scholarly journals The R-Band Hubble Diagram for GPS Galaxies

1996 ◽  
Vol 175 ◽  
pp. 585-587
Author(s):  
Ignas Snellen ◽  
Malcolm Bremer ◽  
Richard Schilizzi ◽  
George Miley ◽  
Rob Van Ojik
Keyword(s):  
High Redshift ◽  
Dynamical Evolution ◽  
Steep Slope ◽  
Hubble Diagram ◽  
Low Dispersion

The Hubble diagram of GPS galaxies has a low dispersion and a steep slope compared with that for 3C galaxies. The relative faintness of GPS galaxies at high redshift may be due to the absence of the aligned optical/uv component seen in high redshift 3C galaxies. The GPS Hubble relation is too steep to fit with evolution models for passively evolving ellipticals. This could be caused by the dynamical evolution of the GPS galaxies.

scholarly journals Global torques and stochasticity as the drivers of massive black hole pairing in the young Universe

2020 ◽  
Vol 498 (3) ◽  
pp. 3601-3615 ◽  
Author(s):  
Elisa Bortolas ◽  
Pedro R Capelo ◽  
Tommaso Zana ◽  
Lucio Mayer ◽  
Matteo Bonetti ◽  
...  
Keyword(s):  
Black Hole ◽  
Large Scale ◽  
High Redshift ◽  
Dynamical Evolution ◽  
Dynamical Friction ◽  
Massive Black Hole ◽  
Orbital Decay ◽  
Orbital Phase ◽  
Order Of Magnitude ◽  
Statistical Sample

ABSTRACT The forthcoming Laser Interferometer Space Antenna (LISA) will probe the population of coalescing massive black hole (MBH) binaries up to the onset of structure formation. Here, we simulate the galactic-scale pairing of ∼106 M⊙ MBHs in a typical, non-clumpy main-sequence galaxy embedded in a cosmological environment at z = 7–6. In order to increase our statistical sample, we adopt a strategy that allows us to follow the evolution of six secondary MBHs concomitantly. We find that the magnitude of the dynamical-friction-induced torques is significantly smaller than that of the large-scale, stochastic gravitational torques arising from the perturbed and morphologically evolving galactic disc, suggesting that the standard dynamical friction treatment is inadequate for realistic galaxies at high redshift. The dynamical evolution of MBHs is very stochastic, and a variation in the initial orbital phase can lead to a drastically different time-scale for the inspiral. Most remarkably, the development of a galactic bar in the host system either significantly accelerates the inspiral by dragging a secondary MBH into the centre, or ultimately hinders the orbital decay by scattering the MBH in the galaxy outskirts. The latter occurs more rarely, suggesting that galactic bars overall promote MBH inspiral and binary coalescence. The orbital decay time can be an order of magnitude shorter than what would be predicted relying on dynamical friction alone. The stochasticity and the important role of global torques have crucial implications for the rates of MBH coalescences in the early Universe: both have to be accounted for when making predictions for the upcoming LISA observatory.

scholarly journals Studying Type II supernovae as cosmological standard candles using the Dark Energy Survey

2020 ◽  
Vol 495 (4) ◽  
pp. 4860-4892 ◽  
Author(s):  
T de Jaeger ◽  
L Galbany ◽  
S González-Gaitán ◽  
R Kessler ◽  
A V Filippenko ◽  
...  
Keyword(s):  
Dark Energy ◽  
High Redshift ◽  
Cosmological Parameters ◽  
Hubble Constant ◽  
Distance Modulus ◽  
Type Ii ◽  
Hubble Diagram ◽  
Dark Energy Survey ◽  
Spectroscopic Information ◽  
Energy Survey

