arXiv subjects

Katherine Alatalo

Publications and source records attributed to Katherine Alatalo.

At least 19 recordsLinked to original sources

arXiv2026

When Jets Don't Quench: Near-Infrared H$_{2}$ in Star Forming Low-Excitation Radio Galaxies

We present new Gemini/GNIRS near-infrared spectroscopic observations of eight low-redshift ($z < 0.1$) blue low-excitation radio galaxies (BLERGs), a rare subset ($\sim 2.5\%$ of low-excitation radio galaxies; LERGs) that complicate the classical jet-mode AGN picture by combining radio activity with star-forming, gas-rich hosts. These star-forming BLERGs exhibit significant warm H$_2$ emission traced via ro-vibrational transitions at $T \sim 2000$--$4000$ K. We find that BLERGs span a broad range of mass-normalized warm H$_2$ luminosities ($L_{\rm H_2}/M_\star$), comparable to radio-emitting early-type galaxies, yet without a clear positive dependence on radio power. Instead, the strongest H$_2$ emission preferentially occurs in morphologically disturbed and advanced-merger systems, while compact radio sources ($\lesssim 20$ kpc) remain plausible sites of localized jet-ISM interaction. Together, these results suggest that merger-driven processes, including tidal shocks, gas inflows, and disturbed interstellar medium conditions, are the dominant drivers of warm molecular gas excitation in BLERGs, although localized jet-driven heating may contribute in individual systems. The compact radio morphologies, gas-rich hosts, and rarity of BLERGs are consistent with a short-lived evolutionary phase in which radio AGN activity coexists with an interaction-driven, molecular-rich interstellar medium prior to the onset of large-scale maintenance-mode feedback. Spatially resolved spectroscopy and higher-resolution radio imaging will be essential to disentangle the relative roles of mergers and jets in regulating the molecular gas of jet-mode AGN.

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arXiv2026

Tracing Radio AGN-Driven Quenching in Post-Starburst Galaxies at Cosmic Noon

We present a radio continuum study of photometrically selected cosmic noon (0.5 10^{11}$M$_\odot$. Massive PSBs have a comparable detection fraction to that of massive quiescent galaxies ($f_{det}=8\pm1\%$), and both classes have lower fractions than that of massive star-forming galaxies ($f_{det}=13\pm1\%$) in the same field. The radio luminosities of detected PSBs, ${\rm L}_{1.4}\sim 10^{22.8}-10^{24.9}$W/Hz, exceed those from star formation by a median factor of 37 indicative of a possible AGN origin. Their compact morphologies ($\lesssim15$ kpc at $z_{med}=1.5$) suggest low-luminosity AGN with less powerful jets. Stacking the undetected PSBs reveals a weak radio detection ($3.9σ$) in the highest mass bin (M$_*>10^{11}$M$_\odot$). In contrast, 1.4 GHz detected quiescent galaxies have radio luminosities reaching radio-loud levels, and a higher prevalence of extended morphologies indicative of large-scale jetted AGN. The AGN contribution is also detected in stacked measurements of quiescent galaxies. Overall, our results support a short radio AGN duty cycle for PSBs, characterized by weak radio jets, suggesting radio-driven maintenance mode feedback may become important at older ages.

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arXiv2026

The Spatially Resolved Hot Gas Properties of NGC 1266's AGN-Driven Outflow

Galactic winds play a critical role in galaxy evolution, yet their structure and driving mechanisms remain poorly understood, especially in low-luminosity AGN (LLAGN) systems. NGC~1266 hosts one such LLAGN, embedded in a massive molecular gas reservoir that is not forming stars, likely due to AGN feedback. We analyze deep archival \textit{Chandra} data to constrain the properties of its hot gas and compare them to other wind systems. We find temperatures of $0.25-1.8$~keV and notably high electron densities of $0.33-4.2$~cm$^{-3}$, suggesting significant mass loading, further supported by charge exchange emission in the southern lobe, one of the few AGN systems where it has been detected. We measure pressures and thermal energies of $10^6-10^8$~K cm$^{-3}$ and $10^{54}-10^{56}$~erg, exceeding the minimum energy needed for the radio jet to power the outflow and implying the hot phase comprises a large fraction of the energy budget. Archival MUSE data reveal a cavity-like feature in the southern outflow, potentially associated with the far side of the outflow cone. At the maximum outflow extent, the warm and hot phases appear to be in pressure equilibrium. Coupled with short cooling timescales of $\sim$1~Myr, comparable to the advection time, this suggests the outflow is undergoing radiative cooling and may have stalled. Finally, we compare NGC~1266 to other local AGN and starburst galaxies, finding NGC~1266 to be the densest wind in the sample.

