Spectral Energy Distribution Analysis Research Articles

Revealing the burning and soft heart of the bright bare active galactic nucleus ESO 141-G55: X-ray broadband and SED analysis

ESO 141-G55 is a nearby X-ray bright broad-line Seyfert\,1 (BLS1) that has been classified as a bare active galactic nucleus (AGN) due to a lack of warm absorption along its line of sight, providing an unhampered view into its disc-corona system. We aim to probe its disc-corona system thanks to the first simultaneous XMM-Newton and NuSTAR observation obtained October 1--2, 2022. We carried out an X-ray broadband spectral analysis to determine the dominant process(es) at work as well as a spectral energy distribution (SED) analysis to determine the disc-corona properties. The simultaneous broadband X-ray spectrum of ESO\,141-G55 is characterised by the presence of a prominent smooth soft X-ray excess, a broad Fe\,Kalpha emission line, and a significant Compton hump. The high-resolution reflection grating spectrometer spectra confirmed the lack of intrinsic warm-absorbing gas along our line of sight in the AGN rest frame, verifying that it is still in a bare state. However, soft X-ray emission lines were observed, indicating substantial warm gas out of our line of sight. The intermediate inclination of the disc-corona system (sim circ $) may offer us a favourable configuration to observe ultra-fast outflows from the disc, but none were found in this 2022 observation, contrary to a previous 2007 XMM-Newton one. We ruled out relativistic reflection alone on a standard disc based on the X-ray broadband analysis, while a combination of soft and hard Comptonisation by a warm and hot corona ( relagn ) plus relativistic reflection ( reflkerrd ) reproduces the ESO\,141-G55 SED quite well. The hot corona temperature is very hot, sim 140\,keV, and much higher than about 80<!PCT!> of AGNs, whereas the warm corona temperature, sim 0.3\,keV, is similar to the values found in other sub-Eddington AGNs. ESO\,141-G55 is accreting at a moderate Eddington accretion rate (sim 10--20<!PCT!>). Our analysis points to a significant contribution of an optically thick warm corona to both the soft X-ray and UV emission in ESO\,141-G55, adding to the growing evidence that the accretion of AGNs (even at a moderate accretion rate) appears to deviate from standard disc theory.

Unsupervised Domain Adaptation for Constraining Star Formation Histories

In astronomy, understanding the evolutionary trajectories of galaxies necessitates a robust analysis of their star formation histories (SFHs), a task complicated by our inability to observe these vast celestial entities throughout their billion-year lifespans. This study pioneers the application of the Kullback–Leibler Importance Estimation Procedure (KLIEP), an unsupervised domain adaptation technique, to address this challenge. By adeptly applying KLIEP, we harness the power of machine learning to innovatively predict SFHs, utilizing simulated galaxy models to forge a novel linkage between simulation and observation. This methodology signifies a substantial advancement beyond the traditional Bayesian approaches to Spectral Energy Distribution (SED) analysis, which are often undermined by the absence of empirical SFH benchmarks. Our empirical investigations reveal that KLIEP markedly enhances the precision and reliability of SFH inference, offering a significant leap forward compared to existing methodologies. The results underscore the potential of KLIEP in refining our comprehension of galactic evolution, paving the way for its application in analyzing actual astronomical observations. Accompanying this paper, we provide access to the supporting code and dataset on GitHub, encouraging further exploration and validation of the efficacy of the KLIEP in the field.

A Protocluster of Massive Quiescent Galaxies at z = 4

We report on discovery of a concentration of massive quiescent galaxies located at z = 4. The concentration is first identified using high-quality photometric redshifts based on deep, multiband data in Subaru/XMM-Newton Deep Field. Follow-up near-infrared spectroscopic observations with MOSFIRE on Keck confirm a massive (∼1011 M ⊙) quiescent galaxy at z = 3.99. Our spectral energy distribution analyses reveal that the galaxy experienced an episode of starburst about 500 Myr prior to the observed epoch, followed by rapid quenching. Since its spectrum is sufficiently good to measure the stellar velocity dispersion, we infer its dynamical mass and find that it is consistent with its stellar mass. The galaxy is surrounded by four massive (>1010 M ⊙) quiescent galaxies on a ∼1 physical Mpc scale, all of which are consistent with being located at the same redshift based on high-accuracy spectrophotometric redshifts. This is likely a (proto)cluster dominated by quiescent galaxies, the first of the kind reported at such a high redshift as z = 4. Interestingly, it is in a large-scale structure revealed by spectroscopic redshifts from VANDELS. Furthermore, it also exhibits a red sequence, adding further support to the physical concentration of the galaxies. We find no such concentration in the Illustris-TNG300 simulation; it may be that the cluster is such a rare system that the simulation box is not sufficiently large to reproduce it. The total halo mass of the quiescent galaxies is ∼1013 M ⊙, suggesting that they form a group-sized halo once they collapse together. We discuss the implications of our findings for the quenching physics and conclude with future prospects.

