We present JWST/NIRSpec high-resolution G395H/F290LP spectroscopy of MACS0647‑JD, a gravitationally lensed galaxy merger at z = 10.167. The new spectroscopy, which is acquired for the two lensed images (JD1 and JD2), detects and resolves emission lines in the rest-frame ultraviolet and blue optical, including the resolved [O II] λ λ3726, 3729 doublet, [Ne III] λ3870, He I λ3890, Hδ, Hγ, and [O III] λ4363. This is the first observation of the resolved [O II] λ λ3726, 3729 doublet for a galaxy at z > 8. We measure a line flux ratio [O II] λ3729/λ3726 = 0.9 ± 0.3, which corresponds to an estimated electron density of . This is significantly higher than the electron densities of local galaxies reported in the literature. We compile measurements from the literature and further analyze the redshift evolution of n e . We find that the redshift evolution follows the power-law form of n_{e} = A × (1 + z)^{p} with A=54^{+31}{-23}cm^{‑3} and p=1.2^{+0.4}{-0.4}. This power-law form may be explained by a combination of metallicity and morphological evolution of galaxies, which become, on average, more metal poor and more compact with increasing redshift.

We present JWST/NIRSpec prism spectroscopy of MACS0647‑JD, a triply lensed z ∼ 11 candidate discovered in Hubble Space Telescope imaging and spatially resolved by JWST imaging into two components, A and B. Spectroscopy of component A yields a spectroscopic redshift z = 10.17 based on seven detected emission lines: C III] λ λ1907, 1909, [O II] λ3727, [Ne III] λ3869, [Ne III] λ3968, Hδ λ4101, Hγ λ4340, and [O III] λ4363. These are the second-most distant detections of these emission lines to date, in a galaxy observed just 460 million years after the Big Bang. Based on observed and extrapolated line flux ratios we derive a gas-phase metallicity 12 + log(O/H) ∼ 7.5–8.0, or Z ∼ (0.06–0.2) Z ⊙, ionization parameter = ‑1.9 ± 0.2, and an ionizing photon production efficiency erg‑1 Hz. The spectrum has a softened Lyα break, evidence for a strong Lyα damping wing. The Lyα damping wing also suppresses the F150W photometry, explaining the slightly overestimated photometric redshift z = 10.6 ± 0.3. MACS0647‑JD has a stellar mass log(M/M ⊙) = 8.1 ± 0.3, including ∼6 × 107 M ⊙ in component A, most of which formed recently (within ∼20 Myr) with a star formation rate ∼ 2 ± 1 M ⊙ yr‑1, all within an effective radius 70 ± 24 pc. Spectroscopy of a fainter companion galaxy C separated by a distance of ∼ 3 kpc reveals a Lyman break consistent with z ∼ 10.17. MACS0647‑JD is likely the most distant galaxy merger known.

We study the spatially resolved stellar populations of 444 galaxies at 0.3 < z < 6.0 in two clusters (WHL 0137-08 and MACS 0647+70) and a blank field, combining imaging data from the Hubble Space Telescope and JWST to perform spatially resolved spectral energy distribution (SED) modeling using PIXEDFIT. The high spatial resolution of the imaging data combined with magnification from gravitational lensing in the cluster fields allows us to resolve a large fraction of our galaxies (109) to subkiloparsec scales. At redshifts around cosmic noon and higher (2.5 ≲ z ≲ 6.0), we find mass-doubling times to be independent of radius, inferred from flat specific star formation rate (sSFR) radial profiles and similarities between the half-mass and half-SFR radii. At lower redshifts (1.5 ≲ z ≲ 2.5), a significant fraction of our star-forming galaxies shows evidence for nuclear starbursts, inferred from a centrally elevated sSFR and a much smaller half-SFR radius compared to the half-mass radius. At later epochs, we find more galaxies suppress star formation in their centers but are still actively forming stars in the disk. Overall, these trends point toward a picture of inside-out galaxy growth consistent with theoretical models and simulations. We also observe a tight relationship between the central mass surface density and global stellar mass with ~0.38 dex scatter. Our analysis demonstrates the potential of spatially resolved SED analysis with JWST data. Future analysis with larger samples will be able to further explore the assembly of galaxy mass and the growth of their structures.

