arXiv subjects

Carlos Garcia Diaz

Publications and source records attributed to Carlos Garcia Diaz.

7 recordsLinked to original sources

arXiv2026

The Koi Pond: A Strongly Lensed Protocluster Core hosting a Diverse Population of DSFGs

We present James Webb Space Telescope (JWST) and Atacama Large Millimeter Array (ALMA) observations of PJ0846+15, \textit{The Koi Pond}, a strongly lensed protocluster core at Cosmic Noon. This field offers a magnified view of 11 dusty star-forming galaxies (DSFGs) all at $z=2.67$ (within $ΔV=800$ km s$^{-1}$) spanning a projected extent of $>300$ kpc lensed by a $z=0.77$ foreground cluster. NIRCam and ALMA Band 6 continuum measurements map the stellar distribution and thermal dust emission respectively at a spatial resolution of $\sim$0.15$^{\prime\prime}$. This analysis reveals a diverse population of DSFGs, with evidence of both interacting and non-interacting systems exhibiting a wide range of morphological features including spiral arms, bars, bulges, clumps/stellar clusters, tidal tails/debris and displaced molecular gas reservoirs. Comparing the rest-frame J- band continuum (F444W) vs (i-J) color (F277W$-$F444W), we find a wide range of values, suggesting a $>$1-dex spread in stellar mass and a dust attenuation reddening of $ΔA_{\mathrm{V}} > 1$ mag. The DSFG members exhibit varying dust sizes relative to the stellar emission, ranging from compact dusty cores to galaxy-wide emission. Resolved color maps of individual sources showing a spread as high as F277W$-$F444W$=2$ mag suggesting complex stellar-to-dust geometry. Although gas-rich mergers are identified in the core, the most red and dust emitting members are disks exhibiting clumpy structure indicating secular growth can drive these starburst events. Such a remarkable range in properties within this sample suggest DSFGs in protocluster core environments follow diverse evolutionary pathways towards their transition into quiescent, elliptical cluster galaxies.

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arXiv2026

PASSAGES: The Discovery of a Strongly Lensed Protocluster Core Candidate at Cosmic Noon

Investigating the processes by which galaxies rapidly build up their stellar mass during the peak of their star formation ($z=2-3$) is crucial to advancing our understanding of the assembly of large-scale structures. We report the discovery of one of the most gas- and dust-rich protocluster core candidates, PJ0846+15 (J0846), from the Planck All-Sky Survey to Analyze Gravitationally lensed Extreme Starbursts (PASSAGES) sample. The exceedingly high total star formation rate (SFR) uncorrected for lensing magnification ($μ$) of $μ\text{SFR} = 39900^{+23000}_{-12900} \text{ M}_\odot\text{ yr}^{-1}$ is the result of a foreground cluster lensing at least 11 dusty star-forming galaxies between $z=2.660-2.669$, where the intrinsic value is estimated to be $\text{SFR} = 5200^{+3200}_{-2000} \text{ M}_\odot\text{ yr}^{-1}$. Atacama Large Millimeter Array (ALMA) observations uncovered 18 CO(3--2) emission-line detections, some of which are multiply-imaged systems, lensed by a foreground cluster at $z=0.77$. We present the first multi-wavelength characterization of this field, constructing a lens model that predicts that these 11 galaxies ($μ\simeq 1.5-25$) are contained within a projected physical extent of $280 \times 150 \text{ kpc}$, with a velocity dispersion of $σ_{v} = 246 \pm 72 \text{ km s}^{-1}$. J0846 exhibits the rare case of a protocluster candidate whose core is strongly-lensed, offering a magnified view of the rapid stellar buildup within an overdense environment at Cosmic Noon.