Probing the inner Galactic halo with blue horizontal-branch stars

Context. Stars that are found on the blue horizontal-branch (BHB) evolved from low-mass stars that have completed their core hydrogen-burning main sequence (MS) stage and undergone the helium flash at the end of their red giant phase. Hence, they are very old objects that can be used as markers in studying galactic structure and formation history. The fact that their luminosity is virtually constant at all effective temperatures also makes them good standard candles. Aims. We have compiled a catalogue of BHB stars with stellar parameters calculated from spectral energy distributions (SEDs) constructed using data from multiple large-scale photometric surveys. In addition, we update our previous Gaia Early Data Release 3 (EDR3) catalogue of BHB stars with parallax errors less than 20% by using the SED results to define the selection criteria. The purpose of these catalogues is to create a set of BHB star candidates with reliable stellar parameters. In addition, they provide a more complete full-sky catalogue with candidate objects found along the whole BHB from where RR-Lyrae are found on the instability strip to the extreme horizontal-branch (EHB). Methods. We selected a large dataset of Gaia Data Release 3 (DR3) objects based only on their position on the colour-magnitude diagram (CMD), along with the tangential velocity and parallax errors. The SEDs were then used to evaluate contamination levels in the dataset and derive optimised data quality acceptance constraints. This allowed us to extend the Gaia DR3 colour and absolute magnitude criteria further towards the EHB. The level of contamination found using SED analysis was confirmed by acquiring spectra using the Ondrejov Echelle spectrograph, attached to the Perek 2m telescope at the Astronomical Institute of the Czech Academy of Sciences. Results. We present a catalogue of 9172 Galactic halo BHB candidate stars with atmospheric and stellar parameters calculated from synthetic SEDs. We also present an extended Gaia DR3-based catalogue of 22 335 BHB candidate stars with a wider range of effective temperatures and Gaia DR3 parallax errors of less than 20%. This represents an increase of 33% compared to the our 2021 catalogue, with a contamination level of 10%.

Active Galactic Nuclei Selection and Demographics: A New Age with JWST/MIRI

Understanding the coevolution of supermassive black holes and their host systems requires a comprehensive census of active galactic nuclei (AGNs) behavior across a wide range of redshift, luminosity, obscuration level, and galaxy properties. We report significant progress with JWST toward this goal from the Systematic Mid-infrared Instrument Legacy Extragalactic Survey (SMILES). Based on comprehensive spectral energy distribution (SED) analysis of 3273 MIRI-detected sources, we identify 217 AGN candidates over a survey area of ∼34 arcmin2, including a primary sample of 111 AGNs in normal massive galaxies (M * > 109.5 M ☉) at z ∼ 0–4, an extended sample of 86 AGN candidates in low-mass galaxies (M * < 109.5 M ☉), and a high-z sample of 20 AGN candidates at z ∼ 4–8.4. Notably, about 80% of our MIRI-selected AGN candidates are new discoveries despite the extensive pre-JWST AGN searches. Even among the massive galaxies where the previous AGN search is believed to be thorough, 34% of the MIRI AGN identifications are new, highlighting the impact of obscuration on previous selections. By combining our results with the efforts at other wavelengths, we build the most complete AGN sample to date and examine the relative performance of different selection techniques. We find the obscured AGN fraction increases from L AGN,bol ∼ 1010 L ⊙ to 1011 L ⊙ and then drops toward higher luminosity. Additionally, the obscured AGN fraction gradually increases from z ∼ 0 to z ∼ 4 with most high-z AGNs obscured. We discuss how AGN obscuration, intrinsic SED variations, galaxy contamination, survey depth, and selection techniques complicate the construction of a complete AGN sample.

