andreas Koch
Keyword(s):  
Structural Analysis ◽  
Sloan Digital Sky Survey ◽  
Wide Field ◽  
Sky Survey ◽  
Field View

scholarly journals The optical luminosity function of LOFAR radio-selected quasars at 1.4 ≤ z ≤ 5.0 in the NDWFS-Boötes field

2020 ◽  
Vol 636 ◽  
pp. A12
Author(s):  
E. Retana-Montenegro ◽  
H. J. A. Röttgering
Keyword(s):  
Radio Emission ◽  
Luminosity Function ◽  
Field Survey ◽  
Sloan Digital Sky Survey ◽  
Spatial Density ◽  
Spectral Energy ◽  
Wide Field ◽  
Infrared Photometry ◽  
Mid Infrared ◽  
Sky Survey

We present an estimate of the optical luminosity function (OLF) of LOFAR radio-selected quasars (RSQs) at 1.4 <  z <  5.0 in the 9.3 deg2 NOAO Deep Wide-field survey (NDWFS) of the Boötes field. The selection was based on optical and mid-infrared photometry used to train three different machine learning (ML) algorithms (Random forest, SVM, Bootstrap aggregation). Objects taken as quasars by the ML algorithms are required to be detected at ≥5σ significance in deep radio maps to be classified as candidate quasars. The optical imaging came from the Sloan Digital Sky Survey and the Pan-STARRS1 3π survey; mid-infrared photometry was taken from the Spitzer Deep, Wide-Field Survey; and radio data was obtained from deep LOFAR imaging of the NDWFS-Boötes field. The requirement of a 5σ LOFAR detection allowed us to reduce the stellar contamination in our sample by two orders of magnitude. The sample comprises 130 objects, including both photometrically selected candidate quasars (47) and spectroscopically confirmed quasars (83). The spectral energy distributions calculated using deep photometry available for the NDWFS-Boötes field confirm the validity of the photometrically selected quasars using the ML algorithms as robust candidate quasars. The depth of our LOFAR observations allowed us to detect the radio-emission of quasars that would be otherwise classified as radio-quiet. Around 65% of the quasars in the sample are fainter than M1450 = −24.0, a regime where the OLF of quasars selected through their radio emission, has not been investigated in detail. It has been demonstrated that in cases where mid-infrared wedge-based AGN selection is not possible due to a lack of appropriate data, the selection of quasars using ML algorithms trained with optical and infrared photometry in combination with LOFAR data provides an excellent approach for obtaining samples of quasars. The OLF of RSQs can be described by pure luminosity evolution at z <  2.4, and a combined luminosity and density evolution at z >  2.4. The faint-end slope, α, becomes steeper with increasing redshift. This trend is consistent with previous studies of faint quasars (M1450 ≤ −22.0). We demonstrate that RSQs show an evolution that is very similar to that exhibited by faint quasars. By comparing the spatial density of RSQs with that of the total (radio-detected plus radio-undetected) faint quasar population at similar redshifts, we find that RSQs may compose up to ∼20% of the whole faint quasar population. This fraction, within uncertainties, is constant with redshift. Finally, we discuss how the compactness of the RSQs radio-morphologies and their steep spectral indices could provide valuable insights into how quasar and radio activity are triggered in these systems.

scholarly journals Synergy of wide-field infrared survey explorer (WISE) and the Sloan Digital Sky Survey in Stripe 82

2018 ◽  
Author(s):  
◽  
Marat Musin
Keyword(s):  
Stellar Mass ◽  
Sloan Digital Sky Survey ◽  
High Mass ◽  
Optical Data ◽  
Wide Field ◽  
Resolution Image ◽  
Sky Survey ◽  
Template Fitting ◽  
Very High ◽  
Infrared Survey

