Galaxy formation and evolution

Abstract:

Residuals between measured galactic radii and those predicted by the Fundamental Plane (FP) are possible tracers of weak lensing magnification. However, observations have shown these to be systematically correlated with the large-scale structure. We use the Horizon-AGN hydrodynamical cosmological simulation to analyse these intrinsic size correlations (ISCs) for both elliptical (early-type) and spiral (late-type) galaxies at z = 0.06. We fit separate FPs to each sample, finding similarly distributed radius residuals, λ, in each case. We find persistent λλ correlations over three-dimensional separations 0.5–17h⁻¹ Mpc in the case of spiral galaxies, at >3σ significance. When relaxing a mass-selection, applied for better agreement with galaxy clustering constraints, the spiral λλ detection strengthens to 9σ; we detect a 5σ density-λ correlation; and we observe intrinsically-large spirals to cluster more strongly than small spirals over scales ≲10h⁻¹ Mpc at >5σ significance. Conversely, and in agreement with the literature, we observe lower-mass, intrinsically-small ellipticals to cluster more strongly than their large counterparts over scales 0.5–17h⁻¹ Mpc at >5σ significance. We model λλ correlations using a phenomenological non-linear size model, and predict the level of contamination for cosmic convergence analyses. We find the systematic contribution to be of similar order to, or dominant over the cosmological signal. We make a mock measurement of an intrinsic, systematic contribution to the projected surface mass density Σ(r), and find statistically significant low-amplitude, positive (negative) contributions from lower-mass spirals (ellipticals), which may be of concern for large-scale (⁠≳7h⁻¹ Mpc) measurements.

Abstract:

The dramatic first images with JWST demonstrated its power to provide unprecedented spatial detail for galaxies in the high-redshift universe. Here, we leverage the resolution and depth of the JWST Cosmic Evolution Early Release Science Survey data in the Extended Groth Strip to perform pixel-level morphological classifications of galaxies in JWST F150W imaging using the Morpheus deep-learning framework for astronomical image analysis. By cross-referencing with existing photometric redshift catalogs from the Hubble Space Telescope (HST) CANDELS survey, we show that JWST images indicate the emergence of disk morphologies before z ∼ 2 and with candidates appearing as early as z ∼ 5. By modeling the light profile of each object and accounting for the JWST point-spread function, we find the high-redshift disk candidates have exponential surface brightness profiles with an average Sérsic index 〈n〉 = 1.04 and >90% displaying “disky” profiles (n < 2). Comparing with prior Morpheus classifications in CANDELS we find that a plurality of JWST disk galaxy candidates were previously classified as compact based on the shallower HST imagery, indicating that the improved optical quality and depth of the JWST helps to reveal disk morphologies that were hiding in the noise. We discuss the implications of these early disk candidates on theories for cosmological disk galaxy formation