ABSTRACT Despite vast improvements in the measurement of the cosmological parameters, the nature of dark energy and an accurate value of the Hubble constant (H0) in the Hubble–Lemaître law remain unknown. To break the current impasse, it is necessary to develop as many independent techniques as possible, such as the use of Type II supernovae (SNe II). The goal of this paper is to demonstrate the utility of SNe II for deriving accurate extragalactic distances, which will be an asset for the next generation of telescopes where more-distant SNe II will be discovered. More specifically, we present a sample from the Dark Energy Survey Supernova Program (DES-SN) consisting of 15 SNe II with photometric and spectroscopic information spanning a redshift range up to 0.35. Combining our DES SNe with publicly available samples, and using the standard candle method (SCM), we construct the largest available Hubble diagram with SNe II in the Hubble flow (70 SNe II) and find an observed dispersion of 0.27 mag. We demonstrate that adding a colour term to the SN II standardization does not reduce the scatter in the Hubble diagram. Although SNe II are viable as distance indicators, this work points out important issues for improving their utility as independent extragalactic beacons: find new correlations, define a more standard subclass of SNe II, construct new SN II templates, and dedicate more observing time to high-redshift SNe II. Finally, for the first time, we perform simulations to estimate the redshift-dependent distance-modulus bias due to selection effects.

Observing SNe Ia at z > 1 with the HST and at z ≃ 0.2 with the SDSS-II

2006 ◽  
Vol 2 (14) ◽  
pp. 314-315
Author(s):  
Hubert Lampeitl ◽  
Adam G. Riess
Keyword(s):  
Hubble Space Telescope ◽  
High Redshift ◽  
Sloan Digital Sky Survey ◽  
Accelerated Expansion ◽  
Hubble Diagram ◽  
Sky Survey ◽  
Direct Measurements ◽  
Expansion Of The Universe ◽  
Intermediate Redshifts ◽  
The Universe

AbstractSNe Ia are currently providing the most direct measurements of the accelerated expansion of the Universe and also put constraints on the nature and evolution of the so-called ‘dark energy’. Despite major efforts to increase the number of known high-redshift SNe Ia with reliable distance estimates, two regions in the Hubble diagram remain only sparsely observed. At redshifts z > 1 the limitations of ground-based instruments require the Hubble Space Telescope and its superior angular resolution to get meaningful distance estimates, while at intermediate redshifts (z ≃ 0.2) the large solid angle necessary presents an obstacle to most surveys that can be overcome with the Sloan Digital Sky Survey, SDSS-II.

scholarly journals Quasars as standard candles

2020 ◽  
Vol 642 ◽  
pp. A150 ◽  
Author(s):  
E. Lusso ◽  
G. Risaliti ◽  
E. Nardini ◽  
G. Bargiacchi ◽  
M. Benetti ◽  
...  
Keyword(s):  
Cold Dark Matter ◽  
High Redshift ◽  
Full Description ◽  
X Rays ◽  
Hubble Diagram ◽  
X Ray ◽  
Flux Limit ◽  
Cold Dark Matter Model ◽  
Systematic Effects ◽  
The Stability

We present a new catalogue of ∼2400 optically selected quasars with spectroscopic redshifts and X-ray observations from either Chandra or XMM–Newton. The sample can be used to investigate the non-linear relation between the ultraviolet (UV) and X-ray luminosity of quasars as well as to build a Hubble diagram up to a redshift of z ∼ 7.5. We selected sources that are neither reddened by dust in the optical and UV nor obscured by gas in the X-rays, and whose X-ray fluxes are free from flux-limit-related biases. After checking for any possible systematics, we confirm, in agreement with our previous works, that the X-ray to UV relation provides distance estimates matching those from supernovae up to z ∼ 1.5, and its slope shows no redshift evolution up to z ∼ 5. We provide a full description of the methodology for testing cosmological models, further supporting a trend whereby the Hubble diagram of quasars is well reproduced by the standard flat cold dark matter model up to z ∼ 1.5–2, but strong deviations emerge at higher redshifts. Since we have minimised all non-negligible systematic effects and proven the stability of the LX − LUV relation at high redshifts, we conclude that an evolution of the expansion rate of the Universe should be considered as a possible explanation for the observed deviation, rather than some systematic (redshift-dependent) effect associated with high-redshift quasars.

scholarly journals The Radio and Infrared Luminosities of 3CR Radio Galaxies - Are They Correlated?

