es/iode’s Post

📃Scientific paper: A star-based method for precise flux calibration of the Chinese Space Station Telescope \(CSST\) slitless spectroscopic survey Abstract: The upcoming Chinese Space Station Telescope \(CSST\) slitless spectroscopic survey poses a challenge of flux calibration, which requires a large number of flux-standard stars. In this work, we design an uncertainty-aware residual attention network, the UaRA-net, to derive the CSST SEDs with a resolution of R = 200 over the wavelength range of 2500-10000 \AA using LAMOST normalized spectra with a resolution of R = 2000 over the wavelength range of 4000-7000 \AA. With the special structure and training strategy, the proposed model can not only provide accurate predictions of SEDs but also their corresponding errors. The precision of the predicted SEDs depends on effective temperature \(Teff\), wavelength, and the LAMOST spectral signal-to-noise ratios \(SNRs\), particularly in the GU band. For stars with Teff = 6000 K, the typical SED precisions in the GU band are 4.2%, 2.1%, and 1.5% at SNR values of 20, 40, and 80, respectively. As Teff increases to 8000 K, the precision increases to 1.2%, 0.6%, and 0.5%, respectively. The precision is higher at redder wavelengths. In the GI band, the typical SED precisions for stars with Teff = 6000 K increase to 0.3%, 0.1%, and 0.1% at SNR values of 20, 40, and 80, respectively. We further verify our model using the empirical spectra of the MILES and find good performance. The proposed method will open up new possibilities for optimal utilization of slitless spectra of the CSST and other surveys. ;Comment: 20 pages, 15 figures, accep... Continued on ES/IODE ➡️ https://etcse.fr/E71fV ------- If you find this interesting, feel free to follow, comment and share. We need your help to enhance our visibility, so that our platform continues to serve you.

📃Scientific paper: X-ray diagnostics of Cassiopeia A's "Green Monster": evidence for dense shocked circumstellar plasma Abstract: The recent survey of the core-collapse supernova remnant Cassiopeia A \(CasA\) with the MIRI instrument on board the James Webb Space Telescope \(JWST\) revealed a large structure in the interior region, referred to as the "Green Monster". Although its location suggests that it is an ejecta structure, the infrared properties of the "Green Monster" hint at a circumstellar medium \(CSM\) origin. In this companion paper to the JWST Cas A paper, we investigate the filamentary X-ray structures associated with the "Green Monster" using Chandra X-ray Observatory data. We extracted spectra along the "Green Monster" as well as from shocked CSM regions. Both the extracted spectra and a principal component analysis show that the "Green Monster" emission properties are similar to those of the shocked CSM. The spectra are well-fit by a model consisting of a combination of a non-equilibrium-ionization model and a power-law component, modified by Galactic absorption. All the "Green Monster" spectra show a blueshift corresponding to a radial velocity of around -2300 km/s, suggesting that the structure is on the near side of Cas A. The ionization age is around $n\_\{e\}t = 1.5 \times 10^\{11\}$ cm$^\{-3\}s. This translates into a pre-shock density of \~12 cm$^\{-3\}$, higher than previous estimates of the unshocked CSM. The relatively high net and relatively low radial velocity suggest that this structure has a relatively high density compared to other shocked CSM plasma. This analysis provides y... Continued on ES/IODE ➡️ https://etcse.fr/KV ------- If you find this interesting, feel free to follow, comment and share. We need your help to enhance our visibility, so that our platform continues to serve you.

📃Scientific paper: Revisiting Gamma-Ray Emission of the Supernova Remnant RCW 103 Abstract: We analyze more than 15 years of the \gr\ data, obtained with the Large Area Telescope \(LAT\) onboard \{\it the Fermi Gamma-ray Space Telescope \(Fermi\)\}, for the region of the young supernova remnant \(SNR\) RCW\~103, since the nearby source 4FGL J1616.2$-$5054e, counterpart to HESS\~J1616$-$518 and $\simeq$13\,arcmin away from the SNR, is determined to be extended in the more recent Fermi-LAT source catalog. Different templates for 4FGL J1616.2$-$5054e and RCW\~103 are tested, and we find that a point source with a power-law \(PL\) spectrum at the southern limb of the SNR best describes the detected gamma-ray emission. The photon index of the PL emission is $\Gamma\simeq 2.31$\(or $\alpha\simeq 2.4$ in a Log-Parabola model\) , softer than the previously reported $\Gamma\simeq 2.0$ when the counterpart to HESS\~J1616$-$518 was considered to be a point source \(which likely caused mis-identification of extended emission at RCW\~103\). In order to produce the \gr\ emission in a hadronic scenario, we estimate that protons with an index$\sim$2.4 PL energy distribution are needed. These results fit with those from multi-wavelength observations that have indicated the remnant at the southern limb is interacting with a molecular cloud. ;Comment: 7 pages, 4 figures, 2 tables, accepted for publication in ApJ Continued on ES/IODE ➡️ https://etcse.fr/tNySC ------- If you find this interesting, feel free to follow, comment and share. We need your help to enhance our visibility, so that our platform continues to serve you.