Highly luminous supernovae associated with gamma-ray bursts

Context. The supernovae (SNe) associated with gamma-ray bursts (GRBs) are generally seen as a homogeneous population, but at least one exception exists: the highly luminous SN 2011kl associated with the ultra-long GRB 111209A. Such outliers may also exist for more typical GRBs. Aims. Within the context of a systematic analysis of photometric signatures of GRB-associated SNe, we found an anomalous bump in the late-time transient following GRB 140506A at redshift z = 0.889. We hereby aim to show this bump is significantly more luminous and blue than usual SNe following GRBs. Methods. We compiled all available data from the literature and added a full analysis of the Swift/UVOT data, which allowed us to trace the light curve from the first minutes all the way to the host galaxy and to construct a broad spectral energy distribution (SED) of the afterglow that extends the previous SED analysis based on ground-based spectroscopy. Results. We find robust evidence of a late-time bump following the afterglow that shows evidence of a strong color change, with the spectral slope becoming flatter in the blue region of the spectrum. This bump can be interpreted as a luminous SN bump that is spectrally dissimilar to typical GRB-SNe. Correcting it for the large line-of-sight extinction makes the SN associated with GRB 140506A the most luminous detected so far. Even so, it would be in agreement with a luminosity-duration relation of GRB-SNe. Conclusions. While not supported by spectroscopic evidence, it is likely the bump following GRB 140506A is the signature of an SN that is spectrally dissimilar to classical GRB-SNe and more similar to SN 2011kl – while being associated with an average GRB, indicating the GRB-SN population is more diverse than previously thought and can reach luminosities comparable to those of superluminous SNe.

ALMA Lensing Cluster Survey: Full Spectral Energy Distribution Analysis of z ∼ 0.5–6 Lensed Galaxies Detected with millimeter Observations

Sub/millimeter galaxies are a key population for the study of galaxy evolution because the majority of star formation at high redshifts occurred in galaxies deeply embedded in dust. To search for this population, we have performed an extensive survey with Atacama Large Millimeter/submillimeter Array (ALMA), called the ALMA Lensing Cluster Survey (ALCS). This survey covers 133 arcmin2 area and securely detects 180 sources at z ∼ 0.5–6 with a flux limit of ∼0.2 mJy at 1.2 mm. Here, we report the results of multiwavelength spectral energy distribution analysis of the whole ALCS sample, utilizing the observed-frame UV to millimeter photometry. We find that the majority of the ALCS sources lie on the star-forming main sequence, with a smaller fraction showing intense starburst activities. The ALCS sample contains high infrared-excess sources ( IRX=log(Ldust/LUV)>1 ), including two extremely dust-obscured galaxies (IRX > 5). We also confirm that the ALCS sample probes a broader range in lower dust mass than conventional submillimeter galaxy samples in the same redshift range. We identify six heavily obscured active galactic nucleus (AGN) candidates that are not detected in the archival Chandra data in addition to the three X-ray AGNs reported by Uematsu et al. (2023). The inferred AGN luminosity density shows a possible excess at z = 2–3 compared with that determined from X-ray surveys below 10 keV.

Physical Properties of Hyperluminous, Dust-obscured Quasars at z ∼ 3: Multiwavelength Spectral Energy Distribution Analysis and Cold Gas Content Revealed by ALMA

We present a UV to millimeter spectral energy distribution (SED) analysis of 16 hyperluminous, dust-obscured quasars at z ∼ 3, selected by the Wide-field Infrared Survey Explorer. We aim to investigate the physical properties of these quasars, with a focus on their molecular gas content. We decompose the SEDs into three components: stellar, cold dust, and active galactic nucleus (AGN). By doing so, we are able to derive and analyze the relevant properties of each component. We determine the molecular gas mass from CO line emission based on Atacama Large Millimeter/submillimeter Array (ALMA) observations. By including ALMA observations in the multiwavelength SED analysis, we derive the molecular gas fractions, gas depletion timescales, and star formation efficiencies (SFEs). Their sample median and 16th–84th quartile ranges are fgas∼0.33−0.17+0.33 , t depl ∼ 39−28+85 Myr, and SFE ∼ 297−195+659 K km s−1 pc−2, respectively. Compared to main-sequence galaxies, they have lower molecular gas content and higher SFEs, similar to quasars in the literature. This suggests that the gas in these quasars is rapidly depleted, likely as the result of intense starburst activity and AGN feedback. The observed correlations between these properties and the AGN luminosities further support this scenario. Additionally, we infer the black hole to stellar mass ratio and black hole mass growth rate, which indicate significant central black hole mass assembly over short timescales. Our results are consistent with the scenario that our sample represents a short transition phase toward unobscured quasars.

