Abstract We present JWST and Atacama Large Millimeter/submillimeter Array (ALMA) imaging for the lensing system SPT0418−47, which includes a strongly lensed, dusty, star-forming galaxy at redshift z ...= 4.225 and an associated multiply imaged companion. The JWST NIRCam and MIRI imaging observations presented in this paper were acquired as part of the Early Release Science program Targeting Extremely Magnified Panchromatic Lensed Arcs and Their Extended Star formation (TEMPLATES). This data set provides robust mutiwavelength detections of stellar light in both the main (SPT0418A) and companion (SPT0418B) galaxies, while the ALMA detection of C ii emission confirms that SPT0418B lies at the same redshift as SPT0418A. We infer that the projected physical separation of the two galaxies is 4.42 ± 0.05 kpc. We derive total magnifications of μ = 29 ± 1 and μ = 4.1 ± 0.7 for SPT0418A and SPT0418B, respectively. We use both prospector and cigale to derive stellar masses. We find that SPT0418A has a stellar mass of M * = 3.4 − 0.6 + 1.1 × 10 10 M ⊙ from prospector or M * = 1.5 ± 0.3 × 10 10 M ⊙ from cigale . The stellar mass ratio of SPT0418A and SPT0418B is roughly between 4 and 7 ( 4.2 − 1.6 + 1.9 for prospector and 7.5 ± 3.7 for cigale ). We see evidence of extended structure associated with SPT0418A that is suggestive of a tidal feature. These features, along with the close projected proximity, imply that the system is interacting. Interestingly, the star formation rates and stellar masses of both galaxies are consistent with the main sequence of star-forming galaxies at this epoch, indicating that this ongoing interaction has not noticeably elevated the star formation levels.
Abstract
SPT0311-58, a system of two interacting galaxies in the Epoch of Reionization, exists in one of the rarest, most massive dark matter halos theoretically possible in that era. Studying the ...interstellar medium (ISM) in these galaxies can illuminate the process of galaxy formation in the early Universe. In this work, we explore the multiphase ISM in this system, using ALMA observations of the C
ii
158, O
i
146, N
ii
122, and O
iii
88 fine-structure lines and dust continuum. We find wide variations in line ratios between the eastern and western galaxies, as well as across the western galaxy. Continuum colors indicate that SPT0311-58 E has a higher ionization parameter (
log
U
≈
−
2.8
) than SPT0311-58 W (
log
U
≈
−
3.1
). The ratio of O
iii
88–N
ii
122 and the ionization parameter constraints combine to demonstrate near-solar metallicity in these objects just 800 Myr after the Big Bang.
Abstract
One of the most fundamental baryonic matter components of galaxies is the neutral atomic hydrogen (H
i
). At low redshifts, this component can be traced directly through the 21 cm ...transition, but to infer the H
i
gas content of the most distant galaxies, a viable tracer is needed. We here investigate the fidelity of the fine-structure transition of the (
2
P
3/2
−
2
P
1/3
) transition of singly ionized carbon C
ii
at 158
μ
m as a proxy for H
i
in a set simulated galaxies at
z
≈ 6, following the work by Heintz et al. We select 11,125 star-forming galaxies from the
simba
simulations, with far-infrared line emissions postprocessed and modeled within the S
igame
framework. We find a strong connection between C
ii
and H
i
, with the relation between this C
ii
-to-H
i
relation (
β
C
II
) being anticorrelated with the gas-phase metallicity of the simulated galaxies. We further use these simulations to make predictions for the total baryonic matter content of galaxies at
z
≈ 6, and specifically the H
i
gas mass fraction. We find mean values of
M
H I
/
M
⋆
= 1.4 and
M
H I
/
M
bar,tot
= 0.45. These results provide strong evidence for H
i
being the dominant baryonic matter component by mass in galaxies at
z
≈ 6.
