arXiv subjects

Luca Di Mascolo

Publications and source records attributed to Luca Di Mascolo.

At least 19 recordsLinked to original sources

arXiv2026

Sensitive 3mm Imaging of Discrete Sources in the Fields of X-ray-Selected Galaxy Clusters

In this paper, we present the results of a blind survey for compact sources in 138 galaxy clusters from the eFEDS X-ray survey. Of these clusters, 96 are new observations. These targets have X-ray mass estimates and redshifts that formally place them above the thermal Sunyaev-Zel'dovich effect (tSZ) survey limits from the Atacama Cosmology Telescope (ACT, DR5), yet were not detected. Compact sources with apparent locations close to (<104") the center of a galaxy cluster can in-fill the tSZ flux decrement, resulting in tSZ surveys missing clusters. To quantify the number of missing clusters from ACT, we carried out a survey at 90GHz using MUSTANG2 on the Green Bank Telescope and achieved a 5-sigma detection limit of 1mJy in the center of each cluster. We detected 11 discrete sources, which when scaled, is slightly lower than our previous tSZ selected sample, M2-ACT (8.0% vs 9.9%). All had radio counterparts. However, unlike the M2-ACT sample, the sources in X-ray selected clusters were concentrated closer to the cluster centers. When their effect on the measured tSZ signal is taken into account the sources we found would result in 4.5% of clusters being missed by tSZ surveys - a result similar to the estimate in recent ACT results. Most of the 96 clusters in eFEDS but not in ACT are a result of noise and overestimation of mass from X-ray measurements.

astro-ph.CO↗

arXiv2026

The SKA View of the Sunyaev-Zeldovich Effect from Massive Cosmic Halos

The thermal intracluster medium (ICM) can be observed via its interaction with Cosmic Microwave Background photons, known as the Sunyaev-Zeldovich (SZ) effect. This effect produces an observable signal at radio to sub-mm wavelengths which probes the pressure of the ICM. The SKA will be sensitive to the thermal SZ effect in its highest frequency band, 5b. In this Chapter, we show that the SKA will provide a high-resolution, high-sensitivity view of the thermal SZ effect, allowing detailed observations of pressure substructures in clusters while retaining sensitivity to the large-scale global ICM emission.

astro-ph.CO↗

arXiv2026

Early thin-disc assembly revealed by JWST edge-on galaxies

The vertical structure of stellar discs provides key constraints on their formation and evolution. Nearby spirals, including the Milky Way, host thin and thick components that may arise either from an early turbulent phase or from the subsequent dynamical heating of an initially thin disc; measuring disc thickness across cosmic time therefore offers a direct test of these scenarios. We present a new methodology to measure the thickness of edge-on galaxies that explicitly accounts for departures from perfectly edge-on orientations by fitting a full three-dimensional model with forward modelling. This improves on traditional approaches that assume an inclination of $90^\circ$ and can bias thicknesses high. Applying the method to JWST imaging of galaxies at $1<z<3$ with stellar masses $\gtrsim 10^9~M_\odot$ from four major surveys, we measure a median scale height of $z_0 = 0.25\pm0.14$~kpc and a median ratio $h_r/z_0=8.4\pm3.7$. These values are consistent with the Milky Way and local thin discs, and indicate scale heights $\sim 1.6$ times smaller than those inferred for local galaxies from single-disc fits. This result implies that thin discs are already present at $z\sim3$. We further show that a thick disc contributing 10\% of the thin-disc luminosity would be detectable in the data considered in this work, implying that any thick disc present must be fainter and favouring a scenario in which thick discs build up progressively through dynamical heating at $z<1$.

astro-ph.GA↗

arXiv2026

A high-dynamic-range view of the growth of structure and the warm/hot Universe

Baryons heat to temperatures above $>\!\!10^5\,\mathrm{K}$ as they accrete onto massive overdensities -- galaxies, groups, clusters, and filaments -- where they ionize and become optically transparent. Deep mm-wave observations such as those with ALMA have begun to probe a handful ($\sim\,$4) of massive systems at $z\!\sim\!2-4$, while low-resolution mm-wave surveys have detected thousands of objects at arcminute resolution out to $z\!\approx\!2$. To truly advance the field of the evolution of large-scale structures, mapping the warm/hot distribution of ionized gas out to the redshift of their formation, the ESO community requires a large-aperture single-dish (sub-)mm telescope. This will need to provide several orders of magnitude higher mapping speeds than currently available while preserving the few arcsecond resolution required for imaging the gas and removing contaminating radio and dusty thermal signals across the full (sub-)mm wavelength range.

