arXiv subjects

L. Cacciapuoti

Publications and source records attributed to L. Cacciapuoti.

At least 19 recordsLinked to original sources

arXiv2026

Pristine composition or size evolution: Can current dust models reproduce emissivities observed in nearby protostars?

Interstellar dust is a crucial asset in many astronomical observations. Characterising grains present in the dense gas and in star-forming environments is also key to constrain the pristine conditions for planetary formation. However, dust properties remain poorly characterised and are still debated: low dust emissivities observed in nearby protostars are not completely explained to this day. In this study, we aim to determine whether it is possible to retrieve the dust properties from multi-wavelength observations of the dust emission towards embedded protostars, and the extent to which current dust models can reproduce the observed values of the dust emissivity index in young protostars. We perform radiative transfer computations of the thermal dust emission from a model protostellar envelope, considering different dust optical properties commonly used in the community. This allows us to explore the effects of dust composition on the spectral index, to try and explain the variation in the emissivity index in nearby protostars observations. We find large variations in the spectral index as the sole result of different dust models, without the need for dust grain size evolution. However, our work does not allow us to reproduce the lowest emissivity index values found in some protostellar envelopes without including unexpectedly large millimetre-sized processed grains. We show that appropriate methods permits to measure the dust emissivity from observations of the spectral index at millimetre wavelengths with very little uncertainty. Variation in emissivity index between the different observed sources and the dust models most commonly used by the community implies that the intrinsic composition of dust is not sufficient to explain the lowest spectral index values. Thus, early dust evolution producing larger dust grains may have to be taken into account to obtain a complete picture.

astro-ph.GA↗

arXiv2026

FAUST XXXI. Grain properties and variability of three sources in GSS 30

To advance our understanding of dust properties in class 0/I young stellar objects, it is crucial to resolve their structures at multiple wavelengths and investigate how grain growth and environmental effects shape their spectral properties. We present 0.5 arcsec resolution ALMA observations of the GSS 30 complex at 1.2-3.0 mm from the FAUST large programme, achieving a linear resolution of 69 au. We analyse the dust continuum emission and perform modelling to constrain dust properties and disk structures. For IRS3, the spectral index increases radially from 2.0 at the centre to 2.5 at the disk edge, while decreasing to 1.6-1.8 along the outflow direction. The asymmetric low-alpha region towards the northeastern blueshifted lobe may result from cold outer envelope dust obscuring warmer inner regions. SED fitting suggests maximum grain sizes of tens of microns and a dust mass of 650-1510 M_earth. IRS1 is associated with an extended north-eastern structure, which may represent an outflow-disk complex, a trailing structure linked to a circumbinary disk, or a gas streamer accreting onto IRS1. The central IRS1 shows alpha < 0.8, consistent with marginally optically thick free-free emission. IRS2 displays brightness variations over 420 s, and multi-epoch comparison suggests a flare lasting tens of minutes, likely caused by magnetic activity in the protostar. Our results highlight the importance of environmental effects, including dust obscuration and streamer structures, in shaping the observed properties of young disks, and reveal millimetre variability associated with possible protostellar magnetic flares.

astro-ph.SR↗

arXiv2026

The environmental imprint on molecular layering in the dusty streamer of M512

Protostellar streamers are elongated structures that channel material from larger scale onto disks, influencing their physical and chemical evolution. The M512 protostar in Orion/Lynds 1641 hosts one of the most massive and extended streamer discovered so far, offering a unique opportunity to study these processes. We investigate the morphology, chemistry, and origin of this streamer,and its potential impact on the protostellar disk. Using archival ALMA observations of C18O, DCO+, N2D+, and HCO+, we compare their spatial distributions through moment maps and spatial profiles. The streamer shows clear chemical stratification: C18O lies on the western side of the protostar, N2D+ is farther out to the east, and DCO+ is in the middle. This suggests that the structure has been shaped by environmental effects rather than tracing a single coherent infalling flow, with only the densest gas near the protostar likely to accrete onto the disk. Overall, the bulk of the streamer reflects the physical and chemical imprint of the surrounding cloud, highlighting the importance of environmental shaping in interpreting streamer-disk connections and their role in disk growth.