We present new observations of MRG-M2129, a quiescent galaxy at z = 2.15, with the Atacama Large Millimeter/submillimeter Array (ALMA). With the combination of the effect of gravitational lensing by the foreground galaxy cluster and the angular resolution provided by ALMA, our data reveal 1.2 mm continuum emission at ~130 pc angular resolution. Compact dust continuum is detected at 7.9σ in the target but displaced from its stellar peak position by 62 ± 38 mas, or ~169 ± 105 pc in the source plane. We find a considerably high dust-to-stellar mass ratio, 4 × 10-4. From nondetection of the [C I] 3P2 → 3P1 line, we derive 3σ upper limits on the molecular gas-to-dust mass ratio δGDR < 60 and the molecular gas-to-stellar mass ratio f_H2 < 2.3%. The derived δ GDR is ≳2× smaller than the typical value assumed for quiescent galaxies in the literature. Our study supports the idea that there exists a broad range of δ GDR and urges submillimeter follow-up observations of quenching/recently quenched galaxies at similar redshifts. Based on the inferred low δ GDR and other observed properties, we argue that the central black hole is still active and regulates star formation in the system. Our study exhibits a rare case of a gravitationally lensed type 2 QSO harbored by a quiescent galaxy.

We study spatially resolved scaling relations among stars, dust, and gas in ten nearby spiral galaxies. In a preceding paper, we have derived spatially resolved properties of the stellar population and dust by a panchromatic spectral energy distribution fitting using piXedfit. Now, we investigate resolved star formation (ΣH2-ΣSFR-Σ*) and dust scaling relations. While the relations with all subgalactic regions of the galaxies are reasonably tight (σ < 0.3 dex), we find that most of the scaling relations exhibit galaxy-to-galaxy variations in normalization and shape. Only two relations of Σdust-Σgas and Σdust-ΣH2 do not show noticeable galaxy-to-galaxy variations among our sample galaxies. We further investigate the correlations among the scaling relations. We find significant correlations among the normalization of the ΣH2-ΣSFR-Σ* relations, which suggest that the galaxies with higher levels of resolved H2 fraction (fH2) tend to have higher levels of resolved star formation efficiency (SFE) and specific star formation rate (sSFR). We also observe that the galaxies with higher levels of resolved dust-to-stellar mass ratios tend to have higher levels of resolved sSFR, SFE, and fH2. Moreover, we find that the galaxies with higher global sSFR and less compact morphology tend to have higher levels of the resolved sSFR, SFE, and fH2, which can explain the variations in the normalization of the ΣH2-ΣSFR-Σ* relationships. Overall, we observe indications of the contributions of both global and local factors in governing the star formation process in galaxies.

We study spatially resolved properties (on spatial scales of ~1-2 kpc out to at least 3 effective radii) of the stars, dust, and gas in 10 nearby spiral galaxies. The properties of the stellar population and dust are derived by fitting the spatially resolved spectral energy distribution (SED) with more than 20 photometric bands ranging from far-ultraviolet to far-infrared. Our newly developed software piXedfit performs point-spread function matching of images, pixel binning, and models the stellar light, dust attenuation, dust emission, and emission from a dusty torus heated by an active galactic nucleus simultaneously through the energy-balance approach. With this self-consistent analysis, we present the spatially resolved version of the IRX-β relation, finding that it is consistent with the relationship from the integrated photometry. We show that the old stellar populations contribute to the dust heating, which causes an overestimation of the star formation rate (SFR) derived from the total ultraviolet and infrared luminosities on kiloparsec scales. With archival high-resolution maps of atomic and molecular gas, we study the radial variation of the properties of the stellar populations (including stellar mass, age, metallicity, and SFR), dust (including dust mass, dust temperature, and abundance of polycyclic aromatic hydrocarbon), and gas, as well as dust-to-stellar mass and dust-to-gas mass ratios. We observe a depletion of the molecular gas mass fraction in the central region of the majority of the galaxies, suggesting that the lack of available fuel is an important factor in suppressing the specific SFR at the center.

