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High-resolution observations of the Perseus B5 "core" have previously revealed that this subsonic region actually consists of several filaments that are likely in the process of forming a quadruple stellar system. Since subsonic filaments are thought to be produced at the $\sim 0.1$ pc sonic scale by turbulent compression, a detailed kinematic study is crucial to test such a scenario in the context of core and star formation. Here we present a detailed kinematic follow-up study of the B5 filaments at a 0.009 pc resolution using the VLA and GBT combined observations fitted with multi-component spectral models. Using precisely identified filament spines, we find a remarkable resemblance between the averaged width profiles of each filament and Plummer-like functions, with filaments possessing FWHM widths of $\sim 0.03$ pc. The velocity dispersion profiles of the filaments also show decreasing trends towards the filament spines. Moreover, the velocity gradient field in B5 appears to be locally well ordered ($\sim 0.04$ pc) but globally complex, with kinematic behaviors suggestive of inhomogeneous turbulent accretion onto filaments and longitudinal flows towards a local overdensity along one of the filaments., Comment: 27 pages, 12 figures, published in The Astrophysical Journal

We present N-PDFs of 29 Galactic regions obtained from Herschel imaging at high angular resolution, covering diffuse and quiescent clouds, and those showing low-, intermediate-, and high-mass star formation (SF), and characterize the cloud structure using the Delta-variance tool. The N-PDFs are double-log-normal at low column densities, and display one or two power law tails (PLTs) at higher column densities. For diffuse, quiescent, and low-mass SF clouds, we propose that the two log-normals arise from the atomic and molecular phase, respectively. For massive clouds, we suggest that the first log-normal is built up by turbulently mixed H2 and the second one by compressed (via stellar feedback) molecular gas. Nearly all clouds have two PLTs with slopes consistent with self-gravity, where the second one can be flatter or steeper than the first one. A flatter PLT could be caused by stellar feedback or other physical processes that slow down collapse and reduce the flow of mass toward higher densities. The steeper slope could arise if the magnetic field is oriented perpendicular to the LOS column density distribution. The first deviation point (DP), where the N-PDF turns from log-normal into a PLT, shows a clustering around values of a visual extinction of AV (DP1) around 2-5. The second DP, which defines the break between the two PLTs, varies strongly. Using the Delta-variance, we observe that the AV value, where the slope changes between the first and second PLT, increases with the characteristic size scale in the variance spectrum. We conclude that at low column densities, atomic and molecular gas is turbulently mixed, while at high column densities, the gas is fully molecular and dominated by self-gravity. The best fitting model N-PDFs of molecular clouds is thus one with log-normal low column density distributions, followed by one or two PLTs., Comment: Astronomy and Astrophysics in presss

Understanding the chemical processes during starless core and prestellar core evolution is an important step in understanding the initial stages of star and disk formation. This project is a study of deuterated ammonia, o-NH$_2$D, in the L1251 star-forming region toward Cepheus. Twenty-two dense cores (twenty of which are starless or prestellar, and two of which have a protostar), previously identified by p-NH$_3$ (1,1) observations, were targeted with the 12m Arizona Radio Observatory telescope on Kitt Peak. o-NH$_2$D J$_{\rm{K_a} \rm{K_c}}^{\pm} =$ $1_{11}^{+} \rightarrow 1_{01}^{-}$ was detected in 13 (59\%) of the NH$_3$-detected cores with a median sensitivity of $\sigma_{T_{mb}} = 17$ mK. All cores detected in o-NH$_2$D at this sensitivity have p-NH$_3$ column densities $> 10^{14}$ cm$^{-2}$. The o-NH$_2$D column densities were calculated using the constant excitation temperature (CTEX) approximation while correcting for the filling fraction of the NH$_3$ source size. The median deuterium fraction was found to be 0.11 (including 3$\sigma$ upper limits). However, there are no strong, discernible trends in plots of deuterium fraction with any physical or evolutionary variables. If the cores in L1251 have similar initial chemical conditions, then this result is evidence of the cores physically evolving at different rates., Comment: 18 pages, 14 figures, MNRAS, in press

A population-level analysis is proposed to address data sparsity when building predictive models for engineering infrastructure. Utilising an interpretable hierarchical Bayesian approach and operational fleet data, domain expertise is naturally encoded (and appropriately shared) between different sub-groups, representing (i) use-type, (ii) component, or (iii) operating condition. Specifically, domain expertise is exploited to constrain the model via assumptions (and prior distributions) allowing the methodology to automatically share information between similar assets, improving the survival analysis of a truck fleet and power prediction in a wind farm. In each asset management example, a set of correlated functions is learnt over the fleet, in a combined inference, to learn a population model. Parameter estimation is improved when sub-fleets share correlated information at different levels of the hierarchy. In turn, groups with incomplete data automatically borrow statistical strength from those that are data-rich. The statistical correlations enable knowledge transfer via Bayesian transfer learning, and the correlations can be inspected to inform which assets share information for which effect (i.e. parameter). Both case studies demonstrate the wide applicability to practical infrastructure monitoring, since the approach is naturally adapted between interpretable fleet models of different in situ examples.

