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Laura Colzi

Publications and source records attributed to Laura Colzi.

At least 19 recordsLinked to original sources
arXiv2026

ACES VIII: A Survey of Compact, High-Velocity Features Observed in CS(2-1)

The extreme kinematics of the Milky Way's Central Molecular Zone (CMZ) are influenced by processes such as dynamical shearing, cloud collisions, and stellar feedback. These events are visible in molecular data as vertically spiked features in position-velocity (PV) diagrams referred to as high velocity dispersion compact clouds (HVCCs). Using ALMA CMZ Exploration Survey (ACES) CS (2-1) molecular data, we identify a total of 235 HVCC candidates, 163 of which are visually identified, and an additional 72 identified via automated dendrogram methods. For each HVCC we catalog and report the physical and kinematic properties, explore line ratios of the cold dense gas tracer \HNCO with C-shock tracers, classify the morphology of their PV diagrams, and view their position-position-velocity distribution. The sample includes structures which are compact (d<5 pc) and have large velocity extents (20 km/s $<Δ\mathrm{V} <$ 140 km/s), with most structures showing thin, `spiked' PV morphologies. We highlight areas of high ratios between HNCO and C-shock tracers along the edge of known orbital streams, implying a buildup of bar lane gas accreting onto the CMZ. We also find a collection of HVCCs overlapping with the 50 km/s cloud and known circumnuclear disk features. This catalog will be used for future investigation of nuclear inflow and determining dominant mechanisms disrupting average CMZ gas flows.

astro-ph.GA↗
arXiv2026

Chemical Demographics of Star-forming Regions

Our understanding of complex organic chemistry during the formation of stars and planets is shaped by a handful of cherry-picked sources with bright molecular emission lines. This observational bias impedes our assessment of how universal chemical complexity is during star formation. The lack of systematic wideband spectral surveys for statistically significant samples of protostars and cores is a major roadblock to properly probing how COM inventories and abundances depend on the vast range of physical conditions, local cloud and global galactic environments, and evolutionary timescales of low- and high-mass star formation. In turn, this limits our ability to constrain and test physicochemical models, which depend critically on these parameters. The next-generation ALMA2040, with a 10x improvement in line sensitivity, is required to observe COMs, that we perceive as common today, in a fraction of the observing time that is needed today with ALMA. Such capabilities will propel us into the era of chemical demographics, whereby wideband (>100 GHz) spectral surveys at high sensitivity (routinely probing COM abundances down to 0.01% relative to CH3OH) will be executed towards >1000-10000 prestellar and protostellar sources. With robust chemical inventories towards large source sample sizes, we will be able to probe for dependencies of chemical complexity on mass regime, feedback processes in a cluster, Galactic position, metallicity, and time-variable accretion. Only with statistically significant samples at high sensitivity will we be able to assess the ubiquity and homogeneity of COM chemistry across the protostellar mass spectrum and natal cores. Constraining the diversity and availability of such species is critical for our understanding of the chemical reservoir available for planet formation, which eventually shapes (exo)planetary atmosphere compositions.

astro-ph.IM↗
arXiv2026

Unveiling star formation at sub-solar metallicity with ALMA2040

A fundamental question in astrophysics is whether the processes governing star formation are universal or depend on the physical conditions of their local galactic environment. The Milky Way and the Magellanic clouds offer ideal laboratories to explore this question, as the gas conditions in them span up to orders of magnitude in metallicity, gas surface density, ambient pressure, dust abundance, radiation field, and cosmic-ray flux. In particular, both the outer Milky Way and the Magellanic clouds provide the closest low-metallicity environments with conditions similar to those of metal-poor galaxies, while remaining sufficiently close to soon allow spatial resolution of individual star-forming cores and disks. Recent observations with ALMA and other facilities have begun to unveil the physical and chemical properties of star-forming regions in low-metallicity environments. Yet, their distances from the Sun still require transformational gains in current ALMA capabilities to address fundamental open questions: (1) Are the properties of prestellar cores universal? (2) Does cloud fragmentation, and the resulting stellar IMF, depend critically on metallicity? (3) How does dust evolution depend on metallicity, and what is the impact in the survival of protoplanetary disks? (4) Is the reduced amount of metals and dust shielding at low metallicity critical for the formation and survival of molecules? ALMA2040 will identify similarities and differences between solar- and sub-solar-metallicity star-forming regions, and answer the question: how do different environmental conditions influence the physical and chemical pathways leading to star formation?