Faint mm NIKA2 dusty star-forming galaxies: Finding the high-redshift population

Aims. High-redshift dusty star-forming galaxies (DSFGs) are proposed to be the progenitors of massive quiescent galaxies arising at cosmic noon, providing a crucial insight into the formation, assembly, and early quenching of massive galaxies in the early Universe. However, their high redshift combined with high dust obscuration adds significant difficulties to their redshift measurement, which is mandatory for detailed studies of their physical properties. Blind mm spectral scans are the most unbiased way in prinicple for obtaining accurate spectroscopic redshifts for these sources, but identifying faint molecular and atomic lines within limited telescope time for faint DSFGs is also difficult with these scans. Methods. We developed a new framework to constrain the source redshift. The method jointly accounts for the detection and/or nondetection of spectral lines and the prior information from the photometric redshift and total infrared luminosity from spectral energy distribution analysis. The method uses the estimated total infrared luminosity to predict the line fluxes at given redshifts and generates model spectra. The redshift-dependent spectral models were then compared with the observed spectra to determine the redshift. Results. We applied this joint redshift analysis method to four high-z dusty star-forming galaxy candidates selected from the NIKA2 observations of the HLSJ091828.6+514223 (HLS) field that were further observed by NOEMA with blind spectral scans. These sources only have Herschel SPIRE photometry as ancillary data. They were selected because SPIRE counterparts are faint or entirely lacking and thus favor to select the highest-redshift candidates. The method finds a spectroscopic redshift of 4 in the five NOEMA-counterpart detected sources, with z &gt; 3. Based on these measurements, we derived the CO and [CI] lines and mm continuum fluxes from the NOEMA data and studied the properties of their interstellar medium and star formation. We find cold dust temperatures in some of the HLS sources compared to the general population of submm galaxies, which might be related to the bias introduced by the SPIRE-dropout selection. All sources except for one have a short gas-depletion time of a few hundred million years, which is typical of high-z submm galaxies. The only exception shows a longer gas-depletion time of up to a few billion years. This is comparable to the gas-depletion times of main-sequence galaxies at the same redshift. Furthermore, we identify a possible overdensity of dusty star-forming galaxies at z = 5.2 that is traced by two sources in our sample, as well as a lensed galaxy HLSJ091828.6+514223. Conclusions. We demonstrate that our method when applied to mm-selected DSFGs is able to determine the redshift accurately. This accuracy with only multiple emission lines with a low signal-to-noise ratio shows promising potential for the blind redshift search in large samples of high-z DSFGs, even in the absence of optical to near infrared photometric redshifts.

Introducing cuDisc: a 2D code for protoplanetary disc structure and evolution calculations

ABSTRACT We present a new two-dimensional (2D) axisymmetric code, cuDisc, for studying protoplanetary discs, focusing on the self-consistent calculation of dust dynamics, grain-size distribution and disc temperature. Self-consistently studying these physical processes is essential for many disc problems, such as structure formation and dust removal, given that the processes heavily depend on one another. To follow the evolution over substantial fractions of the disc lifetime, cuDisc uses the cuda language and libraries to speed up the code through GPU acceleration. cuDisc employs a second-order finite-volume Godonuv solver for dust dynamics, solves the Smoluchowski equation for dust growth, and calculates radiative transfer using a multifrequency hybrid ray-tracing/flux-limited-diffusion method. We benchmark our code against current state-of-the-art codes. Through studying steady-state problems, we find that including 2D structure reveals that when collisions are important, the dust vertical structure appears to reach a diffusion-settling-coagulation equilibrium that can differ substantially from standard models that ignore coagulation. For low fragmentation velocities, we find an enhancement of intermediate-sized dust grains at heights of ∼1 gas scale height due to the variation in collision rates with height, and for large fragmentation velocities, we find an enhancement of small grains around the disc mid-plane due to collisional ‘sweeping’ of small grains by large grains. These results could be important for the analysis of disc spectral energy distributions or scattered light images, given these observables are sensitive to the vertical grain distribution.