The assembly and build-up of neutral atomic hydrogen (H I ) in galaxies is one of the most fundamental processes in galaxy formation and evolution. Studying this process directly in the early ...universe is hindered by the weakness of the hyperfine 21-cm H I line transition, impeding direct detections and measurements of the H I gas masses ( M HI ). Here we present a new method to infer M HI of high-redshift galaxies using neutral, atomic oxygen as a proxy. Specifically, we derive metallicity-dependent conversion factors relating the far-infrared O I -63 μm and O I -145 μm emission line luminosities and M HI in star-forming galaxies at z ≈ 2 − 6 using gamma-ray bursts (GRBs) as probes. We calibrate the O I -to-H I conversion factor relying on a sample of local galaxies with direct measurements of M HI and O I -63 μm and O I -145 μm line luminosities in addition to the S IGAME hydrodynamical simulation framework at similar epochs ( z ≈ 0). We find that the O I 63 μm -to-H I and O I 145 μm -to-H I conversion factors, here denoted β OI−63 μm and β OI−145 μm , respectively, universally appear to be anti-correlated with the gas-phase metallicity. The GRB measurements further predict a mean ratio of L OI−63 μm / L OI−145 μm = 1.55 ± 0.12 and reveal generally less excited C II over O I compared to the local galaxy sample. The z ≈ 0 galaxy sample also shows systematically higher β OI−63 μm and β OI−145 μm conversion factors than the GRB sample, indicating either suppressed O I emission in local galaxies likely due to their lower hydrogen densities or more extended, diffuse H I gas reservoirs traced by the H I 21-cm. Finally, we apply these empirical calibrations to the few detections of O I -63 μm and O I -145 μm line transitions at z ≈ 2 from the literature and further discuss the applicability of these conversion factors to probe the H I gas content in the dense, star-forming interstellar medium (ISM) of galaxies well into the epoch of reionization.
Abstract
We present an update to the framework called Simulator of Galaxy Millimeter/submillimeter Emission (
sígame
).
sígame
derives line emission in the far-infrared (FIR) for galaxies in ...particle-based cosmological hydrodynamics simulations by applying radiative transfer and physics recipes via a postprocessing step after completion of the simulation. In this version, a new technique is developed to model higher gas densities by parameterizing the probability distribution function (PDF) of the gas density in higher-resolution simulations run with the pseudo-Lagrangian, Voronoi mesh code
arepo
. The parameterized PDFs are used as a look-up table, and reach higher densities than in previous work.
sígame
v3 is tested on redshift
z
= 0 galaxies drawn from the
simba
cosmological simulation for eight FIR emission lines tracing vastly different phases of the interstellar medium. This version of
sígame
includes dust radiative transfer with S
kirt
and high-resolution photoionization models with C
loudy
, the latter sampled according to the density PDF of the
arepo
simulations to augment the densities in the cosmological simulation. The quartile distributions of the predicted line luminosities overlap with the observed range for nearby galaxies of similar star formation rate (SFR) for all but two emission lines: O
i
63 and CO(3–2), which are overestimated by median factors of 1.3 and 1.0 dex, respectively, compared to the observed line–SFR relation of mixed-type galaxies. We attribute the remaining disagreement with observations to the lack of precise attenuation of the interstellar light on sub-grid scales (≲200 pc) and differences in sample selection.
Abstract
Debris disks are scaled-up analogs of the Kuiper Belt in which dust is generated by collisions between planetesimals. In the
collisional cascade
model of debris disks, the dust lost to ...radiation pressure and winds is constantly replenished by grinding collisions between planetesimals. The model assumes that collisions are destructive and involve large velocities; this assumption has not been tested beyond our solar system. We present 0.″25 (≈2.4 au) resolution observations of the
λ
= 450
μ
m dust continuum emission from the debris disk around the nearby M dwarf AU Microscopii with the Atacama Large Millimeter/submillimeter Array. We use parametric models to describe the disk structure, and a Monte Carlo Markov Chain (MCMC) algorithm to explore the posterior distributions of the model parameters; we fit the structure of the disk to both our data and archival
λ
= 1.3 mm data (Daley et al. 2019), from which we obtain two aspect ratio measurements at 1.3 mm (
h
1300
=
0.025
−
0.002
+
0.008
) and at 450
μ
m (
h
450
=
0.019
−
0.001
+
0.006
), as well as the grain-size distribution index
q
= 3.03 ± 0.02. Contextualizing our aspect ratio measurements within the modeling framework laid out in Pan & Schlichting (2012), we derive a power-law index of velocity dispersion as a function of grain size
p
= 0.28 ± 0.06 for the AU Mic debris disk. This result implies that smaller bodies are more easily disrupted than larger bodies by collisions, which is inconsistent with the strength regime usually assumed for such small bodies. Possible explanations for this discrepancy are discussed.