astro-ph.IM↗
arXiv2026

Tracking the flow of interstellar gas across scales: from galaxies to star clusters

While the baryon cycle of the interstellar medium - and its ability to form stars - plays a key role in galaxy evolution, unravelling the physical processes driving its evolution remains a critical challenge, given that present-day observing facilities are unable to map entire galactic ecosystems down to the scales of individual star-forming clumps. Here, we outline the technical requirements that would enable, for the first time, to connect the small (pc) scale physics of star formation, to the large (tens-of-kpc) scales of galaxies, enabling an effective tracking of the flows of matter and energy across a vast range of environments, and answering the long-standing question of what regulates star formation across cosmic time.

astro-ph.IM↗
arXiv2026

Molecular atlas of nearby galaxies through sensitive high-resolution multi-band molecular line surveys

Star formation and associated feedback processes play a key role in galaxy evolution. Astrochemistry is a powerful tool for characterising the physical conditions of dense star-forming gas and understanding the reciprocal relation between stellar feedback and the interstellar medium (ISM): from the way feedback influences the ISM to how the ISM conditions regulate the formation of new stars. The advent of large spectral surveys of a few individual galaxy centres have demonstrated the potential of molecular gas inventories to reveal the physical conditions of star-forming gas in great detail. A next-generation (sub)mm facility in the 2040s would extend this science to the local star-forming galaxy population, providing for the first time a comprehensive view of the physical and chemical conditions of the molecular ISM in the local universe.

astro-ph.IM↗
arXiv2026

From local chemistry to galactic evolution: unlocking the power of interstellar isotopes with ALMA2040

Molecular isotopic ratios provide a unique window into the chemical evolution of the interstellar medium, linking stellar nucleosynthesis and Galactic chemical evolution to the physical and chemical processes shaping molecular clouds, star-forming regions, and planetary systems. However, molecular isotopic ratios do not necessarily trace the underlying elemental composition, as chemical isotopic fractionation, isotope-selective photodissociation, grain chemistry, and radiative-transfer effects can significantly alter the observed values. Disentangling these effects requires simultaneous observations of multiple transitions, isotope systems and molecular families, including rare, doubly, and multiply substituted isotopologues involving D, $^{13}$C, $^{15}$N, $^{17,18}$O, $^{29,30}$Si, and $^{33,34,36}$S (e.g., $^{13}$C$^{15}$N, $^{13}$C$^{34}$S, and $^{13}$C$^{18}$O). ALMA2040, with an order-of-magnitude improvement in sensitivity and at least 512 GHz of instantaneous bandwidth, will make these species accessible across statistically significant samples of Galactic and nearby extragalactic sources. By enabling systematic isotopic inventories from molecular clouds and prestellar cores to protoplanetary systems, across the Milky Way and in external galaxies, ALMA2040 will establish molecular isotopes as quantitative probes of chemical inheritance, stellar nucleosynthesis, and galaxy evolution, disentangling local chemical processing from the large-scale evolution of matter from stars to new planetary systems.

astro-ph.IM↗
arXiv2026

Frontiers of chemical complexity in the interstellar medium: unveiling the cosmic origins of life

The interstellar medium (ISM) contains a rich molecular inventory that provides a unique window into the chemistry operating during star and planet formation and its connection to prebiotic chemistry. More than 350 interstellar molecules are currently known, including increasingly complex organic molecules and species containing elements beyond the second row of the periodic table. Yet the limits that interstellar chemical complexity can reach, its evolution from molecular clouds to planetary systems, and its contribution to the molecular feedstock of life remain poorly constrained. Addressing these questions requires sensitive, broadband observations capable of detecting multiple weak rotational transitions of molecular species, such as amino acids, nucleobases, sugars and lipids, towards star- and planet-forming environments. Current facilities, including ALMA, are limited by instantaneous spectral coverage, sensitivity (especially on extended spatial scales), and the trade-off between total bandwidth and integration time. The proposed ALMA2040 facility would overcome these limitations through at least a tenfold improvement in spectral-line sensitivity, high-fidelity imaging from sub-arcsecond to tens-of-arcsecond scales, and ultra-broad instantaneous frequency coverage from 35 to 950 GHz at high spectral resolution. These capabilities would allow systematic detections of species with molecular abundances with respect to H$_2$ below 10$^{-11}$, facilitating the identification of new complex and heavy-element-bearing species through multiple transitions, and providing complete molecular inventories across evolutionary stages. ALMA2040 would thus make it possible to comprehensively investigate the emergence and evolution of chemical complexity, and to determine whether molecular precursors of prebiotic chemistry are widespread throughout the Galaxy.

