Experimental Astronomy最新文献

The transition-edge sensor (TES) as a type of low-temperature superconducting detector offers superior sensitivity due to its low thermal noise. In this work, we present a prototype TES bolometer designed for cosmic microwave background (CMB) polarization measurements. This TES is made of aluminum doped with a low concentration of manganese (2000 ppm by atomic percentage), and is deposited on the SiNx membrane which connects to the silicon substrate via narrow legs. In order to calculate its electrothermal parameters we have performed dark characterizations, which include measuring voltage-current (IV) curve at different bath temperatures, square-wave time response at various bias voltages, and noise level. This TES bolometer shows a noise equivalent power (NEP) of about (5times 10^{-17}) W/(sqrt{textrm{Hz}}), which meets the requirement of CMB observation. However, its saturation power is smaller and time constant is larger than what are expected. We have analyzed the reasons and will make corresponding improvements in our future work.

Aditya-L1 is the first Indian space mission to explore the Sun and solar atmosphere with seven multi-wavelength payloads, with Visible Emission Line Coronagraph (VELC) being the prime payload. It is an internally occulted coronagraph with four channels to image the Sun at 5000 Å  in the field of view 1.05 - 3 (varvec{R}_{odot }), and to pursue spectroscopy at 5303 Å, 7892 Å  and 10747 Å  channels in the FOV (1.05 - 1.5 (varvec{R}_{odot })). In addition, spectropolarimetry is planned at 10747 Å  channel. Therefore, VELC has three sCMOS detectors and one InGaAs detector. In this article, we aim to describe the technical details and specifications of the detectors achieved by way of thermo-vacuum calibration at the CREST campus of the Indian Institute of Astrophysics, Bangalore, India. Furthermore, we report the estimated conversion gain, full-well capacity, and readout noise at different temperatures. Based on the numbers, it is thus concluded that it is essential to operate the sCMOS detectors and InGaAs detector at (varvec{-5^circ }) and (varvec{-17^{circ }}) C, respectively, at the spacecraft level.

The Low Energy X-ray telescope (LE) is one of the main instruments of the Insight-Hard X-ray Modulation Telescope (Insight-HXMT), the first Chinese X-ray astronomical satellite. The scientific objectives of LE focus on scanning and pointed observations of the X-ray sources in the soft X-ray band (0.7–13 keV). LE consists of three detector boxes (LEDs) and an electric control box (LEB). The LEB is composed of data handling unit, monitoring unit, and power distribution unit, with functions including data processing, communication, monitoring, power supply, and distribution. All the functions designed in the LEB were verified during the operation in orbit. To improve the efficiency of astronomical observations and reliability of LE, onboard data processing is designed in the LEB. The results of onboard data processing are immediately transmitted to the ground as important housekeeping data and are verified by comparing them with the processing results of the data transmitted to the ground. In the six years since launch, the LEB has performed well, operated smoothly, and met all expected requirements. The LEB has participated in numerous scientific observations, transmitted a large amount of scientific data, and obtained several observational results.

The Yarkovsky drift represents the semi-major axis variation of a celestial body due to the Yarkovsky effect. This thermodynamic effect acts more significantly on bodies with a diameter between (approx 10 ,text {m}) and (approx 30 ,text {km}). Therefore, the orbits of many minor bodies of the solar system are affected: knowing the value of the Yarkovsky drift can be crucial to accurately predict their positions, especially if the asteroids are Near Earth Asteroids (NEAs) and there may be a non-zero impact probability with the Earth. The direct computation of this effect is not easily achieved due to the scarce availability of NEAs physical information. Thus, the more promising method to estimate the Yarkovsky effect is through an orbital fit using seven parameters, the six orbital elements and a seventh parameter accounting for non-gravitational interactions. In this paper, we show the analysis of 1262 NEAs with Signal-to-Noise Ratio (SNR) greater or equal 2, of which 279 have the parameter S (absolute ratio between the Yarkovsky drift and its expected value) less than 1.5 and are therefore more reliable. Among these, 91 are not present in the literature, thus represent new Yarkovsky drift detections. Furthermore, we used our results to estimate the ratio of the retrograde over prograde rotators and to validate the dependence of the Yarkovsky drift from the diameter, da/dt (approx D^{-1}).

State-of-the-art 19th century spectroscopy led to the discovery of quantum mechanics, and 20th century spectroscopy led to the confirmation of quantum electrodynamics. State-of-the-art 21st century astrophysical spectrographs, especially ANDES at ESO’s ELT, have another opportunity to play a key role in the search for, and characterization of, the new physics which is known to be out there, waiting to be discovered. We rely on detailed simulations and forecast techniques to discuss four important examples of this point: big bang nucleosynthesis, the evolution of the cosmic microwave background temperature, tests of the universality of physical laws, and a real-time model-independent mapping of the expansion history of the universe (also known as the redshift drift). The last two are among the flagship science drivers for the ELT. We also highlight what is required for the ESO community to be able to play a meaningful role in 2030s fundamental cosmology and show that, even if ANDES only provides null results, such ‘minimum guaranteed science’ will be in the form of constraints on key cosmological paradigms: these are independent from, and can be competitive with, those obtained from traditional cosmological probes.