In this dissertation, I aim to study the evolution of galaxies over the last 6 Gyr by measuring the growth of the global stellar mass density (GSMD) since z = 0.8. My work combines the datasets from two very large surveys, namely, the optical data from the Sloan Digital Sky Survey (SDSS) Stripe 82 and the infrared data from the Wide-field Infrared Survey Explorer (WISE), and constructs a unique catalog of galaxies that have their spectral energy distributions (SEDs) measured consistently from 0.3 to 5 [mu]m in seven bands. This catalog, the largest of its kind, contains 9 million galaxies in [about] 300 deg[2] , will have a wide range of applications beyond the scope of this thesis. Extending galaxy SED measurements to restframe near-IR has two significant advantages: (1) dust extinction can be better handled, and (2) emissions from low-mass stars, which are the major contributors to a galaxy's stellar mass, can be better measured. WISE was the only mission to date that provided all-sky IR data that are deep enough for galaxy evolution studies out to z [approximately] 1 (sampling restframe K-band). The only wide-field optical survey data that could match WISE depths are those from the SDSS Stripe 82 over [about] 300 deg2 . The synergy of the two is therefore natural. The implementation, however, is of tremendous difficulty. This is mainly because of the vastly different spatial resolutions between SDSS and WISE. To overcome this problem, we take an approach that is often referred to as "morphological template fitting", i.e., using the high-resolution image to define the morphological template of the galaxy in question, and de-convolving its light profile in the low-resolution image accordingly. In this way, we obtain the SED measurements over the entire 0.3-5[mu]m range in the most self-consistent manner. Using this SED catalog as the basis, we derive photometric redshifts and stellar masses for all the 9 million galaxies that span z = 0-0.8. This provides us an unprecedented statistics when deriving galaxy stellar mass functions (MFs) and GSMD over multiple redshift bins. Some preliminary results are discussed. As a by-product of our morphological template fitting process, an interesting population of objects called "WISE Optical Dropouts" ("WoDrops" for short) are discovered. These objects are significant detections in WISE data but are invisible in all the SDSS Stripe 82 data. Their nature remains a mystery up to this point. Among all possibilities, the only viable interpretation is that they are very high-mass galaxies with very high dust extinctions. To reveal their nature, future observations at larger facilities will be necessary.

scholarly journals Herbig–Haro flows around the BBWo 192E (GM 1–23) nebula

2020 ◽  
Vol 498 (4) ◽  
pp. 5109-5115
Author(s):  
T Yu Magakian ◽  
T A Movsessian ◽  
H R Andreasyan ◽  
J Bally ◽  
A S Rastorguev
Keyword(s):  
Star Formation ◽  
Sloan Digital Sky Survey ◽  
Young Stellar Objects ◽  
Infrared Range ◽  
Wide Field ◽  
Proper Motions ◽  
Dark Cloud ◽  
Stellar Objects ◽  
Reflection Nebula ◽  
Sky Survey

ABSTRACT Looking for evidence of recent star formation, we have studied a small comet-shaped reflection nebula, known as BBWo 192E (GM 1–23), which is located in the dark cloud SL 4 in the Vela Molecular Ridge cloud C, and a young infrared cluster embedded into the nebula. We obtained the images of BBWo 192E in Hα and [S ii] lines and in a Sloan Digital Sky Survey i ′ filter with the Blanco telescope at the Cerro Tololo Inter-American Observatory in order to discover new Herbig–Haro (HH) flows. We used the Two-Micron All-Sky Survey and the Wide-field Infrared Survey Explorer to search for additional member stars of the cluster. We also studied the proper motions and parallaxes of the cluster members using GAIA Data Release 2. Five new groups containing at least nine HH objects, tracing several distinct outflows, were revealed. A previously unreported reflection nebula and a number of probable outflow sources were found in the infrared range. The proper motions allowed us to select eight probable member stars in the visual range. Their parallaxes correspond to a mean distance 800 ± 100 pc for this cluster. The bolometric luminosities of the brightest cluster members are 1010 L⊙ (IRAS 08513−4201, the strong source in the centre of the cluster) and 2–6 L⊙ for the five other stars. The existence of optical HH flows around the infrared cluster of young stellar objects suggests that star formation in this cloud is ongoing around the more massive Herbig Ae/Be star. Considering its morphology and other features, this star-forming region is similar to the zone of star formation near CPM 19.

scholarly journals AGN torus properties with WISE

2013 ◽  
Vol 9 (S304) ◽  
pp. 56-60
Author(s):  
Robert Nikutta ◽  
Maia Nenkova ◽  
Željko Ivezić ◽  
Nicholas Hunt-Walker ◽  
Moshe Elitzur
Keyword(s):  
Color Space ◽  
Sloan Digital Sky Survey ◽  
Wide Field ◽  
Sky Survey ◽  
Very Large Database ◽  
First Time ◽  
Previous Identification ◽  
Infrared Survey

AbstractThe Wide-field Infrared Survey Explorer (WISE) has scanned the entire sky with unprecedented sensitivity in four infrared bands, at 3.4, 4.6, 12, and 22 μm. The WISE Point Source Catalog contains more than 560 million objects, among them hundreds of thousands of galaxies with Active Nuclei (AGN). While type 1 AGN, owing to their bright and unobscured nature, are easy to detect and constitute a rather complete and unbiased sample, their type 2 counterparts, postulated by AGN unification, are not as straightforward to identify. Matching the WISE catalog with known QSOs in the Sloan Digital Sky Survey we confirm previous identification of the type 1 locus in the WISE color space. Using a very large database of the popular Clumpy torus models, we find the colors of the putative type 2 counterparts, and also, for the first time, predict their number vs. flux relation that can be expected to be observed in any given WISE color range. This will allow us to put statistically very significant constraints on the torus parameters. Our results are a successful test of the AGN unification scheme.

