arXiv subjects

S. E. Clark

Publications and source records attributed to S. E. Clark.

At least 19 recordsLinked to original sources

arXiv2026

The Neutral Atomic Hydrogen in the solar neighborhood (NeAtHood) project I. Ghost in the shell: Neutral atomic hydrogen in the extended Orion nebula

The Orion Nebula is the nearest site of ongoing and recent high-mass star formation. It is a unique laboratory for studying the mass, energy, and momentum input from high-mass stars. We present 21-centimeter emission line observations that resolve for the first time the neutral atomic hydrogen (HI) gas in the extended Orion nebula (EON) at a resolution of one arcminute, which corresponds to a physical scale of 0.12 parsecs at the standard distance to the region. Our HI emission maps reveal an expanding shell that matches the EON contours delineated by recent observations of ionized carbon ([CII]) line emission. However, our combination of single-dish and interferometric HI observations suggests 100 solar masses of material for the front hemisphere of the shell, which is lower by roughly a factor of ten than the mass inferred from [CII] observations. This discrepancy suggests that the mass of the nearest wind-blown bubble has been overestimated, although we do not rule out the possibility that a significant amount of molecular hydrogen (H_2) in the shell may account for part of the difference. Our extended 21 cm line maps also reveal uncharted structures in and around the EON. They include a probable secondary bubble and a linear protrusion extending roughly four parsecs from the shell boundary. Our results illustrate the potential of HI interferometric observations to elucidate key aspects of the multiphase structure of star-forming regions and their connection to their surroundings.

astro-ph.GA↗

arXiv2026

Imprints of the Neutral Interstellar Medium on Polarized Synchrotron Emission and Faraday Rotation

The interstellar medium (ISM) is a complex, multiphase medium, where disentangling the distribution of gas and magnetic field structure across different phases remains a considerable challenge. Recently, Faraday tomography enabled by broadband polarized radio observations has emerged as a promising probe of 3D ISM gas and magnetic field structures. However, the interpretation of these observations is obscured by our limited understanding of the different ISM components probed by the distinct Faraday depth features. In this work, we present a comprehensive multi-frequency ($\sim$300 MHz - 23 GHz) analysis comparing features in the Faraday-rotated, polarized synchrotron emission and HI structures over the full high-latitude (|b|>30 degrees) diffuse sky. Using measures of HI structure complexity along the line of sight (LOS), we observe enhanced depolarization across synchrotron radio frequencies in regions with high HI complexity characterized by multiple HI velocity components. We also find that the first and second moments of the Faraday depth spectra are linked to the underlying neutral gas structure. These results indicate that regions of the ISM that are dominated by neutral gas could directly contribute a significant portion of the diffuse synchrotron emission and Faraday rotation. These findings establish new observational constraints for Galactic magnetic field models that synthesize multiphase tracers into a single coherent picture.

astro-ph.GA↗

arXiv2026

Revealing the cold skeleton of the Magellanic Clouds and the Magellanic Bridge with ASKAP

We present the GASKAP-HI pilot absorption survey of neutral hydrogen (HI) in the Magellanic system. This survey provides 3219 sightlines across the Large (LMC) and Small Magellanic Clouds (SMC) and the Magellanic Bridge (MB) towards 1.4-GHz continuum sources, representing a 15-fold increase on pre--GASKAP-HI sampling of the Magellanic System. We find 344 candidate detections of cold gas at Magellanic velocities (vLSRK >= 90 km s-1), with signal-to-noise ratio > 3 detection rates of 44% (LMC; 192 of 438), 73% (SMC; 85 of 117) and 4% (MB; 35 of 793). We examine the candidate detections within the MB, Gaussian decompose these and examine the cold gas across the MB. Here we find that the majority of cold gas detections are found closer to the SMC. We also find potential evidence of the recent formation of cold gas on the outskirts of a shell within the MB. We find a mean cold gas fraction of fCNM = 0.12 +- 0.08 for the MB, which is very similar to the SMC and lower than the LMC value of 0.14. Overall, we reveal cold gas distributed extensively across the Magellanic system, including within the MB, and surmise that the cold gas in the MB is either pulled from the SMC as part of the formation of the MB, or formed in the turbulence of those same interactions.

astro-ph.GA↗

arXiv2025

The Simons Observatory: forecasted constraints on primordial gravitational waves with the expanded array of Small Aperture Telescopes