Multiwavelength Spectral Energy Distribution Analysis of X-Ray Selected Active Galactic Nuclei at z = 0.2–0.8 in the Stripe 82 Region

We perform a systematic, multiwavelength spectral energy distribution (SED) analysis of X-ray detected active galactic nuclei (AGNs) at z = 0.2–0.8 with Sloan Digital Sky Survey (SDSS) counterparts in the Stripe 82 region, consisting of 60 type 1 and 137 type 2 AGNs covering a 2–10 keV luminosity range of 41.6<logLx<44.7 . The latest CIGALE code, where dusty polar components are included, is employed. To obtain reliable host and AGN parameters in type 1 AGNs, we utilize the image-decomposed optical SEDs of host galaxies by Li et al. based on the Subaru Hyper-Suprime Cam images. The mean ratio of black hole masses (M BH) and stellar masses (M stellar) of our X-ray detected type 1 AGN sample, log(MBH/Mstellar)=−2.7±0.5 , is close to the local relation between BH and stellar masses as reported by Li et al. for SDSS quasars. This ratio is slightly lower than that found for more luminous ( logLbol>45 ) type 1 AGNs at z ∼ 1.5. This can be explained by the AGN luminosity dependence of log(MBH/Mstellar) , which little evolves with redshift. We confirm the trend that the UV-to-X-ray slope (α OX) or X-ray-to-bolometric correction factor (κ 2–10) increases with AGN luminosity or Eddington ratio. We find that type 1 and type 2 AGNs with the same luminosity ranges share similar host stellar mass distributions, whereas type 2s tend to show smaller AGN luminosities than type 1s. This supports the luminosity-dependent (or Eddington-ratio-dependent) unified scheme.

An ALMA Spectroscopic Survey of the Brightest Submillimeter Galaxies in the SCUBA-2-COSMOS Field (AS2COSPEC): Physical Properties of z = 2–5 Ultra- and Hyperluminous Infrared Galaxies

We report the physical properties of the 18 brightest (S 870 μm = 12.4–19.2 mJy) and not strongly lensed 870 μm–selected dusty star-forming galaxies (DSFGs), also known as submillimeter galaxies (SMGs), in the COSMOS field. This sample is part of an ALMA band 3 spectroscopic survey (AS2COSPEC), and spectroscopic redshifts are measured in 17 of them at z = 2–5. We perform spectral energy distribution analyses and deduce a median total infrared luminosity of L IR = (1.3 ± 0.1) × 1013 L ⊙, infrared-based star formation rate (SFR) of SFRIR = 1390 ± 150 M ⊙ yr−1, stellar mass of M * = (1.4 ± 0.6) × 1011 M ⊙, dust mass of M dust = (3.7 ± 0.5) × 109 M ⊙, and molecular gas mass of M gas = (α CO/0.8)(1.2 ± 0.1) × 1011 M ⊙, suggesting that they are one of the most massive, ISM-enriched, and actively star-forming systems at z = 2–5. In addition, compared to less massive and less active galaxies at similar epochs, SMGs have comparable gas fractions; however, they have a much shorter depletion time, possibly caused by more active dynamical interactions. We determine a median dust emissivity index of β = 2.1 ± 0.1 for our sample, and by combining our results with those from other DSFG samples, we find no correlation of β with redshift or infrared luminosity, indicating similar dust grain compositions across cosmic time for infrared luminous galaxies. We also find that AS2COSPEC SMGs have one of the highest dust-to-stellar mass ratios, with a median of 0.02 ± 0.01, significantly higher than model predictions, possibly due to too-strong active galactic nucleus feedback implemented in the model. Finally, our complete and uniform survey enables us to put constraints on the most massive end of the dust and molecular gas mass functions.

