scholarly journals The prevalence and physical properties of extremely low-luminosity galaxies in the early universe

2019 ◽  
Vol 15 (S352) ◽  
pp. 19-19
Author(s):  
Rychard Bouwens
Keyword(s):  
Physical Properties ◽  
Galaxy Clusters ◽  
Early Universe ◽  
Gravitational Lensing ◽  
Stellar Population ◽  
Space Telescope ◽  
James Webb Space Telescope ◽  
Luminosity Functions ◽  
The Galaxy ◽  
Stellar Masses

AbstractGravitational lensing from galaxy clusters has great potential for deriving the prevalence and physical properties of ultra-faint galaxies at early times, with recent very impressive results from the Hubble Frontier Fields program. Important issues in deriving the most accurate results are accurate constraints on source sizes and a robust treatment of uncertainties in the magnification models. Using > 3300 z = 2 – 10 galaxies behind the 6 Hubble Frontier Fields clusters and a forwards modeling approach, I describe the efforts of my collaborators and me to map out the galaxy luminosity functions at ∼ − 13 mag from z ∼ 9 to z ∼ 2, i.e, a factor of 1000 below Lå and to the typical luminosity of galaxies suspected to drive cosmic reionization. Additionally, I discuss the constraints we can obtain on the properties of faint sources, in particular their stellar masses, mass-to-light ratios, colors, and stellar population ages. I conclude with a prospective on using cluster lenses to study the distant universe with the James Webb Space Telescope.

scholarly journals Properties of reionization-era galaxies from JWST luminosity functions and 21-cm interferometry

2019 ◽  
Vol 491 (3) ◽  
pp. 3891-3899 ◽  
Author(s):  
Jaehong Park ◽  
Nicolas Gillet ◽  
Andrei Mesinger ◽  
Bradley Greig
Keyword(s):  
Star Formation Rate ◽  
Hubble Space Telescope ◽  
Formation Rate ◽  
Power Spectra ◽  
Mass Relation ◽  
Space Telescope ◽  
James Webb Space Telescope ◽  
Luminosity Functions ◽  
Order Of Magnitude ◽  
Magnitude Improvement

ABSTRACT Upcoming observations will probe the first billion years of our Universe in unprecedented detail. Foremost among these are 21-cm interferometry with the Hydrogen Epoch of Reionization Arrays (HERA) and the Square Kilometre Array (SKA), and high-z galaxy observations with the James Webb Space Telescope (JWST). Here, we quantify how observations from these instruments can be used to constrain the astrophysics of high-z galaxies. We generate several mock JWST luminosity functions (LFs) and SKA1 21-cm power spectra, which are consistent with current observations, but assume different properties for the unseen, ultrafaint galaxies driving the epoch of reionization (EoR). Using only JWST data, we predict up to a factor of 2–3 improvement (compared with Hubble Space Telescope, HST) in the fractional uncertainty of the star formation rate to halo mass relation and the turnover magnitude. Most parameters regulating the ultraviolet (UV) galaxy properties can be constrained at the level of ∼10 per cent or better, if either (i) we are able to better characterize systematic lensing uncertainties than currently possible; or (ii) the intrinsic LFs peak at magnitudes brighter than MUV ≲ −13. Otherwise, improvement over HST-based inference is modest. When combining with upcoming 21-cm observations, we are able to significantly mitigate degeneracies, and constrain all of our astrophysical parameters, even for our most pessimistic assumptions about upcoming JWST LFs. The 21-cm observations also result in an order of magnitude improvement in constraints on the EoR history.

scholarly journals GRAVITATIONAL LENSING STATISTICS AND CONSTRAINTS ON THE COSMOLOGICAL CONSTANT REVISITED

2000 ◽  
Vol 15 (05) ◽  
pp. 697-723 ◽  
Author(s):  
YU-CHUNG N. CHENG ◽  
LAWRENCE M. KRAUSS
Keyword(s):  
Cosmological Constant ◽  
Gravitational Lensing ◽  
Velocity Dispersion ◽  
A Value ◽  
Galaxy Distribution ◽  
Systematic Uncertainties ◽  
Luminosity Functions ◽  
Likelihood Analysis ◽  
The Galaxy ◽  
Velocity Dispersions

