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CHEOPS in-flight performance: A comprehensive look at the first 3.5 yr of operations
Get PDFContext. Since the discovery of the first exoplanet almost three decades ago, the number of known exoplanets has increased dramatically. By beginning of the 2000s it was clear that dedicated facilities to advance our studies in this field were needed. The CHaracterising ExOPlanet Satellite (CHEOPS) is a space telescope specifically designed to monitor transiting exoplanets orbiting bright stars. In September 2023, CHEOPS completed its nominal mission duration of 3.5 yr and remains in excellent operational conditions. As a testament to this, the mission has been extended until the end of 2026. Aims. Scientific and instrumental data have been collected throughout in-orbit commissioning and nominal operations, enabling a comprehensive analysis of the missiona's performance. In this article, we present the results of this analysis with a twofold goal. First, we aim to inform the scientific community about the present status of the mission and what can be expected as the instrument ages. Secondly, we intend for this publication to serve as a legacy document for future missions, providing insights and lessons learned from the successful operation of CHEOPS. Methods. To evaluate the instrument performance in flight, we developed a comprehensive monitoring and characterisation (M&C) programme. It consists of dedicated observations that allow us to characterise the instrumenta's response and continuously monitor its behaviour. In addition to the standard collection of nominal science and housekeeping data, these observations provide valuable input for detecting, modelling, and correcting instrument systematics, discovering and addressing anomalies, and comparing the instrumenta's actual performance with expectations. Results. The precision of the CHEOPS measurements has enabled the mission objectives to be met and exceeded. The satellitea's performance remains stable and reliable, ensuring accurate data collection throughout its operational life. Careful modelling of the instrumental systematics allows the data quality to be significantly improved during the light curve analysis phase, resulting in more precise scientific measurements. Conclusions. CHEOPS is compliant with the driving scientific requirements of the mission. Although visible, the ageing of the instrument has not affected the missiona's performance. The satellitea's capabilities remain robust, and we are confident that we will continue to acquire high-quality data during the mission extension
Black hole jets on the scale of the cosmic web
No full textWhen sustained for megayears (refs. 1,2), high-power jets from supermassive black holes (SMBHs) become the largest galaxy-made structures in the Universe3. By pumping electrons, atomic nuclei and magnetic fields into the intergalactic medium (IGM), these energetic flows affect the distribution of matter and magnetism in the cosmic web4-6 and could have a sweeping cosmological influence if they reached far at early epochs. For the past 50 years, the known size range of black hole jet pairs ended at 4.6-5.0 Mpc (refs. 7-9), or 20-30% of a cosmic void radius in the Local Universe10. An observational lack of longer jets, as well as theoretical results11, thus suggested a growth limit at about 5 Mpc (ref. 12). Here we report observations of a radio structure spanning about 7 Mpc, or roughly 66% of a coeval cosmic void radius, apparently generated by a black hole between 4.4−0.7+0.2 and 6.3 Gyr after the Big Bang. The structure consists of a northern lobe, a northern jet, a core, a southern jet with an inner hotspot and a southern outer hotspot with a backflow. This system demonstrates that jets can avoid destruction by magnetohydrodynamical instabilities over cosmological distances, even at epochs when the Universe was 7 to 1 5−2+6 times denser than it is today. How jets can retain such long-lived coherence is unknown at present...