Unveiling the Cosmic Cradle: clustering and massive star formation in the enigmatic Galactic bubble N59

ABSTRACT In this paper, we have conducted an investigation focused on a segment of the Spitzer mid-infrared bubble N59, specifically referred to as R1 within our study. Situated in the inner Galactic plane, this region stands out for its hosting of five 6.7 GHz methanol masers, as well as numerous compact $\mathrm{H}\, \rm {{\small II}}$ regions, massive clumps, filaments, and prominent bright rims. As 6.7 GHz masers are closely linked to the initial phases of high-mass star formation, exploring regions that exhibit a high abundance of these maser detections provides an opportunity to investigate relatively young massive star-forming sites. To characterize the R1 region comprehensively, we utilize multiwavelength (archival) data from optical to radio wavelengths, together with 13CO and C18O data. Utilizing the Gaia DR3 data, we estimate the distance towards the bubble to be 4.66 ± 0.70 kpc. By combining near-infrared (NIR) and mid-infrared (MIR) data, we identify 12 Class I and 8 Class II sources within R1. Furthermore, spectral energy distribution (SED) analysis of selected sources reveals the presence of four embedded high-mass sources with masses ranging from 8.70 to 14.20 M⊙. We also identified several O and B-type stars from radio continuum analysis. Our molecular study uncovers two distinct molecular clouds in the region, which, although spatially close, occupy different regions in velocity space. We also find indications of a potential hub-filament system fostering star formation within the confines of R1. Finally, we propose that the feedback from the $\mathrm{H}\, \rm {{\small II}}$ regions has led to the formation of prominent Bright Rimmed Clouds (BRCs) within our region of interest.

Investigation of the correlation between optical and γ-ray flux variations in the blazar Ton 599

ABSTRACT The correlation between optical and γ-ray flux variations in blazars reveals a complex behaviour. In this study, we present our analysis of the connection between changes in optical and γ-ray emissions in the blazar Ton 599 over a span of approximately 15 yr, from 2008 August to 2023 March. Ton 599 reached its highest flux state across the entire electromagnetic spectrum during the second week of 2023 January. To investigate the connection between changes in optical and γ-ray flux, we have designated five specific time periods, labelled as epochs A, B, C, D, and E. During periods B, C, D, and E, the source exhibited optical flares, while it was in its quiescent state during period A. The γ-ray counterparts to these optical flares are present during periods B, C, and E; however, during period D, the γ-ray counterpart is either weak or absent. We conducted a broad-band spectral energy distribution (SED) fitting by employing a one-zone leptonic emission model for these epochs. The SED analysis unveiled that the optical–ultraviolet emission primarily emanated from the accretion disc in quiescent period A, whereas synchrotron radiation from the jet dominated during periods B, C, D, and E. Diverse correlated patterns in the variations of optical and γ-ray emissions, like correlated optical and γ-ray flares, could be accounted for by changes in factors such as the magnetic field, bulk Lorentz factor, and electron density. On the other hand, an orphan optical flare could result from increased magnetic field and bulk Lorentz factor.

Magellanic System Stars Identified in SMACS J0723.3-7327 James Webb Space Telescope Early Release Observations Images

We identify 71 distant stars in James Webb Space Telescope/NIRCam early release observations (ERO) images of the field of galaxy cluster SMACS J0723.3-7327 (SMACS 0723). Given the relatively small (∼10°) angular separation between SMACS 0723 and the Large Magellanic Cloud (LMC), it is likely that these stars are associated with the LMC outskirts or the Leading Arm. This is further bolstered by a spectral energy distribution (SED) analysis, which suggests an excess of stars at a physical distance of 40–100 kpc, consistent with being associated with or located behind the Magellanic system. In particular, we find that the overall surface density of stars brighter than 27.0 mag in the field of SMACS 0723 is ∼2.3 times that of stars in a blank field with similar Galactic latitude (the North Ecliptic Pole Time Domain Field), and that the density of stars in the SMACS 0723 field with SED-derived distances consistent with the Magellanic system is ∼6.1 times larger than that of the blank field. The candidate stars at these distances are consistent with a stellar population at the same distance modulus with [Fe/H] = −1.0 and an age of ∼5.0 Gyr. On the assumption that all of the 71 stars are associated with the LMC, then the stellar density of the LMC at the location of the SMACS 0723 field is ∼740 stars kpc−3, which helps trace the density of stars in the LMC outskirts.