We re-analyze constraints on the cosmological constant that can be obtained by examining the statistics of strong gravitational lensing of distant quasars by intervening galaxies, focusing on uncertainties in galaxy models (including velocity dispersion, luminosity functions, core radii and magnification bias effects) and on the parameters of the galaxy distribution and luminosity functions. In the process we derive new results on magnification biasing for galaxy lenses with nonzero core radii, and on how to infer the proper velocity dispersions appropriate for use in lensing statistics. We argue that the existing data do not disfavor a large cosmological constant. In fact, for a set of reasonable parameter choices, using the results of five optical quasar lensing surveys we find that a maximum likelihood analysis favors a value of Ω0 in the range ≈ 0.25–0.55 in a flat universe. An open cosmology is not favored by the same statistical analysis. Systematic uncertainties are likely to be dominant, however, as these results are sensitive to uncertainties in our understanding of galaxy luminosity functions, and dark matter velocity dispersions, as well as the choice of lensing survey, and to a lesser extent the existence of core radii. Further observational work will be required before it is possible to definitively distinguish between cosmological models on the basis of gravitational lensing statistics.

scholarly journals Probing the faintest galaxy population at the epoch of reionization with gravitational lensing

2019 ◽  
Vol 15 (S352) ◽  
pp. 26-26
Author(s):  
Hakim Atek
Keyword(s):  
Gravitational Lensing ◽  
Hubble Space Telescope ◽  
Space Telescope ◽  
Systematic Uncertainties ◽  
James Webb Space Telescope ◽  
Exciting Opportunity ◽  
Complete Dataset ◽  
Galaxy Populations ◽  
Galaxy Population ◽  
The Universe

AbstractUltra-deep observations of blank fields with the Hubble Space Telescope have made important inroads in characterizing galaxy populations at redshift z = 6 – 10. Gravitational lensing by massive galaxy clusters offers a new route to identify the faintest sources at the epoch of reionization. In particular, thanks to the Hubble Frontier Fields program, we robustly pushed the detection limit down to MAB = − 15 mag at z ∼ 6. I will present the latest results based on the complete dataset of the HFF clusters and parallel fields, and their implications on the ability of galaxies to reionize the Universe. I will also discuss the results of a comprehensive end-to-end modeling effort towards constraining the systematic uncertainties of the lens models, which are currently the last hurdle before extending the UV LF to fainter luminosities. Finally, I will discuss the great discoveries awaiting combination of such cosmic lenses with the upcoming James Webb Space Telescope and the exciting opportunity to probe the turnover of the UV LF, hence the limit of the star formation process at those early epochs.

scholarly journals Properties of the Environment of Galaxies in Clusters of Galaxies CL 0024+1654 and RX J0152.7−1357

2021 ◽  
Vol 53 (3) ◽  
pp. 428-250
Author(s):  
Premana Wardayanti Premadi ◽  
Dading Hadi Nugroho ◽  
Anton Timur Jaelani
Keyword(s):  
Physical Properties ◽  
Galaxy Evolution ◽  
Gravitational Lensing ◽  
Mass Density ◽  
Formation Rate ◽  
Close Relation ◽  
Optical Data ◽  
X Ray ◽  
Physical Description ◽  
The Galaxy

We report the results of combined analyses of X-ray and optical data of two galaxy clusters, CL 0024+1654 and RX J0152.7−1357 at redshift z = 0.395 and z = 0.830, respectively, offering a holistic physical description of the two clusters. Our X-ray analysis yielded temperature and density profiles of the gas in the intra-cluster medium (ICM). Using optical photometric and spectroscopic data, complemented with mass distribution from a gravitational lensing study, we investigated any possible correlation between the physical properties of the galaxy members, i.e. their color, morphology, and star formation rate (SFR), and their environments. We quantified the properties of the environment around each galaxy by galaxy number density, ICM temperature, and mass density. Although our results show that the two clusters exhibit a weaker correlation compared to relaxed clusters, it still confirms the significant effect of the ICM on the SFR in the galaxies. The close relation between the physical properties of galaxies and the condition of their immediate environment found in this work indicates the locality of galaxy evolution, even within a larger bound system such as a cluster. Various physical mechanisms are suggested to explain the relation between the properties of galaxies and their environment.