astro-ph.CO↗

arXiv2025

A large thermal energy reservoir in the nascent intracluster medium at a redshift of 4.3

Most baryons in present-day galaxy clusters exist as hot gas ($\boldsymbol{\gtrsim10^7\,\rm}\mathrm{K}$), forming the intracluster medium (ICM). Cosmological simulations predict that the mass and temperature of the ICM rapidly decrease with increasing cosmological redshift, as intracluster gas in younger clusters is still accumulating and being heated. The thermal Sunyaev-Zeldovich (tSZ) effect arises when cosmic microwave background (CMB) photons are scattered to higher energies through interactions with energetic electrons in hot ICM, leaving a localized decrement in the CMB at a long wavelength. The depth of this decrement is a measure of the thermal energy and pressure of the gas. To date, the effect has been detected in only three systems at or above $z\sim2$, when the Universe was 4 billion years old, making the time and mechanism of ICM assembly uncertain. Here, we report observations of this effect in the protocluster SPT2349$-$56 with Atacama Large Millimeter/submillimeter Array (ALMA). SPT2349$-$56 contains a large molecular gas reservoir, with at least 30 dusty star-forming galaxies (DSFGs) and three radio-loud active galactic nuclei (AGN) in a 100-kpc region at $z=4.3$, corresponding to 1.4 billion years after the Big Bang. The observed tSZ signal implies a thermal energy of $\mathbf{\sim 10^{61}\,\mathrm{erg}}$, exceeding the possible energy of a virialized ICM by an order of magnitude. Contrary to current theoretical expectations, the strong tSZ decrement in SPT2349$-$56 demonstrates that substantial heating can occur and deposit a large amount of thermal energy within growing galaxy clusters, overheating the nascent ICM in unrelaxed structures, two billion years before the first mature clusters emerged at $\mathbf{z \sim 2}$.

astro-ph.GA↗

arXiv2025

X-ray view of a massive node of the Cosmic Web at z=3 II. Discovery of extended X-ray emission around a hyperluminous QSO

While the warm, ionized gas in the CGM at z>3 is now routinely observed around bright QSOs in Lya emission, little is known about the CGM hot phase due to its expected faintness in the X-ray band, often referred to as the ICM. Here, we report the analysis of 634 ks of Chandra X-ray observations in the MQN01 Cosmic Node, a region containing one of the brightest Lya nebulae and the largest galaxy overdensity discovered so far at z>3. We detect 66 net counts of X-ray emission in the 0.5-2 keV band extending to at least 30 kpc from the brightest QSO in MQN01. The morphology and spectrum are consistent with thermal emission from hot plasma in CIE. Photoionization is negligible, and IC is disfavored. A joint spatial and spectral MCMC analysis provides consistency with a beta-model with a steep density profile and a gas temperature kT~1.8 keV and virial halo mass Mvir~3e13 Mo. The inferred hot gas mass is Mhot(<Rvir)~2.6e12 Mo, which is ~8.3% of Mvir, or ~56% of the theoretical cosmological baryon budget of the halo. The hot gas also emits an exceptionally high Lx, with a measured L2-10~2.3e45 erg/s within the central 30 kpc. This system is a clear outlier in the Lx-Tx plane, indicating a thermodynamic state distinct from that of evolved lower-redshift hot halos. The cooling time in the inner 15-30 kpc is comparable to the local dynamical time, suggesting that the gas could become locally unstable in the absence of heating or feedback. Moreover, the thermal pressure associated with the detected CGM hot phase is large enough to confine the cold and dense clumps, which are required to reproduce the high Lya emission associated with the inner regions of the MQN01 structure. Although limited to a single system, our results provide unique information on the multi-phase properties of the CGM and a view of the nascent thermal hot gas phase observed in local galaxy clusters.

astro-ph.GA↗

arXiv2025

Atacama Large Aperture Submillimeter Telescope (AtLAST) Science: Resolving the Hot and Ionized Universe through the Sunyaev-Zeldovich effect