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arXiv2026

The JWST EXCELS survey: Insights into the nature of quenching at cosmic noon

We study 24 massive quiescent galaxies with $\log \textrm{M}_*/\textrm{M}_\odot > 10$ at $1 < z < 3$ with JWST/NIRSpec medium-resolution observations from the Early eXtragalactic Continuum and Emission Line Survey (EXCELS). We reconstruct their star formation histories and find that they have large bursts ($100\textrm{ M}_{\odot} \textrm{yr}^{-1} -1000 \textrm{ M}_{\odot} \textrm{yr}^{-1}$), followed by a rapid truncation of star formation. The number densities of the quenched galaxies in our sample that we predict underwent a submillimeter phase are consistent with submillimeter galaxies being the progenitors of our quenched population. The median post-starburst visibility time is $\sim600$ Myr, with more massive galaxies ($\log \textrm{M}_*/\textrm{M}_\odot > 10.7$) exhibiting shorter visibility times than lower mass galaxies. The range of quenching times -- defined as the time from the peak starburst to the time of quiescence -- found in this sample ($0.06-1.75$ Gyr) suggests multiple quenching pathways, consistent with previous studies. We do not see evidence for quenching mechanisms varying with redshift between $1<z<3$. We detect evidence for weak AGN activity in 4 out of the 8 galaxies with robust emission line detections, based on line ratio diagnostics. Our findings suggest that there are a diverse range of quenching mechanisms at cosmic noon, and support a scenario in which the primary quenching mechanisms are rapid ($<500$ Myr) following a starburst.

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arXiv2026

A Multiwavelength Evaluation of AGN in the Post-Starburst Phase

The quenching of star formation is a crucial phase in galaxy evolution. Although active galactic nuclei (AGN) feedback has been proposed as a key driver of this transition, the lack of strong AGN in nearby quenching galaxies raises questions about its effectiveness. In this study, we investigate AGN activity in post-starburst galaxies (PSBs), star-forming galaxies (SFGs), and quiescent galaxies (QGs) at $z<$ 0.2, using multiwavelength data from eROSITA/eFEDS (X-ray), WISE (mid-infrared), and FIRST (radio). We assess AGN incidence and strength across different stages and apply stacking techniques to undetected galaxies to recover average AGN properties. Comparisons between observed luminosity and that expected from star formation (L$_{\rm obs}$/L$_{\rm SF}$) show that PSBs are consistent with star formation dominating their radio and X-ray emission. Although PSBs exhibit a MIR AGN incidence rate twice that of SFGs, their estimated AGN luminosities are small compared to those of MIR AGN in the literature. PSBs overall do not display significantly enhanced AGN emission relative to mass- and redshift-matched SFGs and QGs. While the presence of obscured, low-luminosity AGN in PSBs cannot be excluded, such AGN, if present, could be fueled by residual gas from the preceding starburst and may not play a dominant role in quenching. Our findings suggest that AGN's role in quenching at low redshift is more subtle than violently removing the gas -- the feedback is likely more "preventive" than "ejective".

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arXiv2026

Constraining Nuclear Molecular Gas Content with High-resolution CO Imaging of GOALS Galaxies

We present measurements of the cool molecular gas mass around the nuclei of two gas-rich mergers, III Zw 035 and IRAS F01364-1042, whose enclosed masses (M$_\mathrm{enc}$) within the central 40-80 pc would be overmassive if attributed entirely to the supermassive black hole mass (SMBH) and compared to SMBH-galaxy scaling relations. Our gas mass measurements are derived from Atacama Large Millimeter/submillimeter Array (ALMA) Band 6 long-baseline observations of CO(J=2-1) and 230 GHz continuum emission at 14-20 pc resolution, which probes below the resolving limit of the previous black hole mass measurements. Subtracting molecular gas mass from these enclosed masses is not enough to reconcile with BH-galaxy relationships, but independently measuring M$_\mathrm{enc}$ using the cold CO(2-1) gas does shift the black holes down to their expected values. Still, these ALMA data reveal respective molecular gas masses of $\sim$3$\times$10$^7$ to $\sim$6$\times$10$^8$ M$_\odot$ within 70 pc of these black holes, which could challenge some black hole accretion models that assume nuclear gas like this has no angular momentum.

