Intrinsic Characteristics of Quasars Redshifts

AbstractUsing star counts method, we estimated the Galactic structure parameters in high latitude field (50° ≤ l ≤ 55°, −46° ≤ b ≤ −44°), 10 deg2 field with Sloan Digital Sky Survey (SDSS) and South Galactic Cap of U-band Sky Survey (SCUSS), to explore their possible variations with absolute magnitude. Here we just considered three components: double exponential thin disk and thick disk and a de Vaucouleurs halo. And these parameters were obtained by minimising χ2.

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A catalogue of white dwarfs in Gaia EDR3

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab2672 ◽

2021 ◽

Author(s):

N P Gentile Fusillo ◽

P-E Tremblay ◽

E Cukanovaite ◽

A Vorontseva ◽

R Lallement ◽

...

Keyword(s):

Effective Temperature ◽

White Dwarf ◽

Proper Motion ◽

White Dwarfs ◽

Absolute Magnitude ◽

Sloan Digital Sky Survey ◽

Atmospheric Models ◽

Sky Survey ◽

Cross Match ◽

Temperature Surface

Abstract We present a catalogue of white dwarf candidates selected from Gaia early data release three (EDR3). We applied several selection criteria in absolute magnitude, colour, and Gaia quality flags to remove objects with unreliable measurements while preserving most stars compatible with the white dwarf locus in the Hertzsprung-Russell diagram. We then used a sample of over 30 000 spectroscopically confirmed white dwarfs and contaminants from the Sloan Digital Sky Survey (SDSS) to map the distribution of these objects in the Gaia absolute magnitude-colour space. Finally, we adopt the same method presented in our previous work on Gaia DR2 to calculate a probability of being a white dwarf (PWD) for ≃ 1.3 million sources which passed our quality selection. The PWD values can be used to select a sample of ≃ 359 000 high-confidence white dwarf candidates. We calculated stellar parameters (effective temperature, surface gravity, and mass) for all these stars by fitting Gaia astrometry and photometry with synthetic pure-H, pure-He and mixed H-He atmospheric models. We estimate an upper limit of 93 per cent for the overall completeness of our catalogue for white dwarfs with G ≤ 20 mag and effective temperature (Teff) >7000 K, at high Galactic latitudes (|b| > 20○). Alongside the main catalogue we include a reduced-proper-motion extension containing ≃ 10 200 white dwarf candidates with unreliable parallax measurements which could, however be identified on the basis of their proper motion. We also performed a cross-match of our catalogues with SDSS DR16 spectroscopy and provide spectral classification based on visual inspection for all resulting matches.

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Possible Relations between Brightest Central Galaxies and Their Host Galaxies Clusters and Groups

Applied Mathematics and Nonlinear Sciences ◽

10.2478/amns.2021.1.00002 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

R. M. Samir ◽

A. A. Shaker

Keyword(s):

Velocity Dispersion ◽

Absolute Magnitude ◽

Effective Radius ◽

Sloan Digital Sky Survey ◽

The Other ◽

Host Galaxies ◽

Cluster Galaxies ◽

Brightest Cluster Galaxies ◽

Sky Survey ◽

Environmental Relations

Abstract The r-band of the Sloan Digital Sky Survey (SDSS) for 17,924 brightest cluster galaxies (BCGs) in clusters and groups within 0.02 ⩽ z ⩽ 0.20 are used to study possible environmental relations affecting the nature of these galaxies. We find a correlation between BCGs physical properties (the effective radius (Re ), absolute magnitude and central velocity dispersion (σ 0)) and their host groups and clusters velocity dispersion (σcl ). This type of relations suggests that the most massive groups or clusters host larger central galaxies. On the other hand, the σ 0/σcl ratio as a function of σcl is consistent with [10].

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Characterizing the abundance, properties, and kinematics of the cool circumgalactic medium of galaxies in absorption with SDSS DR16

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stab871 ◽

2021 ◽

Vol 504 (1) ◽

pp. 65-88

Author(s):

Abhijeet Anand ◽

Dylan Nelson ◽

Guinevere Kauffmann

Keyword(s):