1987 ◽  
Vol 124 ◽  
pp. 143-146
Author(s):  
M.G. Yates ◽  
L. Miller ◽  
J.A. Peacock
Keyword(s):  
High Redshift ◽  
Stellar Populations ◽  
Radio Galaxies ◽  
Photometric Study ◽  
Powerful Radio ◽  
Hubble Diagram ◽  
Limited Sample

The infrared photometric study of a sample of 90 3CR radio galaxies by Lilly & Longair (1984, hereafter LL) has demonstrated that the high redshift objects are brighter in the infrared than their low redshift counterparts; this has been interpreted as being entirely due to the evolution of their constituent stellar populations. There is however a great difference between the radio luminosities of the high and low redshift objects in this flux limited sample and we have therefore examined statistically the possibility of a correlation between the infrared and radio luminosities of these galaxies, the presence of which could bias our interpretation of the infrared Hubble diagram. We find that the radio and infrared luminosities do indeed correlate for the most powerful radio galaxies.

scholarly journals Test of the cosmic distance duality relation for arbitrary spatial curvature

2021 ◽  
Vol 502 (3) ◽  
pp. 3500-3509
Author(s):  
Jin Qin ◽  
Fulvio Melia ◽  
Tong-Jie Zhang
Keyword(s):  
Gravitational Lensing ◽  
High Redshift ◽  
Duality Relation ◽  
Spatial Curvature ◽  
Hubble Diagram ◽  
Sis Model ◽  
Strong Gravitational Lensing ◽  
Best Fitting ◽  
Model Independent ◽  
The Universe

ABSTRACT The cosmic distance duality relation (CDDR), η(z) = (1 + z)2dA(z)/dL(z) = 1, is one of the most fundamental and crucial formulae in cosmology. This relation couples the luminosity and angular diameter distances, two of the most often used measures of structure in the Universe. We here propose a new model-independent method to test this relation, using strong gravitational lensing (SGL) and the high-redshift quasar Hubble diagram reconstructed with a Bézier parametric fit. We carry out this test without pre-assuming a zero spatial curvature, adopting instead the value ΩK = 0.001 ± 0.002 optimized by Planck in order to improve the reliability of our result. We parametrize the CDDR using η(z) = 1 + η0z, 1 + η1z + η2z2, and 1 + η3z/(1 + z), and consider both the SIS and non-SIS lens models for the strong lensing. Our best-fitting results are: $\eta _0=-0.021^{+0.068}_{-0.048}$, $\eta _1=-0.404^{+0.123}_{-0.090}$, $\eta _2=0.106^{+0.028}_{-0.034}$, and $\eta _3=-0.507^{+0.193}_{-0.133}$ for the SIS model, and $\eta _0=-0.109^{+0.044}_{-0.031}$ for the non-SIS model. The measured η(z), based on the Planck parameter ΩK, is essentially consistent with the value (=1) expected if the CDDR were fully respected. For the sake of comparison, we also carry out the test for other values of ΩK, but find that deviations of spatial flatness beyond the Planck optimization are in even greater tension with the CDDR. Future measurements of SGL may improve the statistics and alter this result but, as of now, we conclude that the CDDR favours a flat Universe.

scholarly journals Gamma-ray bursts: cosmic rulers for the high-redshift universe?

2007 ◽  
Vol 365 (1854) ◽  
pp. 1395-1397 ◽  
Author(s):  
Fiona C Speirits ◽  
Martin A Hendry ◽  
Alejandro Gonzalez
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
Current Data ◽  
Gamma Ray Bursts ◽  
Luminosity Distance ◽  
Conformal Gravity ◽  
Hubble Diagram ◽  
Cosmological Distance Scale ◽  
Standard Candle ◽  
High Redshift Universe

The desire to extend the Hubble Diagram to higher redshifts than the range of current Type 1a Supernovae observations has prompted investigation into spectral correlations in gamma-ray bursts (GBRs), in the hope that standard candle-like properties can be identified. In this paper, we discuss the potential of these new ‘cosmic rulers’ and highlight their limitations by investigating the constraints that current data can place on an alternative Cosmological model in the form of Conformal Gravity. By fitting current Type 1a Supernovae and GRB data to the predicted luminosity distance redshift relation of both the standard Concordance Model and the Conformal Gravity, we show that currently neither model is strongly favoured at high redshift. The scatter in the current GRB data testifies to the further work required if GRBs are to cement their place as effective probes of the cosmological distance scale.

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