scholarly journals Effectiveness of WISE colour-based selection techniques to uncover obscured AGN

2013 ◽  
Vol 9 (S304) ◽  
pp. 209-212
Author(s):  
S. Mateos
Keyword(s):  
Sloan Digital Sky Survey ◽  
Spectral Energy ◽  
Wide Field ◽  
Mid Infrared ◽  
Selection Technique ◽  
X Ray ◽  
Sky Survey ◽  
Two Samples ◽  
Optical Surveys

AbstractWe present a highly reliable and efficient mid-infrared colour-based selection technique for luminous active galactic nuclei (AGN) using the Wide-field Infrared Survey Explorer (WISE) survey. Our technique is designed to identify objects with red mid-infrared power-law spectral energy distributions. We studied the dependency of our mid-infrared selection on the AGN intrinsic luminosity and the effectiveness of our technique to uncover obscured AGN missed in X-ray surveys. To do so we used two samples of luminous AGN independently selected in hard X-ray and optical surveys. We used the largest catalogue of 887 [OIII] λ5007-selected type 2 quasars (QSO2s) at z≲0.83 in the literature from the Sloan Digital Sky Survey (SDSS), and the 258 hard (>4.5 keV) X-ray-selected AGN from the Bright Ultrahard XMM-Newton Survey (BUXS). The effectiveness of our mid-infrared selection technique increases with the AGN luminosity. At high luminosities and at least up to z~1 our technique is very effective at identifying both Compton-thin and Compton-thick AGN.

scholarly journals The second u-band extension of the WINGS cluster survey

2020 ◽  
Vol 637 ◽  
pp. A54
Author(s):  
M. D’Onofrio ◽  
A. Grado ◽  
D. Bettoni ◽  
J. Fritz ◽  
M. Gullieuszik ◽  
...  
Keyword(s):  
Formation Rate ◽  
Galaxy Cluster ◽  
Sloan Digital Sky Survey ◽  
Cluster Center ◽  
Wide Field ◽  
Nearby Galaxy ◽  
Cluster Survey ◽  
Sky Survey ◽  
Magnitude Diagram ◽  
Multi Wavelength

Context. This is the second u-band extension of the WIde-field Nearby Galaxy-cluster Survey (WINGS) whereby 39 clusters were imaged with the ESO-VLT survey telescope. This follows the first part of the survey which was performed with several telescopes of the northern hemisphere in the U Cousin–Bessel filter band covering 17 clusters. Aims. The u-band data, in combination with those already collected by the WINGS survey, permit a detailed multi-wavelength investigation of the properties of the member galaxies from the cluster center out to the periphery. Methods. We used SExtractor to derive the main properties of the galaxies in the observed fields and measure the u − V colors on circular apertures of increasing radius. The photometric accuracy of the magnitudes was calibrated with the standard stars and was tested by means of comparisons with the u-band data of the Sloan Digital Sky Survey (SDSS). Results. We present the catalogs of the photometric analysis performed by SExtractor. We also provide a brief analysis of the u − V versus V color–magnitude diagram of our clusters, the plots of the color as a function of the cluster-centric distance (for cluster members only), the mass–color relation and the correlation of the current star formation rate (SFR) with the absolute V and u magnitudes for the galaxies in the observed fields.

scholarly journals The Wendelstein Weak Lensing (WWL) pathfinder: accurate weak lensing masses for Planck clusters

2019 ◽  
Vol 486 (1) ◽  
pp. 77-100 ◽  
Author(s):  
R L Rehmann ◽  
D Gruen ◽  
S Seitz ◽  
R Bender ◽  
A Riffeser ◽  
...  
Keyword(s):  
Sample Selection ◽  
Sloan Digital Sky Survey ◽  
Weak Lensing ◽  
Wide Field ◽  
Clusters Of Galaxies ◽  
Dynamical Mass ◽  
Calibration Uncertainty ◽  
Sky Survey ◽  
Upper Limits ◽  
Intermediate Redshift