BayeSED-GALAXIES. I. Performance Test for Simultaneous Photometric Redshift and Stellar Population Parameter Estimation of Galaxies in the CSST Wide-field Multiband Imaging Survey

The forthcoming Chinese Space Station Telescope (CSST) wide-field multiband imaging survey will produce seven-band photometric spectral energy distributions (SEDs) for billions of galaxies. The effective extraction of astronomical information from these massive data sets of SEDs relies on the techniques of SED synthesis (or modeling) and SED analysis (or fitting). We evaluate the performance of the latest version of the BayeSED code combined with SED models with increasing complexity for simultaneously determining the photometric redshifts and stellar population parameters of galaxies in this survey. By using an empirical statistics–based mock galaxy sample without SED modeling errors, we show that the random observational errors in photometries are more important sources of errors than the parameter degeneracies and Bayesian analysis method and tool. By using a Horizon-AGN hydrodynamical simulation–based mock galaxy sample with SED modeling errors about the star formation histories (SFHs) and dust attenuation laws (DALs), the simple typical assumptions lead to significantly worse parameter estimation with CSST photometries only. SED models with more flexible (or complicated) forms of SFH/DAL do not necessarily lead to better estimation of redshift and stellar population parameters. We discuss the selection of the best SED model by means of Bayesian model comparison in different surveys. Our results reveal that Bayesian model comparison with Bayesian evidence may favor SED models with different complexities when using photometries from different surveys. Meanwhile, the SED model with the largest Bayesian evidence tends to give the best performance of parameter estimation, which is clearer for photometries with higher discriminative power.

Hidden Giants in JWST's PEARLS: An Ultramassive z = 4.26 Submillimeter Galaxy that Is Invisible to HST

We present a multiwavelength analysis using the Submillimeter Array (SMA), James Clerk Maxwell Telescope, NOEMA, JWST, the Hubble Space Telescope (HST), and the Spitzer Space Telescope of two dusty strongly star-forming galaxies, 850.1 and 850.2, seen through the massive cluster lens A 1489. These SMA-located sources both lie at z = 4.26 and have bright dust continuum emission, but 850.2 is a UV-detected Lyman-break galaxy, while 850.1 is undetected at ≲ 2 μm, even with deep JWST/NIRCam observations. We investigate their stellar, interstellar medium, and dynamical properties, including a pixel-level spectral energy distribution analysis to derive subkiloparsec-resolution stellar-mass and A V maps. We find that 850.1 is one of the most massive and highly obscured, A V ∼ 5, galaxies known at z > 4 with M * ∼1011.8 M ⊙ (likely forming at z > 6), and 850.2 is one of the least massive and least obscured, A V ∼ 1, members of the z > 4 dusty star-forming population. The diversity of these two dust-mass-selected galaxies illustrates the incompleteness of galaxy surveys at z ≳ 3–4 based on imaging at ≲ 2 μm, the longest wavelengths feasible from HST or the ground. The resolved mass map of 850.1 shows a compact stellar-mass distribution, ∼1 kpc, but its expected evolution means that it matches both the properties of massive, quiescent galaxies at z ∼ 1.5 and ultramassive early-type galaxies at z ∼ 0. We suggest that 850.1 is the central galaxy of a group in which 850.2 is a satellite that will likely merge in the near future. The stellar morphology of 850.1 shows arms and a linear bar feature that we link to the active dynamical environment it resides within.

ALMA FIR View of Ultra-high-redshift Galaxy Candidates at z ∼ 11–17: Blue Monsters or Low-z Red Interlopers?