astro-ph.IM↗
arXiv2026

From Scaling Relations to Physical Laws: Constraining the Physics of Star Formation Across Local Galaxies

The conversion of cold dense gas, traced by molecular line emission, into stars remains one of the fundamental unsolved problems in galaxy evolution. Observations over the past decades have established empirical relations between gas and star formation, yet their physical origin remains uncertain. Gravity, turbulence, and stellar feedback as main drivers provide fundamentally different pictures of how star formation is regulated, while reproducing remarkably similar galaxy-scale scaling relations. To disentangle the individual importance of each process, not only its mass and distribution, but also its temperature, density, excitation, and chemistry must be probed. However, current or planned (sub)millimetre facilities cannot combine statistical breadth, cloud-scale resolution, and multi-line diagnostics across large galaxy samples. A new, flagship interferometer with increased line sensitivity and bandwidth enables obtaining multi-transition, multi-isotopologue observations of molecular gas at GMC-resolved scales across nearby galaxies, enabling millions of independent measurements of its physical state across a wide range of extragalactic environments. This will transform molecular gas from an empirical tracer into a quantitative probe of the physical processes governing the relation between the dense gas and star formation. With the 2040s landscape of optical and radio facilities, ALMA2040 will facilitate a predictive theory of the conversion of gas into stars.

astro-ph.GA↗
arXiv2026

Star Formation across the Galaxy

Star formation is both a multi-scale and highly dynamic process. It is regulated by the combination of gravity, turbulence, feedback and magnetic fields, which connect more than six orders of magnitude in scale: from large molecular clouds (several 10s to 100s pc in size) down to protoplanetary disks (a few 10s to 100s of astronomical units in size, or 10^{-5} to 10^{-4} pc). Resolving the processes of fragmentation, accretion, and feedback that result in the formation of stellar systems throughout all relevant scales, from clouds to disks, and across the entire range of different environments in the Milky Way is key to constructing a comprehensive understanding and a predictive model of the formation process of stars of all masses that populate not only our Galaxy but the wider Universe across cosmic times. With current astronomical facilities, we are only able to grasp the details of star formation in <5% of Galactic star-forming regions, being heavily biased towards those close to us. Thus, characterizing this multi-scale phenomenon at the necessary sensitivity and resolution across all Galactic environments requires the next generation (sub)millimeter-wavelength facility: ALMA2040.

astro-ph.IM↗
arXiv2026

Chemistry on solar system scales

The initial chemical composition of planets, primitive bodies in our solar system, and exoplanets is ultimately set by their nascent protoplanetary disks. Yet observing key carbon-, oxygen-, and nitrogen-bearing molecules (as well as rarer but important sulphur- and phosphorus-bearing species) in the inner (exo)planet-forming zone ($\lesssim 10$~au) remains extremely challenging with current facilities. Therefore, to construct a complete picture of the chemistry of planet formation and understand how (exo)planetary composition is set by physical and chemical processes within the protoplanetary disk, a more powerful observing facility, i.e., ALMA2040, is needed. Compared to current ALMA (the Atacama Large Millimeter/submillimeter Array) this new facility must provide >~ a factor of 10 in line sensitivity at a spatial resolution of <~ 5 au at 140 pc, i.e., a factor of 3 - 4 better resolution to low surface brightness emission than currently possible. This distance includes many star-forming regions such as Taurus and Lupus that are host to populations of Sun-like stars. ALMA2040 will enable mapping of disk chemical composition on terrestrial planet-forming scales (within the water snowline) and detect molecules that are the feedstock for potentially habitable worlds.