We present updated forecasts for the scientific performance of the degree-scale (0.5 deg FWHM at 93 GHz), deep-field survey to be conducted by the Simons Observatory (SO). By 2027, the SO Small Aperture Telescope (SAT) complement will be doubled from three to six telescopes, including a doubling of the detector count in the 93 GHz and 145 GHz channels to 48,160 detectors. Combined with a planned extension of the survey duration to 2035, this expansion will significantly enhance SO's search for a $B$-mode signal in the polarisation of the cosmic microwave background, a potential signature of gravitational waves produced in the very early Universe. Assuming a $1/f$ noise model with knee multipole $\ell_{\rm knee} = 50$ and a moderately complex model for Galactic foregrounds, we forecast a $1\sigma$ (or 68% confidence level) constraint on the tensor-to-scalar ratio $r$ of $\sigma_r = 1.2\times10^{-3}$, assuming no primordial $B$-modes are present. This forecast assumes that 70% of the $B$-mode lensing signal can ultimately be removed using high resolution observations from the SO Large Aperture Telescope (LAT) and overlapping large-scale structure surveys. For more optimistic assumptions regarding foregrounds and noise, and assuming the same level of delensing, this forecast constraint improves to $\sigma_r = 7\times10^{-4}$. These forecasts represent a major improvement in SO's constraining power, being a factor of around 2.5 times better than what could be achieved with the originally planned campaign, which assumed the existing three SATs would conduct a five-year survey.

astro-ph.CO↗

arXiv2025

A three-dimensional model for the reversal in the local large-scale interstellar magnetic field

We probe the three-dimensional geometry of the large-scale Galactic magnetic field within 1 kpc of the Sun using the Dominion Radio Astrophysical Observatory (DRAO) Global Magneto-Ionic Medium Survey (GMIMS) of the Northern Sky (DRAGONS). DRAGONS is a new full polarization survey of the Northern sky from 350 to 1030 MHz covering declinations -20{\deg} < $\delta$ < 90{\deg} and a component of GMIMS. The first moment of the Faraday depth spectra produced from DRAGONS above 500 MHz reveals large-angular-scale Faraday depth structures with signs that alternate only once in the Southern Galactic hemisphere and twice in the Northern hemisphere, patterns shared by other Faraday rotation datasets. DRAGONS is the first survey to achieve high Faraday depth resolution while maintaining sensitivity to broad Faraday depth structures, enabling the first use of Galactic longitude-Faraday depth plots. These plots reveal Faraday-complex structures across the sky, indicating a slab-like scenario in which emission and Faraday rotation are mixed. This complexity is overlaid on the same large-scale Faraday depth patterns that appear in the first moment map. We model these patterns as a magnetic reversal slicing through the disk on a diagonal and passing above the Sun in Galactic coordinates. We describe this reversal as a plane with a normal vector parallel to the line directed along ($\ell$, b) = (168.5{\deg}, -60{\deg}) and estimate its distance to be between 0.25 and 0.55 kpc. Our results show that much of the observed Faraday sky may be dominated by the local magnetic field configuration.

astro-ph.GA↗

arXiv2025

A Catalog of Galactic Atomic Hydrogen Position-Position-Velocity Filaments

We present a catalog of 3D Galactic HI filaments over 1/3 of the sky using Galactic Arecibo L-band Feed Array HI (GALFA-HI) data. The 3D filaments are defined to be linear HI features that are continuous in position-position-velocity (PPV) and are found with fil3d, an algorithm that expands on the 2D FilFinder. The catalog contains 3333 HI filaments between +/- 50 km/s at a range of Galactic positions. 1542 of the PPV filaments are identified as local at the distance of the wall of the Local Bubble, and 209 are likely at the disk-halo interface of our Galaxy. The catalog and properties of the PPV filaments are obtained after an unsharp mask (USM) is applied to the data. The widths of the filaments are consistently ~12' (0.34 pc at 100 pc), and constrained by the 4' resolution. The local filaments have median properties of N_HI = $6 \times 10^{18}$ cm$^{-2}$, M_HI = 0.17 M_sun, FWHM = 3.2 km/s, and length of 6.4 pc. The disk-halo population has similar column densities, but the median FWHM = 7.7 km/s, consistent with them being higher z-height, warmer structures. The L $\propto$ M$^{0.5}$ relationship found for the HI filaments and their bundling on the sky are consistent with a hierarchical structure, and is likely related to turbulence playing a role in their formation.

astro-ph.GA↗

arXiv2025

Neutral gas phase distribution from HI morphology: phase separation with scattering spectra and variational autoencoders