Formation Rate ◽

Sloan Digital Sky Survey ◽

Gas Absorption ◽

Dark Matter Halo ◽

Star Forming ◽

Sky Survey ◽

Optical Continuum ◽

Circumgalactic Medium ◽

Emission Line Galaxies ◽

Red Galaxies

ABSTRACT In order to study the circumgalactic medium (CGM) of galaxies we develop an automated pipeline to estimate the optical continuum of quasars and detect intervening metal absorption line systems with a matched kernel convolution technique and adaptive S/N criteria. We process ∼ one million quasars in the latest Data Release 16 (DR16) of the Sloan Digital Sky Survey (SDSS) and compile a large sample of ∼ 160 000 Mg ii absorbers, together with ∼ 70 000 Fe ii systems, in the redshift range 0.35 < zabs < 2.3. Combining these with the SDSS DR16 spectroscopy of ∼1.1 million luminous red galaxies (LRGs) and ∼200 000 emission line galaxies (ELGs), we investigate the nature of cold gas absorption at 0.5 < z < 1. These large samples allow us to characterize the scale dependence of Mg ii with greater accuracy than in previous work. We find that there is a strong enhancement of Mg ii absorption within ∼50 kpc of ELGs, and the covering fraction within 0.5rvir of ELGs is 2–5 times higher than for LRGs. Beyond 50 kpc, there is a sharp decline in Mg ii for both kinds of galaxies, indicating a transition to the regime where the CGM is tightly linked with the dark matter halo. The Mg ii-covering fraction correlates strongly with stellar mass for LRGs, but weakly for ELGs, where covering fractions increase with star formation rate. Our analysis implies that cool circumgalactic gas has a different physical origin for star-forming versus quiescent galaxies.

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The Quest for Relics: Massive compact galaxies in the local Universe

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002045 ◽

2019 ◽

Vol 15 (S359) ◽

pp. 441-443

Author(s):

F. S. Lohmann ◽

A. Schnorr-Müller ◽

M. Trevisan ◽

R. Riffel ◽

N. Mallmann ◽

...

Keyword(s):

High Redshift ◽

Control Sample ◽

Sloan Digital Sky Survey ◽

Integral Field Spectroscopy ◽

Sky Survey ◽

Size Evolution ◽

Compact Galaxies ◽

Minor Mergers ◽

Significant Size ◽

Integral Field

AbstractObservations at high redshift reveal that a population of massive, quiescent galaxies (called red nuggets) already existed 10 Gyr ago. These objects undergo a significant size evolution over time, likely due to minor mergers. In this work we present an analysis of local massive compact galaxies to assess if their properties are consistent with what is expected for unevolved red nuggets (relic galaxies). Using integral field spectroscopy (IFS) data from the MaNGA survey from the Sloan Digital Sky Survey (SDSS), we characterized the kinematics and properties of stellar populations of massive compact galaxies, and find that these objects exhibit, on average, a higher rotational support than a control sample of average sized early-type galaxies. This is in agreement with a scenario in which these objects have a quiet accretion history, rendering them candidates for relic galaxies.

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The weak imprint of environment on the stellar populations of galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3545 ◽

2020 ◽

Vol 500 (4) ◽

pp. 4469-4490 ◽

Cited By ~ 1

Author(s):

James Trussler ◽

Roberto Maiolino ◽

Claudia Maraston ◽

Yingjie Peng ◽

Daniel Thomas ◽

...

Keyword(s):

Environmental Effects ◽

Unique Feature ◽

Stellar Populations ◽

Stellar Mass ◽

Sloan Digital Sky Survey ◽

Star Forming ◽

Sky Survey ◽

Satellite Galaxies ◽

Projected Distance ◽

Environmental Dependence

ABSTRACT We investigate the environmental dependence of the stellar populations of galaxies in Sloan Digital Sky Survey Data Release 7 (SDSS DR7). Echoing earlier works, we find that satellites are both more metal-rich (<0.1 dex) and older (<2 Gyr) than centrals of the same stellar mass. However, after separating star-forming, green valley, and passive galaxies, we find that the true environmental dependence of both stellar metallicity (<0.03 dex) and age (<0.5 Gyr) is in fact much weaker. We show that the strong environmental effects found when galaxies are not differentiated result from a combination of selection effects brought about by the environmental dependence of the quenched fraction of galaxies, and thus we strongly advocate for the separation of star-forming, green valley, and passive galaxies when the environmental dependence of galaxy properties are investigated. We also study further environmental trends separately for both central and satellite galaxies. We find that star-forming galaxies show no environmental effects, neither for centrals nor for satellites. In contrast, the stellar metallicities of passive and green valley satellites increase weakly (<0.05 and <0.08 dex, respectively) with increasing halo mass, increasing local overdensity and decreasing projected distance from their central; this effect is interpreted in terms of moderate environmental starvation (‘strangulation’) contributing to the quenching of satellite galaxies. Finally, we find a unique feature in the stellar mass–stellar metallicity relation for passive centrals, where galaxies in more massive haloes have larger stellar mass (∼0.1 dex) at constant stellar metallicity; this effect is interpreted in terms of dry merging of passive central galaxies and/or progenitor bias.