astro-ph.IM↗
arXiv2026

The environments forming stellar and planetary systems

How does a star's birth environment set the mass, angular momentum and chemical complexity delivered to its planet-forming disk, and thereby whether it builds planets, brown dwarfs or stellar companions? This requires following material from the cloud to the sub-au to few-au scales where infalling gas, magnetized winds and the disk interact, across all star-forming environments. At frequencies where young disks are optically thin, current facilities, even ALMA after its Wideband Sensitivity Upgrade, fall short by a factor of a few in angular resolution and an order of magnitude in sensitivity. Likewise, resolving how disks around distant high-mass stars fragment into tight multiples requires a linear resolution of a few to a few tens of au, currently out of reach. Yet the disks characterized so far lie almost exclusively in nearby, isolated clouds at near-solar metallicity, although the environment (radiation field, ionization rate, gas and stellar density, pressure and metallicity) varies by orders of magnitude across the Galaxy. Most stars, probably including the Sun, form in clustered regions at kpc distances, and the widest metallicity range lies farther still, in the outer Galaxy, the Central Molecular Zone and the Magellanic Clouds. With three times finer angular resolution and ten times the sensitivity, ALMA2040 will follow the path of material from cloud to disk across the full stellar-mass spectrum and, for the first time, measure how this path changes with environment: resolving the sub-au infall-impact and wind-launching zones nearby, disk fragmentation and the onset of multiplicity in distant high-mass regions, and disk formation at a few tenths of solar metallicity. It will thereby reveal the dust-obscured, embedded origins of planetary systems that optical and infrared facilities, including the ELT, see only once they emerge, and show how the birth environment shapes them.

astro-ph.IM↗
arXiv2026

Isotopic ratios as probes of star formation and the origin of molecular gas in the Central Molecular Zone

The Central Molecular Zone (CMZ) contains most of the dense molecular gas in the Milky Way but forms stars at a surprisingly low rate. Isotopic ratios provide a unique tool to investigate both the local physical conditions and the nucleosynthetic history of this gas. I summarize recent isotopic studies toward the molecular cloud G$+$0.693$-$0.027. Deuterium fractionation (D/H ratios) reveals a cold ($T_{\rm kin}\lesssim30$ K), relatively quiescent gas component embedded within the otherwise warm and turbulent CMZ, indicating that the earliest stages of star formation can survive in this extreme environment. I also present new $^{12}$C/$^{13}$C measurements from HC$_3$N and HC$_5$N, including the first constraints from doubly substituted $^{13}$C isotopologues. After accounting for isotopic fractionation with astrochemical models, the inferred elemental ratio ($\sim37$--48) exceeds the canonical CMZ assumed value ($\sim$20), supporting a scenario in which the Galactic center is replenished by less chemically processed gas flowing inward along the Galactic bar.

astro-ph.GA↗
arXiv2026

ACES VII. Compact Continuum Source Catalog of the Central Molecular Zone

The Central Molecular Zone (CMZ) resides in the inner few hundred parsecs of our Galaxy, and despite being the largest reservoir of dense molecular gas in the Milky Way, it has a relatively low present-day star formation rate (SFR) of $\sim0.08~M_{\odot}~\text{yr}^{-1}$. Continuum and spectral line observations from the Atacama Large Millimeter/submillimeter Array (ALMA) CMZ Exploration Survey (ACES) provide the first full-coverage, high-resolution map of the inner 200 parsecs of the CMZ at 3 mm. In this paper we present the ACES catalog of compact continuum sources, the most complete catalog of potential sites of star formation in the CMZ to date. Using an automated dendrogram-based source extraction procedure in combination with a by-eye morphological classification scheme, we produce a `full' catalog of 1735 detections in total. Additionally, we use spectral index measurements to generate a `filtered' catalog of 567 sources with minimal contamination from non-thermal filaments and extended free-free emission. We find that 359 ($\sim63\%$) of the filtered catalog sources are located at column densities $< 10^{23}$ cm$^{-2}$, outside of the densest molecular cloud regions, 195 of which have not been identified in previous surveys. After cross-referencing with various catalogs generated from data at different wavelengths, we consider it likely that many of these newly discovered detections are produced by pre/protostellar sources or compact HII regions.

