Jahmour J. Givans
A5016282841- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Cosmology and Gravitation Theories
- Astronomy and Astrophysical Research
- Adaptive optics and wavefront sensing
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Dark Matter and Cosmic Phenomena
- CCD and CMOS Imaging Sensors
- Gamma-ray bursts and supernovae
- Particle physics theoretical and experimental studies
- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- solar cell performance optimization
- Planetary Science and Exploration
Princeton University
2022-2025
Flatiron Health (United States)
2022-2025
Flatiron Institute
2022-2025
The Ohio State University
2020
We present cosmological constraints from a gravitational lensing mass map covering 9400 sq. deg. reconstructed CMB measurements made by the Atacama Cosmology Telescope (ACT) 2017 to 2021. In combination with BAO (from SDSS and 6dF), we obtain amplitude of matter fluctuations $\sigma_8 = 0.819 \pm 0.015$ at 1.8% precision, $S_8\equiv\sigma_8({\Omega_{\rm m}}/0.3)^{0.5}=0.840\pm0.028$ Hubble constant $H_0= (68.3 1.1)\, \text{km}\,\text{s}^{-1}\,\text{Mpc}^{-1}$ 1.6% precision. A joint...
Observations of the millimeter sky contain valuable information on a number signals, including blackbody cosmic microwave background (CMB), Galactic emissions, and Compton-y distortion due to thermal Sunyaev-Zel'dovich (tSZ) effect. Extracting new insight into cosmological astrophysical questions often requires combining multiwavelength observations spectrally isolate one component. In this work, we present arc-minute-resolution map, which traces out line-of-sight-integrated electron...
The sum of neutrino masses can be measured cosmologically, as the sub-eV particles behave “hot” dark matter whose main effect is to suppress clustering compared a universe with same amount purely cold matter. Current astronomical data provide an upper limit on <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:mo>∑</a:mo><a:msub><a:mrow><a:mi>m</a:mi></a:mrow><a:mrow><a:mi>ν</a:mi></a:mrow></a:msub></a:mrow></a:math> between 0.07–0.12 eV at 95% confidence,...
ABSTRACT We present and validate 20 deg2 of overlapping synthetic imaging surveys representing the full depth Nancy Grace Roman Space Telescope High-Latitude Imaging Survey (HLIS) 5 yr observations Vera C. Rubin Observatory Legacy Time (LSST). The two are summarized, with reference to existing 300 LSST simulated produced as part Dark Energy Science Collaboration (DESC) Data Challenge 2 (DC2). Both observe same DESC DC2 universe. For survey, we simulate for first time fully chromatic images...
ABSTRACT The upcoming Nancy Grace Roman Space Telescope will carry out a wide-area survey in the near-infrared. A key science objective is measurement of cosmic structure via weak gravitational lensing. data be undersampled, which introduces new challenges source galaxy shapes; potential solution to use linear algebra-based coaddition techniques such as imcom that combine multiple undersampled images produce single oversampled output mosaic with desired ‘target’ point spread function (PSF)....
Abstract Three-dimensional correlations of the Lyman- α (Ly ) forest and cross between Ly quasars have been measured on large scales, allowing a precise measurement baryon acoustic oscillation (BAO) feature at redshifts z > 2. These 3D are often modelled using linear perturbation theory, but full-shape analyses to extract cosmological information beyond BAO will require more realistic models capable describing non-linearities present smaller scales. We flux power spectrum from...
The baryon acoustic oscillation (BAO) scale acts as a standard ruler for measuring cosmological distances and has therefore emerged leading probe of cosmic expansion history. However, any physical effect that alters the length can lead to bias in our determination distance rate. One these effects is streaming velocity, relative velocity between baryons dark matter early Universe, which couples BAO due their common origin waves at recombination. In this work, we investigate impact on feature...
ABSTRACT One challenge for applying current weak lensing analysis tools to the Nancy Grace Roman Space Telescope is that individual images will be undersampled. Our companion paper presented an initial application of Imcom – algorithm builds optimal mapping from input output pixels reconstruct a fully sampled combined image on simulations. In this paper, we measure noise power spectra, identify sources major features in and show simple analytic models ignore sampling effects underestimate...
Weak gravitational lensing has emerged as a leading probe of the growth cosmic structure. However, shear signal is very small and accurate measurement depends critically on our ability to understand how non-ideal instrumental effects affect astronomical images. WFIRST will fly focal plane containing 18 Teledyne H4RG-10 near infrared detector arrays, which present different instrument calibration challenges from previous weak observations. Previous work shown that correlation functions flat...