https://lnkd.in/ddF9M2MN Researchers push toward further advances in space-based gravitational wave detection, beyond what's been realized by the first direct detection back in 2015 and current ground-based detectors. Ground detectors can only detect the higher-frequency gravitational waves because their signal is modified by the gravity and vibration of Earth. Detectors in space, like the proposed TianQin Project, will overcome these limitations through a wider range of frequencies. Designed by the Chinese researchers, led by Professor Hong Ma, the new capacitance sensor introduced for TianQin, a three-satellite formation flying, triangular constellation 100,000 km above Earth, was equipped with six independent capacitive sensing channels and should be able to detect the minute effects produced by gravitational waves. The tiny changes in distance between satellites are measured using this sensor when gravitational waves pass through. Its sensor can counter non-gravitational disturbances such as spacecraft vibrations or solar radiation pressure. Preliminary tests of the sensor have shown that it can spot capacitance well within the millihertz range-an important requirement for early universe waves and massive black holes. Still, there is much work ahead to make sure its sensing circuits dovetail smoothly. TianQin, a planned launch in the mid-2030s at about the same time as a similar effort, the Laser Interferometer Space Antenna being developed by the European Space Agency, hopes to crack the nut.

Deep Space Laser Communication Record, How Much Room For Imagination?Part One Recently, the US Spirit probe completed a deep space laser communication test with ground facilities 16 million kilometers away, setting a new space optical communication distance record. So what are the advantages of laser communication? Based on technical principles and mission requirements, what difficulties does it need to overcome? What is the prospect of its application in the field of deep space exploration in the future? Technological breakthroughs, not afraid of challenges Deep space exploration is an extremely challenging task in the course of space researchers exploring the universe. Probes need to cross distant interstellar space, overcome extreme environments and harsh conditions, acquire and transmit valuable data, and communication technology plays a vital role. On October 13, the Spirit probe launched, beginning a journey of exploration that will last at least eight years. At the beginning of the mission, it worked with the Hale telescope at the Palomar Observatory in the United States to test deep-space laser communication technology, using near-infrared laser coding to communicate data with teams on Earth. To this end, the detector and its laser communication equipment need to overcome at least four types of difficulties. Respectively, the distant distance, signal attenuation and interference, bandwidth limitation and delay, energy limitation and heat dissipation problems deserve attention. Researchers have long anticipated and prepared for these difficulties, and have broken through a series of key technologies, laying a good foundation for the Spirit probe to carry out deep space laser communication experiments. First of all, the Spirit detector uses high-speed data transmission technology, selected laser beam as the transmission medium, equipped with a high-power laser transmitter, using the advantages of laser transmission rate and high stability, trying to establish laser communication links in the deep space environment. #Optical #photonics #semiconductor #Optics #opticalcenter #SiliconPhotonics #photodetectors #optomechanics #laser Read more: https://lnkd.in/ecz8dEKR

📃Scientific paper: Experimental comparison of model-free and model-based dark hole algorithms for future space telescopes Abstract: Coronagraphic instruments provide a great chance of enabling high contrast spectroscopy for the pursuit of finding a habitable world. Future space telescope coronagraph instruments require high performing focal plane masks in combination with precise wavefront sensing and control techniques to achieve dark holes for planet detection. Several wavefront control algorithms have been developed in recent years that might vary in performance depending on the coronagraph they are paired with. This study compares 3 model-free and model-based algorithms when coupled with either a Vector (VVC) or a Scalar (SVC) Vortex Coronagraph mask in the same laboratory conditions: Pairwise Probing with Electric Field Conjugation, the Self-Coherent Camera with Electric Field Conjugation, and Implicit Electric Field Conjugation. We present experimental results from the In-Air Coronagraph Testbed (IACT) at JPL in narrowband and broadband light, comparing the pros and cons of each of these wavefront sensing and control algorithms with respect to their potential for future space telescopes. ;Comment: Conference Proceedings of SPIE: Techniques and Instrumentation for Detection of Exoplanets XI, vol. 12680 (2023) Continued on ES/IODE ➡️ https://etcse.fr/uyTn ------- If you find this interesting, feel free to follow, comment and share. We need your help to enhance our visibility, so that our platform continues to serve you.