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arXiv2026

JWST+ALMA reveal the build up of stellar mass in the cores of dusty star-forming galaxies at Cosmic Noon

Dusty star-forming galaxies have long been suspected to serve as the missing evolutionary bridge between the star-forming and quiescent phases of massive galaxy evolution. With the combined power of JWST and ALMA, it is now possible to use high resolution imaging at rest-frame ultraviolet (UV), optical, near-infrared (NIR), and sub-mm wavelengths to study the multi-wavelength morphologies tracing both the stellar populations and dust during this key phase. We present the joint analysis of JWST/NIRCam imaging in GOODS-S and mm dust emission traced by ALMA for a sample of 33 galaxies at $z=1.5$ to $z=5.5$ selected from the 1.1mm GOODS-ALMA 2.0 survey, and compare the morphologies of this population to mass- and redshift-selected samples of field star-forming and quiescent galaxies. The 1.1mm-selected sample is morphologically distinct from other similarly massive star-forming galaxies; we find a steeper size-wavelength gradient from 1.5-4.4$μ$m, with a more dramatic decrease in size towards longer wavelengths. While the rest-NIR surface brightness profiles of the 1.1mm-selected galaxies are brighter in the inner regions relative to the field star-forming population, they are remarkably similar to the quiescent population. These morphological differences could suggest that dusty star-forming galaxies, unlike more typical star-forming galaxies, have already built up stellar mass in a severely dust-obscured core, leading to extended and clumpy morphologies at rest-UV and rest-optical wavelengths and more compact emission in the rest-NIR that is co-spatial with dust. If the bulge is already established, we speculate that mm-selected galaxies may imminently evolve to join their quiescent descendants.

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arXiv2025

The complicated nature of the X-ray emission from the field of the strongly lensed hyperluminous infrared galaxy PJ1053+60 at z=3.549

We present an analysis of XMM-Newton X-ray observations of PJ1053+60, a hyperluminous infrared galaxy (HyLIRG) at z=3.549 that is strongly lensed by a foreground group at z=0.837. We also present GNIRS spectroscopy confirming the presence of an active galactic nucleus (AGN) to the southwest of PJ1053+60 ($AGN_{SW}$) at $z_{SW}$ = 1.373 $\pm$ 0.006. Using this redshift prior, we decompose the X-ray spectrum of PJ1053+60 into $AGN_{SW}$ and high-mass X-ray binary (HMXB) components from the HyLIRG. The HMXB component has an unusually high luminosity, $\sim$ 50 times higher than calibration derived from local galaxies, and a characteristic photon index likely too flat to be caused by high-mass X-ray binaries at rest frame energies above a few keV. Our 2-D spatial decomposition also suggests a similarly high X-ray HMXB luminosity, although the limited spatial resolution prevents meaningful morphological constraints on the component. We conclude that the enhanced X-ray emission may only be explained by the presence of another AGN ($AGN_{FG}$) embedded in the foreground group lensing the PJ1053+60 system. The presence of $AGN_{FG}$ is further supported by the detection of a point-like radio continuum source that coincides with the brightest group galaxy (BGG) of the foreground lens. Our study demonstrates the limited capability of current X-ray observatories while highlighting the need for higher angular resolution observations to definitively characterize the nature of X-ray emission in distant, strongly lensed HyLIRGs.

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arXiv2025

Forecasting the Observable Rates of Gravitationally Lensed Supernovae for the PASSAGES Dusty Starbursts

More than 60 years have passed since the first formal suggestion to use strongly-lensed supernovae to measure the expansion rate of the Universe through time-delay cosmography. Yet, fewer than 10 such objects have ever been discovered. We consider the merits of a targeted strategy focused on lensed hyperluminous infrared galaxies -- among the most rapidly star-forming galaxies known in the Universe. With star formation rates (SFRs) $\sim {200 - 6000}~\textrm{M}_\odot~\textrm{yr}^{-1}$, the $\sim 30$ objects in the Planck All-Sky Survey to Analyze Gravitationally-lensed Extreme Starbursts (PASSAGES) are excellent candidates for a case study, in particular, and have already led to the discovery of the multiply-imaged SN H0pe. Considering their lens model-corrected SFRs, we estimate their intrinsic supernova rates to be an extraordinary ${1.8 - 65}~\textrm{yr}^{-1}$ (core-collapse) and ${0.2 - 6.4}~\textrm{yr}^{-1}$ (Type Ia). Moreover, these massive starbursts typically have star-forming companions which are unaccounted for in this tally. We demonstrate a strong correlation between Einstein radius and typical time delays, with cluster lenses often exceeding several months (and therefore most favorable for high-precision $H_0$ inferences). A multi-visit monitoring campaign with a sensitive infrared telescope (namely, JWST) is necessary to mitigate dust attenuation. Still, a porous interstellar medium and clumpy star formation in these extreme galaxies might produce favorable conditions for detecting supernovae as transient point sources. Targeted campaigns of known lensed galaxies to discover new lensed supernovae can greatly complement wide-area cadenced surveys. Increasing the sample size helps to realize the potential of supernova time-delay cosmography to elucidate the Hubble tension through a single-step measurement, independent of other $H_0$ techniques.

