The Extremely Luminous Quasar Survey in the Sloan Digital Sky Survey Footprint. III. The South Galactic Cap Sample and the Quasar Luminosity Function at Cosmic Noon

ABSTRACT We present the radio luminosity function (RLF) of optically selected quasars below 1 mJy, constructed by applying a Bayesian-fitting stacking technique to objects well below the nominal radio flux density limit. We test the technique using simulated data, confirming that we can reconstruct the RLF over three orders of magnitude below the typical 5σ detection threshold. We apply our method to 1.4-GHz flux densities from the Faint Images of the Radio Sky at Twenty-Centimeters (FIRST) survey, extracted at the positions of optical quasars from the Sloan Digital Sky Survey over seven redshift bins up to z = 2.15, and measure the RLF down to two orders of magnitude below the FIRST detection threshold. In the lowest redshift bin (0.2 < z < 0.45), we find that our measured RLF agrees well with deeper data from the literature. The RLF for the radio-loud quasars flattens below $\log _{10}[L_{1.4}/{\rm W\, Hz}^{-1}] \approx 25.5$ and becomes steeper again below $\log _{10}[L_{1.4}/{\rm W\, Hz}^{-1}] \approx 24.8$, where radio-quiet quasars start to emerge. The radio luminosity where radio-quiet quasars emerge coincides with the luminosity where star-forming galaxies are expected to start dominating the radio source counts. This implies that there could be a significant contribution from star formation in the host galaxies, but additional data are required to investigate this further. The higher redshift bins show a similar behaviour to the lowest z bin, implying that the same physical process may be responsible.

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A hot white dwarf luminosity function from the Sloan Digital Sky Survey

Astronomy and Astrophysics ◽

10.1051/0004-6361/200912094 ◽

2009 ◽

Vol 508 (1) ◽

pp. 339-344 ◽

Cited By ~ 25

Author(s):

J. Krzesinski ◽

S. J. Kleinman ◽

A. Nitta ◽

S. Hügelmeyer ◽

S. Dreizler ◽

...

Keyword(s):

White Dwarf ◽

Luminosity Function ◽

Sloan Digital Sky Survey ◽

Sky Survey

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High-Redshift Quasars Found in Sloan Digital Sky Survey Commissioning Data. IV. Luminosity Function from the Fall Equatorial Stripe Sample

The Astronomical Journal ◽

10.1086/318033 ◽

2001 ◽

Vol 121 (1) ◽

pp. 54-65 ◽

Cited By ~ 295

Author(s):

Xiaohui Fan ◽

Michael A. Strauss ◽

Donald P. Schneider ◽

James E. Gunn ◽

Robert H. Lupton ◽

...

Keyword(s):

Luminosity Function ◽

High Redshift ◽

Sloan Digital Sky Survey ◽

Sky Survey

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

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936577 ◽

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.

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The Luminosity Function of Void Galaxies in the Sloan Digital Sky Survey

The Astrophysical Journal ◽

10.1086/427176 ◽

2005 ◽

Vol 620 (2) ◽

pp. 618-628 ◽

Cited By ~ 105

Author(s):

Fiona Hoyle ◽

Randall R. Rojas ◽

Michael S. Vogeley ◽

Jon Brinkmann

Keyword(s):

Luminosity Function ◽

Sloan Digital Sky Survey ◽

Sky Survey ◽

Void Galaxies

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The Hα Luminosity Function of Morphologically Classified Galaxies in the Sloan Digital Sky Survey

The Astronomical Journal ◽

10.1086/386350 ◽

2004 ◽

Vol 127 (5) ◽

pp. 2511-2521 ◽

Cited By ~ 47

Author(s):

Osamu Nakamura ◽

Masataka Fukugita ◽

Jon Brinkmann ◽

Donald P. Schneider

Keyword(s):

Luminosity Function ◽

Sloan Digital Sky Survey ◽

Sky Survey

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Inclination Dependent Luminosity Function of Spiral Galaxies

Proceedings of the International Astronomical Union ◽

10.1017/s1743921306005837 ◽

2006 ◽

Vol 2 (S235) ◽

pp. 151-151

Author(s):

Zhengyi Shao

Keyword(s):