astro-ph.GA↗
arXiv2026

Electron temperature and emission measure of HII regions in the central molecular zone (CMZ) from H40 αrecombination line and continuum emissions by ALMA CMZ Exploration Survey - ACES -

Star formation activity in the Central Molecular Zone (CMZ) directly manifests itself as radio continuum free-free emission (Bremsstrahlung) and radio recombination line emission from HII regions surrounding newly formed massive stars. We derive the overall distribution of the HII regions and their fundamental properties: electron temperature ($\Te$) and emission measure ($EM$), and hence electron density in the form of two dimensional distribution maps over the CMZ by analyzing the ACES (ALMA CMZ Exploration Survey) \h40 (99.02 GHz) recombination line and 99.6 GHz continuum emission data with synthesized beam widths of $2''.45$ (0.097 pc at 8.2 kpc) and $2''.14$, respectively. We apply the 'TeEM' method ($\Te$--$EM$ mapping), which creates $\Te$ and $EM$ maps from input 2D maps of the continuum and integrated line intensity. The analysis covers the entire ACES field from $l\sim -0^\circ.6$ to $+0^\circ.8$ and from $b\sim -0^\circ.2$ to $+0^\circ.1$. The area analyzed is complete and includes previously known HII regions such as Sgr B2, Sgr B1, the Sickle, the Pistol, thermal filaments (Bridges), Sgr A HII regions, the Minispiral, and many other known HII regions. Sgr C is not included in the analysis due to the insufficient signal-to-noise ratio in the recombination line map. The mean electron temperature over the CMZ is determined to be $\Tcmz= 5872 \pm 78 ~{\rm (SE)} ~\pm 3682~{\rm (SD)}$ K (SE:standard error of the mean, SD: pixel-to-pixel standard deviation). Some HII regions, such as Sgr B2 Main and the Minispiral, exhibit large scatter and an internal $\Te$ gradient of several thousand K per parsec. The $EM$ distribution is more diverse, varying by orders of magnitude from $\sim 10^5$ to $\sim 3\times 10^8$ \emunit within the CMZ, as well as within individual HII regions.

astro-ph.GA↗
arXiv2026

A tale of two isotopes: Spatial variation in HCN fractionation toward young cores

Context. Isotopic fractionation can serve as a powerful tracer of the chemical evolution during star and planet formation. To accurately interpret observations, it is crucial to identify the dominant pathways of nitrogen and carbon fractionation at different evolutionary stages. Aims. We aim to study nitrogen and carbon fractionation in a sample of young cores at the onset of star formation. Methods. We map H$^{13}$CN and HC$^{15}$N around one starless and three pre-stellar cores. We compute the $N$(H$^{13}$CN)/$N$(HC$^{15}$N) column density ratio across the cores and compare the distribution with $N$(H$_2$) maps from $\textit{Herschel}$/SPIRE. In addition, we calculate $^{14}$N/$^{15}$N maps using the double isotope method for comparison with earlier studies. The results are compared with astrochemical modeling of carbon and nitrogen fractionation for a one-dimensional pre-stellar core model. Results. The computed $N$(H$^{13}$CN)/$N$(HC$^{15}$N) ratio exhibit clear spatial variation across the maps. This variation is correlated with $N$(H$_2$) in three out of four cores. Conclusions. Our analysis reveals a correlation between the H$^{13}$CN/HC$^{15}$N ratios and the $N$(H$_2$) maps. According to the astrochemical model, the correlation is mainly due to variations in the $^{12}$C/$^{13}$C ratio. Consequently, the results caution against applying the double-isotope method to derive $^{14}$N/$^{15}$N ratios without independently assessing possible spatial variations in the $^{12}$C/$^{13}$C ratio. Furthermore, the leading cause of the isotopic variation in the model is not isotope-selective photodissociation, but rather more efficient fractionation through exchange reactions at lower temperatures in the denser regions of the cores.