astro-ph.GA↗

arXiv2025

FAUST. XXVIII. High-Resolution ALMA Observations of Class 0/I Disks: Structure, Optical Depths, and Temperatures

We present high-resolution (~7.5 au) ALMA observations at 1.3 and 3 mm of 16 disks around Class 0/I protostars across multiple star-forming regions and a variety of multiplicities, showing a range of disk sizes (~2-100 au) and including circumbinary disks (CBDs) in binaries with separations <100 au. The disk properties show similarities to Class II disks, including (a) low spectral index (SI) values (alpha=2.1) that increase with disk radius, (b) 3 mm disk sizes only marginally smaller than at 1.3 mm (<10%), and (c) radial intensity profiles well described by modified self-similar profiles. We also find key differences: (i) SI values increasing with radius, but exceeding 2 only at the disk edge (ii) higher brightness temperatures Tb, in some cases higher than the predicted temperatures due to irradiation, and (iii) ~10x higher luminosity at a given size compared to the Class II disks. These results confirm significant optical depth in the observed Class 0/I disks, at both 1.3 and 3 mm, helping to explain their higher luminosities, but higher temperatures are also required for the most compact (< 40 au) disks, suggesting additional viscous heating. Considering optical depth, most disk dust masses are estimated in the range 30-900 Mearth (0.01-0.3 Msun in gas), resulting in some disks reaching marginal gravitational instability. The median location of the water iceline is ~3 au, but it can extend beyond 10-20 au for the hottest disks. CBDs exhibit lower optical depths at both wavelengths and hence higher SI values (alpha=3.0), dust masses of 100 Mearth, and beta~1.5 (2 Class 0 CBDs) and beta~1 (1 Class I CBD), suggesting substantial grain growth only in the more evolved CBD. The inferred high optical depths provide a compelling explanation for the apparent scarcity of dust substructures in the younger disks at ~ 1 mm, despite mounting evidence for early planet formation (ABRIDGED).

astro-ph.SR↗

arXiv2025

First results from ALPPS: a sub-Alfv\'enic streamer in SVS13A

We present the first results from the ALMA Perseus Polarization Survey (ALPPS), focusing on the magnetic field in the SVS13A circumbinary disk. The dataset includes full-Stokes dust continuum observations at $\sim0\farcs3$ and 870 $\mu$m, as well as molecular line emission from C$^{17}$O$(J=3 \rightarrow 2)$ at $\sim0\farcs3$, C$^{18}$O$(J=2 \rightarrow 1)$ at $\sim0\farcs2$, and DCN$(J=3 \rightarrow 2)$ at $\sim0\farcs1$ angular resolution. Our observations resolve both a previously identified dust spiral and an infalling streamer, capturing their spatial and kinematic structures. The streamer is traced from scales $>300$ au down to the circumbinary disk. Using alignment measure (AM) maps and histograms that compare the orientations of the plane-of-sky magnetic field with local intensity and velocity gradients, we find that the AM distribution peaks at a value of 1. This AM peak strongly suggests alignment between the field and the dust total intensity emission, as well as between the field and the gas velocity, which in turn suggests grain alignment by magnetic fields. From our data, we derive a magnetic field strength, B$_{\mathrm{pos}} \sim 1.1 \pm 0.6$\, mG, and a kinetic to magnetic energy ratio of $0.5 \pm 0.4$, suggesting magnetic dominance. We also produced a map of the Alfv\'enic Mach number, finding $\mathcal{M}_{\rm A} < 1$ along the streamer, consistent with sub-Alfv\'enic infalling motions. Therefore, the field is likely facilitating the inflow of material from the envelope onto the disk by constraining movement across the field lines. This represents the first detection of a magnetically sub-Alfv\'enic infalling streamer in a protostellar system.