Unraveling the multi-phase structure of the diffuse interstellar medium (ISM) as traced by neutral hydrogen (HI) is essential to understanding the lifecycle of the Milky Way. However, HI phase separation is a challenging and under-constrained problem. The neutral gas phase distribution is often inferred from the spectral line structure of HI emission. In this work, we develop a data-driven phase separation method that extracts HI phase structure solely from the spatial morphology of HI emission intensity structures. We combine scattering spectra (SS) statistics with a Gaussian-mixture variational autoencoder (VAE) model to: 1. derive an interpretable statistical model of different HI phases from their multi-scale morphological structures; 2. use this model to decompose the 2D channel maps of GALFA-HI emission in diffuse high latitude ($|b|>30$\degree) regions over narrow velocity channels ($Δv=3$ km/s) into cold neutral medium (CNM), warm neutral medium (WNM), and noise components. We integrate our CNM map over velocity channels to compare it to an existing map produced by a spectrum-based method, and find that the two maps are highly correlated, while ours recovers more spatially coherent structures at small scales. Our work illustrates and quantifies a clear physical connection between the HI morphology and HI phase structure, and unlocks a new avenue for improving future phase separation techniques by making use of both HI spectral and spatial information to decompose HI in 3D position-position-velocity (PPV) space. These results are consistent with a physical picture where processes that drive HI phase transitions also shape the morphology of HI gas, imprinting a sparse, filamentary CNM that forms out of a diffuse, extended WNM.

astro-ph.GA↗

arXiv2025

The Simons Observatory: Science Goals and Forecasts for the Enhanced Large Aperture Telescope

We describe updated scientific goals for the wide-field, millimeter-wave survey that will be produced by the Simons Observatory (SO). Significant upgrades to the 6-meter SO Large Aperture Telescope (LAT) are expected to be complete by 2028, and will include a doubled mapping speed with 30,000 new detectors and an automated data reduction pipeline. In addition, a new photovoltaic array will supply most of the observatory's power. The LAT survey will cover about 60% of the sky at a regular observing cadence, with five times the angular resolution and ten times the map depth of Planck. The science goals are to: (1) determine the physical conditions in the early universe and constrain the existence of new light particles; (2) measure the integrated distribution of mass, electron pressure, and electron momentum in the late-time universe, and, in combination with optical surveys, determine the neutrino mass and the effects of dark energy via tomographic measurements of the growth of structure at $z < 3$; (3) measure the distribution of electron density and pressure around galaxy groups and clusters, and calibrate the effects of energy input from galaxy formation on the surrounding environment; (4) produce a sample of more than 30,000 galaxy clusters, and more than 100,000 extragalactic millimeter sources, including regularly sampled AGN light-curves, to study these sources and their emission physics; (5) measure the polarized emission from magnetically aligned dust grains in our Galaxy, to study the properties of dust and the role of magnetic fields in star formation; (6) constrain asteroid regoliths, search for Trans-Neptunian Objects, and either detect or eliminate large portions of the phase space in the search for Planet 9; and (7) provide a powerful new window into the transient universe on time scales of minutes to years, concurrent with observations from Rubin of overlapping sky.

astro-ph.IM↗

arXiv2025

Zero-polarization candidate regions for calibration of wide-field optical polarimeters

Context. Calibration of optical polarimeters relies on the use of stars with negligible polarization (unpolarized standard stars) for determining the instrumental polarization zero-point. For wide-field polarimeters, calibration is often done by imaging the same star over multiple positions in the field of view - a process which is time-consuming. A more effective technique is to target fields containing multiple standard stars. While this method has been used for fields with highly polarized stars, there are no such sky regions with well-measured unpolarized standard stars. Aims. We aim to identify sky regions with tens of stars exhibiting negligible polarization, which are suitable for zero-point calibration of wide-field polarimeters. Methods. We selected stars in regions with extremely low reddening, located at high Galactic latitudes. We targeted four ~ 400 x 400 fields in the northern, and eight in the southern Equatorial hemisphere. Observations were carried out at the Skinakas Observatory and the South African Astronomical Observatory respectively. Results. We find two fields in the North and seven in the South with mean polarization lower than p < 0.1%. Conclusions. At least nine out of twelve fields can be used for zero-point calibration of wide-field polarimeters.