scholarly journals On the detection of supermassive primordial stars – II. Blue supergiants

2019 ◽  
Vol 488 (3) ◽  
pp. 3995-4003 ◽  
Author(s):  
Marco Surace ◽  
Erik Zackrisson ◽  
Daniel J Whalen ◽  
Tilman Hartwig ◽  
S C O Glover ◽  
...  
Keyword(s):  
Gravitational Lensing ◽  
Near Infrared ◽  
Detection Limits ◽  
Wide Field ◽  
Spectral Features ◽  
Field Surveys ◽  
Space Telescope ◽  
Surface Temperatures ◽  
James Webb Space Telescope ◽  
The Universe

ABSTRACT Supermassive primordial stars in hot, atomically cooling haloes at z ∼ 15–20 may have given birth to the first quasars in the Universe. Most simulations of these rapidly accreting stars suggest that they are red, cool hypergiants, but more recent models indicate that some may have been bluer and hotter, with surface temperatures of 20 000–40 000 K. These stars have spectral features that are quite distinct from those of cooler stars and may have different detection limits in the near-infrared today. Here, we present spectra and AB magnitudes for hot, blue supermassive primordial stars calculated with the tlusty and cloudy codes. We find that photometric detections of these stars by the James Webb Space Telescope will be limited to z ≲ 10–12, lower redshifts than those at which red stars can be found, because of quenching by their accretion envelopes. With moderate gravitational lensing, Euclid and the Wide-Field Infrared Space Telescope could detect blue supermassive stars out to similar redshifts in wide-field surveys.

scholarly journals The Galaxy Populations of Clusters at High Redshifts: A “Hubble Atlas”

1996 ◽  
Vol 171 ◽  
pp. 455-455
Author(s):  
S.C. Trager ◽  
S.M. Faber ◽  
A. Dressler ◽  
Keyword(s):  
Galaxy Clusters ◽  
Hubble Space Telescope ◽  
Space Telescope ◽  
The Galaxy ◽  
First Results ◽  
Galaxy Populations

We present first results of a Hubble Space Telescope imaging and a Palomar and Keck Observatories spectroscopy program of distant, rich galaxy clusters in the form of a “Hubble Atlas” of morphological types at z ≥ 0.75. Two clusters from the compilation of Gunn, Hoessel & Oke (1985) have been studied to date, Cl1322+3027 at z ≈ 0.76 and Cl1603+4313 at z ≈ 0.90.

The evolution of the luminosity function faint end of cluster galaxies in the Cluster-EAGLE simulation

2018 ◽  
Vol 14 (S344) ◽  
pp. 495-497
Author(s):  
Andrea Negri ◽  
Claudio Dalla Vecchia ◽  
Alfonso Aguerri ◽  
Yannick Bahé ◽  
David Barnes ◽  
...  
Keyword(s):  
Galaxy Clusters ◽  
Luminosity Function ◽  
Cluster Galaxies ◽  
Cluster Mass ◽  
Luminosity Functions ◽  
The Galaxy ◽  
Zoom In ◽  
Dust Attenuation ◽  
Galaxy Luminosity Function

AbstractIn the last decade observations have been able to probe the evolution of the galaxy luminosity function, in particular showing a variation of its faint-end with redshift. We employ the data of the Cluster-EAGLE project, a set of cosmological, hydrodynamical zoom-in simulations of 30 galaxy clusters, to study the evolution of the galaxy luminostity functions in clusters with redshift. We compile a catalogue of simulated galaxies’ luminosities in the SDSS bands using the E-MILES spectra database, and taking into account dust attenuation. Stacked luminosity functions present little evolution with redshift of the faint-end slope from z=3.5 to z=0, regardless of the cluster mass.

scholarly journals The distribution and physical properties of high-redshift [Oiii] emitters in a cosmological hydrodynamics simulation

