Instrumentation and Methods for Astrophysics
New submissions
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New submissions for Fri, 10 May 24
- [1] arXiv:2405.05309 [pdf, other]
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Title: Hyperfine Structure Investigation of Singly Ionized Thulium in FT SpectraAuthors: T. Y. Kebapci, S. Parlatan, S. Sert, I. K. Ozturk, G. Basar, T. Sahin, S. Bilir, R. Ferber, M. Tamanis, S. KrogerComments: 15 pages, 6 figures and 3 tables, accepted for publication in ApJSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
The hyperfine structure of 40 spectral lines of singly ionized thulium (Tm II) in emission spectra from a hollow cathode discharge lamp measured with a Fourier transform spectrometer in the wavelength range from 335 nm to 2345 nm has been investigated. As a result of the analysis, the magnetic dipole hyperfine structure constants $A$ for 27 fine structure levels of Tm II were determined for the first time. In addition, the values of two magnetic dipole hyperfine structure constants $A$ from the literature were declared incorrect and the corrected values were given.
- [2] arXiv:2405.05311 [pdf, other]
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Title: Characterization of the decametre sky at subarcminute resolutionAuthors: C. Groeneveld, R. J. van Weeren, E. Osinga, W. L. Williams, J. R. Callingham, F. de Gasperin, A. Botteon, T. Shimwell, J. M. G. H. J. de Jong, L. F. Jansen, G. K. Miley, G. Brunetti, M. Brüggen, H. J. A. RöttgeringComments: 19 pages, 9 figures, 1 table. Submitted version, full version is published by Nature AstronomySubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
The largely unexplored decameter radio band (10-30 MHz) provides a unique window for studying a range of astronomical topics, such as auroral emission from exoplanets, inefficient cosmic ray acceleration mechanisms, fossil radio plasma, and free-free absorption. The scarcity of low-frequency studies is mainly due to the severe perturbing effects of the ionosphere. Here we present a calibration strategy that can correct for the ionosphere in the decameter band. We apply this to an observation from the Low Frequency Array (LOFAR) between 16 to 30 MHz . The resulting image covers 330 square degrees of sky at a resolution of 45", reaching a sensitivity of 12 mJy/beam. Residual ionospheric effects cause additional blurring ranging between 60 to 100". This represents an order of magnitude improvement in terms of sensitivity and resolution compared to previous decameter band observations. In the region we surveyed, we have identified four fossil plasma sources. These rare sources are believed to contain old, possibly re-energised, radio plasma originating from previous outbursts of active galactic nuclei. At least three of them are situated near the center of low-mass galaxy clusters. Notably, two of these sources display the steepest radio spectral index among all the sources detected at 23 MHz. This indicates that fossil plasma sources constitute the primary population of steep-spectrum sources at these frequencies, emphasising the large discovery potential of ground-based decameter observations.
- [3] arXiv:2405.05453 [pdf, other]
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Title: Spelunker: A quick-look Python pipeline for JWST NIRISS FGS Guide Star DataSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
The James Webb Space Telescope produces some of the highest sensitivity imaging of the cosmos across all instruments. One of them, the NIRISS Fine Guidance Sensor, provides guide star imaging with a passband of 0.6 to 5 microns through two separate channels, each with a 2.3' x 2.3' field of view (FOV) and a sampling rate of 64 ms$-$data that is taken in parallel and is thus available for every JWST observing program. While the onboard system uses guide stars to provide information to the attitude control system (ACS), which stabilizes the observatory, the astronomical community can also use the data products associated with these 64 ms cadence images as science products. Usages range from studying guide star photometry in search of transient phenomena to using these data to identify and investigate technical anomalies that might occur during scientific observations with the rest of the JWST instruments. Despite this wide range of possible usages, these data products are not straightforward to manipulate and analyze, and there is no publicly available package to download, investigate, and research guide star data. Spelunker is a Python library that was developed to enable access to these guide star data products and their analysis.