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arXiv2025

Clumpy, dense gas in the outflow of NGC 1266

Outflows are one of the most spectacular mechanisms through which active galactic nuclei (AGN) impact their host galaxy, though the role of AGN-driven outflows in global star formation regulation across the galaxy population is unclear. NGC 1266 is an excellent case study for investigating the outflows and star formation quenching because it is a nearby (D\sim30 Mpc) AGN host galaxy with an outflow driving shocks through the interstellar medium (ISM) and has recently quenched its star formation outside the nucleus. While previous works have studied the molecular outflow from its CO emission, to fully characterize the impact the outflow has on the ISM observations probing the dense, cold gas are necessary. Our ALMA cycle 0 observations do not detect a molecular outflow in 13CO(2-1) and yield a lower limit 12CO/13CO \geq 250, suggesting a highly optically thin CO outflow with low 13CO abundance. In contrast, we detect substantial HCN(1-0) emission in the outflow, with an HCN(1-0)/12CO(1-0) ratio of 0.09, consistent with global measurements of many star-forming galaxies and Luminous InfraRed Galaxies (LIRGs). We conclude that the CO emission traces a diffuse component of the molecular gas with a low optical depth, whereas the HCN(1-0) traces dense clumps of gas entrained in the outflow. We measure an upper limit molecular outflow rate of < 85 Msun/yr. Assuming the ongoing nuclear star formation and outflow continue at the same rates, NGC 1266 will deplete its gas reservoirs in 450 Myr or longer, indicating that relatively low-level AGN feedback is capable of gradually expelling the molecular gas reservoir after a rapid quenching event.

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arXiv2025

No evidence for excess AGN activity in recently quenched massive galaxies at cosmic noon

We present an analysis of AGN activity within recently quenched massive galaxies at cosmic noon ($z\sim 2$), using deep Chandra X-ray observations of the Ultra-Deep Survey (UDS) field. Our sample includes over 4000 massive galaxies ($M_\ast > 10^{10.5}$ M$_{\odot}$) in the redshift range $1 < z < 3$, including more than 200 transitionary post-starburst (PSB) systems. We find that X-ray emitting AGN are detected in $6.2 \pm 1.5$ per cent of massive PSBs at these redshifts, a detection rate that lies between those of star-forming and passive galaxies ($8.2 \pm 0.5$ per cent and $5.7 \pm 0.8$ per cent, respectively). A stacking analysis shows that the average X-ray luminosity for PSBs is comparable to older passive galaxies, but a factor of $2.6 \pm 0.3$ below star-forming galaxies of similar redshift and stellar mass. The average X-ray luminosity in all populations appears to trace the star-formation rate, with PSBs showing low levels of AGN activity consistent with their reduced levels of star formation. We conclude that, on average, we see no evidence for excess AGN activity in the post-starburst phase. However, the low levels of AGN activity can be reconciled with the high-velocity outflows observed in many PSBs, assuming the rare X-ray detections represent short-lived bursts of black hole activity, visible $\sim$5 per cent of the time. Thus, X-ray AGN may help to maintain quiescence in massive galaxies at cosmic noon, but the evidence for a direct link to the primary quenching event remains elusive.

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arXiv2024

Shocked POststarburst Galaxy Survey. IV. Outflows in Shocked Post-Starburst Galaxies Are Not Responsible For Quenching

Shocked POst-starburst Galaxies (SPOGs) exhibit both emission lines suggestive of shock-heated gas and post-starburst-like stellar absorption, resulting in a unique subset for galaxy evolution studies. We have observed 77 galaxies that fulfilled the SPOGs criteria selection using the DeVeny Spectrograph on the Lowell Discovery Telescope. Our long-slit minor axis spectra detect H$α$ and [O III] in some SPOGs out to 6 kpc above the galactic plane. We find extraplanar ionized gas in 31 targets of our sample overall. Using their internal and external kinematics, we argue that 22 galaxies host outflows with ionized gas masses ranging from $10^2 M_{\odot}$ to $10^5 M_{\odot}$. The rest are likely extended diffuse ionized gas. A positive correlation exists between AGN luminosity and the extraplanar gas extent, velocity dispersion, and mass$\unicode{x2013}\unicode{x2013}$suggesting that the AGN may indeed drive the outflows detected in AGN hosts. The low masses of the extraplanar gas suggest that these outflows are not depleting each galaxy's gas reserves. The outflows, therefore, are not likely a significant quenching mechanism in these SPOGs.