astro-ph.SR↗

arXiv2025

Hybrid simulations of FRC merging and compression

An improved understanding of Field Reversed Configuration (FRC) merging and stability in high acceleration and compression magnetic fields is needed to speed up the development of the pulsed fusion concept developed at Helion Energy. All previous theoretical and simulation work on FRC merging and compression was performed using 2D MHD models. The results of novel 2D hybrid simulations (fluid electrons and full-orbit kinetic ions) of FRC merging and compression are presented. Results of kinetic and MHD simulations, computed using the HYM code, are compared and analyzed. In cases without axial magnetic compression, both the MHD and hybrid simulations show a high sensitivity to the initial parameters (i.e. FRC separation, velocity, normalized separatrix radius, and plasma viscosity), showing that FRCs with large elongation and separatrix radius either do not merge or merge partially, forming a doublet FRC. Application of a mirror coil field at the FRC ends with increasing strength is shown to lead to fast and complete merging of the FRCs in MHD and kinetic simulations.

physics.plasm-ph↗

arXiv2025

A New Constraint on the Relative Disorder of Magnetic Fields between Neutral Interstellar Medium Phases

Utilizing Planck polarized dust emission maps at 353 GHz and new large-area maps of the neutral hydrogen (HI) cold neutral medium (CNM) fraction ($f_\mathrm{CNM}$), we investigate the relationship between dust polarization fraction ($p_{353}$) and $f_\mathrm{CNM}$ in the diffuse high latitude ($|b|>30^{\circ}$) sky. We find that the correlation between $p_{353}$ and $f_\mathrm{CNM}$ is qualitatively distinct from the $p_{353}$-HI column density ($N_\mathrm{H\,I}$) relationship. At low column densities ($N_\mathrm{H\,I}<4\times10^{20}~\mathrm{cm^{-2}}$) where $p_{353}$ and $N_\mathrm{H\,I}$ are uncorrelated, there is a strong positive $p_{353}$-$f_\mathrm{CNM}$ correlation. We fit the $p_{353}$-$f_{\rm CNM}$ correlation with data-driven models to constrain the degree of magnetic field disorder between phases along the line-of-sight. We argue that an increased magnetic field disorder in the warm neutral medium (WNM) relative to the CNM best explains the positive $p_{353}$-$f_\mathrm{CNM}$ correlation in diffuse regions. Modeling the CNM-associated dust column as being maximally polarized, with a polarization fraction $p_{\rm CNM} \sim$ 0.2, we find that the best-fit mean polarization fraction in the WNM-associated dust column is 0.22$p_{\rm CNM}$. The model further suggests that a significant $f_{\rm CNM}$-correlated fraction of the non-CNM column (an additional ~18.4% of the HI mass on average) is also more magnetically ordered, and we speculate that the additional column is associated with the unstable medium (UNM). Our results constitute a new large-area constraint on the average relative disorder of magnetic fields between the neutral phases of the ISM, and are consistent with the physical picture of a more magnetically aligned CNM column forming out of a disordered WNM.

astro-ph.GA↗

arXiv2024

The magnetic field of the Radcliffe Wave: starlight polarization at nearest approach to the Sun

We investigate the geometry of the magnetic field towards the Radcliffe Wave, a coherent 3-kpc-long part of the nearby Local Arm recently discovered via three-dimensional dust mapping. We use archival stellar polarization in the optical and new measurements in the near-infrared to trace the magnetic field as projected on the plane of the sky. Our new observations cover the portion of the structure that is closest to the Sun, between Galactic longitudes of 122$^\circ$ and 188$^\circ$. The polarization angles of stars immediately background to the Radcliffe Wave appear to be aligned with the structure as projected on the plane of the sky. The observed magnetic field configuration is inclined with respect to the Galactic disk at an angle of 18$^\circ$. This departure from a geometry parallel to the plane of the Galaxy is contrary to previous constraints from more distant stars and polarized dust emission. We confirm that the polarization angle of stars at larger distances shows a mean orientation parallel to the Galactic disk. We discuss implications of the observed morphology of the magnetic field for models of the large-scale Galactic magnetic field, as well as formation scenarios for the Radcliffe Wave itself.

astro-ph.GA↗

arXiv2024

Emergence of high-mass stars in complex fiber networks (EMERGE) V. From filaments to spheroids: the origin of the hub-filament systems