A "MeerKAT-meets-LOFAR" study of the complex multi-component (mini-)halo in the extreme sloshing cluster Abell 2142
No full textContext. Clusters of galaxies are known to be turbulent environments, whether they are merging systems where turbulence is injected via the conversion of gravitational potential energy into the intracluster medium (ICM), or whether they are relaxed systems in which small-scale core sloshing is occurring within the potential well. In many such systems, diffuse radio sources associated with the ICM are found: radio haloes and mini-haloes. Aims: Abell 2142 is a rich cluster undergoing an extreme episode of core sloshing, which has given rise to four cold fronts and a complex multi-component radio halo. Recent work revealed that there are three primary components to the halo that spans a distance of up to around 2.4 Mpc. The underlying physics of particle acceleration on these scales is poorly explored, and requires high-quality multi-frequency data with which to perform precision spectral investigation. We aim to perform such an investigation. Methods: We used new deep MeerKAT L-band (1283 MHz) observations in conjunction with LOFAR HBA (143 MHz) data as well as X-ray data from XMM-Newton and Chandra to study the spectrum of the halo and the connection between the thermal and non-thermal components of the ICM. Results: We confirm the presence of the third halo component, detecting it for the first time at 1283 MHz and confirming its ultra-steep spectrum nature, as we recovered an integrated spectrum of αH3, total = −1.68 ± 0.10. All halo components follow power-law spectra with increasingly steep spectra moving towards the cluster outskirts. We profiled the halo in three directions, finding evidence of asymmetry and spectral steepening along an axis perpendicular to the main axis of the cluster. Our investigation of the thermal non-thermal connection shows sub-linear correlations that are steeper at 1283 MHz than 143 MHz, and we find evidence of different connections in different components of the halo. In particular, we find both a moderate anti-correlation (H1, the core) and positive correlation (H2, the ridge) between the radio spectral index and X-ray temperature. Conclusions: Our results are broadly consistent with an interpretation of turbulent (re-)acceleration following an historic minor cluster merger scenario in which we must invoke some inhomogeneities. However, the anti-correlation between the radio spectral index and X-ray temperature in the cluster core is more challenging to explain; the presence of three cold fronts and a generally lower temperature may provide the foundations of an explanation, but detailed modelling is required to study this further. The full-field MeerKAT image is available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/686/A44</A
A New Deep Learning Model to Detect Gamma-Ray Bursts in the AGILE Anticoincidence System
Get PDFThe AGILE space mission was launched in 2007 to study X-ray and gamma-ray astrophysics. AGILE operated in spinning mode from 2009 until 2024 February 14, when it re-entered the Earth’s atmosphere. This work uses data acquired from the AGILE anticoincidence system (ACS) from 2019 January 1 to 2022 December 31. The ACS is designed to reject charged background particles. It also detects X-ray photons in the 50-200 KeV energy range and saves each panel count rate in the telemetry as ratemeter data, a time series with a resolution of 1.024 s. We developed a method that uses a deep learning model to predict the background count rates of the AGILE ACS top panel (perpendicular to the pointing direction of the payload detectors) using the satellite’s orbital parameters as input. Then, we use the difference between predicted and acquired count rates to detect gamma-ray bursts (GRB). We trained the model with a background-only data set. After the training, the model can predict the ACS count rates with a mean reconstruction error of 3.8%. We used the GRBs listed in the GRBweb catalog to search for significant anomalies in the ACS data. We extracted light curves of 140 bins of 1.024 s for each GRB from the AGILE ACS to cover the trigger time of the GRBs. The model detected 39 GRBs with a significance of σ ≥ 3. The results contain four GRBs detected for the first time in the AGILE data
Influencer, quanto mi costi? Strategie di comunicazione su Instagram per “Macchine del Tempo” la mostra dell’INAF. Numeri e risultati su Media INAF.