astro-ph.GA↗

arXiv2025

FAUST XXIV. Large dust grains in the protostellar outflow cavity walls of the Class I binary L1551 IRS5

Planet formation around young stars requires the growth of interstellar dust grains from mm-sized particles to km-sized planetesimals. Numerical simulations have shown that large ($\sim$mm-sized) grains found in the inner envelope of young protostars could be lifted from the disc via winds. However we are still lacking unambiguous evidence for large grains in protostellar winds/outflows. We investigate dust continuum emission in the envelope of the Class I binary L1551 IRS5 in the Taurus molecular cloud, aiming to identify observational signatures of grain growth, such as variations in the dust emissivity index ($\beta_{\rm mm}$). In this context, we present new, high-angular resolution (50 au), observations of thermal dust continuum emission at 1.3 mm and 3 mm in the envelope ($\sim$3000 au) of L1551 IRS5 , obtained as part of the ALMA-FAUST Large Program. We analyse dust emission along the cavity walls of the CO outflow, extended up to $\sim$1800 au. We find an H$_2$ volume density $>2\times10^5$ cm$^{-3}$, a dust mass of $\sim$58 M$_\oplus$, and $\beta_{\rm mm}$<1, implying the presence of grains $\sim$10$^3$ times larger than the typical ISM sizes. We provide the first spatially resolved observational evidence of large grains within an outflow cavity wall. Our results suggest that these grains have been transported from the inner disc to the envelope by protostellar winds and may subsequently fall back into the outer disc by gravity and/or via accretion streamers. This cycle provides longer time for grains to grow, playing a crucial role in the formation of planetesimals.

astro-ph.GA↗

arXiv2025

FAUST XX. The chemical structure and temperature profile of the IRAS 4A2 hot corino at 20-50 au

Young low-mass protostars often possess hot corinos, compact, hot and dense regions bright in interstellar Complex Organic Molecules (iCOMs). Besides of their prebiotic role, iCOMs can be used as a powerful tool to characterize the chemical and physical properties of hot corinos. Using ALMA/FAUST data we aim to explore the iCOMs emission at < 50 au scale around the Class 0 prototypical hot corino IRAS 4A2. We imaged IRAS 4A2 in six abundant, common iCOMs (CH$_3$OH, HCOOCH$_3$, CH$_3$CHO, CH$_3$CH$_2$OH, CH$_2$OHCHO, and NH$_2$CHO), and derived their emitting size. The column density and gas temperature for each species were derived at 1$\sigma$ from a multi-line analysis by applying a non-LTE approach for CH$_3$OH, and LTE population or rotational diagram analysis for the other iCOMs. Thanks to the unique estimates of the absorption from foreground millimeter dust toward IRAS 4A2, we derived for the first time unbiased gas temperatures and column densities. We resolved the IRAS 4A2 hot corino finding evidence for a chemical spatial distribution in the inner 50 au, with the outer emitting radius increasing from ~ 22-23 au for NH$_2$CHO and CH$_2$OHCHO, followed by CH$_3$CH$_2$OH (~ 27 au), CH$_3$CHO (~ 28 au), HCOOCH$_3$ (~ 36 au), and out to ~ 40 au for CH$_3$OH. Combining our estimate of the gas temperature probed by each iCOM with their beam-deconvolved emission sizes, we inferred the gas temperature profile of the hot corino on scales of 20-50 au in radius, finding a power-law index $q$ of approximately -1. We observed, for the first time, a chemical segregation in iCOMs of the IRAS 4A2 hot corino, and derived the gas temperature profile of its inner envelope. The derived profile is steeper than when considering a simple spherical collapsing and optically-thin envelope, hinting at a partially optically-thick envelope or a gravitationally unstable disk-like structure.