During the transition phase from a prestellar to a protostellar cloud core, one or several protostars can form within a single gas core. The detailed physical processes of this transition, however, still remain unclear. We present 1.3 mm dust continuum and molecular line observations with the Atacama Large Millimeter/submillimeter Array (ALMA) toward 43 protostellar cores in the Orion Molecular Cloud Complex ($\lambda$ Orionis, Orion B, and Orion A) with an angular resolution of $\sim$ 0.35" ($\sim$ 140 au). In total, we detect 13 binary/multiple systems. We derive an overall multiplicity frequency (MF) of 28$\%$ $\pm$ 4$\%$ and a companion star fraction (CSF) of 51$\%$ $\pm$ 6$\%$, over a separation range of 300-8900 au. The median separation of companions is about 2100 au. The occurrence of stellar multiplicity may depend on the physical characteristics of the dense cores. Notably, those containing binary/multiple systems tend to show higher gas density and Mach number than cores forming single stars. The integral-shaped filament (ISF) of Orion A giant molecular cloud (GMC), which has the highest gas density and hosts high-mass star formation in its central region (the Orion Nebula cluster), shows the highest MF and CSF among the Orion GMCs. In contrast, the $\lambda$ Orionis Giant Molecular Cloud (GMC) has a lower MF and CSF than the Orion B and Orion A GMCs, indicating that feedback from HII regions may suppress the formation of multiple systems. We also find that the protostars comprising a binary/multiple system are usually at different evolutionary stages., Comment: This paper was accepted by APJ. 31 pages and 9 figures

Prestellar cores are generally spheroidal, some of which appear oblate while others appear prolate. Very few of them appear circular in projection. Little, however, is understood about the processes or the physical conditions under which prolate/oblate cores form. We find that an initially sub-critical filament experiencing relatively low pressure ($\lesssim 10^{4}$ K cm$^{-3}$) forms prolate cores (i.e., those with axial ratios in excess of unity) via gradual accumulation of gas in density crests. Meanwhile, a filament that is initially transcritical and experiences pressure similar to that in the Solar neighbourhood (between $\mathrm{few}\ \times 10^{4}$ K cm$^{-3}$ - $\mathrm{few}\ \times 10^{5}$ K cm$^{-3}$) forms oblate cores (i.e., those with axial ratios less than unity) via \emph{Jeans like} fragmentation. At higher pressure, however, fragments within the filament do not tend to survive as they rebound soon after formation. We also argue that quasi-oscillatory features of velocity gradient observed along the filament axis, and in the direction orthogonal to the axis, are integral to the filament evolution process and arise due to the growth of corrugations on its surface. The axial component of the velocity gradient, in particular, traces the gas-flow along the filament length. We therefore posit that it could be used to constrain the filament-formation mechanism. The magnitude of the respective components of velocity gradients increases with increasing external pressure., Comment: 20 pages; 15 figures; Accepted for publication in MNRAS Low resolution figures have been deliberately included here to make the article compatible with Arxiv submission rules

In this paper, we propose a new exogenous model to address the problem of negative interest rates that preserves the analytical tractability of the original Cox-Ingersoll-Ross (CIR) model with a perfect fit to the observed term-structure. We use the difference of two independent CIR processes and apply the deterministic-shift extension technique. To allow for a fast calibration to the market swaption surface, we apply the Gram-Charlier expansion to calculate the swaption prices in our model. We run several numerical tests to demonstrate the strengths of this model by using Monte-Carlo techniques. In particular, the model produces close Bermudan swaption prices compared to Bloomberg's Hull-White one-factor model. Moreover, it finds constant maturity swap (CMS) rates very close to Bloomberg's CMS rates.