Identified as parsec-size, gas clumps at the junction of multiple filaments, hub-filament systems (HFS) play a crucial role during the formation of young clusters and high-mass stars. These HFS appear nevertheless to be detached from most galactic filaments when compared in the mass-length (M-L) phase-space. We aim to characterize the early evolution of HFS as part of the filamentary description of the interstellar medium. Combining previous scaling relations with new analytic calculations, we created a toy model to explore the different physical regimes described by the M-L diagram. Despite its simplicity, our model accurately reproduces several observational properties reported for filaments and HFS such as their expected typical aspect ratio ($A$), mean surface density ($Σ$), and gas accretion rate ($\dot{m}$). Moreover, this model naturally explains the different mass and length regimes populated by filaments and HFS, respectively. Our model predicts a dichotomy between filamentary ($A\geq 3$) and spheroidal ($A<3$) structures connected to the relative importance of their fragmentation, accretion, and collapse timescales. Individual filaments with low accretion rates are dominated by an efficient internal fragmentation. In contrast, the formation of compact HFS at the intersection of filaments triggers a geometric phase-transition leading to the gravitational collapse of these structures at parsec-scales in $\sim$1Myr also inducing higher accretion rates.

astro-ph.GA↗

arXiv2024

Imprints of the Local Bubble and Dust Complexity on Polarized Dust Emission

Using 3D dust maps and Planck polarized dust emission data, we investigate the influence of the 3D geometry of the nearby interstellar medium (ISM) on the statistics of the dust polarization on large ($80'$) scales. We test recent models that assume that the magnetic field probed by the polarized dust emission is preferentially tangential to the Local Bubble wall, but we do not find an imprint of the Local Bubble geometry on the dust polarization fraction. We also test the hypothesis that the complexity of the 3D dust distribution drives some of the measured variation of the dust polarization fraction. We compare sightlines with similar total column densities and find that, on average, the dust polarization fraction decreases when the dust column is substantially distributed among multiple components at different distances. Conversely, the dust polarization fraction is higher for sightlines where the dust is more concentrated in 3D space. This finding is statistically significant for the dust within 1.25 kpc, but the effect disappears if we only consider dust within 270 pc. In conclusion, we find that the extended 3D dust distribution, rather than solely the dust associated with the Local Bubble, plays a role in determining the observed dust polarization fraction at 80$'$. This conclusion is consistent with a simple analytical prediction and remains robust under various modifications to the analysis. These results illuminate the relationship between the 3D geometry of the ISM and tracers of the interstellar magnetic field. We discuss implications for our understanding of the polarized dust foreground to the cosmic microwave background.

astro-ph.GA↗

arXiv2024

Faraday moments of the Southern Twenty-centimeter All-sky Polarization Survey (STAPS)

Faraday tomography of broadband radio polarization surveys enables us to study magnetic fields and their interaction with the interstellar medium (ISM). Such surveys include the Global Magneto-Ionic Medium Survey (GMIMS), which covers the northern and southern hemispheres at $\sim$ 300-1800 MHz. In this work, we used the GMIMS High Band South (1328-1768 MHz), also named the Southern Twenty-centimeter All-sky Polarization Survey (STAPS), which observes the southern sky at a resolution of 18$\arcmin$. To extract the key parameters of the magnetized ISM from STAPS, we computed the Faraday moments of the tomographic data cubes. These moments include the total polarized intensity, the mean Faraday depth weighted by the polarized intensity, the weighted dispersion of the Faraday spectrum, and its skewness. We compared the Faraday moments to those calculated over the same frequency range in the northern sky (using the Dominion Radio Astrophysical Observatory, DRAO), in a strip of $360\degr \times 30\degr$ that overlaps with STAPS coverage. We find that the total polarized intensity is generally dominated by diffuse emission that decreases at longitudes of $l \leq 300\degr$. The Faraday moments reveal a variety of polarization structures. Low-intensity regions at high latitudes usually have a single Faraday depth component. Due to its insufficiently large frequency coverage, STAPS cannot detect Faraday thick structures. Comparing the Faraday depths from STAPS to total rotation measures from extragalactic sources suggests that STAPS frequencies are high enough that the intervening ISM causes depolarization to background emission at intermediate and high Galactic latitudes. Where they overlap, the STAPS and DRAO surveys exhibit broad correspondence but differ in polarized intensity by a factor of $\sim$1.8.

astro-ph.GA↗

arXiv2024

The first degree-scale starlight-polarization-based tomography map of the magnetized interstellar medium