We present Atacama Large Millimeter/submillimeter Array (ALMA) Band 7 observations of a remarkably bright galaxy candidate at (M UV = −21.6), S5-z17-1, identified in James Webb Space Telescope (JWST) Early Release Observation data of Stephen’s Quintet. We do not detect the dust continuum at 866 μm, ruling out the possibility that S5-z17-1 is a low-z dusty starburst with a star formation rate of ≳30 M ⊙ yr−1. We detect a 5.1σ line feature at 338.726 ± 0.007 GHz exactly coinciding with the JWST source position, with a 2% likelihood of the signal being spurious. The most likely line identification would be [O iii]52 μm at z = 16.01 or [C ii]158 μm at z = 4.61, whose line luminosities do not violate the nondetection of the dust continuum in both cases. Together with three other z ≳ 11–13 candidate galaxies recently observed with ALMA, we conduct a joint ALMA and JWST spectral energy distribution (SED) analysis and find that the high-z solution at z ∼ 11–17 is favored in every candidate as a very blue (UV continuum slope of ≃−2.3) and luminous (M UV ≃ [ − 24:−21]) system. Still, we find in several candidates that reasonable SED fits (Δχ 2 ≲ 4) are reproduced by type II quasar and/or quiescent galaxy templates with strong emission lines at z ∼ 3–5, where such populations predicted from their luminosity functions and EW([O iii]+Hβ) distributions are abundant in survey volumes used for the identification of the z ∼ 11–17 candidates. While these recent ALMA observation results have strengthened the likelihood of the high-z solutions, lower-z possibilities are not completely ruled out in several of the z ∼ 11–17 candidates, indicating the need to consider the relative surface densities of the lower-z contaminants in the ultra-high-z galaxy search.

Exploring the evolution of dust temperature using spectral energy distribution fitting in a large photometric survey

ABSTRACT Panchromatic analysis of galaxy spectral energy distributions, spanning from the ultraviolet to the far-infrared, probes not only the stellar population but also the properties of interstellar dust through its extinction and long-wavelength re-emission. However, little work has exploited the full power of such fitting to constrain the redshift evolution of dust temperature in galaxies. To do so, we simultaneously fit ultraviolet, optical, and infrared observations of stacked galaxy subsamples at a range of stellar masses and photometric redshifts at 0 &amp;lt; z &amp;lt; 5, using an energy-balance formalism. However, we find UV-emission beyond the Lyman limit in some photometric redshift selected galaxy subsamples, giving rise to the possibility of contaminated observations. We carefully define a robust clean subsample which extends to no further than z ∼ 2. This has consistently lower derived temperatures by $4.0^{+5.0}_{-1.9}$ K, relative to the full sample. We find a linear increase in dust temperature with redshift, with Td (z) = (4.8 ± 1.5) × z + (26.2 ± 1.5) K. Our inferred temperature evolution is consistent with a modest rise in dust temperature with redshift, but inconsistent with some previous analyses. We also find a majority of photometrically selected subsamples at z &amp;gt; 4.5 underpredict the IR emission while giving reasonable fits to the UV-optical. This could be due to a spatial disconnect in the locations of the UV and IR emission peaks, suggesting that an energy-balance formalism may not always be applicable in the distant Universe.

TOI-2084 b and TOI-4184 b: Two new sub-Neptunes around M dwarf stars

We present the discovery and validation of two TESS exoplanets orbiting nearby M dwarfs: TOI-2084 b, and TOI-4184b. We characterized the host stars by combining spectra from Shane/Kast and Magellan/FIRE, spectral energy distribution analysis, and stellar evolutionary models. In addition, we used Gemini-South/Zorro &amp; -North/Alopeke high-resolution imaging, archival science images, and statistical validation packages to support the planetary interpretation. We performed a global analysis of multi-colour photometric data from TESS and ground-based facilities in order to derive the stellar and planetary physical parameters for each system. We find that TOI-2084 band TOI-4184 bare sub-Neptune-sized planets with radii of Rp = 2.47 ± 0.13R⊕ and Rp = 2.43 ± 0.21 R⊕, respectively. TOI-2084 b completes an orbit around its host star every 6.08 days, has an equilibrium temperature of Teq = 527 ± 8 K and an irradiation of Sp = 12.8 ± 0.8 S⊕. Its host star is a dwarf of spectral M2.0 ± 0.5 at a distance of 114 pc with an effective temperature of Teff = 3550 ± 50 K, and has a wide, co-moving M8 companion at a projected separation of 1400 au. TOI-4184 b orbits around an M5.0 ± 0.5 type dwarf star (Kmag = 11.87) each 4.9 days, and has an equilibrium temperature of Teq = 412 ± 8 K and an irradiation of Sp = 4.8 ± 0.4 S⊕. TOI-4184 is a metal poor star ([Fe/H] = −0.27 ± 0.09 dex) at a distance of 69 pc with an effective temperature of Teff = 3225 ± 75 K. Both planets are located at the edge of the sub-Jovian desert in the radius-period plane. The combination of the small size and the large infrared brightness of their host stars make these new planets promising targets for future atmospheric exploration with JWST.