An omnipresent feature of the multi-phase ``cosmic web'' is that warm/hot (>$10^5$ K) ionized gas pervades it. This gas constitutes a relevant contribution to the overall universal matter budget across multiple scales, from the several tens of Mpc-scale IGM filaments, to the Mpc ICM, all the way down to the CGM surrounding individual galaxies from ~1 kpc up to their respective virial radii (~100 kpc). The study of the hot baryonic component of cosmic matter density represents a powerful means for constraining the intertwined evolution of galactic populations and large-scale cosmological structures, for tracing the matter assembly in the Universe and its thermal history. To this end, the SZ effect provides the ideal observational tool for measurements out to the beginnings of structure formation. The SZ effect is caused by the scattering of the photons from the cosmic microwave background off the hot electrons embedded within cosmic structures, and provides a redshift-independent perspective on the thermal and kinematic properties of the warm/hot gas. Still, current and future (sub)mm facilities have been providing only a partial view of the SZ Universe due to any combination of: limited angular resolution, spectral coverage, field of view, spatial dynamic range, sensitivity. In this paper, we motivate the development of a wide-field, broad-band, multi-chroic continuum instrument for the Atacama Large Aperture Submillimeter Telescope (AtLAST) by identifying the scientific drivers that will deepen our understanding of the complex thermal evolution of cosmic structures. On a technical side, this will necessarily require efficient multi-wavelength mapping of the SZ signal with an unprecedented spatial dynamic range (from arcsecond to tens of arcminutes) and we employ theoretical forecasts to determine the key instrumental constraints for achieving our goals. [abridged]

astro-ph.CO↗

arXiv2025

Quantifying the detection likelihood of faint peaks in interferometric data through jackknifing: Test application on finding $z>10$ galaxy candidates

False-positive emission-line detections bias our understanding of astronomical sources; for example, falsely identifying $z\sim3-4$ passive galaxies as $z>10$ galaxies leads to incorrect number counts and flawed tests of cosmology. In this work, we provide a novel but simple tool to better quantify the detection of faint lines in interferometric data sets and properly characterize the underlying noise distribution. We demonstrate the method on three sets of archival observations of $z>10$ galaxy candidates, taken with the Atacama Large Millimeter/Submillimeter Array (ALMA). By jackknifing the visibilities using our tool, $jackknify$, we create observation-specific noise realizations of the interferometric measurement set. We apply a line-finding algorithm to both the noise cubes and the real data and determine the likelihood that any given positive peak is a real signal by taking the ratio of the two sampled probability distributions. We show that the previously reported, tentative emission-line detections of these $z>10$ galaxy candidates are consistent with noise. We further expand upon the technique and demonstrate how to properly incorporate prior information on the redshift of the candidate from auxiliary data, such as from JWST. Our work highlights the need to achieve a significance of $\gtrsim 5σ$ to confirm an emission line when searching in broad 30 GHz bandwidths. Using our publicly available method enables the quantification of false detection likelihoods, which are crucial for accurately interpreting line detections.

astro-ph.GA↗

arXiv2024

herakoi: a sonification experiment for astronomical data

Recent research is revealing data-sonification as a promising complementary approach to vision, benefiting both data perception and interpretation. We present herakoi, a novel open-source software that uses machine learning to allow real-time image sonification, with a focus on astronomical data. By tracking hand movements via a webcam and mapping them to image coordinates, herakoi translates visual properties into sound, enabling users to "hear" images. Its swift responsiveness allows users to access information in astronomical images with short training, demonstrating high reliability and effectiveness. The software has shown promise in educational and outreach settings, making complex astronomical concepts more engaging and accessible to diverse audiences, including blind and visually impaired individuals. We also discuss future developments, such as the integration of large language and vision models to create a more interactive experience in interpreting astronomical data.

astro-ph.IM↗

arXiv2024

Atacama Large Aperture Submillimeter Telescope (AtLAST) Science: Solar and stellar observations

