scholarly journals Assessing the photometric redshift precision of the S-PLUS survey: the Stripe-82 as a test-case

2020 ◽  
Vol 499 (3) ◽  
pp. 3884-3908 ◽  
Author(s):  
A Molino ◽  
M V Costa-Duarte ◽  
L Sampedro ◽  
F R Herpich ◽  
L Sodré ◽  
...  
Keyword(s):  
Simultaneous Detection ◽  
Control Sample ◽  
Emission Lines ◽  
Test Case ◽  
Local Universe ◽  
Photometric Redshift ◽  
Luminosity Functions ◽  
Passband Filter ◽  
Statistical Studies ◽  
Narrow Bands

ABSTRACT In this paper we present a thorough discussion about the photometric redshift (photo-z) performance of the Southern Photometric Local Universe Survey (S-PLUS). This survey combines a seven narrow +5 broad passband filter system, with a typical photometric-depth of r ∼ 21 AB. For this exercise, we utilize the Data Release 1 (DR1), corresponding to 336 deg2 from the Stripe-82 region. We rely on the BPZ2 code to compute our estimates, using a new library of SED models, which includes additional templates for quiescent galaxies. When compared to a spectroscopic redshift control sample of ∼100 k galaxies, we find a precision of σz <0.8 per cent, <2.0 per cent, or <3.0 per cent for galaxies with magnitudes r < 17, <19, and <21, respectively. A precision of 0.6 per cent is attained for galaxies with the highest Odds values. These estimates have a negligible bias and a fraction of catastrophic outliers inferior to 1 per cent. We identify a redshift window (i.e. 0.26 < z < 0.32) where our estimates double their precision, due to the simultaneous detection of two emission lines in two distinct narrow bands; representing a window opportunity to conduct statistical studies such as luminosity functions. We forecast a total of ∼2 M, ∼16 M and ∼32 M galaxies in the S-PLUS survey with a photo-z precision of σz <1.0 per cent, <2.0 per cent, and <2.5 per cent after observing 8000 deg2. We also derive redshift probability density functions, proving their reliability encoding redshift uncertainties and their potential recovering the n(z) of galaxies at z < 0.4, with an unprecedented precision for a photometric survey in the Southern hemisphere.

scholarly journals A comparative study of satellite galaxies in Milky Way-like galaxies from HSC, DECaLS, and SDSS

2020 ◽  
Vol 500 (3) ◽  
pp. 3776-3801
Author(s):  
Wenting Wang ◽  
Masahiro Takada ◽  
Xiangchong Li ◽  
Scott G Carlsten ◽  
Ting-Wen Lan ◽  
...  
Keyword(s):  
Dark Matter ◽  
Milky Way ◽  
Statistical Study ◽  
Satellite System ◽  
Large Scatter ◽  
Local Universe ◽  
Good Representative ◽  
Luminosity Functions ◽  
Satellite Galaxies ◽  
Good Agreement

ABSTRACT We conduct a comprehensive and statistical study of the luminosity functions (LFs) for satellite galaxies, by counting photometric galaxies from HSC, DECaLS, and SDSS around isolated central galaxies (ICGs) and paired galaxies from the SDSS/DR7 spectroscopic sample. Results of different surveys show very good agreement. The satellite LFs can be measured down to MV ∼ −10, and for central primary galaxies as small as 8.5 < log10M*/M⊙ < 9.2 and 9.2 < log10M*/M⊙ < 9.9, which implies there are on average 3–8 satellites with MV < −10 around LMC-mass ICGs. The bright end cutoff of satellite LFs and the satellite abundance are both sensitive to the magnitude gap between the primary and its companions, indicating galaxy systems with larger magnitude gaps are on average hosted by less massive dark matter haloes. By selecting primaries with stellar mass similar to our Milky Way (MW), we discovered that (i) the averaged satellite LFs of ICGs with different magnitude gaps to their companions and of galaxy pairs with different colour or colour combinations all show steeper slopes than the MW satellite LF; (ii) there are on average more satellites with −15 < MV < −10 than those in our MW; (iii) there are on average 1.5 to 2.5 satellites with MV < −16 around ICGs, consistent with our MW; (iv) even after accounting for the large scatter predicted by numerical simulations, the MW satellite LF is uncommon at MV > −12. Hence, the MW and its satellite system are statistically atypical of our sample of MW-mass systems. In consequence, our MW is not a good representative of other MW-mass galaxies. Strong cosmological implications based on only MW satellites await additional discoveries of fainter satellites in extra-galactic systems. Interestingly, the MW satellite LF is typical among other MW-mass systems within 40 Mpc in the local Universe, perhaps implying the Local Volume is an underdense region.