We present piXedfit, pixelized spectral energy distribution (SED) fitting, a Python package that provides tools for analyzing spatially resolved properties of galaxies using multiband imaging data alone or in combination with integral field spectroscopy (IFS) data. It has six modules that can handle all tasks in the spatially resolved SED fitting. The SED-fitting module uses the Bayesian inference technique with two kinds of posterior sampling methods: Markov Chain Monte Carlo (MCMC) and random dense sampling of parameter space (RDSPS). We test the performance of the SED-fitting module using mock SEDs of simulated galaxies from IllustrisTNG. The SED fitting with both posterior sampling methods can recover physical properties and star formation histories of the IllustrisTNG galaxies well. We further test the performance of piXedfit modules by analyzing 20 galaxies observed by the CALIFA and MaNGA surveys. The data are comprised of 12-band imaging data from the Galaxy Evolution Explorer, SDSS, 2MASS, and WISE and the IFS data from CALIFA or MaNGA. The piXedfit package can spatially match (in resolution and sampling) the imaging and IFS data. By fitting only the photometric SEDs, piXedfit can predict the spectral continuum, Dn4000, Hα, and Hβ well. The star formation rate derived by piXedfit is consistent with that derived from Hα emission. The RDSPS method gives equally good fitting results as the MCMC and is much faster. As a versatile tool, piXedfit is equipped with a parallel computing module for efficient analysis of large data sets and will be made publicly available (https://github.com/aabdurrouf/piXedfit) .

We investigate a relation between surface densities of star formation rate (SFR) and stellar mass (M*) at a ∼1 kpc scale namely spatially resolved star formation main sequence (SFMS) in massive (log (M*/M⊙) > 10.5) face-on disc galaxies at 0.01 < z < 0.02 and 0.8 < z < 1.8 and examine evolution of the relation. The spatially resolved SFMS of z ∼ 0 galaxies is discussed in a companion paper. For z ∼ 1 sample, we use eight bands imaging data set from Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey and 3D- HST and perform a pixel-to-pixel spectral energy distribution fitting to derive the spatially resolved SFR and M*. We find a linear spatially resolved SFMS in the z ∼ 1 galaxies that lie on the global SFMS, while a `flattening’ at high Σ* end is found in that relation for the galaxies that lie below the global SFMS. Comparison with the spatially resolved SFMS of the z ∼ 0 galaxies shows smaller difference in the specific SFR (sSFR) at low Σ* than that at high Σ*. This trend is consistent with the evolution of the sSFR(r) radial profile, which shows a faster decrease in the central region than in the outskirt, agrees with the inside-out quenching scenario. We then derive an empirical model for the evolution of the Σ*(r), ΣSFR(r), and sSFR(r) radial profiles. Based on the empirical model, we estimate the radial profile of the quenching time-scale and reproduce the observed spatially resolved SFMS at z ∼ 1 and ∼0.

We investigate the relation between star formation rate (SFR) and stellar mass (M*) at the sub-galactic scale (∼1 kpc) of 93 local (0.01 < z < 0.02) massive (M* > 1010.5 M⊙) spiral galaxies. To derive a spatially resolved SFR and stellar mass, we perform the so-called pixel-to-pixel spectral energy distribution (SED) fitting, which fits an observed spatially resolved multiband SED with a library of model SEDs using Bayesian statistics. We use two bands (far-ultraviolet or FUV and near-ultraviolet or NUV) and five bands (u, g, r, I and z) of imaging data from Galaxy Evolution Explorer (GALEX) and Sloan Digital Sky Survey (SDSS), respectively. We find a tight nearly linear relation between the local surface density of SFR (ΣSFR) and stellar mass (Σ*), which is flattened at high Σ*. The near linear relation between Σ* and ΣSFR suggests a constant specific SFR (sSFR) throughout the galaxies, and the scatter of the relation is directly related to that of the sSFR. Therefore, we analyse the variation of the sSFR in various scales. More massive galaxies on average have lower sSFR throughout them than less massive galaxies. We also find that barred galaxies have a lower sSFR in the core region than non-barred galaxies. However, in the outer region, the sSFRs of barred and non-barred galaxies are similar and lead to a similar total sSFR.