Observations at (sub-)millimeter wavelengths offer a complementary perspective on our Sun and other stars, offering significant insights into both the thermal and magnetic composition of their chromospheres. Despite the fundamental progress in (sub-)millimeter observations of the Sun, some important aspects require diagnostic capabilities that are not offered by existing observatories. In particular, simultaneous observations of the radiation continuum across an extended frequency range would facilitate the mapping of different layers and thus ultimately the 3D structure of the solar atmosphere. Mapping large regions on the Sun or even the whole solar disk at a very high temporal cadence would be crucial for systematically detecting and following the temporal evolution of flares, while synoptic observations, i.e., daily maps, over periods of years would provide an unprecedented view of the solar activity cycle in this wavelength regime. As our Sun is a fundamental reference for studying the atmospheres of active main sequence stars, observing the Sun and other stars with the same instrument would unlock the enormous diagnostic potential for understanding stellar activity and its impact on exoplanets. The Atacama Large Aperture Submillimeter Telescope (AtLAST), a single-dish telescope with 50\,m aperture proposed to be built in the Atacama desert in Chile, would be able to provide these observational capabilities. Equipped with a large number of detector elements for probing the radiation continuum across a wide frequency range, AtLAST would address a wide range of scientific topics including the thermal structure and heating of the solar chromosphere, flares and prominences, and the solar activity cycle. In this white paper, the key science cases and their technical requirements for AtLAST are discussed.

astro-ph.SR↗

arXiv2024

Sensitive 3mm Imaging of Discrete Sources in the Fields of tSZ-Selected Galaxy Clusters

In this paper we present the results of a blind survey for compact sources in 243 Galaxy clusters that were identified using the thermal Sunyaev-Zeldovich effect (tSZ). The survey was carried out at 90 GHz using MUSTANG2 on the Green Bank telescope and achieved a $5σ$ detection limit of 1 mJy in the center of each cluster. We detected 24 discrete sources. The majority (18) of these correspond to known radio sources, and of these, 5 show signs of significant variability, either with time or in spectral index. The remaining sources have no clear counterparts at other wavelengths. Searches for galaxy clusters via the tSZ effect strongly rely on observations at 90 GHz, and the sources found have the potential to bias mass estimates of clusters. We compare our results to the simulation Websky that can be used to estimate the source contamination in galaxy cluster catalogs. While the simulation showed a good match to our observations at the clusters' centers, it does not match our source distribution further out. Sources over 104" from a cluster's center bias the tSZ signal high, for some of our sources, by over 50%. When averaged over the whole cluster population the effect is smaller but still at a level of 1 to 2%. We also discovered that unlike previous measurements and simulations we see an enhancement of source counts in the outer regions of the clusters and fewer sources than expected in the centers of this tSZ selected sample.

astro-ph.CO↗

arXiv2024

AtLAST Science Overview Report

Submillimeter and millimeter wavelengths provide a unique view of the Universe, from the gas and dust that fills and surrounds galaxies to the chromosphere of our own Sun. Current single-dish facilities have presented a tantalising view of the brightest (sub-)mm sources, and interferometers have provided the exquisite resolution necessary to analyse the details in small fields, but there are still many open questions that cannot be answered with current facilities. In this report we summarise the science that is guiding the design of the Atacama Large Aperture Submillimeter Telescope (AtLAST). We demonstrate how tranformational advances in topics including star formation in high redshift galaxies, the diffuse circumgalactic medium, Galactic ecology, cometary compositions and solar flares motivate the need for a 50m, single-dish telescope with a 1-2 degree field of view and a new generation of highly multiplexed continuum and spectral cameras. AtLAST will have the resolution to drastically lower the confusion limit compared to current single-dish facilities, whilst also being able to rapidly map large areas of the sky and detect extended, diffuse structures. Its high sensitivity and large field of view will open up the field of submillimeter transient science by increasing the probability of serendipitous detections. Finally, the science cases listed here motivate the need for a highly flexible operations model capable of short observations of individual targets, large surveys, monitoring programmes, target of opportunity observations and coordinated observations with other observatories. AtLAST aims to be a sustainable, upgradeable, multipurpose facility that will deliver orders of magnitude increases in sensitivity and mapping speeds over current and planned submillimeter observatories.

astro-ph.IM↗

arXiv2024

The RAdio Galaxy Environment Reference Survey (RAGERS): Evidence of an anisotropic distribution of submillimeter galaxies in the 4C 23.56 protocluster at z=2.48