scholarly journals The quest for relics: Massive compact galaxies in the local Universe

2019 ◽  
Vol 15 (S352) ◽  
pp. 320-321
Author(s):  
A. Schnorr-Müller ◽  
M. Trevisan ◽  
F. S. Lohmann ◽  
N. Mallmann ◽  
R. Riffel ◽  
...  
Keyword(s):  
Matched Control ◽  
High Redshift ◽  
Control Sample ◽  
Stellar Populations ◽  
Velocity Fields ◽  
Current Data ◽  
Early Type ◽  
Local Universe ◽  
Compact Galaxies

AbstractIn the local Universe there exists a rare population of compact galaxies resembling the high-redshift quiescent population in mass and size. It has been found that some of these objects have survived largely unchanged since their formation at high-z. They are called relic galaxies. With the goal of finding relic galaxies, we searched the SDSS-MaNGA DR15 release for massive compact galaxies. We find that massive compact galaxies are mostly composed of old, metal-rich and alpha enhanced stellar populations. In terms of kinematics, massive compact galaxies show ordered rotation in their velocity fields and σ* profiles rising towards the center. They are predominantly fast rotators and show increased rotational support when compared to a mass-matched control sample of average-sized early-type galaxies. These properties are consistent with these objects being relic galaxies. However, to confirm their relic status, we need to probe larger radii (⪎3Re) than probed with the current data.

scholarly journals Simultaneous detection and analysis of optical and ultraviolet broad emission lines in quasars at z ~ 2.2

2017 ◽  
Vol 603 ◽  
pp. A1 ◽  
Author(s):  
S. Bisogni ◽  
S. di Serego Alighieri ◽  
P. Goldoni ◽  
L. C. Ho ◽  
A. Marconi ◽  
...  
Keyword(s):  
Simultaneous Detection ◽  
Emission Lines ◽  
Broad Emission

scholarly journals Infrared luminosity functions and dust mass functions in the EAGLE simulation

2020 ◽  
Vol 494 (2) ◽  
pp. 2912-2924 ◽  
Author(s):  
Maarten Baes ◽  
Ana Trčka ◽  
Peter Camps ◽  
James Trayford ◽  
Antonios Katsianis ◽  
...  
Keyword(s):  
Radiative Transfer ◽  
Mass Density ◽  
Local Universe ◽  
Luminosity Functions ◽  
Simulation Based ◽  
Dust Mass ◽  
Slow Evolution ◽  
Mass Functions ◽  
Luminosity Evolution ◽  
Good Agreement

ABSTRACT We present infrared luminosity functions and dust mass functions for the EAGLE cosmological simulation, based on synthetic multiwavelength observations generated with the SKIRT radiative transfer code. In the local Universe, we reproduce the observed infrared luminosity and dust mass functions very well. Some minor discrepancies are encountered, mainly in the high luminosity regime, where the EAGLE-SKIRT luminosity functions mildly but systematically underestimate the observed ones. The agreement between the EAGLE-SKIRT infrared luminosity functions and the observed ones gradually worsens with increasing lookback time. Fitting modified Schechter functions to the EAGLE-SKIRT luminosity and dust mass functions at different redshifts up to z = 1, we find that the evolution is compatible with pure luminosity/mass evolution. The evolution is relatively mild: within this redshift range, we find an evolution of L⋆,250 ∝ (1 + z)1.68, L⋆,TIR ∝ (1 + z)2.51 and M⋆,dust ∝ (1 + z)0.83 for the characteristic luminosity/mass. For the luminosity/mass density we find ε250 ∝ (1 + z)1.62, εTIR ∝ (1 + z)2.35, and ρdust ∝ (1 + z)0.80, respectively. The mild evolution of the dust mass density is in relatively good agreement with observations, but the slow evolution of the infrared luminosity underestimates the observed luminosity evolution significantly. We argue that these differences can be attributed to increasing limitations in the radiative transfer treatment due to increasingly poorer resolution, combined with a slower than observed evolution of the SFR density in the EAGLE simulation and the lack of AGN emission in our EAGLE-SKIRT post-processing recipe.

scholarly journals The XXL Survey

2018 ◽  
Vol 620 ◽  
pp. A13 ◽  
Author(s):  
M. Ricci ◽  
C. Benoist ◽  
S. Maurogordato ◽  
C. Adami ◽  
L. Chiappetti ◽  
...  
Keyword(s):  
Near Infrared ◽  
Mass Range ◽  
Selection Function ◽  
Photometric Redshifts ◽  
Statistical Tool ◽  
Cluster Galaxy ◽  
Photometric Redshift ◽  
Luminosity Functions ◽  
The Galaxy ◽  
The Individual