Luminosity Function ◽

Spiral Galaxies ◽

Power Index ◽

Sloan Digital Sky Survey ◽

Extinction Curve ◽

Patchy Distribution ◽

Axis Ratio ◽

Dust Extinction ◽

Sky Survey ◽

Linear Fit

We study the inclination dependent luminosity function (LF) of spiral galaxies of the Sloan Digital Sky Survey (SDSS). Up to 60000 sample galaxies are selected from the 2nd data release of SDSS by fracdeVr < 0.5. Magnitudes and other related photometric parameters are taken from NYU-VAGC(Blanton et al.2005). The apparent axis ratio (b/a)is used as an observational inclination indicator to define sub-samples. LFs of all 5 SDSS bands (u, g, r, i, z) are drawn for different sub-samples. Significant correlation is found between characteristic magnitudes (M*) of sub-samples and their inclinations, which can be fairly explained by dust extinction. A linear fit of the relation between M* and log(b/a) measures the M*(0) (for expected face-on spirals, with 0.2 ~ 0.3 mag brighter than that of LF of whole sample) and the intensity of dust extinction γ, for each band (Figure 1(a)). Additionally, since γ ∝ τ (optical depth), the wavelength dependent γ describes the extinction curve. Figure 1(b) shows a good linear fit that implies the extinction curve obeys the power law very well, with τλ = τV(λ/5500Å)−0.97±0.07. The power index n ~ 1 is shallower than that of the MW, LMC and SMC (n=1.1~1.5), but significantly steeper than the value of Charlot et al. (2000) (n=0.7), which under the assumption of a patchy distribution of dust in spiral galaxies. So our result implies that dust distributed in spirals, on average, are not as patchy as Charlot et al. assumed.

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A comparison of cosmological filaments catalogues

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa320 ◽

2020 ◽

Vol 493 (2) ◽

pp. 1936-1947 ◽

Cited By ~ 4

Author(s):

Agustín Rost ◽

Federico Stasyszyn ◽

Luis Pereyra ◽

Héctor J Martínez

Keyword(s):

Luminosity Function ◽

Statistical Properties ◽

Sloan Digital Sky Survey ◽

Identification Algorithm ◽

Filament Length ◽

Limited Sample ◽

Redshift Distribution ◽

Sky Survey ◽

Red Galaxies ◽

Identification Techniques

ABSTRACT In this work, we compare three catalogues of cosmological filaments identified in the Sloan Digital Sky Survey by means of different algorithms by Tempel et al., Pereyra et al., and Martínez et al. We analyse how different identification techniques determine differences in the filament statistical properties: length, elongation, redshift distribution, and abundance. We find that the statistical properties of the filaments strongly depend on the identification algorithm. We use a volume-limited sample of galaxies to characterize other properties of filaments such as: galaxy overdensity, luminosity function of galaxies, mean galaxy luminosity, filament luminosity, and the overdensity profile of galaxies around filaments. In general, we find that these properties primarily depended on filament length. Shorter filaments have larger overdensities, are more populated by red galaxies, and have better defined galaxy overdensity profiles, than longer filaments. Concluding that galaxies belonging to filaments have characteristic signatures depending on the identification algorithm used.

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A homogeneous sample of 34 000 M7−M9.5 dwarfs brighter than J = 17.5 with accurate spectral types

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834591 ◽

2019 ◽

Vol 623 ◽

pp. A127 ◽

Cited By ~ 1

Author(s):

S. Ahmed ◽

S. J. Warren

Keyword(s):

Luminosity Function ◽

Galactic Plane ◽

Effective Area ◽

Sloan Digital Sky Survey ◽

M Dwarfs ◽

Homogeneous Sample ◽

Type Method ◽

Sky Survey ◽

Better Than

The space density of late M dwarfs, subtypes M7–M9.5, is not well determined. We applied the photo-type method to iz photometry from the Sloan Digital Sky Survey and YJHK photometry from the UKIRT Infrared Deep Sky Survey, over an effective area of 3070 deg2, to produce a new, bright J(Vega) < 17.5, homogeneous sample of 33 665 M7–M9.5 dwarfs. The typical S/N of each source summed over the six bands is > 100. Classifications are provided to the nearest half spectral subtype. Through a comparison with the classifications in the BOSS Ultracool Dwarfs (BUD) spectroscopic sample, the typing is shown to be accurately calibrated to the BUD classifications and the precision is better than 0.5 subtypes rms; i.e. the photo-type classifications are as precise as good spectroscopic classifications. Sources with large χ2 > 20 include several catalogued late-type subdwarfs. The new sample of late M dwarfs is highly complete, but there is a bias in the classification of rare peculiar blue or red objects. For example, L subdwarfs are misclassified towards earlier types by approximately two spectral subtypes. We estimate that this bias affects only ∼1% of the sources. Therefore the sample is well suited to measure the luminosity function and investigate the softening towards the Galactic plane of the exponential variation of density with height.

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On the Luminosity Function of Galaxies in Groups in the Sloan Digital Sky Survey

The Astrophysical Journal ◽

10.1086/503894 ◽

2006 ◽

Vol 650 (1) ◽

pp. 137-147 ◽

Cited By ~ 47

Author(s):

Ariel Zandivarez ◽

Hector J. Martinez ◽

Manuel E. Merchan

Keyword(s):

Luminosity Function ◽

Sloan Digital Sky Survey ◽

Sky Survey

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