Abstract Weak gravitational lensing is a powerful tool for studying the growth of structure across cosmic time. The shear signal required weak analyses very small, so any undesirable detector-level effects which distort astronomical images can significantly contaminate inferred shear. Nancy Grace Roman Space Telescope (Roman) will fly focal plane with 18 Teledyne H4RG-10 near-infrared (IR) detector arrays; these have never before been used and they present different instrument calibration...
The relative velocity between baryons and dark matter in the early Universe can suppress formation of small-scale baryonic structure leave an imprint on baryon acoustic oscillation (BAO) scale at low redshifts after reionization. This "streaming velocity" affects post-reionization gas distribution by directly reducing abundance pre-existing mini-halos ($\lesssim 10^7 M_{\bigodot}$) that could be destroyed reionization indirectly modulating history via photoionization within these mini-halos....
PFS (Prime Focus Spectrograph), a next generation facility instrument on the Subaru telescope, is now being tested telescope. The equipped with very wide (1.3 degrees in diameter) field of view Subaru's prime focus, high multiplexity by 2394 reconfigurable fibers, and waveband spectrograph that covers from 380nm to 1260nm simultaneously one exposure. Currently engineering observations are ongoing Prime Instrument (PFI), Metrology Camera System (MCS), first spectrpgraph module (SM1) visible...
One challenge for applying current weak lensing analysis tools to the Nancy Grace Roman Space Telescope is that individual images will be undersampled. Our companion paper presented an initial application of Imcom - algorithm builds optimal mapping from input output pixels reconstruct a fully sampled combined image on simulations. In this paper, we measure noise power spectra, identify sources major features in and show simple analytic models ignore sampling effects underestimate spectra...
The upcoming Nancy Grace Roman Space Telescope will carry out a wide-area survey in the near infrared. A key science objective is measurement of cosmic structure via weak gravitational lensing. data be undersampled, which introduces new challenges source galaxy shapes; potential solution to use linear algebra-based coaddition techniques such as Imcom that combine multiple undersampled images produce single oversampled output mosaic with desired "target" point spread function (PSF). We...
Observations of the millimeter sky contain valuable information on a number signals, including blackbody cosmic microwave background (CMB), Galactic emissions, and Compton-$y$ distortion due to thermal Sunyaev-Zel'dovich (tSZ) effect. Extracting new insight into cosmological astrophysical questions often requires combining multi-wavelength observations spectrally isolate one component. In this work, we present arcminute-resolution map, which traces out line-of-sight-integrated electron...
Abstract Active galactic nuclei (AGN) are the signposts of black hole growth, and likely play an important role in galaxy evolution. An outstanding question is whether AGN different spectral types indicate evolutionary stages coevolution holes galaxies. We present angular correlation function between sample selected from Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) optical photometry Wide-field Infrared Survey Explorer mid-IR a luminous red (LRG) HSC-SSP. investigate clustering...
The sum of cosmic neutrino masses can be measured cosmologically, as the sub-eV particles behave `hot' dark matter whose main effect is to suppress clustering compared a universe with same amount purely cold matter. Current astronomical data provide an upper limit on $\Sigma m_{\nu}$ between 0.07 - 0.12 eV at 95% confidence, depending choice data. This bound assumes that cosmological model $\Lambda$CDM, where energy constant, spatial geometry flat, and primordial fluctuations follow pure...
Active galactic nuclei (AGN) are the signposts of black hole growth, and likely play an important role in galaxy evolution. An outstanding question is whether AGN different spectral types indicate evolutionary stages coevolution holes galaxies. We present angular correlation function between sample selected from Hyper Suprime Camera Subaru Strategic Program (HSC-SSP) optical + Wide-field Infrared Survey Explorer (WISE) mid-IR photometry, a luminous red (LRG) HSC-SSP. investigate clustering...
This paper presents thermal system and imaging performance test results from the first of four near infrared cameras for SuMIRe (Subaru Measurement Images Redshifts) Prime Focus Spectrograph (PFS) being developed Subaru Telescope. The PFS camera is a large (330 mm entrance aperture to accommodate 275 collimated beam diameter) cryogenically cooled vacuum Schmidt with 300 focal length that images dispersed light onto 4k x 4k, 15 µm pixel, HgCdTe substrate-removed Teledyne 1.7 detector. 230 kg...
The large-angular-scale falloff in the autocorrelation function for cosmic microwave background (CMB) temperature has long intrigued cosmologists and fueled speculation about suppressed superhorizon power. Here we highlight an inconsistency between quadrupole more recently obtained E-mode polarization from Planck PR3. arises primarily at CMB surface of last scatter, while epoch reionization, but two still probe comparable distance scales. Although is intriguingly low (much greater than a...