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arXiv2024

Pulling back the curtain on shocks and star-formation in NGC 1266 with Gemini-NIFS

We present Gemini near-infrared integral field spectrograph (NIFS) K-band observations of the central 400 pc of NGC 1266, a nearby (D$\approx$30 Mpc) post-starburst galaxy with a powerful multi-phase outflow and a shocked ISM. We detect 7 H$_2$ ro-vibrational emission lines excited thermally to $T$$\sim$2000 K, and weak Br$γ$ emission, consistent with a fast C-shock. With these bright H$_2$ lines, we observe the spatial structure of the shock with an unambiguous tracer for the first time. The Br$γ$ emission is concentrated in the central $\lesssim$100 pc, indicating that any remaining star-formation in NGC 1266 is in the nucleus while the surrounding cold molecular gas has little on-going star-formation. Though it is unclear what fraction of this Br$γ$ emission is from star-formation or the AGN, assuming it is entirely due to star-formation we measure an instantaneous star-formation rate of 0.7 M$_\odot$ yr$^{-1}$, though the star-formation rate may be significantly higher in the presence of additional extinction. NGC 1266 provides a unique laboratory to study the complex interactions between AGN, outflows, shocks, and star-formation, all of which are necessary to unravel the evolution of the post-starburst phase.

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arXiv2024

Characterizing the Molecular Gas in Infrared Bright Galaxies with CARMA

We present the CO(1-0) maps of 28 infrared-bright galaxies from the Great Observatories All-Sky Luminous Infrared Galaxy Survey (GOALS) taken with the Combined Array for Research in Millimeter Astronomy (CARMA). We detect 100GHz continuum in 16 of 28 galaxies, which trace both active galactic nuclei (AGNs) and compact star-forming cores. The GOALS galaxies show a variety of molecular gas morphologies, though in the majority of cases, the average velocity fields show a gradient consistent with rotation. We fit the full continuum SEDs of each of the source using either MAGPHYS or SED3FIT (if there are signs of an AGN) to derive the total stellar mass, dust mass, and star formation rates of each object. We adopt a value determined from luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) of $α_{\rm CO}=1.5^{+1.3}_{-0.8}~M_\odot$ (K km s$^{-1}$ pc$^2)^{-1}$, which leads to more physical values for $f_{\rm mol}$ and the gas-to-dust ratio. Mergers tend to have the highest gas-to-dust ratios. We assume the cospatiality of the molecular gas and star formation, and plot the sample on the Schmidt-Kennicutt relation, we find that they preferentially lie above the line set by normal star-forming galaxies. This hyper-efficiency is likely due to the increased turbulence in these systems, which decreases the freefall time compared to star-forming galaxies, leading to "enhanced" star formation efficiency. Line wings are present in a non-negligible subsample (11/28) of the CARMA GOALS sources and are likely due to outflows driven by AGNs or star formation, gas inflows, or additional decoupled gas components.

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arXiv2024

RMS asymmetry: a robust metric of galaxy shapes in images with varied depth and resolution

Structural disturbances, such as galaxy mergers or instabilities, are key candidates for driving galaxy evolution, so it is important to detect and quantify galaxies hosting these disturbances spanning a range of masses, environments, and cosmic times. Traditionally, this is done by quantifying the asymmetry of a galaxy as part of the concentration-asymmetry-smoothness system, $A_{\rm{CAS}}$, and selecting galaxies above a certain threshold as merger candidates. However, in this work, we show that $A_{\rm{CAS}}$, is extremely dependent on imaging properties -- both resolution and depth -- and thus defining a single $A_{\rm{CAS}}$ threshold is impossible. We analyze an alternative root-mean-squared asymmetry, $A_{\rm{RMS}}$, and show that it is independent of noise down to the average SNR per pixel of 1. However, both metrics depend on the resolution. We argue that asymmetry is, by design, always a scale-dependent measurement, and it is essential to define an asymmetry at a given physical resolution, where the limit should be defined by the size of the smallest features one wishes to detect. We measure asymmetry of a set of $z\approx0.1$ galaxies observed with HST, HSC, and SDSS, and show that after matching the resolution of all images to 200 pc, we are able to obtain consistent $A_{\rm{RMS, 200pc}}$ measurements with all three instruments despite the vast differences in the original resolution or depth. We recommend that future studies use $A_{\rm{RMS, x pc}}$ measurement when evaluating asymmetry, where $x$ is defined by the physical size of the features of interest, and is kept consistent across the dataset, especially when the redshift or image properties of galaxies in the dataset vary.