Self-assembled structures are possible solutions to the problem of increasing the density and connectivity of memristive units in massive arrays. Although they would allow surpassing the limit imposed by the lithographic feature size, the spontaneous formation of highly interconnected networks poses a new challenge: how to characterize and control the obtained assemblies. In view of a flourishing field of such experimental realizations, this study explores the collective electrical response of simulated memristive units when assembled in geometrically organized and progressively distorted configurations. We show that highly idealized memristive arrays already display a degree of complexity that needs to be taken into account when characterizing self-assemblies to be technologically exploited. Moreover, the introduction of simple distortions has a considerable impact on the available resistance states and their evolution upon cycling. Considering arrays of a limited size, we also demonstrate that the collective response resembles aspects of the individual model while also revealing its own phenomenology.

We present 850 $\mu$m polarimetric observations toward the Serpens Main molecular cloud obtained using the POL-2 polarimeter on the James Clerk Maxwell Telescope (JCMT) as part of the B-fields In STar-forming Region Observations (BISTRO) survey. These observations probe the magnetic field morphology of the Serpens Main molecular cloud on about 6000 au scales, which consists of cores and six filaments with different physical properties such as density and star formation activity. Using the histogram of relative orientation (HRO) technique, we find that magnetic fields are parallel to filaments in less dense filamentary structures where $N_{H_2} < 0.93\times 10^{22}$ cm$^{-2}$ (magnetic fields perpendicular to density gradients), while being perpendicular to filaments (magnetic fields parallel to density gradients) in dense filamentary structures with star formation activity. Moreover, applying the HRO technique to denser core regions, we find that magnetic field orientations change to become perpendicular to density gradients again at $N_{H_2} \approx 4.6 \times 10^{22}$ cm$^{-2}$. This can be interpreted as a signature of core formation. At $N_{H_2} \approx 16 \times 10^{22}$ cm$^{-2}$ magnetic fields change back to being parallel to density gradients once again, which can be understood to be due to magnetic fields being dragged in by infalling material. In addition, we estimate the magnetic field strengths of the filaments ($B_{POS} = 60-300~\mu$G)) using the Davis-Chandrasekhar-Fermi method and discuss whether the filaments are gravitationally unstable based on magnetic field and turbulence energy densities., Comment: 18 pages, accepted for publication in ApJ

The Orion molecular cloud complex harbours the nearest GMCs and site of high-mass star formation. Its YSO populations are thoroughly characterized. The region is therefore a prime target for the study of star formation. Here, we verify the performance of the SuperCAM 64 pixel heterodyne array on APEX. We give a descriptive overview of a set of wide-field CO(3-2) spectral cubes obtained towards the Orion GMC complex, aimed at characterizing the dynamics and structure of the extended molecular gas in diverse regions of the clouds, ranging from very active sites of clustered star formation in Orion B to comparatively quiet regions in southern Orion A. We present a 2.7 square degree (130pc$^2$) mapping survey in the CO(3-2) transition, obtained using SuperCAM on APEX at an angular resolution of 19'' (7600AU or 0.037pc at a distance of 400pc), covering L1622, NGC2071, NGC2068, OriB9, NGC2024, and NGC2023 in Orion B, and the southern part of the L1641 cloud in Orion A. We describe CO integrated emission and line moment maps and position-velocity diagrams and discuss a few sub-regions in some detail. Evidence for expanding bubbles is seen with lines splitting into double components, most prominently in NGC2024, where we argue that the bulk of the molecular gas is in the foreground of the HII region. High CO(3-2)/CO(1-0) line ratios reveal warm CO along the western edge of Orion B in the NGC2023/NGC2024 region facing the IC434 HII region. Multiple, well separated radial velocity components seen in L1641-S suggest that it consists of a sequence of clouds at increasingly larger distances. We find a small, spherical cloud - the 'Cow Nebula' globule - north of NGC2071. We trace high velocity line wings for the NGC2071-IR outflow and the NGC2024 CO jet. The protostellar dust core FIR4 (rather than FIR5) is the true driving source of the NGC2024 monopolar outflow., Comment: Accepted for publication in Astronomy and Astrophysics

The $SL(2,\mathbb Z)$-symmetry of Cherednik's spherical double affine Hecke algebras in Macdonald theory includes a distinguished generator which acts as a discrete time evolution of Macdonald operators, which can also be interpreted as a torus Dehn twist in type $A$. We prove for all twisted and untwisted affine algebras of type $ABCD$ that the time-evolved $q$-difference Macdonald operators, in the $t\to\infty$ $q$-Whittaker limit, form a representation of the associated discrete integrable quantum Q-systems, which are obtained, in all but one case, via the canonical quantization of suitable cluster algebras. The proof relies strongly on the duality property of Macdonald and Koornwinder polynomials, which allows, in the $q$-Whittaker limit, for a unified description of the quantum Q-system variables and the conserved quantities as limits of the time-evolved Macdonald operators and the Pieri operators, respectively. The latter are identified with relativistic $q$-difference Toda Hamiltonians. A crucial ingredient in the proof is the use of the "Fourier transformed" picture, in which we compute time-translation operators and prove that they commute with the Pieri operators or Hamiltonians. We also discuss the universal solutions of Koornwinder-Macdonald eigenvalue and Pieri equations, for which we prove a duality relation, which simplifies the proofs further., Comment: 94 pages, 1 figure