astro-ph.EP↗

arXiv2024

Atomic Clock Ensemble in Space

The Atomic Clock Ensemble in Space (ACES) mission is developing high performance clocks and links for space to test Einstein's theory of general relativity. From the International Space Station, the ACES payload will distribute a clock signal with fractional frequency stability and accuracy of 1E-16 establishing a worldwide network to compare clocks in space and on the ground. ACES will provide an absolute measurement of Einstein's gravitational redshift, it will search for time variations of fundamental constants, contribute to test topological dark matter models, and perform Standard Model Extension tests. Moreover, the ground clocks connected to the ACES network will be compared over different continents and used to measure geopotential differences at the clock locations. After solving some technical problems, the ACES flight model is now approaching its completion. System tests involving the laser-cooled Cs clock PHARAO, the active H-maser SHM and the on-board frequency comparator FCDP have measured the performance of the clock signal delivered by ACES. The ACES microwave link MWL is currently under test. The single-photon avalanche detector of the optical link ELT has been tested and will now be integrated in the ACES payload. The ACES mission concept, its scientific objectives, and the recent test results are discussed here together with the major milestones that will lead us to the ACES launch.

gr-qc↗

arXiv2024

Planet Formation and Disk Chemistry: Dust and Gas Evolution during Planet Formation

Over the past decade, progress in observational capabilities, combined with theoretical advancements, have transformed our comprehension of the physics and chemistry during planet formation. Despite these important steps forward, open questions persist on the chemical and physical evolution of solids in their journey from the collapsing molecular cores to disks and planetary bodies. This chapter is a repository of such burning questions. It has the ambition to identify the most promising avenues for future research based on current observational and modeling opportunities.

astro-ph.SR↗

arXiv2023

Protostellar chimney flues: are jets and outflows lifting submillimetre dust grains from discs into envelopes?

Low dust opacity spectral indices ($\beta < 1$) measured in the inner envelopes of class 0/I young stellar objects (age $\sim 10^{4-5}$ yr) have been interpreted as the presence of (sub-)millimetre dust grains in these environments. The density conditions and the lifetimes of collapsing envelopes have proven unfavorable for the growth of solids up to millimetre sizes. As an alternative, magneto-hydrodynamical simulations suggest that protostellar jets and outflows might lift grains from circumstellar discs and diffuse them in the envelope. We reframe available data for the CALYPSO sample of Class 0/I sources and show tentative evidence for an anti-correlation between the value of $\beta_{1-3mm}$ measured in the inner envelope and the mass loss rate of their jets and outflows, supporting a connection between the two. We discuss the implications that dust transport from the disc to the inner envelope might have for several aspects of planet formation. Finally, we urge for more accurate measurements of both correlated quantities and extension of this work to larger samples, necessary to further test the transport scenario.

astro-ph.EP↗

arXiv2023

A dusty streamer infalling onto the disk of a class I protostar. ALMA dual-band constraints on grain properties and mass infall rate

Observations of interstellar material infalling onto star- and planet-forming systems have become increasingly common thanks to recent advancements in radio interferometry. These structures replenish disks with fresh material, have the potential to significantly alter their dynamics, trigger the formation of substructures, induce shocks, and modify their physical and chemical properties. In this study, we combine new ALMA band 3 and archival band 6 observations to characterize the dust content and mass infall rate of a 4,000 au arc-like structure infalling onto M512, a class I young stellar object located in the Lynds 1641 region of the Orion A molecular cloud. We measure for the first time spectral index maps and derive a dust opacity index profile along a streamer, constraining grain properties and its dust mass. We measure a spectral index $\alpha \sim$ 3.2 across the entire structure, and a dust opacity index $\beta \sim$ 1.6. Given grain properties consistent with the measured $\beta$, the structure can host up to 245 M$_{\oplus}$ of dust, being comparable or even exceeding the mass of the inner, unresolved 600 au, which contains the protoplanetary disk of M512. Such a massive streamer can strongly affect the evolution of the star- and planet-forming inner system. Assuming typical ISM dust-to-gas ratio of 1%, free-fall timescales (50 kyr) imply total mass infall rates up to 1.5 $\cdot$ 10$^{-6}$ M$_{\odot}$/yr. M512 has been classified as an outbursting source with multi-epoch photometry, thus representing an interesting case study to explore the possible connection between infalling streamers and accretion outbursts.