High-redshift radio(-loud) galaxies (H$z$RGs) are massive galaxies with powerful radio-loud active galactic nuclei (AGNs) and serve as beacons for protocluster identification. However, the interplay between H$z$RGs and the large-scale environment remains unclear. To understand the connection between H$z$RGs and the surrounding obscured star formation, we investigated the overdensity and spatial distribution of submillimeter-bright galaxies (SMGs) in the field of 4C\,23.56, a well-known H$z$RG at $z=2.48$. We used SCUBA-2 data ($σ\,{\sim}\,0.6$\,mJy) to estimate the $850\,{\rm μm}$ source number counts and examine the radial and azimuthal overdensities of the $850\,{\rm μm}$ sources in the vicinity of the H$z$RG. The angular distribution of SMGs is inhomogeneous around the H$z$RG 4C\,23.56, with fewer sources oriented along the radio jet. We also find a significant overdensity of bright SMGs (${\rm S}_{850\rm\,μm}\geq5\,$mJy). Faint and bright SMGs exhibit different spatial distributions. The former are concentrated in the core region, while the latter prefer the outskirts of the H$z$RG field. High-resolution observations show that the seven brightest SMGs in our sample are intrinsically bright, suggesting that the overdensity of bright SMGs is less likely due to the source multiplicity.

astro-ph.GA↗

arXiv2024

The key science drivers for the Atacama Large Aperture Submillimeter Telescope (AtLAST)

Sub-mm and mm wavelengths provide a unique view of the Universe, from the gas and dust that fills and surrounds galaxies to the chromosphere of our own Sun. Current single-dish facilities have presented a tantalising view of the brightest (sub-)mm sources, and interferometers have provided the exquisite resolution necessary to analyse the details in small fields, but there are still many open questions that cannot be answered with current facilities: Where are all the baryons? How do structures interact with their environments? What does the time-varying (sub-)mm sky look like? In order to make major advances on these questions and others, what is needed now is a facility capable of rapidly mapping the sky spatially, spectrally, and temporally, which can only be done by a high throughput, single-dish observatory. An extensive design study for this new facility is currently being undertaken. In this paper, we focus on the key science drivers and the requirements they place on the observatory. As a 50m single dish telescope with a 1-2° field of view, the strength of the Atacama Large Aperture Submillimeter Telescope (AtLAST) is in science where a large field of view, highly multiplexed instrumentation and sensitivity to faint large-scale structure is important. AtLAST aims to be a sustainable, upgradeable, multipurpose facility that will deliver orders of magnitude increases in sensitivity and mapping speeds over current and planned telescopes.

astro-ph.IM↗

arXiv2024

Evaluating the efectiveness of sonifcation in science education using Edukoi

Science, Technology, Engineering, and Mathematics classes are mainly taught using visual supports. However, the advancement of technology and the increasing eforts to equip schools with digital instrumentation have opened up the possibility of exploring new teaching avenues, such as sonifcation. We explored the efcacy of sonifcation in education using a novel interactive tool, Edukoi, in the context of astronomy, which is predominantly disseminated through spectacular images, animations, and visuals. Edukoi is a motion-sensing sonifcation tool that converts images to sound in real-time for educational applications. Our study, conducted with nearly 150 middle-school students, included a preliminary questionnaire investigating the perception, engagement, and motivation of students towards science; two sessions dedicated to testing Edukoi and assessing the potentiality of the software for the recognition of the colour and the shape of real and sketchy images; and a fnal second administration of the questionnaire to capture a possible benefcial efect of the use of the tool in the engagement towards science. Results showed the efectiveness of Edukoi in colour recognition and reasonable efcacy in shape identifcation. Although the questionnaire did not reveal an increment in science engagement over the time of the study, oral feedback from the students was positive. Edukoi presents a possible alternative teaching aid, potentially benefting diverse learners, including the visually impaired. Further developments of the software are needed to enhance its efectiveness in conveying more complex features such as composite colours or shapes.

physics.ed-ph↗

arXiv2024

Atacama Large Aperture Submillimeter Telescope \mbox{(AtLAST)} Science: Probing the Transient and Time-variable Sky