Abstract
Detecting the line-intensity mapping (LIM) signal from the galaxies of the epoch of reionization is an emerging tool to constrain their role in reionization. Ongoing and upcoming experiments ...target the signal fluctuations across the sky to reveal statistical and astrophysical properties of these galaxies via signal statistics, e.g. the power spectrum. Here, we revisit the C ii$_{158 \, \mu \text{m}}$ LIM power spectrum under non-uniform line–luminosity scatter, which has a halo-mass variation of statistical properties. Line–luminosity scatter from a cosmological hydrodynamic and radiative transfer simulation of galaxies at $z$ = 6 is considered in this study. We test the robustness of different model frameworks that interpret the impact of the line-luminosity scatter on the signal statistics. We use a simple power-law model to fit the scatter and demonstrate that the mean luminosity–halo mass correlation fit cannot preserve the mean intensity of the LIM signal (hence the clustering power spectrum) under non-uniform scatter. In our case, the mean intensity changes by ∼48 per cent compared to the mean correlation fit in contrast to the general case with semi-analytical scatter. However, we find that the prediction for the mean intensity from the most-probable fit can be modelled robustly, considering the generalized and more realistic non-uniform scatter. We also explore the possibility of diminishing luminosity bias under non-uniform scatter, affecting the clustering power spectrum, although this phenomenon might not be statistically significant. Therefore, we should adopt appropriate approaches that can consistently interpret the LIM power spectrum from observations.
Context. Deep spectroscopic surveys with the Atacama Large Millimeter/submillimeter Array (ALMA) have revealed that some of the brightest infrared sources in the sky correspond to concentrations of ...submillimeter galaxies (SMGs) at high redshift. Among these, the SPT2349-56 protocluster system is amongst the most extreme examples given its high source density and integrated star formation rate. Aims. We conducted a deep Lyman- α line emission survey around SPT2349-56 using the Multi-Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope (VLT) in order to characterize this uniquely dense environment. Methods. Taking advantage of the deep three-dimensional nature of this survey, we performed a sensitive search for Lyman- α emitters (LAEs) toward the core and northern extension of the protocluster, which correspond to the brightest infrared regions in this field. Using a smoothed narrowband image extracted from the MUSE datacube around the protocluster redshift, we searched for possible extended structures. Results. We identify only three LAEs at z = 4.3 in this field. This number is lower than expectations for blank fields, and is significantly lower than the number of previously identified SMGs in this system. We find an extended Lyman- α structure of about 60 × 60 kpc 2 in size located 56 kpc east of the protocluster core. Three SMGs coincide spatially with the location of this structure. All the other SMGs are undetected in Lyman- α emission, which is consistent with the conspicuous dust obscuration in these systems. We conclude that either the three co-spatial SMGs or the protocluster core itself are feeding ionizing photons to the Lyman- α structure.
![Investigating the [C ii]-to...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/2041-8205/small "Investigating the [C ii]-to-H i Conversion Factor and the H i Gas Budget of Galaxies at z ≈ 6 with Hydrodynamic Simulations")
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![Revisiting the [C ii ] 158...](http://api.summon.serialssolutions.com/2.0.0/image/issn/XR4PS5YY4K/0035-8711/small "Revisiting the [C ii ] 158 μm line-intensity mapping power spectrum from the EoR using non-uniform line-luminosity scatter")