astro-ph.EP↗

arXiv2023

FAUST IX. Multi-band, multi-scale dust study of L1527 IRS. Evidence for dust properties variations within the envelope of a Class 0/I YSO

Early dust grain growth in protostellar envelopes infalling on young discs has been suggested in recent studies, supporting the hypothesis that dust particles start to agglomerate already during the Class 0/I phase of young stellar objects (YSOs). If this early evolution were confirmed, it would impact the usually assumed initial conditions of planet formation, where only particles with sizes $\lesssim 0.25 \mu$m are usually considered for protostellar envelopes. We aim to determine the maximum grain size of the dust population in the envelope of the Class 0/I protostar L1527 IRS, located in the Taurus star-forming region (140 pc). We use Atacama Large millimetre/sub-millimetre Array (ALMA) and Atacama Compact Array (ACA) archival data and present new observations, in an effort to both enhance the signal-to-noise ratio of the faint extended continuum emission and properly account for the compact emission from the inner disc. Using observations performed in four wavelength bands and extending the spatial range of previous studies, we aim to place tight constraints on the spectral ($\alpha$) and dust emissivity ($\beta$) indices in the envelope of L1527 IRS. We find a rather flat $\alpha \sim$ 3.0 profile in the range 50-2000 au. Accounting for the envelope temperature profile, we derive values for the dust emissivity index, 0.9 < $\beta$ < 1.6, and reveal a tentative, positive outward gradient. This could be interpreted as a distribution of mainly ISM-like grains at 2000 au, gradually progressing to (sub-)millimetre-sized dust grains in the inner envelope, where at R=300 au, $\beta$ = 1.1 +/- 0.1. Our study supports a variation of the dust properties in the envelope of L1527 IRS. We discuss how this can be the result of in-situ grain growth, dust differential collapse from the parent core, or upward transport of disc large grains.

astro-ph.SR↗

arXiv2022

Atom Interferometry with the Rb Blue Transitions

We demonstrate a novel scheme for Raman-pulse and Bragg-pulse atom interferometry based on the $5\mathrm{S} - 6\mathrm{P}$ blue transitions of $^{87}$Rb that provides an increase by a factor $\sim 2$ of the interferometer phase due to accelerations with respect to the commonly used infrared transition at 780 nm. A narrow-linewidth laser system generating more than 1 W of light in the 420-422 nm range was developed for this purpose. Used as a cold-atom gravity gradiometer, our Raman interferometer attains a stability to differential acceleration measurements of $1\times10^{-8}$ $g$ at 1 s and $2\times 10^{-10}$ $g$ after 2000 s of integration time. When operated on first-order Bragg transitions, the interferometer shows a stability of $6\times10^{-8}$ g at 1 s, averaging to $1\times10^{-9}$ g after 2000 s of integration time. The instrument sensitivity, currently limited by the noise due to spontaneous emission, can be further improved by increasing the laser power and the detuning from the atomic resonance. The present scheme is attractive for high-precision experiments as, in particular, for the determination of the Newtonian gravitational constant.

physics.atom-ph↗

arXiv2021

New apparatus design for high-precision measurement ofG with atom interferometry

We propose a new scheme for an improved determination of the Newtonian gravitational constant G and evaluate it by numerical simulations. Cold atoms in free fall are probed by atom interferometry measurements to characterize the gravitational field generated by external source masses. Two source mass configurations having different geometry and using different materials are compared to identify an optimized experimental setup for the G measurement. The effects of the magnetic fields used to manipulate the atoms and to control the interferometer phase are also characterized.