astro-ph.SR↗
arXiv2026

Chemical Complexity in the Early Stages of Star Formation in the SKAO Era

About 350 molecules have been identified in the interstellar medium (ISM), including complex molecules relevant to prebiotic chemistry. A remarkable level of molecular diversity has been observed from the earliest stages of star formation, providing the initial chemical inventory inherited by planetary systems. Radio observations have played a pivotal role in these discoveries, starting with the identification of the first polyatomic molecule, $\text{NH}_3$ (Cheung et al. 1968). (Sub-)millimeter observations have revealed complex organic molecules of prebiotic relevance, including formamide ($\text{NH}_2\text{CHO}$), glycolaldehyde ($\text{CH}_2\text{OHCHO}$), and even urea ($(\text{NH}_2)_2\text{CO}$), and hydroxylamine ($\text{NH}_2\text{OH}$), which are possible precursors of RNA nucleotides (Ceccarelli et al. 2023; Jiménez-Serra et al. 2020). However, in dense protostellar regions, dust opacity hampers the detection of molecular emission. Additionally, large molecules and those containing heavy atoms, which have rotational transitions at lower frequencies, often remain inaccessible to current instruments. The Square Kilometre Array Observatory (SKAO) will provide an unprecedented combination of sensitivity and angular resolution at radio wavelengths. This will allow for the detection of prebiotic species and offer new insights into the chemical pathways that shape emerging planetary systems (Jiménez-Serra et al. 2022). This chapter details the scientific questions and advancements that the SKAO, and more specifically, SKA-Mid equipped with the Band 5 receivers, will pursue in the field of astrochemistry, focusing on the chemical complexity in both high-mass and solar-type star-forming regions.

astro-ph.SR↗
arXiv2026

ALMA Central molecular zone Exploration Survey (ACES) VI: ALMA Large Program Reveals a Highly Filamentary Central Molecular Zone

The Central Molecular Zone (CMZ) of the Milky Way is the way station that primarily controls how much gas flows from the disk of the Galaxy towards the central nucleus. While this region is well documented to have extreme gas properties that clearly distinguish it from the rest of the Galaxy, the properties of the bulk molecular gas at high angular resolution are relatively unexplored. Band 3 data from the ALMA (Atacama Large Millimeter/Submillimeter Array) large program ACES (ALMA CMZ Exploration Survey) reveal the highly filamentary nature of CMZ molecular gas at high resolution (3" or 0.1pc) across the entire CMZ. Visual inspection of these data suggests that there are at least two general classes of elongated structures, which we identify as: i) large-scale (10 pc) filamentary structures (LFs) and ii) a ubiquitous population of small-scale (about 1 pc) filamentary structures (SFs). We present detailed morphological and kinematic properties towards three structures in each category, as well as their association with magnetic fields and the correlation of HNCO 4(0,4)-3(0,3) with other molecular species. Our investigation reveals that these structures are largely coherent in position-position-velocity space. The alignment with the magnetic field structure is mixed, with some parallel, some perpendicular, and some intermediate alignments. We find that LFs likely trace pieces of contiguous CMZ orbital structures and are a manifestation of global CMZ dynamics. The second class, SFs, are pervasive and may be the result of complicated turbulence and shearing dynamics in the CMZ gas flows, as seen in numerical simulations.

astro-ph.GA↗
arXiv2026

Detection of a four-carbon sugar in interstellar space

Sugars are essential biomolecules, serving as metabolic fuels, nucleic acid backbone components, and structural or energy-storage polymers. A central question in origin-of-life research is how monosaccharides formed on the primitive Earth, as laboratory experiments under prebiotic conditions yield insufficient concentrations. The detection of ribose, glucose and other monosaccharides in asteroids and meteorites suggests an exogenous origin, possibly in the interstellar medium (ISM) prior to meteoritic parent-body formation. However, no sugar has been observed in the ISM so far. We report the discovery of erythrulose, a chiral four-carbon ketose, in the ISM. The detection has been achieved thanks to ultrasensitive, broadband spectral surveys toward the Galactic Center molecular cloud G+0.693-0.027 obtained using the Yebes 40m and IRAM 30m telescopes. Erythrulose appears to be at least eight times more abundant than analogous three-carbon sugars, which remain undetected in our ultrasensitive observations. Quantum chemical and astrochemical models indicate that erythrulose forms efficiently on interstellar dust grains from simpler two-carbon aldehydes and alcohols. As ketoses readily isomerize into aldoses in aqueous conditions, interstellar erythrulose could have contributed to the sugar inventory available for early metabolic and replication processes.

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