Context. The luminosity function (LF) is a powerful statistical tool used to describe galaxies and learn about their evolution. In particular, the LFs of galaxies inside clusters allow us to better understand how galaxies evolve in these dense environments. Knowledge of the LFs of galaxies in clusters is also crucial for clusters studies in the optical and near-infrared (NIR) as they encode, along with their density profiles, most of their observational properties. However, no consensus has been reached yet about the evolution of the cluster galaxy LF with halo mass and redshift. Aims. The main goal of this study is to investigate the LF of a sample of 142 X-ray selected clusters, with spectroscopic redshift confirmation and a well defined selection function, spanning a wide redshift and mass range, and to test the LF dependence on cluster global properties, in a homogeneous and unbiased way. Methods. Our study is based on the Canada–France–Hawaii Telescope Legacy Survey (CFHTLS) photometric galaxy catalogue, associated with photometric redshifts. We constructed LFs inside a scaled radius using a selection in photometric redshift around the cluster spectroscopic redshift in order to reduce projection effects. The width of the photometric redshift selection was carefully determined to avoid biasing the LF and depended on both the cluster redshift and the galaxy magnitudes. The purity was then enhanced by applying a precise background subtraction. We constructed composite luminosity functions (CLFs) by stacking the individual LFs and studied their evolution with redshift and richness, analysing separately the brightest cluster galaxy (BCG) and non-BCG members. We fitted the dependences of the CLFs and BCG distributions parameters with redshift and richness conjointly in order to distinguish between these two effects. Results. We find that the usual photometric redshift selection methods can bias the LF estimate if the redshift and magnitude dependence of the photometric redshift quality is not taken into account. Our main findings concerning the evolution of the galaxy luminosity distribution with redshift and richness are that, in the inner region of clusters and in the redshift-mass range we probe (about 0 < z < 1 and 1013 M⊙ < M500 < 5 × 1014 M⊙), the bright part of the LF (BCG excluded) does not depend much on mass or redshift except for its amplitude, whereas the BCG luminosity increases both with redshift and richness.

scholarly journals Large Scale Structure in the Local Universe — The 2MASS Galaxy Catalog

2004 ◽  
Vol 21 (4) ◽  
pp. 396-403 ◽  
Author(s):  
Thomas Jarrett
Keyword(s):  
Large Scale ◽  
Near Infrared ◽  
Local Universe ◽  
Extended Source ◽  
Large Scale Structures ◽  
Photometric Redshift ◽  
Sky Survey ◽  
Nearby Galaxies ◽  
Scale Structures ◽  
Zone Of Avoidance

AbstractUsing twin ground-based telescopes, the Two-Micron All Sky Survey (2MASS) scanned both equatorial hemispheres, detecting more than 500 million stars and resolving more than 1.5 million galaxies in the near-infrared (1–2.2 μm) bands. The Extended Source Catalog (XSC) embodies both photometric and astrometric whole sky uniformity, revealing large scale structures in the local Universe and extending our view into the Milky Way's dust-obscured ‘Zone of Avoidance’. The XSC represents a uniquely unbiased sample of nearby galaxies, particularly sensitive to the underlying, dominant, stellar mass component of galaxies. The basic properties of the XSC, including photometric sensitivity, source counts, and spatial distribution, are presented here. Finally, we employ a photometric redshift technique to add depth to the spatial maps, reconstructing the cosmic web of superclusters spanning the sky.

scholarly journals First HETDEX Spectroscopic Determinations of Lyα and UV Luminosity Functions at z = 2–3: Bridging a Gap between Faint AGNs and Bright Galaxies

2021 ◽  
Vol 922 (2) ◽  
pp. 167
Author(s):  
Yechi Zhang ◽  
Masami Ouchi ◽  
Karl Gebhardt ◽  
Erin Mentuch Cooper ◽  
Chenxu Liu ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Rest Frame ◽  
High Redshift ◽  
Galactic Nuclei ◽  
Emission Lines ◽  
Bright Galaxy ◽  
Number Density ◽  
Luminosity Functions ◽  
Best Fit