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arXiv2023

The Dragonfly Galaxy. III. Jet-brightening of a High-redshift Radio Source Caught in a Violent Merger of Disk Galaxies

The Dragonfly Galaxy (MRC 0152-209), the most infrared-luminous radio galaxy at redshift z~2, is a merger system containing a powerful radio source and large displacements of gas. We present kpc-resolution data from ALMA and the VLA of carbon monoxide (6-5), dust, and synchrotron continuum, combined with Keck integral-field spectroscopy. We find that the Dragonfly consists of two galaxies with rotating disks that are in the early phase of merging. The radio jet originates from the northern galaxy and brightens when it hits the disk of the southern galaxy. The Dragonfly Galaxy therefore likely appears as a powerful radio galaxy because its flux is boosted into the regime of high-z radio galaxies by the jet-disk interaction. We also find a molecular outflow of (1100 $\pm$ 550) M$_{\odot}$/yr associated with the radio host galaxy, but not with the radio hot-spot or southern galaxy, which is the galaxy that hosts the bulk of the star formation. Gravitational effects of the merger drive a slower and longer lived mass displacement at a rate of (170 $\pm$ 40) M$_{\odot}$/yr, but this tidal debris contain at least as much molecular gas mass as the much faster outflow, namely M(H2) = (3 $\pm$ 1) x 10$^9$ (alpha(CO)/0.8) M$_{\odot}$. This suggests that both the AGN-driven outflow and mass transfer due to tidal effects are important in the evolution of the Dragonfly system. The Keck data show Ly$α$ emission spread across 100 kpc, and CIV and HeII emission across 35 kpc, confirming the presence of a metal-rich and extended circumgalactic medium previously detected in CO(1-0).

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arXiv2022

Resolved Molecular Gas Observations of MaNGA Post-starbursts Reveal a Tumultuous Past

Post-starburst galaxies (PSBs) have recently and rapidly quenched their star-formation, thus they are an important way to understand how galaxies transition from star-forming late-types to quiescent early-types. The recent discovery of large cold gas reservoirs in PSBs calls into question the theory that galaxies must lose their gas to become quiescent. Optical Integral Field Spectroscopy (IFS) surveys have revealed two classes of PSBs: central PSBs with central quenching regions and ring PSBs with quenching in their outskirts. We analyze a sample of 13 nearby (z < 0.1) PSBs with spatially resolved optical IFS data from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey and matched resolution Atacama Large (sub-)Millimeter Array (ALMA) observations of $^{12}$CO(1-0). Disturbed stellar kinematics in 7/13 of our PSBs and centrally concentrated molecular gas is consistent with a recent merger for most of our sample. In galaxies without merger evidence, alternate processes may funnel gas inwards and suppress star-formation, which may include outflows, stellar bars, and minor mergers or interactions. The star-formation efficiencies of the post-starburst regions in nearly half our galaxies are suppressed while the gas fractions are consistent with star-forming galaxies. AGN feedback may drive this stabilization, and we observe AGN-consistent emission in the centers of 5/13 galaxies. Finally, our central and ring PSBs have similar properties except the ionized and molecular gas in central PSBs is more disturbed. Overall, the molecular gas in our PSBs tends to be compact and highly disturbed, resulting in concentrated gas reservoirs unable to form stars efficiently.

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arXiv2022

Forming Stars in a Dual AGN Host: Molecular and Ionized Gas in the Nearby, Luminous Infrared Merger, Mrk 266

We present star formation rates based on cold and ionized gas measurements of Mrk 266 (NGC 5256), a system composed of two colliding gas-rich galaxies, each hosting an active galactic nucleus. Using $^{12}$CO (1-0) observations with the Combined Array for Research in Millimeter-Wave Astronomy (CARMA), we find a total H$_2$ mass in the central region of $1.1\pm0.3\times10^{10}$ $M_\odot$ which leads to a possible future star formation rate of $25\pm10 M_\odot$ yr$^{-1}$. With the Fourier Transform Spectrograph (SITELLE) on the Canada-France-Hawaii Telescope, we measure an integrated H$α$ luminosity and estimate a present-day star formation rate of $15\pm2 M_\odot$ yr$^{-1}$ in the core of the system (avoiding the two active nuclei). These results confirm that Mrk 266 is an intermediate stage merger with a relatively high recent star formation rate and enough molecular gas to sustain it for a few hundred million years. Inflowing gas associated with the merger may have triggered both the starburst episode and two AGN but the two galaxy components differ: the region around the SW nucleus appears to be more active than the NE nucleus, which seems relatively quiet. We speculate that this difference may originate in the properties of the interstellar medium in the two systems.

