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 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 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 The Hubble PanCET program: Transit and Eclipse Spectroscopy of the Hot-Jupiter WASP-74b

2021 ◽  
Vol 162 (6) ◽  
pp. 271
Author(s):  
Guangwei Fu ◽  
Drake Deming ◽  
Erin May ◽  
Kevin Stevenson ◽  
David K. Sing ◽  
...  
Keyword(s):  
Rayleigh Scattering ◽  
Hubble Space Telescope ◽  
Absorption Feature ◽  
Spectral Library ◽  
Data Set ◽  
Space Telescope ◽  
Methane Absorption ◽  
James Webb Space Telescope ◽  
Hot Jupiter

Abstract Planets are like children with each one being unique and special. A better understanding of their collective properties requires a deeper understanding of each planet. Here we add the transit and eclipse spectra of hot-Jupiter WASP-74b into the ever growing data set of exoplanet atmosphere spectral library. With six transits and three eclipses using the Hubble Space Telescope and Spitzer Space Telescope (Spitzer), we present the most complete and precise atmospheric spectra of WASP-74b. We found no evidence for TiO/VO nor super-Rayleigh scattering reported in previous studies. The transit shows a muted water feature with strong Rayleigh scattering extending into the infrared. The eclipse shows a featureless blackbody-like WFC3/G141 spectrum and a weak methane absorption feature in the Spitzer 3.6 μm band. Future James Webb Space Telescope follow-up observations are needed to confirm these results.

9. The next telescopes

2016 ◽  
pp. 122-138
Author(s):  
Geoff Cottrell
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Adaptive Optics ◽  
Hubble Space Telescope ◽  
Scientific Instrument ◽  
Space Telescope ◽  
James Webb Space Telescope ◽  
First Galaxies ◽  
New Generation ◽  
Optical Telescopes

Each question that telescopes have helped answer has led to new questions: what is dark matter and dark energy? How did the first galaxies form? Are there habitable, Earth-like exoplanets? To address these questions, a new generation of telescopes are being built. ‘The next telescopes’ describes some of these, including the three extremely large infrared/optical telescopes, equipped with adaptive optics systems, due to start operating in the next decade. Other new telescopes discussed are the Square Kilometre Array, a radio telescope that will soon be the world’s largest scientific instrument, and the James Webb Space Telescope due to be launched in 2018, which is the 100 times more powerful successor to the Hubble Space Telescope.

scholarly journals Studying the physical properties of tidal features – I. Extracting morphological substructure in CANDELS observations and VELA simulations

2019 ◽  
Vol 486 (2) ◽  
pp. 2643-2659 ◽  
Author(s):  
Kameswara Bharadwaj Mantha ◽  
Daniel H McIntosh ◽  
Cody P Ciaschi ◽  
Rubyet Evan ◽  
Henry C Ferguson ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Hubble Space Telescope ◽  
High Redshift ◽  
Software Tool ◽  
Space Telescope ◽  
Visual Appearance ◽  
James Webb Space Telescope ◽  
Profile Fitting ◽  
Major Merger ◽  
Merger Rate

Abstract The role of major mergers in galaxy evolution remains a key open question. Existing empirical merger identification methods use non-parametric and subjective visual classifications that can pose systematic challenges to constraining merger histories. As a first step towards overcoming these challenges, we develop and share publicly a new python-based software tool that identifies and extracts the flux-wise and area-wise significant contiguous regions from the model-subtracted residual images produced by popular parametric light-profile fitting tools (e.g. galfit). Using Hubble Space Telescope (HST) H-band single-Sérsic residual images of 17 CANDELS galaxies, we demonstrate the tools ability to measure the surface brightness and improve the qualitative identification of a variety of common residual features (disc structures, spiral substructures, plausible tidal features, and strong gravitational arcs). We test our method on synthetic HST observations of a z ∼ 1.5 major merger from the VELA hydrodynamic simulations. We extract H-band residual features corresponding to the birth, growth, and fading of tidal features during different stages and viewing orientations at CANDELS depths and resolution. We find that the extracted features at shallow depths have noisy visual appearance and are susceptible to viewing angle effects. For a VELA z ∼ 3 major merger, we find that James Webb Space Telescope NIRCam observations can probe high-redshift tidal features with considerable advantage over existing HST capabilities. Further quantitative analysis of plausible tidal features extracted with our new software hold promise for the robust identification of hallmark merger signatures and corresponding improvements to merger rate constraints.