Abstract We present Lyα and ultraviolet (UV)-continuum luminosity functions (LFs) of galaxies and active galactic nuclei (AGNs) at z = 2.0–3.5 determined by the untargeted optical spectroscopic survey of the Hobby–Eberly Telescope Dark Energy Experiment (HETDEX). We combine deep Subaru imaging with HETDEX spectra resulting in 11.4 deg2 of fiber spectra sky coverage, obtaining 18,320 galaxies spectroscopically identified with Lyα emission, 2126 of which host type 1 AGNs showing broad (FWHM > 1000 km s−1) Lyα emission lines. We derive the Lyα (UV) LF over 2 orders of magnitude covering bright galaxies and AGNs in log L Ly α / [ erg s − 1 ] = 43.3 – 45.5 (−27 < M UV < −20) by the 1/V max estimator. Our results reveal that the bright-end hump of the Lyα LF is composed of type 1 AGNs. In conjunction with previous spectroscopic results at the faint end, we measure a slope of the best-fit Schechter function to be α Sch = − 1.70 − 0.14 + 0.13 , which indicates that α Sch steepens from z = 2–3 toward high redshift. Our UV LF agrees well with previous AGN UV LFs and extends to faint-AGN and bright-galaxy regimes. The number fraction of Lyα-emitting objects (X LAE) increases from M UV * ∼ − 21 to bright magnitude due to the contribution of type 1 AGNs, while previous studies claim that X Lyα decreases from faint magnitudes to M UV * , suggesting a valley in the X Lyα –magnitude relation at M UV * . Comparing our UV LF of type 1 AGNs at z = 2–3 with those at z = 0, we find that the number density of faint (M UV > −21) type 1 AGNs increases from z ∼ 2 to 0, as opposed to the evolution of bright (M UV < −21) type 1 AGNs, suggesting AGN downsizing in the rest-frame UV luminosity.

scholarly journals The effect of emission lines on the performance of photometric redshift estimation algorithms

2021 ◽  
Author(s):  
Géza Csörnyei ◽  
László Dobos ◽  
István Csabai
Keyword(s):  
Emission Line ◽  
Signal To Noise Ratio ◽  
Emission Lines ◽  
Estimation Methods ◽  
Physical Parameters ◽  
Model Parameters ◽  
Colour Space ◽  
Strong Emission ◽  
Photometric Redshift ◽  
Photometric Error

Abstract We investigate the effect of strong emission line galaxies on the performance of empirical photometric redshift estimation methods. In order to artificially control the contribution of photometric error and emission lines to total flux, we develop a PCA-based stochastic mock catalogue generation technique that allows for generating infinite signal-to-noise ratio model spectra with realistic emission lines on top of theoretical stellar continua. Instead of running the computationally expensive stellar population synthesis and nebular emission codes, our algorithm generates realistic spectra with a statistical approach, and – as an alternative to attempting to constrain the priors on input model parameters – works by matching output observational parameters. Hence, it can be used to match the luminosity, colour, emission line and photometric error distribution of any photometric sample with sufficient flux-calibrated spectroscopic follow-up. We test three simple empirical photometric estimation methods and compare the results with and without photometric noise and strong emission lines. While photometric noise clearly dominates the uncertainty of photometric redshift estimates, the key findings are that emission lines play a significant role in resolving colour space degeneracies and good spectroscopic coverage of the entire colour space is necessary to achieve good results with empirical photo-z methods. Template fitting methods, on the other hand, must use a template set with sufficient variation in emission line strengths and ratios, or even better, first estimate the redshift empirically and fit the colours with templates at the best-fit redshift to calculate the K-correction and various physical parameters.

scholarly journals The Center for Astrophysics Redshift Survey

1988 ◽  
Vol 130 ◽  
pp. 105-112
Author(s):  
J. Huchra ◽  
M. Geller ◽  
V. de Lapparent ◽  
R. Burg
Keyword(s):  
Emission Lines ◽  
Clusters Of Galaxies ◽  
Local Universe ◽  
Abell Clusters ◽  
The Poor ◽  
Redshift Survey ◽  
The Mean

The first CfA Survey is now over 90% spectroscopically complete. Over 60% of all galaxies exhibit detectable emission lines. We have also completed five slices of the Center for Astrophysics (CfA) redshift survey extension. The geometry of the structures in the first slice persists; galaxies are distributed on thin surfaces of “bubble-like” structures. Empty regions or “voids” are common, come in a variety of sizes ranging up to 5,000 km s−1, and are underdense by factors of up to 5 w.r.t. the mean. These voids fill ∼ 80% of the volume of the local universe. Clusters of galaxies lie at the interstices of bubbles; some of the poor Abell clusters do not exist as “fingers” in redshift space. The surfaces are very thin with an average FWHM less than 500 km s−1 in redshift space (σ ∼ 200 to 250 km s−1).

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