- [4] arXiv:2405.05472 [pdf, other]
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Title: Transformer neural networks for closed-loop adaptive optics using non-modulated pyramid wavefront sensorsComments: 8 pages, 9 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Optics (physics.optics)
The Pyramid Wavefront Sensor (PyWFS) is highly nonlinear and requires the use of beam modulation to successfully close an AO loop under varying atmospheric turbulence conditions, at the expense of a loss in sensitivity. In this work we train, analyse, and compare the use of deep neural networks (NNs) as non-linear estimators for the non-modulated PyWFS, identifying the most suitable NN architecture for reliable closed-loop AO. We develop a novel training strategy for NNs that seeks to accommodate for changes in residual statistics between open and closed-loop, plus the addition of noise for robustness purposes. Through simulations, we test and compare several deep NNs, from classical to new convolutional neural networks (CNNs), plus a state-of-the-art transformer neural network (TNN, Global Context Visual Transformer, GCViT), first in open-loop and then in closed-loop. Using open-loop simulated data, we observe that a TNN (GCViT) largely surpasses any CNN in estimation accuracy in a wide range of turbulence conditions. Also, the TNN performs better in simulated closed-loop than CNNs, avoiding estimation issues at the pupil borders. When closing the loop at strong turbulence and low noise, the TNN using non-modulated PyWFS data is able to close the loop similar to a PyWFS with $12\lambda/D$ of modulation. When raising the noise only the TNN is able to close the loop, while the standard linear reconstructor fails, even with modulation. Using the GCViT, we close a real AO loop in the optical bench achieving a Strehl ratio between 0.28 and 0.77 for turbulence conditions ranging from 6cm to 20cm, respectively. In conclusion, we demonstrate that a TNN is the most suitable architecture to extend the dynamic range without sacrificing sensitivity for a non-modulated PyWFS. It opens the path for using non-modulated Pyramid WFSs under an unprecedented range of atmospheric and noise conditions.
- [5] arXiv:2405.05501 [pdf, ps, other]
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Title: Implicit Electric Field Conjugation Through a Single-mode FiberAuthors: Joshua Liberman, Jorge Llop-Sayson, Arielle Bertrou-Cantou, Dimitri Mawet, Niyati Desai, Sebastiaan Y Haffert, A J Eldorado RiggsComments: 29 pages, 7 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Connecting a coronagraph instrument to a spectrograph via a single-mode optical fiber is a promising technique for characterizing the atmospheres of exoplanets with ground and space-based telescopes. However, due to the small separation and extreme flux ratio between planets and their host stars, instrument sensitivity will be limited by residual starlight leaking into the fiber. To minimize stellar leakage, we must control the electric field at the fiber input. Implicit electric field conjugation (iEFC) is a model-independent wavefront control technique in contrast with classical electric field conjugation (EFC) which requires a detailed optical model of the system. We present here the concept of an iEFC-based wavefront control algorithm to improve stellar rejection through a single-mode fiber. As opposed to image-based iEFC which relies on minimizing intensity in a dark hole region, our approach aims to minimize the amount of residual starlight coupling into a single-mode fiber. We present broadband simulation results demonstrating a normalized intensity greater than 10^{-10} for both fiber-based EFC and iEFC. We find that both control algorithms exhibit similar performance for the low wavefront error (WFE) case, however, iEFC outperforms EFC by approximately 100x in the high WFE regime. Having no need for an optical model, this fiber-based approach offers a promising alternative to EFC for ground and space-based telescope missions, particularly in the presence of residual WFE.
