arXiv subjects

S. O. Dabironezare

Publications and source records attributed to S. O. Dabironezare.

4 recordsLinked to original sources

arXiv2026

gateau: an observation simulator for ground-based submillimeter astronomy with integral field units and kinetic inductance detectors

Submillimeter (submm) integral field units (IFUs) utilising kinetic inductance detectors (KIDs) are a promising instrument architecture for the study of galaxies, galaxy clusters, and the large-scale structure of the Universe. In order to design successful experiments targeting these science cases, several aspects such as instrument design, observation and calibration strategies, and data reduction pipelines must be collectively developed, tested, and optimised. This can be achieved through end-to-end simulations of the experiment, allowing for quantitative assessment of the aforementioned aspects. To this end, we have developed gateau, a modular, flexible, and efficient simulator for submm IFU observations of astronomical sources. The simulator consists of a Python interface, powered by a C/C++ backend that uses CUDA for GPU-acceleration, and is publicly available and fully open-source. gateau simulates observations by taking user input such as an astronomical source, a set of atmospheric screens, a scan pattern, and telescope and instrument parameters. It then propagates the source signal to the detectors. A physically motivated photon-noise model is used to add a white noise component to the received power. Detector noise is added as temporally correlated pink noise. The output is stored in the form of time-ordered datasets. We validated gateau against observations with DESHIMA 2.0, a superconducting, ultra-wideband spectrometer utilising KIDs and on-chip filterbank technology. We show that we can reproduce real observations of the atmosphere and Uranus with gateau simulations. Lastly, we present a use case to show how gateau can simulate long observations in timespans orders of magnitude smaller than the observation time itself, highlighting its applicability and efficiency.

astro-ph.IM↗

arXiv2026

Advances in the Fabrication of On-chip Superconducting Integral Field Units for CMB and Line-Intensity Astronomy

Studying the polarization and spectral distortion of the Cosmic Microwave Background (CMB) in tandem with intensity fluctuations of the Cosmic Infrared Background (CIB) allows us to verify our assumptions on cosmic inflation and investigate the dynamics and evolution of galaxy clusters in the last 10 billion years. Because of its broadband emission and being an all-sky extended source, observing the entire CMB in detail is a very time-consuming and expensive exercise. Fortunately, in the last few years, the on-chip superconducting spectrometer technology has moved out of the lab and into the telescope. With its compact size and background-limited sensitivity, this family of instruments is particularly well-suited for fast and large area observations in a relatively unexplored range of the electromagnetic spectrum. However, recent examples of this technology do not yet reach the requirements needed for large spectroscopic and polarimetric surveys of the CMB. We formulate several of these requirements and introduce novel on-chip components and fabrication techniques. We introduce a cross-over to enable distinguishing signal polarization, minimize signal loss by locally optimized lithography of a coplanar-waveguide (CPW), lower the spectral resolution of microstrip filters by deposition of a dielectric layer, and increase the yield of the spectrometer array by removing individual line shorts. These together have culminated in the successful fabrication of a fourteen-spaxel IFU.

physics.ins-det↗

arXiv2025

Alignment and optical verification of DESHIMA 2.0 at ASTE

We developed, characterized, and verified an alignment procedure for the DESHIMA 2.0 instrument, an ultra wide-band spectrometer operating between 200--400 GHz, at the ASTE telescope. To this end, we mounted the warm optics, consisting of a modified Dragonian dual reflector system, on a motor controlled hexapod. Crucial in the alignment procedure is our sky chopper, which allows fast beam switching. It has a small entrance and exit aperture coupling to (cold) sky, which creates a measurable signal with respect to the warm cabin environment. By scanning the instrument beam across the entrance aperture of the sky chopper using the hexapod, we found the hexapod configuration that produced the lowest signal on our detectors, implying the beam is coupled fully to cold sky and not the warm cabin. We first characterized the alignment procedure in the laboratory, where we used a vat containing liquid nitrogen as the cold source behind the sky chopper. Then, we applied the alignment procedure to DESHIMA 2.0 at ASTE. We found that the alignment procedure significantly improved the aperture efficiency compared to previously reported values of the aperture efficiency of DESHIMA at ASTE, which indicates the veracity of the alignment procedure.

astro-ph.IM↗

arXiv2024

Optimisation-based alignment of wideband integrated superconducting spectrometers for sub-mm astronomy

Integrated superconducting spectrometers (ISSs) for wideband sub-mm astronomy utilise quasi-optical systems for coupling radiation from the telescope to the instrument. Misalignment in these systems is detrimental to the system performance. The common method of using an optical laser to align the quasi-optical components requires accurate alignment of the laser to the sub-mm beam coming from the instrument, which is not always guaranteed to a sufficient accuracy. We develop an alignment strategy for wideband ISSs directly utilising the sub-mm beam of the wideband ISS. The strategy should be applicable in both telescope and laboratory environments. Moreover, the strategy should deliver similar quality of the alignment across the spectral range of the wideband ISS. We measure misalignment in a quasi-optical system operating at sub-mm wavelengths using a novel phase and amplitude measurement scheme, capable of simultaneously measuring the complex beam patterns of a direct-detecting ISS across a harmonic range of frequencies. The direct detection nature of the MKID detectors in our device-under-test, DESHIMA 2.0, necessitates the use of this measurement scheme. Using geometrical optics, the measured misalignment, a mechanical hexapod, and an optimisation algorithm, we follow a numerical approach to optimise the positioning of corrective optics with respect to a given cost function. Laboratory measurements of the complex beam patterns are taken across a harmonic range between 205 and 391 GHz and simulated through a model of the ASTE telescope in order to assess the performance of the optimisation at the ASTE telescope. Laboratory measurements show that the optimised optical setup corrects for tilts and offsets of the sub-mm beam. Moreover, we find that the simulated telescope aperture efficiency is increased across the frequency range of the ISS after the optimisation.

astro-ph.IM↗