ABSTRACT We present results from the Wendelstein Weak Lensing (WWL) pathfinder project, in which we have observed three intermediate-redshift Planck clusters of galaxies with the new 30 arcmin × 30 arcmin wide field imager at the 2 m Fraunhofer Telescope at Wendelstein Observatory. We investigate the presence of biases in our shear catalogues and estimate their impact on our weak lensing mass estimates. The overall calibration uncertainty depends on the cluster redshift and is below 8.1–16 per cent for z ≈ 0.27–0.77. It will decrease with improvements on the background sample selection and the multiplicative shear bias calibration. We present the first weak lensing mass estimates for PSZ1 G109.88+27.94 and PSZ1 G139.61+24.20, two Sunyaev-Zeldovich (SZ)-selected cluster candidates. Based on Wendelstein colours and SDSS (Sloan Digital Sky Survey) photometry, we find that the redshift of PSZ1 G109.88+27.94 has to be corrected to z ≈ 0.77. We investigate the influence of line-of-sight structures on the weak lensing mass estimates and find upper limits for two groups in each of the fields of PSZ1 G109.88+27.94 and PSZ1 G186.98+38.66. We compare our results to SZ and dynamical mass estimates from the literature, and in the case of PSZ1 G186.98+38.66 to previous weak lensing mass estimates. We conclude that our pathfinder project demonstrates that weak lensing cluster masses can be accurately measured with the 2 m Fraunhofer Telescope.

scholarly journals Galaxy pairs in the Sloan Digital Sky Survey – IX. Merger-induced AGN activity as traced by the Wide-field Infrared Survey Explorer

2014 ◽  
Vol 441 (2) ◽  
pp. 1297-1304 ◽  
Author(s):  
Shobita Satyapal ◽  
Sara L. Ellison ◽  
William McAlpine ◽  
Ryan C. Hickox ◽  
David R. Patton ◽  
...  
Keyword(s):  
Sloan Digital Sky Survey ◽  
Wide Field ◽  
Sky Survey ◽  
Infrared Survey

scholarly journals Revised and Updated Catalogue of the First Byurakan Survey Late-Type Stars. 2nd Edition

2018 ◽  
pp. 262-267
Author(s):  
K. S. Gigoyan ◽  
A. M. Mickaelian ◽  
G. R. Kostandyan
Keyword(s):  
Variable Stars ◽  
Sloan Digital Sky Survey ◽  
Asymptotic Giant Branch ◽  
Wide Field ◽  
Late Type ◽  
Byurakan Survey ◽  
First Byurakan Survey ◽  
Sky Survey ◽  
Search And Selection ◽  
Low Dispersion

Eighteen lists of late-type stars (LTSs) have been published between 1990 and 2016. These LTSs have been found in the low-dispersion spectroscopic plates of the First Byurakan Survey (FBS). The systematic search and selection was carried out on a surface _16000 deg2 on almost the whole area of the FBS. As a result, \Revised And Updated Catalogue Of The First Byurakan Survey Of Late-Type Stars" was generated (LTSs, _rst version). Since 2007, all FBS low-resolution spectral plates are digitized, and Digitized First Byurakan Survey (DFBS) database and second catalog of objects has been assembled. All DFBS spectral plates are analysed with the help of standard image analysis softwares (FITSView and SAO Image ds9) and numerous of comparatively faint LTSs were discovered. We present the 2nd version of the FBS catalogue of LTSs with new data. We have made cross-correlation with the Digitized First Byurakan Survey (DFBS), the United State Naval Observatory-B1.0 Catalogue, the Two Micron All-Sky Survey (2MASS), the Wide-Field Infrared Survey Explorer (new version-ALLWISE) catalogue, the Infrared Astronomical Satellite Point Source Catalogue/Faint Source Catalogue, the AKARI catalogue, the ROSAT Bright Source Catalogue/Faint Source Catalogue, the General Catalogue of Variable Stars, Sloan Digital Sky Survey (SDSS) photometric catalogue. We have added updated IMBAD data for the objects. For numerous of the new detected objects we present accurate Digitized Sky Survey 2 positions, approximate spectral subtypes refined from the DFBS low-dispersion spectra, luminosity classes estimated from 2MASS colours, and available proper motions for 1471 FBS LTSs. 2nd Version of the Revised and Updated Catalogue lists a large number of completely new objects, which promise to extend very significantly the census of M giants, faint N-type Asymptotic Giant Branch (AGB) carbon stars, CH {type carbon giants at high Galactic latitudes, also M dwarfs in the vicinity of the Sun up to 16.0-17.0 mag. in visual. We present also some important data from the Gaia DR2 data base for FBS LTSs. Some supplementary spectra obtained with the Byurakan Observatory 2.6 m telescope and LAMOST telescope are shown.

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