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 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 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 Using u band emission to trace star formation rates of galaxies

2016 ◽  
Vol 12 (S323) ◽  
pp. 392-393
Author(s):  
Zhimin Zhou
Keyword(s):  
Star Formation ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Sloan Digital Sky Survey ◽  
Wide Field ◽  
The South ◽  
Evolution Of Galaxies ◽  
Band Emission ◽  
Sky Survey ◽  
Infrared Survey

AbstractStar formation rate (SFR) is one of the most important diagnostics in understanding the evolution of galaxies across cosmic times. In order to explore the possibility of using the optical u-band luminosities to estimate SFRs of galaxies, we show the correlations between u band, Hα and infrared luminosities by combing the data from the South Galactic Cap u band Sky Survey (SCUSS) with the Sloan Digital Sky Survey (SDSS) and the Wide-field Infrared Survey Explorer (WISE). We derive the u versus Hα relation and the u and 12 μm relations to calibrate the u-band luminosity as an SFR indicator.

scholarly journals A 22μm selected sample from WISE and SDSS spectra catalogs

2012 ◽  
Vol 8 (S292) ◽  
pp. 376-376
Author(s):  
Xiao-Qing Wen ◽  
Hong-Wei Yin
Keyword(s):  
Rest Frame ◽  
Control Sample ◽  
Sloan Digital Sky Survey ◽  
Optical Control ◽  
Wide Field ◽  
Signal To Noise ◽  
Sky Survey ◽  
Infrared Survey

AbstractWe cross-matched Wide-field Infrared Survey Explorer sources with the Sloan Digital Sky Survey galaxy spectroscopic catalog within 6 arcsec to produce 182798 galaxies with 22 μm signal to noise > 3. The different redshift bins of the sample show that the rest-frame 22μm luminosities increase with redshift, for rest-frame 22μm luminosities in the range of 106 − 1012 L⊙. The infrared sample is located in the blue sequence. The Seyfert fraction increases with redshift more obviously in the IR sample than in an optical control sample. The Seyfert fraction increases significantly with increasing rest-frame 22 μm luminosity below 1011 L⊙.

scholarly journals H i galaxies with little star formation: an abundance of LIERs

2019 ◽  
Vol 485 (3) ◽  
pp. 3169-3184 ◽  
Author(s):  
Vaishali Parkash ◽  
Michael J I Brown ◽  
T H Jarrett ◽  
A Fraser-McKelvie ◽  
M E Cluver
Keyword(s):  
Star Formation ◽  
Emission Line ◽  
Central Star ◽  
Wide Field ◽  
Dark Energy Survey ◽  
Sky Survey ◽  
Low Levels ◽  
Field Unit ◽  
Energy Survey ◽  
Infrared Survey

Abstract We present a sample of 91 H i galaxies with little or no star formation, and discuss the analysis of the integral field unit (IFU) spectra of 28 of these galaxies. We identified H i galaxies from the H i Parkes All-Sky Survey Catalog (HICAT) with Wide-field Infrared Survey Explorer (WISE) colours consistent with low specific star formation (<10−10.4 yr−1), and obtained optical IFU spectra with the Wide-Field Spectrograph (WiFeS). Visual inspection of the PanSTARRS, Dark Energy Survey, and Carnegie-Irvine imaging of 62 galaxies reveals that at least 32 galaxies in the sample have low levels of star formation, primarily in arms/rings. New IFU spectra of 28 of these galaxies reveals 3 galaxies with central star formation, 1 galaxy with low-ionization nuclear emission-line regions (LINERs), 20 with extended low-ionization emission-line regions (LIERs), and 4 with high excitation Seyfert (Sy) emission. From the spectroscopic analysis of H i selected galaxies with little star formation, we conclude that 75 per cent of this population are LINERs/LIERs.