- [6] arXiv:2405.05550 [pdf, other]
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Title: The Simons Observatory: Design, integration, and testing of the small aperture telescopesAuthors: Nicholas Galitzki, Tran Tsan, Jake Spisak, Michael Randall, Max Silva-Feaver, Joseph Seibert, Jacob Lashner, Shunsuke Adachi, Sean M. Adkins, Thomas Alford, Kam Arnold, Peter C. Ashton, Jason E. Austermann, Carlo Baccigalupi, Andrew Bazarko, James A. Beall, Sanah Bhimani, Bryce Bixler, Gabriele Coppi, Lance Corbett, Kevin D. Crowley, Kevin T. Crowley, Samuel Day-Weiss, Simon Dicker, Peter N. Dow, Cody J. Duell, Shannon M. Duff, Remington G. Gerras, John C. Groh, Jon E. Gudmundsson, Kathleen Harrington, Masaya Hasegawa, Erin Healy, Shawn W. Henderson, Johannes Hubmayr, Jeffrey Iuliano, Bradley R. Johnson, Brian Keating, Ben Keller, Kenji Kiuchi, Anna M. Kofman, Brian J. Koopman, Akito Kusaka, Adrian T. Lee, Richard A. Lew, Lawrence T. Lin, Michael J Link, Tammy J. Lucas, Marius Lungu, Aashrita Mangu, et al. (27 additional authors not shown)Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The Simons Observatory (SO) is a cosmic microwave background (CMB) survey experiment that includes small-aperture telescopes (SATs) observing from an altitude of 5,200 m in the Atacama Desert in Chile. The SO SATs will cover six spectral bands between 27 and 280 GHz to search for primordial B-modes to a sensitivity of $\sigma(r)=0.002$, with quantified systematic errors well below this value. Each SAT is a self-contained cryogenic telescope with a 35$^\circ$ field of view, 42 cm diameter optical aperture, 40 K half-wave plate, 1 K refractive optics, and $<0.1$ K focal plane that holds $>12,000$ TES detectors. We describe the nominal design of the SATs and present details about the integration and testing for one operating at 93 and 145 GHz.
- [7] arXiv:2405.05591 [pdf, other]
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Title: Identification of problematic epochs in Astronomical Time Series through Transfer LearningAuthors: Stefano Cavuoti, Demetra De Cicco, Lars Doorenbos, Massimo Brescia, Olena Torbaniuk, Giuseppe Longo, Maurizio PaolilloComments: accepted for publication in A&ASubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
We present a novel method for detecting outliers in astronomical time series based on the combination of a deep neural network and a k-nearest neighbor algorithm with the aim of identifying and removing problematic epochs in the light curves of astronomical objects. We use an EfficientNet network pre-trained on ImageNet as a feature extractor and perform a k-nearest neighbor search in the resulting feature space to measure the distance from the first neighbor for each image. If the distance is above the one obtained for a stacked image, we flag the image as a potential outlier. We apply our method to time series obtained from the VLT Survey Telescope (VST) monitoring campaign of the Deep Drilling Fields of the Vera C. Rubin Legacy Survey of Space and Time (LSST)\thanksObservations were provided by the ESO programs 088.D-4013, 092.D-0370, and 094.D-0417 (PI G. Pignata).. We show that our method can effectively identify and remove artifacts from the VST time series and improve the quality and reliability of the data. This approach may prove very useful in sight of the amount of data that will be provided by the LSST, which will prevent the inspection of individual light curves. We also discuss the advantages and limitations of our method and suggest possible directions for future work.