We propose a future mission concept, the MeV Astrophysical Spectroscopic Surveyor (MASS), which is a large area Compton telescope using 3D position sensitive cadmium zinc telluride (CZT) detectors optimized for emission line detection. The payload consists of two layers of CZT detectors in a misaligned chessboard layout, with a total geometric area of 4096 cm(^2) for on-axis observations. The detectors can be operated at room-temperature with an energy resolution of 0.6% at 0.662 MeV. The in-orbit background is estimated with a mass model. At energies around 1 MeV, a line sensitivity of about (10^{-5}) photons cm(^{-2}) s(^{-1}) can be obtained with a 1 Ms observation. The main science objectives of MASS include nucleosynthesis in astrophysics and high energy astrophysics related to compact objects and transient sources. The payload CZT detectors weigh roughly 40 kg, suggesting that it can be integrated into a micro- or mini-satellite. We have constructed a pathfinder, named as MASS-Cube, to have a direct test of the technique with 4 detector units in space in the near future.

The Chasing All Transients Constellation Hunters (CATCH) space mission is an intelligent constellation consisting of 126 micro-satellites in three types (A, B, and C), designed for X-ray observation with the objective of studying the dynamic universe. Currently, we are actively developing the first Pathfinder (CATCH-1) for the CATCH mission, specifically for type-A satellites. CATCH-1 is equipped with Micro Pore Optics (MPO) and a 4-pixel Silicon Drift Detector (SDD) array. To assess its scientific performance, including the effective area of the optical system, on-orbit background, and telescope sensitivity, we employ the Monte Carlo software Geant4 for simulation in this study. The MPO optics exhibit an effective area of 41 cm(^2) at the focal spot for 1 keV X-rays, while the entire telescope system achieves an effective area of 29 cm(^2) at 1 keV when taking into account the SDD detector’s detection efficiency. The primary contribution to the background is found to be from the Cosmic X-ray Background. Assuming a 625 km orbit with an inclination of (29^circ ), the total background for CATCH-1 is estimated to be (8.13times 10^{-2}) counts s(^{-1}) in the energy range of 0.5–4 keV. Based on the background within the central detector and assuming a Crab-like source spectrum, the estimated ideal sensitivity could achieve (1.9times 10^{-12}) erg cm(^{-2}) s(^{-1}) for an exposure of 10(^4) s in the energy band of 0.5–4 keV. Furthermore, after simulating the background caused by low-energy charged particles near the geomagnetic equator, we have determined that there is no need to install a magnetic deflector.

The solar gravitational lens (SGL) provides a factor of (10^{11}) amplification for viewing distant point sources beyond our solar system. As such, it may be used for resolved imaging of extended sources, such as exoplanets, not possible otherwise. To use the SGL, a spacecraft carrying a modest telescope and a coronagraph must reach the SGLs focal region, that begins at (sim )550 astronomical units (AU) from the Sun and is oriented outward along the line connecting the distant object and the Sun. No spacecraft has ever reached even a half of that distance; and to do so within a reasonable mission lifetime (e.g., less than 25 years) and affordable cost requires a new type of mission design, using solar sails and microsats ((<100) kg). The payoff is high – using the SGL is the only practical way we can ever get a high-resolution, multi-pixel image of an Earth-like exoplanet, one that we identify as potentially habitable. This paper describes a novel mission design starting with a rideshare launch from the Earth, spiraling in toward the Sun, and then flying around it to achieve solar system exit speeds of over 20 AU/year. A new sailcraft design is used to make possible high area to mass ratio for the sailcraft. The mission design enables other fast solar system missions, starting with a proposed very low cost technology demonstration mission (TDM) to prove the functionality and operation of the microsat-solar sail design and then, building on the TDM, missions to explore distant regions of the solar system, and those to study Kuiper Belt objects (KBOs) and the recently discovered interstellar objects (ISOs) are also possible.

HERMES Pathfinder is an in-orbit demonstration consisting of a constellation of six 3U nano-satellites hosting simple but innovative detectors for the monitoring of cosmic high-energy transients. The main objective of HERMES Pathfinder is to prove that accurate position of high-energy cosmic transients can be obtained using miniaturized hardware. The transient position is obtained by studying the delay time of arrival of the signal to different detectors hosted by nano-satellites on low-Earth orbits. In this context, we need to develop novel tools to fully exploit the future scientific data output of HERMES Pathfinder. In this paper, we introduce a new framework to assess the background count rate of a spaceborne, high energy detector; a key step towards the identification of faint astrophysical transients. We employ a neural network to estimate the background lightcurves on different timescales. Subsequently, we employ a fast change-point and anomaly detection technique called Poisson-FOCuS to identify observation segments where statistically significant excesses in the observed count rate relative to the background estimate exist. We test the new software on archival data from the NASA Fermi Gamma-ray Burst Monitor (GBM), which has a collecting area and background level of the same order of magnitude to those of HERMES Pathfinder. The neural network performances are discussed and analyzed over period of both high and low solar activity. We were able to confirm events in the Fermi-GBM catalog, both solar flares and gamma-ray bursts, and found events, not present in Fermi-GBM database, that could be attributed to solar flares, terrestrial gamma-ray flashes, gamma-ray bursts and galactic X-ray flashes. Seven of these are selected and further analyzed, providing an estimate of localisation and a tentative classification.

The paper presents a methodology for the digitization and processing of our own spectral data archive and the results of comparing the obtained data with those of modern observations. An Epson Perfection V850 Pro scanner with optional SilverFast8 software was used to scan photographic films. More than 2,000 archive spectra of Seyfert galaxies obtained in 1970–1990 with the AZT-8 telescope have been scanned to date (resolution 2400 dpi). The work describes the reduction of distortion for the scanned spectra using the program code, created in Python. Our code has been registered on the web service “GitHub” and a link to the code is given in the work. The results of digitization and subsequent spectra processing are presented in the example of the Seyfert galaxy Mrk 3. For the absolute calibration of the early spectra (Jan. 25, 1976) the radiation fluxes in the emission lines of [SII] were used. The lines were measured on the modern spectrogram obtained in 2023 on telescope AZT-8 (Mar. 14, 2023)