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 Evidence of AGN-driven Outflows in Young Radio Quasars Selected from the Wide-field Infrared Survey Explorer

2013 ◽  
Vol 9 (S304) ◽  
pp. 347-348
Author(s):  
Minjin Kim ◽  
Luis C. Ho ◽  
Carol J. Lonsdale ◽  
Mark Lacy ◽  
Andrew W. Blain ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Near Infrared ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
Wide Field ◽  
Near Infrared Spectra ◽  
Sky Survey ◽  
Line Widths ◽  
Infrared Survey ◽  
Narrow Emission

AbstractWe present near-infrared spectra of young radio quasars selected by cross-correlating the Wide-field Infrared Survey Explorer (WISE) all-sky survey catalog with the radio catalog [Faint Images of the Radio Sky at Twenty cm (FIRST) and NRAO VLA Sky Survey (NVSS)]. The objects have typical redshifts of z ≈ 2 and [O III] luminosities of 107 erg s−1 comparable to those of luminous quasars. The observed flux ratios of narrow emission lines indicate that these objects appear to be powered by active galactic nuclei. The [O III] line is broad, with full width at half maximum ~1300 to 2100 km s−1, significantly larger than that of ordinary quasars. These large line widths might be explained by jet-induced outflows.

scholarly journals Local AGN survey (LASr): I. Galaxy sample, infrared colour selection, and predictions for AGN within 100 Mpc

2020 ◽  
Vol 494 (2) ◽  
pp. 1784-1816
Author(s):  
D Asmus ◽  
C L Greenwell ◽  
P Gandhi ◽  
P G Boorman ◽  
J Aird ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Galaxy Evolution ◽  
Galactic Nuclei ◽  
Wide Field ◽  
X Ray ◽  
Sky Survey ◽  
Galaxy Sample ◽  
Redshift Survey ◽  
Infrared Survey

ABSTRACT To answer major questions on supermassive black hole (SMBH) and galaxy evolution, a complete census of SMBH growth, i.e. active galactic nuclei (AGN), is required. Thanks to all-sky surveys by the Wide-field Infrared Survey Explorer (WISE) and the Spectrum-Roentgen-Gamma (SRG) missions, this task is now feasible in the nearby Universe. We present a new survey, the Local AGN Survey (LASr), with the goal of identifying AGN unbiased against obscuration and determining the intrinsic Compton-thick (CT) fraction. We construct the most complete all-sky galaxy sample within 100 Mpc ($90{{\ \rm per\ cent}}$ completeness for log (M*/M⊙) ∼ 9.4), four times deeper than the current reference, the Two Micron All-Sky Survey Redshift Survey (2MRS), which misses ${\sim}20{{\ \rm per\ cent}}$ of known luminous AGN. These 49k galaxies serve as parent sample for LASr, called LASr-GPS. It contains 4.3k already known AGN, $\ge 82{{\ \rm per\ cent}}$ of these are estimated to have $L^\mathrm{nuc}(12\, \mu \mathrm{m})\lt 10^{42.3}$ erg s−1, i.e. are low-luminosity AGN. As a first method for identifying Seyfert-like AGN, we use WISE-based infrared colours, finding 221 galaxies at $L^\mathrm{nuc}(12\, \mu \mathrm{m})\ge 10^{42.3}$ erg s−1 to host an AGN at $90{{\ \rm per\ cent}}$ reliability. This includes 61 new AGN candidates and implies an optical type 2 fraction of 50–71 per cent. We quantify the efficiency of this technique and estimate the total number of AGN with $L^\mathrm{int}(\rm {2-10\,keV})\ge 10^{42}$ erg s−1 in the volume to be $362^{+145}_{-116}$ ($8.6^{+3.5}_{-2.8}\, \times$ 10−5 Mpc−3). X-ray brightness estimates indicate the CT fraction to be 40–55 per cent to explain the Swift non-detections of the infrared selected objects. One third of the AGN within 100 Mpc remain to be identified, and we discuss the prospects for the eROSITA all-sky survey to detect them.

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