- [8] arXiv:2405.05649 [pdf, other]
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Title: Evaluation of the X-ray SOI pixel detector with the on-chip ADCAuthors: Hiroumi Matsuhashi, Kouichi Hagino, Aya Bamba, Ayaki Takeda, Masataka Yukumoto, Koji Mori, Yusuke Nishioka, Takeshi Go Tsuru, Mizuki Uenomachi, Tomonori Ikeda, Masamune Matsuda, Takuto Narita, Hiromasa Suzuki, Takaaki Tanaka, Ikuo Kurachi, Takayoshi Kohmura, Yusuke Uchida, Yasuo Arai, Shoji KawahitoComments: 17 pages, 9 figuresJournal-ref: Nuclear Instruments and Methods in Physics Research section A (NIM-A) 2024Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
XRPIX is the monolithic X-ray SOI (silicon-on-insulator) pixel detector, which has a time resolution better than 10 $\rm{\mu}$s as well as a high detection efficiency for X-rays above 10 keV. XRPIX is planned to be installed on future X-ray satellites. To mount on satellites, it is essential that the ADC (analog-to-digital converter) be implemented on the detector because such peripheral circuits must be as compact as possible to achieve a large imaging area in the limited space in satellites. Thus, we developed a new XRPIX device with the on-chip ADC, and evaluated its performances. As the results, the integral non-linearity was evaluated to be 6 LSB (least significant bit), equivalent to 36~eV. The differential non-linearity was less than 0.7 LSB, and input noise from the on-chip ADC was 5~$\rm{e^{-}}$. Also, we evaluated end-to-end performance including the sensor part as well as the on-chip ADC. As the results, energy resolution at 5.9~keV was 294 $\rm{\pm}$ 4~eV in full-width at half maximum for the best pixel.
- [9] arXiv:2405.05969 [pdf, other]
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Title: Learned harmonic mean estimation of the Bayesian evidence with normalizing flowsComments: 14 pages, 8 figures, harmonic code available at this https URLSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Methodology (stat.ME)
We present the learned harmonic mean estimator with normalizing flows - a robust, scalable and flexible estimator of the Bayesian evidence for model comparison. Since the estimator is agnostic to sampling strategy and simply requires posterior samples, it can be applied to compute the evidence using any Markov chain Monte Carlo (MCMC) sampling technique, including saved down MCMC chains, or any variational inference approach. The learned harmonic mean estimator was recently introduced, where machine learning techniques were developed to learn a suitable internal importance sampling target distribution to solve the issue of exploding variance of the original harmonic mean estimator. In this article we present the use of normalizing flows as the internal machine learning technique within the learned harmonic mean estimator. Normalizing flows can be elegantly coupled with the learned harmonic mean to provide an approach that is more robust, flexible and scalable than the machine learning models considered previously. We perform a series of numerical experiments, applying our method to benchmark problems and to a cosmological example in up to 21 dimensions. We find the learned harmonic mean estimator is in agreement with ground truth values and nested sampling estimates. The open-source harmonic Python package implementing the learned harmonic mean, now with normalizing flows included, is publicly available.
Cross-lists for Fri, 10 May 24
- [10] arXiv:2405.05282 (cross-list from astro-ph.EP) [pdf, other]
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Title: The Detection of a Possible Exoplanet Orbiting KIC 1718360 Using Machine LearningAuthors: Jakob RocheComments: 6 pages, 6 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (cs.LG)
This paper presents the detection of a periodic dimming event in the lightcurve of the G1.5IV-V type star KIC 1718360. This is based on visible-light observations conducted by both the TESS and Kepler space telescopes. Analysis of the data points toward a possible orbiting body with a radius of approximately 1.048 Earth Radii with a period of 2.938 days, as well as a semi-major axis of 0.04 AU. The initial observation was made in Kepler Quarter 16 data using the One-Class SVM machine learning method. Subsequent observations by the TESS space telescope corroborate these findings. While still requiring further data to validate, these results may contribute to a growing body of data of Earthlike planets with short-period orbits.