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arXiv2023

X-ray detection of the most extreme star-forming galaxies at the cosmic noon via strong lensing

Hyper-luminous infrared galaxies (HyLIRGs) are the most extreme star-forming systems observed in the early Universe, and their properties still elude comprehensive understanding. We have undertaken a large XMM-Newton observing program to probe the total accreting black hole population in three HyLIRGs at z = 2.12, 3.25, and 3.55, gravitationally lensed by foreground galaxies. Selected from the Planck All-Sky Survey to Analyze Gravitationally-lensed Extreme Starbursts (PASSAGES), these HyLIRGs have apparent infrared luminosities > E14 Lsun. Our observations revealed X-ray emission in each of them. PJ1336+49 appears to be dominated by high-mass X-ray binaries (HMXBs). Remarkably, the luminosity of this non-AGN X-ray emission exceeds by a factor of about three the value obtained by calibration with local galaxies with much lower star formation rates. This enhanced X-ray emission most likely highlights the efficacy of dynamical HMXB production within compact clusters, which is an important mode of star formation in HyLIRGs. The remaining two (PJ0116-24 and PJ1053+60) morphologically and spectrally exhibit a compact X-ray component in addition to the extended non-AGN X-ray emission, indicating the presence of Active Galactic Nuclei (AGNs). The AGN appears to be centrally located in the reconstructed source plane images of PJ0116-24, which manifests its star-forming activity predominantly within an extended galactic disk. In contrast, the AGN in the field of PJ1053+60 is projected 60 kpc away from the extreme star-forming galaxy and could be ejected from it. These results underline the synergistic potential of deep X-ray observations with strong lensing for the study of high-energy astrophysical phenomena in HyLIRGs.

astro-ph.HE↗

arXiv2023

PASSAGES: the wide-ranging, extreme intrinsic properties of Planck-selected, lensed dusty star-forming galaxies

The PASSAGES ($Planck$ All-Sky Survey to Analyze Gravitationally-lensed Extreme Starbursts) collaboration has recently defined a sample of 30 gravitationally-lensed dusty star-forming galaxies (DSFGs). These rare, submillimeter-selected objects enable high-resolution views of the most extreme sites of star formation in galaxies at Cosmic Noon. Here, we present the first major compilation of strong lensing analyses using LENSTOOL for PASSAGES, including 15 objects spanning $z=1.1-3.3$, using complementary information from $0.6^{\prime\prime}$-resolution 1 mm Atacama Large Millimeter/submillimeter Array (ALMA) and $0.4^{\prime\prime}$ 5 cm Jansky Very Large Array continuum imaging, in tandem with 1.6$μ$m $Hubble$ and optical imaging with Gemini-S. Magnifications range from $μ= 2 - 28$ (median $μ=7$), yielding intrinsic infrared luminosities of $L_{\rm IR} = 0.2 - 5.9 \times 10^{13}~L_\odot$ (median ${1.4}\times 10^{13}~L_\odot$) and inferred star formation rates of $170-6300~M_\odot~{\rm yr}^{-1}$ (median $1500~M_\odot~{\rm yr}^{-1}$). These results suggest that the PASSAGES objects comprise some of the most extreme known starbursts, rivaling the luminosities of even the brightest unlensed objects, further amplified by lensing. The intrinsic sizes of far-infrared continuum regions are large ($R_{\rm e} = {1.7 - 4.3}$ kpc; median $3.0$ kpc) but consistent with $L_{\rm IR}-R_{\rm e}$ scaling relations for $z>1$ DSFGs, suggesting a widespread spatial distribution of star formation. With modestly-high angular resolution, we explore if these objects might be maximal starbursts. Instead of approaching Eddington-limited surface densities, above which radiation pressure will disrupt further star formation, they are safely sub-Eddington -- at least on global, galaxy-integrated scales.

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