Quantum Atomic Clocks and Photon Registration in Space Telescopes **Quantum atomic clocks** offer exceptional precision and stability, making them ideal for applications that require highly accurate timekeeping. In the context of space telescopes, these clocks could play a crucial role in **photon registration and recognition**. How Quantum Atomic Clocks Work Quantum atomic clocks utilize the precise oscillations of atoms or ions to measure time. These oscillations are incredibly stable, making quantum atomic clocks far more accurate than traditional atomic clocks. Applications in Space Telescopes 1. **Precise Timekeeping:** * **Synchronization:** Quantum atomic clocks can ensure that different instruments on a space telescope are synchronized with extreme precision. * **Data Analysis:** Accurate timekeeping is essential for analyzing data collected by telescopes, especially when studying rapidly changing phenomena. 2. **Photon Registration:** * **Timing:** Quantum atomic clocks can provide precise timestamps for each photon detected by the telescope, allowing for detailed analysis of the photon's properties. * **Frequency Measurement:** By comparing the frequency of the incoming photons to the frequency of the clock's atomic oscillations, it's possible to measure the energy and wavelength of the photons with extreme accuracy. 3. **Quantum Communication:** * **Quantum Key Distribution (QKD):** Quantum atomic clocks can be used to generate and distribute quantum keys for secure communication, protecting sensitive data transmitted by the telescope. Advantages of Quantum Atomic Clocks in Space Telescopes * **Unprecedented Accuracy:** Quantum atomic clocks offer far greater accuracy than traditional clocks, enabling more precise measurements and data analysis. * **Stability:** They are less susceptible to environmental factors like temperature and radiation, making them ideal for space-based applications. * **Miniaturization:** Quantum atomic clocks have become increasingly miniaturized, making them suitable for integration into space telescopes. **In conclusion, quantum atomic clocks are a valuable technology for space telescopes, offering exceptional precision in timekeeping, photon registration, and quantum communication.** Their capabilities can significantly enhance the scientific potential of future space missions.

As reported on by The Quantum Insider team, European researchers are now advancing space sensor technology by integrating quantum mechanics into satellite-based instruments with the CARIOQA Quantum Pathfinder project. 🌏 This project is part of a broader effort to enhance gravity mapping by employing quantum accelerometers. The €17 million CARIOQA-PMP project, funded by the European Commission and Quantum Flagship, aims to develop the world’s first quantum accelerometer for space. 🛰 This technology would create highly precise measurements of Earth’s gravity field, which could help track changes in glaciers, sea levels, and groundwater and is projected to be operational by 2030. https://lnkd.in/etsNyqWi #SpaceSatellite #SpaceTechnology #SpaceImpulse #QuantumMechanics

Our new article in Space Weather Journal. This work focused on developing a new ML-based Auroral Ionospheric electrodynamics Model (ML-AIM)

📃Scientific paper: Quasars with Flare/Eclipse-like Variability Identified in ZTF Abstract: Active galactic nuclei (AGNs) are known to exhibit optical/UV variability and most of them can be well modeled by the damped random walks. Physical processes that are not related to the accretion disk, such as tidal disruption events (TDE) or moving foreground dusty clouds, can cause flare-like and eclipse-like features in the optical light curve. Both long-term and high-cadence monitoring are needed to identify such features. By combining the Sloan Digital Sky Survey (SDSS), Panoramic Survey Telescope, and Rapid Response System (Pan-STARRS) with the Zwicky Transient Facility (ZTF) survey, we are able to identify a rare sample (11) out of the SDSS quasar catalog (around 83, 000). These quasars exhibit more or less constant brightness but show rapid optical variation in the ZTF DR2 epochs. To investigate the possible origins of these flare/eclipse-like variabilities, we propose the second epoch spectroscopic observations with the Gran Telescopio CANARIAS (GTC). We find that the change in accretion rate plays a significant role in these quasar variabilities. Among them, we identify two Changing-Look Active Galactic Nuclei (CL-AGN) candidates: SDSS J1427+2930 and SDSS J1420+3757. The luminosity change of the former may be caused by the enhanced SMBH accretion or the tidal disruption event, while the latter is more related to the change in the accretion rate. ;Comment: 11 pages, 13 figures, 2 tables, accepted for publication in MNRAS Continued on ES/IODE ➡️ https://etcse.fr/60Ydt ------- If you find this interesting, feel free to follow, comment and share. We need your help to enhance our visibility, so that our platform continues to serve you.