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Selection of M-dwarfs using Gaia, WISE, and 2MASS

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stz2823 ◽

2019 ◽

Vol 490 (3) ◽

pp. 4107-4120

Author(s):

J Bentley ◽

C G Tinney ◽

S Sharma ◽

D Wright

Keyword(s):

Absolute Magnitude ◽

Contamination Rate ◽

M Dwarfs ◽

Sky Survey ◽

Model Predictions ◽

Galaxy Model ◽

M Dwarf ◽

Different Sources ◽

Sources Of Contamination ◽

Selection Of

ABSTRACT We present criteria for the selection of M-dwarfs down to G < 14.5 using all-sky survey data, with a view to identifying potential M-dwarfs, to be confirmed spectroscopically by the FunnelWeb survey. Two sets of criteria were developed. The first, based on absolute magnitude in the Gaia G passband, with MG > 7.7, selects 76,392 stars, with 81.0 per cent expected to be M-dwarfs at a completeness of >97 per cent. The second is based on colour and uses Gaia, WISE, and 2MASS all-sky photometry. This criteria identifies 94,479 candidate M-dwarfs, of which between 29.4 per cent and 47.3 per cent are expected to be true M-dwarfs, and which contains 99.6 per cent of expected M-dwarfs. Both criteria were developed using synthetic galaxy model predictions, and a previously spectroscopically classified set of M- and K-dwarfs, to evaluate both M-dwarf completeness and false-positive detections (i.e. the non-M-dwarf contamination rate). Both criteria used in combination demonstrate how each excludes different sources of contamination. We therefore developed a final set of criteria that combines absolute magnitude and colour selection to identify 74,091 stars. All these sets of criteria select numbers of objects feasible for confirmation via massively multiplexed spectroscopic surveys like FunnelWeb.

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CONSTRAINTS ON THE SHAPE OF THE MILKY WAY DARK MATTER HALO FROM JEANS EQUATIONS APPLIED TO SLOAN DIGITAL SKY SURVEY DATA

The Astrophysical Journal ◽

10.1088/2041-8205/758/1/l23 ◽

2012 ◽

Vol 758 (1) ◽

pp. L23 ◽

Cited By ~ 14

Author(s):

Sarah R. Loebman ◽

Željko Ivezić ◽

Thomas R. Quinn ◽

Fabio Governato ◽

Alyson M. Brooks ◽

...

Keyword(s):

Dark Matter ◽

Survey Data ◽

Milky Way ◽

Sloan Digital Sky Survey ◽

Dark Matter Halo ◽

Sky Survey

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Are sdAs helium core stars?

Open Astronomy ◽

10.1515/astro-2017-0433 ◽

2017 ◽

Vol 26 (1) ◽

Cited By ~ 4

Author(s):

Ingrid Pelisoli ◽

S. O. Kepler ◽

Detlev Koester

Keyword(s):

Main Sequence ◽

Galactic Disk ◽

Physical Nature ◽

Sloan Digital Sky Survey ◽

Distance Modulus ◽

Main Sequence Stars ◽

Sky Survey ◽

Balmer Lines ◽

Low Mass ◽

Binary Evolution

AbstractEvolved stars with a helium core can be formed by non-conservative mass exchange interaction with a companion or by strong mass loss. Their masses are smaller than 0.5 M⊙. In the database of the Sloan Digital Sky Survey (SDSS), there are several thousand stars which were classified by the pipeline as dwarf O, B and A stars. Considering the lifetimes of these classes on the main sequence, and their distance modulus at the SDSS bright saturation, if these were common main sequence stars, there would be a considerable population of young stars very far from the galactic disk. Their spectra are dominated by Balmer lines which suggest effective temperatures around 8 000-10 000 K. Several thousand have significant proper motions, indicative of distances smaller than 1 kpc. Many show surface gravity in intermediate values between main sequence and white dwarf, 4.75 < log g < 6.5, hence they have been called sdA stars. Their physical nature and evolutionary history remains a puzzle. We propose they are not H-core main sequence stars, but helium core stars and the outcomes of binary evolution. We report the discovery of two new extremely-low mass white dwarfs among the sdAs to support this statement.

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