We present the first degree-scale tomography map of the dusty magnetized interstellar medium (ISM) from stellar polarimetry and distance measurements. We used the RoboPol polarimeter at Skinakas Observatory to conduct a survey of starlight polarization in a region of the sky of 4 square degrees. We propose a Bayesian method to decompose the stellar-polarization source field along the distance to invert the 3D volume occupied by the observed stars. We used it to obtain the first 3D map of the dusty magnetized ISM. Specifically, we produced a tomography map of the orientation of the plane-of-sky (POS) component of the magnetic field threading the diffuse, dusty regions responsible for the stellar polarization. For the targeted region centered on Galactic coordinates $(l,b) \approx (103.3^\circ, 22.3^\circ)$, we identified several ISM clouds. Most of the lines of sight intersect more than one cloud. A very nearby component was detected in the foreground of a dominant component from which most of the polarization signal comes. Farther clouds, with a distance of up to 2~kpc, were similarly detected. Some of them likely correspond to intermediate-velocity clouds seen in HI spectra in this region of the sky. We found that the orientation of the POS component of the magnetic field changes along distance for most of the lines of sight. Our study demonstrates that starlight polarization data coupled to distance measures have the power to reveal the great complexity of the dusty magnetized ISM in 3D and, in particular, to provide local measurements of the POS component of the magnetic field. This demonstrates that the inversion of large data volumes, as expected from the PASIPHAE survey, will provide the necessary means to move forward in the modeling of the Galactic magnetic field and of the dusty magnetized ISM as a contaminant in observations of the cosmic microwave background polarization.

astro-ph.GA↗

arXiv2023

Tensor-to-scalar ratio forecasts for extended LiteBIRD frequency configurations

LiteBIRD is a planned JAXA-led CMB B-mode satellite experiment aiming for launch in the late 2020s, with a primary goal of detecting the imprint of primordial inflationary gravitational waves. Its current baseline focal-plane configuration includes 15 frequency bands between 40 and 402 GHz, fulfilling the mission requirements to detect the amplitude of gravitational waves with the total uncertainty on the tensor-to-scalar ratio, $δr$, down to $δr<0.001$. A key aspect of this performance is accurate astrophysical component separation, and the ability to remove polarized thermal dust emission is particularly important. In this paper we note that the CMB frequency spectrum falls off nearly exponentially above 300 GHz relative to the thermal dust SED, and a relatively minor high frequency extension can therefore result in even lower uncertainties and better model reconstructions. Specifically, we compare the baseline design with five extended configurations, while varying the underlying dust modeling, in each of which the HFT (High-Frequency Telescope) frequency range is shifted logarithmically towards higher frequencies, with an upper cutoff ranging between 400 and 600 GHz. In each case, we measure the tensor-to-scalar ratio $r$ uncertainty and bias using both parametric and minimum-variance component-separation algorithms. When the thermal dust sky model includes a spatially varying spectral index and temperature, we find that the statistical uncertainty on $r$ after foreground cleaning may be reduced by as much as 30--50 % by extending the upper limit of the frequency range from 400 to 600 GHz, with most of the improvement already gained at 500 GHz. We also note that a broader frequency range leads to better ability to discriminate between models through higher $χ^2$ sensitivity. (abridged)

astro-ph.CO↗

arXiv2023

Polarization fraction of Planck Galactic cold clumps and forecasts for the Simons Observatory

We measure the polarization fraction of a sample of $6282$ Galactic cold clumps at $353 \, \mathrm{GHz} $, consisting of $Planck$ Galactic cold clump (PGCC) catalogue category 1 objects (flux densities measured with signal-to-noise ratio $(\mathrm{S/N}) > 4$). We find the mean-squared polarization fraction at $353 \, \mathrm{GHz} $ to be $ \langle Π^ 2 \rangle = [ 4.79 \pm 0.44 ] \times 10 ^ {-4} $ equating to an $ 11 \, σ$ detection of polarization. We test if the polarization fraction depends on the clumps' physical properties, including flux density, luminosity, Galactic latitude and physical distance. We see a trend towards increasing polarization fraction with increasing Galactic latitude, but find no evidence that polarization depends on the other tested properties. The Simons Observatory, with an angular resolution of order $1 \, \mathrm{arcmin } $ and noise levels between $22$ and $54$ $ μ\mathrm{ K-arcmin } $ at high frequencies, will substantially enhance our ability to determine the magnetic field structure in Galactic cold clumps. At $\ge5\,σ$ significance, we predict the Simons Observatory will detect at least $\sim12,000$ cold clumps in intensity and $\sim430$ cold clumps in polarization. This number of polarization detections would represent a two orders of magnitude increase over the current $Planck$ results. We also release software that can be used to mask these Galactic cold clumps in other analyses.

astro-ph.GA↗