We present the first data release of the ALMA-IMF Large Program, which covers the 12m-array continuum calibration and imaging. The ALMA-IMF Large Program is a survey of fifteen dense molecular cloud regions spanning a range of evolutionary stages that aims to measure the core mass function (CMF). We describe the data acquisition and calibration done by the Atacama Large Millimeter/submillimeter Array (ALMA) observatory and the subsequent calibration and imaging we performed. The image products are combinations of multiple 12m array configurations created from a selection of the observed bandwidth using multi-term, multi-frequency synthesis imaging and deconvolution. The data products are self-calibrated and exhibit substantial noise improvements over the images produced from the delivered data. We compare different choices of continuum selection, calibration parameters, and image weighting parameters, demonstrating the utility and necessity of our additional processing work. Two variants of continuum selection are used and will be distributed: the "best-sensitivity" data, which include the full bandwidth, including bright emission lines that contaminate the continuum, and "cleanest", which select portions of the spectrum that are unaffected by line emission. We present a preliminary analysis of the spectral indices of the continuum data, showing that the ALMA products are able to clearly distinguish free-free emission from dust emission, and that in some cases we are able to identify optically thick emission sources. The data products are made public with this release., Comment: Data released on Zenodo at https://zenodo.org/record/5702966. Accepted for publication in A&A

The ALMA-IMF Large Program imaged a total noncontiguous area of 53pc2, covering 15 extreme, nearby protoclusters of the Milky Way. They were selected to span relevant early protocluster evolutionary stages. Our 1.3mm and 3mm observations provide continuum images that are homogeneously sensitive to point-like cores with masses of 0.2 and 0.6Msun, respectively, with a matched spatial resolution of 2000au. We also detect lines that probe the protocluster structure, kinematics, chemistry, and feedback over scales from clouds to filaments to cores. We classify ALMA-IMF protoclusters as Young, Intermediate, or Evolved based on the amount of dense gas in the cloud that has potentially been impacted by HII regions. The ALMA-IMF catalog contains 700 cores that span a mass range of 0.15-250Msun at a typical size of 2100au. We show that this core sample has no significant distance bias and can be used to build core mass functions at similar physical scales. Significant gas motions, which we highlight here in the G353.41 region, are traced down to core scales and can be used to look for inflowing gas streamers and to quantify the impact of the possible associated core mass growth on the shape of the CMF with time. Our first analysis does not reveal any significant evolution of the matter concentration from clouds to cores or from the youngest to more evolved protoclusters, indicating that cloud dynamical evolution and stellar feedback have for the moment only had a slight effect on the structure of high-density gas in our sample. Furthermore, the first-look analysis of the line richness toward bright cores indicates that the survey encompasses several tens of hot cores, of which we highlight the most massive in the G351.77 cloud. Their homogeneous characterization can be used to constrain the emerging molecular complexity in protostars of high to intermediate masses., Comment: 27 pages, 9 figures, accepted for publication by A&A

We investigate the internal 3D magnetic structure of dense interstellar filaments within NGC 1333 using polarization data at $850 \mu\mathrm{m}$ from the $B$-fields In STar-forming Region Observations survey at the James Clerk Maxwell Telescope. Theoretical models predict that the magnetic field lines in a filament will tend to be dragged radially inward (i.e., pinched) toward the central axis due to the filament's self-gravity. We study the cross-sectional profiles of the total intensity ($I$) and polarized intensity (PI) of dust emission in four segments of filaments unaffected by local star formation that are expected to retain a pristine magnetic field structure. We find that the filaments' FWHM in PI are not the same as those in $I$, with two segments being appreciably narrower in PI (FWHM ratio $\simeq 0.7-0.8$) and one segment being wider (FWHM ratio $\simeq 1.3$). The filament profiles of the polarization fraction ($P$) do not show a minimum at the spine of the filament, which is not in line with an anticorrelation between $P$ and $I$ normally seen in molecular clouds and protostellar cores. Dust grain alignment variation with density cannot reproduce the observed $P$ distribution. We demonstrate numerically that the $I$ and PI cross-sectional profiles of filaments in magnetohydrostatic equilibrium will have differing relative widths depending on the viewing angle. The observed variations of FWHM ratios in NGC 1333 are therefore consistent with models of pinched magnetic field structures inside filaments, and especially if they are magnetically near-critical or supercritical., Comment: Accepted for publication in ApJL