Get PDFIdeata e realizzata dall’Istituto Nazionale di Astrofisica in collaborazione con Pleiadi, la mostra “Macchine del Tempo” è stata inaugurata il 25 novembre 2023 a Palazzo Esposizioni a Roma. Fino al 24 marzo 2024, al percorso espositivo si sono svolti incontri, attività collaterali, laboratori per i più piccoli, aperitivi scientifici ed eventi speciali. Ben prima dell’inaugurazione è stata avviata una campagna pubblicitaria sui social di Media
INAF che puntava a suscitare attesa e curiosità negli utenti già fidelizzati e ad attirare nuovi potenziali follower che ancora non conoscevano questo aspetto più accessibile del nostro Istituto. Con questo report intendiamo dare qualche numero sull’esperienza della mostra e sui risultati prodotti sulla cittadinanza e il grande pubblico, che conta 106 giorni di esposizione in oltre 550 mq di allestimento grafico
The eROSITA view of the Abell 3391/95 field. Cluster outskirts and filaments
Get PDFContext. About 30% - 40% of the baryons in the local Universe remain unobserved. Many of these "missing" baryons are expected to reside in the warm-hot intergalactic medium (WHIM) of the cosmic web filaments that connect clusters of galaxies. SRG/eROSITA performance verification (PV) observations covered about 15 square degrees of the A3391/95 system and have revealed a ~15 Mpc continuous soft emission connecting several galaxy groups and clusters. Aims: We aim to characterize the gas properties in the cluster outskirts (R500 200) and in the detected inter-cluster filaments (> R200) and to compare them to predictions. Methods: We performed X-ray image and spectral analyses using the eROSITA PV data in order to assess the gas morphology and properties in the outskirts and the filaments in the directions of the previously detected Northern and Southern Filament of the A3391/95 system. We constructed surface brightness profiles using particle-induced background-subtracted, exposure- and Galactic absorption-corrected eROSITA products in the soft band (0.3-2.0 keV). We constrained the temperatures, metallicities, and electron densities through X-ray spectral fitting and compared them with the expected properties of the WHIM. We took particular care of the foreground. Results: In the filament-facing outskirts of A3391 and the Northern Clump, we find higher temperatures than typical cluster outskirts profiles, with a significance of between 1.6 and 2.8σ, suggesting heating due to their connections with the filaments. We confirm surface brightness excess in the profiles of the Northern, Eastern, and Southern Filaments. From spectral analysis, we detect hot gas of 0.96−0.14+0.17 keV and 1.09−0.06+0.09 for the Northern and Southern Filament, respectively, which are close to the upper WHIM temperature limit. The filament metallicities are below 10% solar metallicity and the electron densities are ranging between 2.6 and 6.3 × 10−5 cm−3. The characteristic properties of the Little Southern Clump (LSC), which is located at a distance of ~1.5R200 from A3395S in the Southern Filament, suggest that it is a small galaxy group. Excluding the LSC from the analysis of the Southern Filament does not significantly change the temperature or metallicity of the gas, but it decreases the gas density by 30%. This shows the importance of taking into account any clumps in order to avoid overestimation of the gas measurement in the outskirts and filament regions. Conclusions: We present measurements of morphology, temperature, metallicity, and density of individual warm-hot filaments. The electron densities of the filaments are consistent with the WHIM properties as predicted by cosmological simulations, but the temperatures are higher. As both filaments are short (1.8 and 2.7 Mpc) and located in a denser environment, stronger gravitational heating may be responsible for this temperature enhancement. The metallicities are low, but still within the expected range from the simulations. Image that is displayed in Fig. 1 is available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (ftp://130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/681/A108</A
General Relativistic effects and the NIR variability of Sgr A* II: A systematic approach to temporal asymmetry
Get PDFA systematic study, based on the third-moment structure function, of Sgr A*'s
variability finds an exponential rise time
and decay time
. This symmetry of the
flux-density variability is consistent with earlier work, and we interpret it
as caused by the dominance of Doppler boosting, as opposed to gravitational
lensing, in Sgr~A*'s light curve. A relativistic, semi-physical model of Sgr~A*
confirms an inclination angle degrees. The model also shows that the