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arXiv2022

A Multiwavelength view of IC 860: What Is in Action inside Quenching Galaxies

We present a multiwavelength study of IC 860, a nearby post-starburst galaxy at the early stage of transitioning from blue and star-forming to red and quiescent. Optical images reveal a galaxy-wide, dusty outflow originating from a compact core. We find evidence for a multiphase outflow in the molecular and neutral gas phase from the CO position-velocity diagram and NaD absorption features. We constrain the neutral mass outflow rate to be ~0.5 M$_{\odot}/$yr, and the total hydrogen mass outflow rate to be ~12 M$_{\odot}$/yr. Neither outflow component seems able to escape the galaxy. We also find evidence for a recent merger in the optical images, CO spatial distribution, and kinematics, and evidence for a buried AGN in the optical emission line ratios, mid-IR properties, and radio spectral shape. The depletion time of the molecular gas reservoir under the current star formation rate is ~7 Gyr, indicating that the galaxy could stay at the intermediate stage between the blue and red sequence for a long time. Thus the timescales for a significant decline in star formation rate ("quenching") and gas depletion are not necessarily the same. Our analysis supports the quenching picture where outflows help suppress star formation by disturbing rather than expelling the gas and shed light on possible ongoing activities in similar quenching galaxies.

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arXiv2022

Are Active Galactic Nuclei in Post-Starburst Galaxies Driving the Change or Along for the Ride?

We present an analysis of 10 ks snapshot Chandra observations of 12 shocked post-starburst galaxies, which provide a window into the unresolved question of active galactic nuclei (AGN) activity in post-starburst galaxies and its role in the transition of galaxies from actively star forming to quiescence. While 7/12 galaxies have statistically significant detections (with 2 more marginal detections), the brightest only obtained 10 photons. Given the wide variety of hardness ratios in this sample, we chose to pursue a forward modeling approach to constrain the intrinsic luminosity and obscuration of these galaxies rather than stacking. We constrain intrinsic luminosity of obscured power-laws based on the total number of counts and spectral shape, itself mostly set by the obscuration, with hardness ratios consistent with the data. We also tested thermal models. While all the galaxies have power-law models consistent with their observations, a third of the galaxies are better fit as an obscured power-law and another third are better fit as thermal emission. If these post-starburst galaxies, early in their transition, contain AGN, then these are mostly confined to a lower obscuration ($n_H \leq10^{23}$ cm$^{-2}$) and lower luminosity ($L_{2-10~ \rm keV}\leq10^{42}$erg s$^{-1}$). Two galaxies, however, are clearly best fit as significantly obscured AGN. At least half of this sample show evidence of at least low luminosity AGN activity, though none could radiatively drive out the remaining molecular gas reservoirs. Therefore, these AGN are more likely along for the ride, having been fed gas by the same processes driving the transition.

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arXiv2021

The Galaxy Evolution Probe

The Galaxy Evolution Probe (GEP) is a concept for a mid- and far-infrared space observatory to measure key properties of large samples of galaxies with large and unbiased surveys. GEP will attempt to achieve zodiacal light and Galactic dust emission photon background-limited observations by utilizing a 6 Kelvin, 2.0 meter primary mirror and sensitive arrays of kinetic inductance detectors. It will have two instrument modules: a 10 - 400 micron hyperspectral imager with spectral resolution R = 8 (GEP-I) and a 24 - 193 micron, R = 200 grating spectrometer (GEP-S). GEP-I surveys will identify star-forming galaxies via their thermal dust emission and simultaneously measure redshifts using polycyclic aromatic hydrocarbon emission lines. Galaxy luminosities derived from star formation and nuclear supermassive black hole accretion will be measured for each source, enabling the cosmic star formation history to be measured to much greater precision than previously possible. Using optically thin far-infrared fine-structure lines, surveys with GEP-S will measure the growth of metallicity in the hearts of galaxies over cosmic time and extraplanar gas will be mapped in spiral galaxies in the local universe to investigate feedback processes. The science case and mission architecture designed to meet the science requirements are described, and the kinetic inductance detector and readout electronics state of the art and needed developments are described. This paper supersedes the GEP concept study report cited in it by providing new content, including: a summary of recent mid-infrared KID development, a discussion of microlens array fabrication for mid-infrared KIDs, and additional context for galaxy surveys. The reader interested in more technical details may want to consult the concept study report.

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