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 Automated distant galaxy merger classifications from Space Telescope images using the Illustris simulation

2019 ◽  
Vol 486 (3) ◽  
pp. 3702-3720 ◽  
Author(s):  
Gregory F Snyder ◽  
Vicente Rodriguez-Gomez ◽  
Jennifer M Lotz ◽  
Paul Torrey ◽  
Amanda C N Quirk ◽  
...  
Keyword(s):  
Galaxy Evolution ◽  
Hubble Space Telescope ◽  
Machine Learning Techniques ◽  
Galaxy Mergers ◽  
Distant Galaxy ◽  
Space Telescope ◽  
James Webb Space Telescope ◽  
Learning Techniques ◽  
Merger Rate ◽  
Do So

ABSTRACT We present image-based evolution of galaxy mergers from the Illustris cosmological simulation at 12 time-steps over 0.5 < z < 5. To do so, we created approximately one million synthetic deep Hubble Space Telescope and James Webb Space Telescope images and measured common morphological indicators. Using the merger tree, we assess methods to observationally select mergers with stellar mass ratios as low as 10:1 completing within ±250 Myr of the mock observation. We confirm that common one- or two-dimensional statistics select mergers so defined with low purity and completeness, leading to high statistical errors. As an alternative, we train redshift-dependent random forests (RFs) based on 5–10 inputs. Cross-validation shows the RFs yield superior, yet still imperfect, measurements of the late-stage merger fraction, and they select more mergers in bulge-dominated galaxies. When applied to CANDELS morphology catalogues, the RFs estimate a merger rate increasing to at least z = 3, albeit two times higher than expected by theory. This suggests possible mismatches in the feedback-determined morphologies, but affirms the basic understanding of galaxy merger evolution. The RFs achieve completeness of roughly $70{{\ \rm per\ cent}}$ at 0.5 < z < 3, and purity increasing from $10{{\ \rm per\ cent}}$ at z = 0.5–60 per cent at z = 3. At earlier times, the training sets are insufficient, motivating larger simulations and smaller time sampling. By blending large surveys and large simulations, such machine learning techniques offer a promising opportunity to teach us the strengths and weaknesses of inferences about galaxy evolution.

scholarly journals The predicted properties of helium-enriched globular cluster progenitors at high redshift

2020 ◽  
Vol 496 (3) ◽  
pp. 3222-3234
Author(s):  
David M Nataf ◽  
Shunsaku Horiuchi ◽  
Guglielmo Costa ◽  
Rosemary F G Wyse ◽  
Yuan-Sen Ting ◽  
...  
Keyword(s):  
Adaptive Optics ◽  
Globular Cluster ◽  
Globular Clusters ◽  
Hubble Space Telescope ◽  
High Redshift ◽  
Cluster Formation ◽  
Stellar Populations ◽  
Space Telescope ◽  
James Webb Space Telescope ◽  
Galactic Astronomy

ABSTRACT Globular cluster progenitors may have been detected by Hubble Space Telescope, and are predicted to be observable with James Webb Space Telescope (JWST) and ground-based extremely large telescopes with adaptive optics. This has the potential to elucidate the issue of globular cluster formation and the origins of significantly helium-enriched subpopulations, a problem in Galactic astronomy with no satisfactory theoretical solution. Given this context, we use model stellar tracks and isochrones to investigate the predicted observational properties of helium-enriched stellar populations in globular cluster progenitors. We find that, relative to helium-normal populations, helium-enriched (ΔY = +0.12) stellar populations similar to those inferred in the most massive globular clusters, are expected, modulo some rapid fluctuations in the first ∼30 Myr, to be brighter and redder in the rest frame. At fixed age, stellar mass, and metallicity, a helium-enriched population is predicted to converge to being ∼0.40 mag brighter at $\lambda \approx 2.0\, {\mu \rm m}$, and to be 0.30-mag redder in the JWST–NIRCam colour (F070W − F200W), and to actually be fainter for $\lambda \lesssim 0.50 \, {\mu \rm m}$. Separately, we find that the time-integrated shift in ionizing radiation is a negligible $\sim \!5{{\ \rm per\ cent}}$, though we show that the Lyman-α escape fraction could end up higher for helium-enriched stars.

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