emission of the intrinsic radiative process can have some asymmetry even though
the observed emission does not. The third-moment structure function, which is a
measure of the skewness of the light-curve increments, may be a useful summary
statistic in other contexts of astronomy because it senses only temporal
asymmetry, i.e., it averages to zero for any temporally symmetric signal
Magnetic Fields in Massive Star-forming Regions (MagMaR): Unveiling an Hourglass Magnetic Field in G333.46–0.16 Using ALMA
Get PDFThe contribution of the magnetic field to the formation of high-mass stars is poorly understood. We report the high angular resolution (∼0.″3, 870 au) map of the magnetic field projected on the plane of the sky (B POS) toward the high-mass star-forming region G333.46‑0.16 (G333), obtained with the Atacama Large Millimeter/submillimeter Array at 1.2 mm as part of the Magnetic fields in Massive star-forming Regions survey. The B POS morphology found in this region is consistent with a canonical "hourglass" with an embedded flattened envelope in a perpendicular direction, which suggests a dynamically important field. This region is fragmented into two protostars that appear to be gravitationally bound in a stable binary system with a separation of ∼1740 au. Interestingly, by analyzing H13CO+ (J = 3–2) line emission, we find no velocity gradient over the extent of the continuum, which is consistent with a strong field. We model the B POS, obtaining a marginally supercritical mass-to-flux ratio of 1.43, suggesting an initially strongly magnetized environment. Based on the Davis–Chandrasekhar–Fermi method, the magnetic field strength toward G333 is estimated to be 5.7 mG. The absence of strong rotation and outflows toward the central region of G333 suggests strong magnetic braking, consistent with a highly magnetized environment. Our study shows that despite being a strong regulator, the magnetic energy fails to prevent the process of fragmentation, as revealed by the formation of the two protostars in the central region
Unveiling the role of magnetic fields in an accreting filament onto a young protocluster
Get PDFIn order to develop a more comprehensive picture of star formation, it is
essential to understand the physical relationship between dense cores and the
filaments embedding them. There is evidence that magnetic fields play a crucial
role in this context. We aim to understand how magnetic fields influence the
properties and kinematics of an isolated filament located east of the Barnard
59 clump, belonging to the Pipe Nebula. We use near infrared polarization
observations to determine the magnetic field configuration, and we apply the
Davis Chandrasekhar Fermi method to infer the magnetic field strength in the
plane of the sky. Furthermore, we use complementary data from the James Clerk
Maxwell Submillimetre Telescope (JCMT) of C18O and 13CO J=3-2 transition to
determine the filament's kinematics. Finally, we model the radial density
profile of the filament with polytropic cylindrical models. Our results
indicate that the filament is stable to radial collapse and is radially
supported by agents other than thermal pressure. In addition, based on previous
observations of emission lines on this source, we suggest that gas is flowing
toward the hub, while C18O (3-2) non-thermal motions indicate that the cloud is
in a quiescent state
G321.3–3.9: A new supernova remnant observed with multi-band radio data and in the SRG/eROSITA All-Sky Surveys
Get PDFAims. G321.3–3.9 was first identified as a partial shell at radio frequencies a few decades ago. Although it continued to be observed, no additional studies were undertaken until recently. Methods. In this paper, we present results from a large selection of radio and X-ray data that cover the position of G321.3–3.9. We confirmed G321.3–3.9 as a new supernova remnant (SNR) using data collected by several radio surveys, spanning a frequency range from 200 to 2300 MHz. Stacked eROSITA data from four consecutive all-sky surveys (eRASS:4) provide spectro-imaging information in the energy band 0.2–8.0 keV. Results. G321.3–3.9 has an elliptical shape with major and minor axes of approximately 1.°7 × 1.°1. From CHIPASS and S-PASS data, we calculate a spectral index α = ‑0.8 ± 0.2, consistent with synchrotron emission from an expanding shell in the radiative phase. The eROSITA data show an X-ray diffuse structure filling almost the entire radio shell. Based on our spectral analysis, we found the temperature to be approximately 0.6 keV and the column absorption density about 1021 cm‑2. Comparing this absorption density to optical extinction maps, we estimated the distance to fall within the range of (1.0–1.7) kpc, considering the 1σ uncertainty range