physics.atom-ph↗

arXiv2020

Precision Gravity Tests and the Einstein Equivalence Principle

General Relativity is today the best theory of gravity addressing a wide range of phenomena. Our understanding of physical laws, from cosmology to local scales, cannot be properly formulated without taking into account it. It is based on one of the most fundamental principles of Nature, the Equivalence Principle, which represents the core of the Einstein theory of gravity. The confirmation of its validity at different scales and in different contexts represents one of the main challenges of modern physics both from the theoretical and the experimental points of view. A major issue related to this principle is the fact that we actually do not know if it is valid at quantum level. Furthermore, recent progress on relativistic theories of gravity have to take into account new issues like Dark Matter and Dark Energy, as well as the validity of fundamental principles like local Lorentz and position invariance. Experiments allow to set stringent constraints on well established symmetry laws, on the physics beyond the Standard Model of particles and interactions, and on General Relativity and its possible extensions. In this review, we discuss precision tests of gravity in General Relativity and alternative theories and their relation with the Equivalence Principle. In the first part, we discuss the Einstein Equivalence Principle according to its weak and strong formulation. We recall some basic topics of General Relativity and the necessity of its extension. Some models of modified gravity are presented in some details. The second part of the paper is devoted to the experimental tests of the Equivalence Principle in its weak formulation. We present the results and methods used in high-precision experiments, and discuss the potential and prospects for future experimental tests.

gr-qc↗

arXiv2019

SAGE: A Proposal for a Space Atomic Gravity Explorer

The proposed mission "Space Atomic Gravity Explorer" (SAGE) has the scientific objective to investigate gravitational waves, dark matter, and other fundamental aspects of gravity as well as the connection between gravitational physics and quantum physics using new quantum sensors, namely, optical atomic clocks and atom interferometers based on ultracold strontium atoms.

astro-ph.IM↗

arXiv2018

Measuring the gravitational acceleration with precision matter-wave velocimetry

One of the major limitations of atomic gravimeters is represented by the vibration noise of the measurement platform, which cannot be distinguished from the relevant acceleration signal. We demonstrate a new method to perform an atom interferometry measurement of the gravitational acceleration without any need for a vibration isolation system or post-corrections based on seismometer data monitoring the residual accelerations at the sensor head. With two subsequent Ramsey interferometers, we measure the velocity variation of freely falling cold atom samples, thus determining the gravitational acceleration experienced by them. Our instrument has a fractional stability of $ 9 \times 10^{-6}$ at 1 s of integration time, one order of magnitude better than a standard Mach-Zehnder interferometer when operated without any vibration isolation or applied post-correction. Using this technique, we measure the gravitational acceleration in our laboratory, which is found in good agreement with a previous determination obtained with a FG5 mechanical gravimeter.

physics.atom-ph↗

arXiv2017

Quantum test of the equivalence principle for atoms in superpositions of internal energy eigenstates

The Einstein Equivalence Principle (EEP) has a central role in the understanding of gravity and space-time. In its weak form, or Weak Equivalence Principle (WEP), it directly implies equivalence between inertial and gravitational mass. Verifying this principle in a regime where the relevant properties of the test body must be described by quantum theory has profound implications. Here we report on a novel WEP test for atoms. A Bragg atom interferometer in a gravity gradiometer configuration compares the free fall of rubidium atoms prepared in two hyperfine states and in their coherent superposition. The use of the superposition state allows testing genuine quantum aspects of EEP with no classical analogue, which have remained completely unexplored so far. In addition, we measure the Eotvos ratio of atoms in two hyperfine levels with relative uncertainty in the low $10^{-9}$, improving previous results by almost two orders of magnitude.

physics.atom-ph↗