A Morphology Catalog of Galaxies in CEERS: Evolution in the Size and Color Gradients of Galaxies Since Cosmic Dawn

Abstract

We present measurements of morphological parameters from fitting 53,885 galaxies detected to a magnitude limit of F356W$< 28.5$ in the CEERS NIRCam imaging with galfit in six broadband filters: F115W, F150W, F200W, F277W, F356W, and F444W. We provide a public catalog of Sérsic index, effective semi-major axis, axis ratio, integrated magnitude, and position angle for these galaxies in each of the filters. Uncertainties in the measured parameters are estimated from simulated galaxies that have similar noise and background properties as the observed galaxies. We compare our measurements with those in the CANDELS/EGS field measured with HST/WFC3 and find that the sizes agree to within 0.09 dex and the Sérsic indices agree to within 0.13 dex. We further present the evolution in the size-mass relation, and find that the evolution to $z\sim9$ is consistent with previous results derived at lower redshift. Finally, we look at the color gradients of galaxies at $1<z<5$ and find that for late-type galaxies ($n<2.5$), there is a strong dependence on mass, but no apparent evolution with redshift, indicating that the stellar populations and dust attenuation in more massive galaxies vary substantially with radius and contribute to significant morphological $k-$corrections. For early type galaxies ($n>2.5$), the color gradients are nearly flat with no dependence on mass, indicating that the stellar populations are more uniform throughout. The structural measurements presented are accurate to $20\%$ or better for most galaxies with F356W $<27.0$ mag and will enable further studies of galaxy morphology to $z\sim10$.

Figures (4)

• Figure 1: Left: Difference between F277W galfit model magnitudes and SExtractor magnitudes for galaxies where the galfit solution converged successfully (89% of all sources). The magenta line shows a running median of the offset between the two magnitudes. Galaxies with good fits (flag=0) are shown in black. Galaxies whose galfit magnitude is more than $3\sigma$ away from the median offset (flag=1) are shown in blue. Galaxies whose fits reached a constraint limit in one or more parameters (flag=2) are shown in red. Right: Histogram of sources as a function of difference between F277W galfit magnitude and SExtractor magnitude. Colors are the same as in the left-hand panel.
• Figure 2: An illustration of the galfit fitting in six broadband filters for three galaxies of different morphological types. Images are 3$.\!\!^{\prime\prime}$0 on a side. Results for each galaxy are shown in three rows; top row: a color composite followed by images of the galaxy in each individual filter, middle row: model color composite followed by the galfit model in each filter, bottom row: residual color composite followed by the residuals obtained by subtracting the best-fit model in each filter. The galaxy ID in the CEERS catalog and its photometric redshift are listed in the color composite image panel. The best fitting Sérsic index $n$ and effective semi-major axis $r_e$ for each filter are listed in the middle row for each model. CEERS-56498 (top) is an elliptical galaxy, well-fit by an $n\sim4$ profile in all bands. CEERS-80909 (middle) is a face-on disk whose spiral arms are noticeable in the residuals. CEERS-74656 is an edge-on disk with a dust-lane that is noticeable in the transition from blue to red wavelengths, and results in uneven residuals.
• Figure 3: Correlation between errors for simulated galaxies, presented as the difference between (recovered - input) values for each parameter of interest: $m$, $n$, $r_e$, and $q$. Objects whose recovered magnitudes are brighter than truth tend to have larger recovered sizes and Sérsic indices (upper left and middle left panels). Likewise, objects with larger recovered $n$ tend to have larger recovered $r_e$ values (middle panel). There is no obvious correlation between errors in axis ratio with the other parameters (bottom row).
• Figure 4: From left to right we show a comparison between measured effective radii, $r_e$; Sérsic indices, $n$; and axis ratios, $q$ for galaxies detected in both the CEERS and CANDELS surveys, restricted to galaxies with $m_{\rm{F150W}} < 24.5$ ($r_e$ and $q$) or $m_{\rm{F150W}} < 23.5$ ($n$), where the CANDELS values are quoted to have random uncertainties less than $\sim20\%$vanderWel12. CEERS values are from JWST/NIRCam F150W images, while CANDELS datapoints are from HST/WFC3 F160W images vanderWel12. The top panels show the 1:1 comparison between surveys while the bottom panels show the offset (in log space) of the CEERS values from CANDELS. The 1:1 correspondence is shown as a dotted line in each panel, along with the $1\sigma$ spread shown as the upper and lower dashed lines whose magnitude is quoted in the lower right corner of the top panels. For $n$, there is a noticeable offset in the best-fit value between CEERS and CANDELS, with CEERS $n$ being larger by 0.055 dex (i.e., $14\%$ larger in linear units), and we have offset the 1:1 line and corresponding spread by this amount accordingly. There is a slightly less noticeable offset between CEERS and CANDELS $r_e$ values, with CEERS $r_e$ being 0.01 dex larger over this magnitude range. We have similarly offset the 1:1 line and corresponding spread by this value in the left-hand panels. Shaded regions in the lower middle and right panels indicate either unphysical regions of parameter space, or regions disallowed by a constraint set on a parameter in one or both datasets.