Jets and outflows trace the accretion history of protostars. High-velocity molecular jets have been observed from several protostars in the early Class\,0 phase of star formation, detected with the high-density tracer SiO. Until now, no clear jet has been detected with SiO emission from isolated evolved Class\,I protostellar systems. We report a prominent dense SiO jet from a Class\,I source G205S3 (HOPS\,315: T$_{bol}$ $\sim$ 180 K, spectral index $\sim$ 0.417), with a moderately high mass-loss rate ($\sim$ 0.59 $\times$ 10$^{-6}$ M$_\odot$ yr$^{-1}$) estimated from CO emission. Together, these features suggest that G205S3 is still in a high accretion phase, similar to that expected of Class\,0 objects. We compare G205S3 to a representative Class\,0 system G206W2 (HOPS\,399) and literature Class\,0/I sources to explore the possible explanations behind the SiO emission seen at the later phase. We estimate a high inclination angle ($\sim$ 40$^\circ$) for G205S3 from CO emission, which may expose the infrared emission from the central core and mislead the spectral classification. However, the compact 1.3\,mm continuum, C$^{18}$O emission, location in the bolometric luminosity to sub-millimeter fluxes diagram, outflow force ($\sim$ 3.26 $\times$ 10$^{-5}$ M$_\odot$km s$^{-1}$/yr) are also analogous to that of Class\,I systems. We thus consider G205S3 to be at the very early phase of Class\,I, and in the late phase of ``high-accretion". The episodic ejection could be due to the presence of an unknown binary, a planetary companion, or dense clumps, where the required mass for such high accretion could be supplied by a massive circumbinary disk., Comment: 13 pages, 5 figures, Accepted for publication in the Astrophysical Journal

We present the results of simultaneous 450 $\mu$m and 850 $\mu$m polarization observations toward the massive star forming region NGC 2071IR, a target of the BISTRO (B-fields in Star-Forming Region Observations) Survey, using the POL-2 polarimeter and SCUBA-2 camera mounted on the James Clerk Maxwell Telescope. We find a pinched magnetic field morphology in the central dense core region, which could be due to a rotating toroidal disk-like structure and a bipolar outflow originating from the central young stellar object, IRS 3. Using the modified Davis-Chandrasekhar-Fermi method, we obtain a plane-of-sky magnetic field strength of 563$\pm$421 $\mu$G in the central $\sim$0.12 pc region from 850 $\mu$m polarization data. The corresponding magnetic energy density of 2.04$\times$10$^{-8}$ erg cm$^{-3}$ is comparable to the turbulent and gravitational energy densities in the region. We find that the magnetic field direction is very well aligned with the whole of the IRS 3 bipolar outflow structure. We find that the median value of polarization fractions, 3.0 \%, at 450 $\mu$m in the central 3 arcminute region, which is larger than the median value of 1.2 \% at 850 $\mu$m. The trend could be due to the better alignment of warmer dust in the strong radiation environment. We also find that polarization fractions decrease with intensity at both wavelengths, with slopes, determined by fitting a Rician noise model, of $0.59 \pm 0.03$ at 450 $\mu$m and $0.36 \pm 0.04$ at 850 $\mu$m, respectively. We think that the shallow slope at 850 $\mu$m is due to grain alignment at the center being assisted by strong radiation from the central young stellar objects., Comment: 17 pages, 11 figures, 4 tables

We study a particle approximation for one-dimensional first-order Mean-Field-Games (MFGs) with local interactions with planning conditions. Our problem comprises a system of a Hamilton-Jacobi equation coupled with a transport equation. As we deal with the planning problem, we prescribe initial and terminal distributions for the transport equation. The particle approximation builds on a semi-discrete variational problem. First, we address the existence and uniqueness of a solution to the semi-discrete variational problem. Next, we show that our discretization preserves some previously identified conserved quantities. Finally, we prove that the approximation by particle systems preserves displacement convexity. We use this last property to establish uniform estimates for the discrete problem. We illustrate our results for the discrete problem with numerical examples., Comment: 25 pages, 10 figures