2019 ◽  
Vol 15 (S341) ◽  
pp. 249-252
Author(s):  
Kana Moriwaki
Keyword(s):  
Physical Properties ◽  
Physical Model ◽  
High Redshift ◽  
Gas Density ◽  
Space Telescope ◽  
James Webb Space Telescope ◽  
Local Relation

AbstractAtacama Large Millimeter/submillimeter Array (ALMA) has enabled us to detect [Oiii] 88 μm line even at z > 9. To study the properties of high-redshift [Oiii] emitters, we calculate [Oiii] luminosities of galaxies in a cosmological simulation by applying a physical model of Hii region and using the photoionization code cloudy. We find that the [Oiii] 88 μm luminosity, LOIII,88, scales with SFR with slightly larger LOIII,88 than a local relation. Some [Oiii] emitters have extended disk-like structure. We propose to use the ratio between [Oiii] 88 μm line and [Oiii] 5007 Å line, which can be detected with James Webb Space Telescope (JWST), to estimate the gas density and the metallicity in HII region of high-redshift [Oiii] emitters.

scholarly journals Free-form grale lens inversion of galaxy clusters with up to 1000 multiple images

2020 ◽  
Vol 494 (3) ◽  
pp. 3998-4014 ◽  
Author(s):  
Agniva Ghosh ◽  
Liliya L R Williams ◽  
Jori Liesenborgs
Keyword(s):  
Galaxy Clusters ◽  
Hubble Space Telescope ◽  
Free Form ◽  
Inversion Method ◽  
Space Telescope ◽  
Multiple Images ◽  
Mass Distributions ◽  
James Webb Space Telescope ◽  
Order Of Magnitude ◽  
Galaxy Population

ABSTRACT In the near future, ultra deep observations of galaxy clusters with Hubble Space Telescope or James Webb Space Telescope will uncover 300–1000 lensed multiple images, increasing the current count per cluster by up to an order of magnitude. This will further refine our view of clusters, leading to a more accurate and precise mapping of the total and dark matter distribution in clusters, and enabling a better understanding of background galaxy population and their luminosity functions. However, to effectively use that many images as input to lens inversion will require a re-evaluation of, and possibly upgrades to the existing methods. In this paper, we scrutinize the performance of the free-form lens inversion method grale in the regime of 150–1000 input images, using synthetic massive galaxy clusters. Our results show that with an increasing number of input images, grale produces improved reconstructed mass distributions, with the fraction of the lens plane recovered at better than $10{{\ \rm per\ cent}}$ accuracy increasing from $40\!-\!50{{\ \rm per\ cent}}$ for ∼150 images to $65{{\ \rm per\ cent}}$ for ∼1000 images. The reconstructed time delays imply a more precise measurement of H0, with $\lesssim 1{{\ \rm per\ cent}}$ bias. While the fidelity of the reconstruction improves with the increasing number of multiple images used as model constraints, ∼150 to ∼1000, the lens plane rms deteriorates from ∼0.11 to ∼0.28 arcsec. Since lens plane rms is not necessarily the best indicator of the quality of the mass reconstructions, looking for an alternative indicator is warranted.

scholarly journals Lensing Effects in Retarded Gravity

Symmetry ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 1062
Author(s):  
Asher Yahalom
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Gravitational Lensing ◽  
Relativistic Effects ◽  
Newtonian Theory ◽  
Typical Size ◽  
Physical Systems ◽  
The Galaxy ◽  
General Relativistic ◽  
Retardation Effects

Galaxies are gigantic physical systems having a typical size of many tens of thousands of light years. Thus, any change at the center of the galaxy will affect the rim only tens of millennia later. Those retardation effects seem to be ignored in present day modelling used to calculate rotational velocities of matter in the outskirts of the galaxy and the surrounding gas. The significant discrepancies between the velocities predicted by Newtonian theory and observed velocities are usually handled by either assuming an unobservable type of matter denoted “dark matter” or by modifying the laws of gravity (MOND as an example). Here, we will show that considering general relativistic effects without neglecting retardation can explain the apparent excess matter leading to gravitational lensing in both galaxies and galaxy clusters.

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