The study of transient and variable events, including novae, active galactic nuclei, and black hole binaries, has historically been a fruitful path for elucidating the evolutionary mechanisms of our universe. The study of such events in the millimeter and submillimeter is, however, still in its infancy. Submillimeter observations probe a variety of materials, such as optically thick dust, which are hard to study in other wavelengths. Submillimeter observations are sensitive to a number of emission mechanisms, from the aforementioned cold dust, to hot free-free emission, and synchrotron emission from energetic particles. Study of these phenomena has been hampered by a lack of prompt, high sensitivity submillimeter follow-up, as well as by a lack of high-sky-coverage submillimeter surveys. In this paper, we describe how the proposed Atacama Large Aperture Submillimeter Telescope (AtLAST) could fill in these gaps in our understanding of the transient universe. We discuss a number of science cases that would benefit from AtLAST observations, and detail how AtLAST is uniquely suited to contributing to them. In particular, AtLAST's large field of view will enable serendipitous detections of transient events, while its anticipated ability to get on source quickly and observe simultaneously in multiple bands make it also ideally suited for transient follow-up. We make theoretical predictions for the instrumental and observatory properties required to significantly contribute to these science cases, and compare them to the projected AtLAST capabilities. Finally, we consider the unique ways in which transient science cases constrain the observational strategies of AtLAST, and make prescriptions for how AtLAST should observe in order to maximize its transient science output without impinging on other science cases.

astro-ph.CO↗

arXiv2024

Atacama Large Aperture Submillimeter Telescope (AtLAST) Science: Planetary and Cometary Atmospheres

The study of planets and small bodies within our Solar System is fundamental for understanding the formation and evolution the Earth and other planets. Compositional and meteorological studies of the giant planets provide a foundation for understanding the nature of the most commonly observed exoplanets, while spectroscopic observations of the atmospheres of terrestrial planets, moons, and comets provide insights into the past and present-day habitability of planetary environments, and the availability of the chemical ingredients for life. While prior and existing (sub)millimeter observations have led to major advances in these areas, progress is hindered by limitations in the dynamic range, spatial and temporal coverage, as well as sensitivity of existing telescopes and interferometers. Here, we summarize some of the key planetary science use cases that factor into the design of the Atacama Large Aperture Submillimeter Telescope (AtLAST), a proposed 50-m class single dish facility: (1) to more fully characterize planetary wind fields and atmospheric thermal structures, (2) to measure the compositions of icy moon atmospheres and plumes, (3) to obtain detections of new, astrobiologically relevant gases and perform isotopic surveys of comets, and (4) to perform synergistic, temporally-resolved measurements in support of dedicated interplanetary space missions. The improved spatial coverage (several arcminutes), resolution ($\sim1.2''-12''$), bandwidth (several tens of GHz), dynamic range ($\sim10^5$) and sensitivity ($\sim1$ mK km s$^{-1}$) required by these science cases would enable new insights into the chemistry and physics of planetary environments, the origins of prebiotic molecules and the habitability of planetary systems in general.

astro-ph.EP↗

arXiv2024

Atacama Large Aperture Submillimeter Telescope (AtLAST) Science: Surveying the distant Universe

During the most active period of star formation in galaxies, which occurs in the redshift range 1<z<3, strong bursts of star formation result in significant quantities of dust, which obscures new stars being formed as their UV/optical light is absorbed and then re-emitted in the infrared, which redshifts into the mm/sub-mm bands for these early times. To get a complete picture of the high-z galaxy population, we need to survey a large patch of the sky in the sub-mm with sufficient angular resolution to resolve all galaxies, but we also need the depth to fully sample their cosmic evolution, and therefore obtain their redshifts using direct mm spectroscopy with a very wide frequency coverage. This requires a large single-dish sub-mm telescope with fast mapping speeds at high sensitivity and angular resolution, a large bandwidth with good spectral resolution and multiplex spectroscopic capabilities. The proposed 50-m Atacama Large Aperture Submillimeter Telescope (AtLAST) will deliver these specifications. We discuss how AtLAST allows us to study the whole population of high-z galaxies, including the dusty star-forming ones which can only be detected and studied in the sub-mm, and obtain a wealth of information for each of these up to z~7: gas content, cooling budget, star formation rate, dust mass, and dust temperature. We present worked examples of surveys that AtLAST can perform, both deep and wide, and also focused on galaxies in proto-clusters. In addition we show how such surveys with AtLAST can measure the growth rate and the Hubble constant with high accuracy, and demonstrate the power of the line-intensity mapping method in the mm/sub-mm wavebands to constrain the cosmic expansion history at high redshifts, as good examples of what can uniquely be done by AtLAST in this research field.

astro-ph.CO↗