- [11] arXiv:2405.05330 (cross-list from astro-ph.GA) [pdf, other]
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Title: Chemo-dynamical Evolution of Simulated Satellites for a Milky Way-like GalaxyAuthors: Yutaka Hirai, Evan N. Kirby, Masashi Chiba, Kohei Hayashi, Borja Anguiano, Takayuki R. Saitoh, Miho N. Ishigaki, Timothy C. BeersComments: 15 pages, 9 figures, submitted to The Astrophysical JournalSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
The chemical abundances of Milky Way's satellites reflect their star formation histories (SFHs), yet, due to the difficulty of determining the ages of old stars, the SFHs of most satellites are poorly measured. Ongoing and upcoming surveys will obtain around ten times more medium-resolution spectra for stars in satellites than are currently available. To correctly extract SFHs from large samples of chemical abundances, the relationship between chemical abundances and SFHs needs to be clarified. Here, we perform a high-resolution cosmological zoom-in simulation of a Milky Way-like galaxy with detailed models of star formation, supernova feedback, and metal diffusion. We quantify SFHs, metallicity distribution functions, and the $\alpha$-element (Mg, Ca, and Si) abundances in satellites of the host galaxy. We find that star formation in most simulated satellites is quenched before infalling to their host. Star formation episodes in simulated satellites are separated by a few hundred Myr owing to supernova feedback; each star formation event produces groups of stars with similar [$\alpha$/Fe] and [Fe/H]. We then perform a mock observation of the upcoming Subaru Prime Focus Spectrograph (PFS) observations. We find that Subaru PFS will be able to detect distinct groups of stars in [$\alpha$/Fe] vs. [Fe/H] space, produced by episodic star formation. This result means that episodic SFHs can be estimated from the chemical abundances of $\gtrsim$ 1,000 stars determined with medium-resolution spectroscopy.
- [12] arXiv:2405.05651 (cross-list from astro-ph.CO) [pdf, ps, other]
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Title: Development of realistic simulations for the polarization of the cosmic microwave backgroundAuthors: Marta MonelliComments: PhD thesis. Abstract abridged for arXiv submissionSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Polarization of the cosmic microwave background (CMB) can help probe cosmic inflation (via primordial $B$ modes) and test parity-violating physics (via cosmic birefringence), but realizing the potential of these opportunities requires precise control and mitigation of systematic effects. To this end, some experiments (including LiteBIRD) will use rotating half-wave plates (HWPs) as polarization modulators. Ideally, this choice should remove the $1/f$ noise component in the observed polarization and reduce intensity-to-polarization leakage, but any real HWP is characterized by non-idealities that, if not properly treated in the analysis, can lead to new systematics. In this thesis, after briefly introducing the science case, we discuss the macro steps that make up any CMB experiment, introduce the HWP, and present a new time-ordered data (TOD) simulation pipeline tailored to a LiteBIRD-like experiment that returns TOD and binned maps for realistic beams and HWPs. We show that the simulation framework can be used to study how the HWP non-idealities affect the measured cosmic birefringence angle, resulting in a few degrees bias for a realistic choice of HWP. We also derive analytical formulae to model the observed temperature and polarization maps and test them against the simulations. Finally, we present a simple, semi-analytical end-to-end model to propagate the non-idealities through the macro-steps that make up any CMB experiment (observation of multi-frequency maps, foreground cleaning, and power spectra estimation) and compute the HWP-induced bias on the estimated tensor-to-scalar ratio, $r$, finding that the HWP leads to underestimating $r$. We also show how gain calibration of the CMB temperature can be used to partially mitigate the non-idealities' effect and present a set of recommendations for the HWP design that can help maximize the benefits of gain calibration. [abridged]
- [13] arXiv:2405.05840 (cross-list from astro-ph.CO) [pdf, other]
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Title: FREmu: Power Spectrum Emulator for $f(R)$ GravityComments: 11 pages, 4 figures, 1 table, submitted to The Astrophysical Journal (ApJ)Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)
To investigate gravity in the non-linear regime of cosmic structure using measurements from Stage-IV surveys, it is imperative to accurately compute large-scale structure observables, such as non-linear matter power spectra, for gravity models that extend beyond general relativity. However, the theoretical predictions of non-linear observables are typically derived from N-body simulations, which demand substantial computational resources. In this study, we introduce a novel public emulator, termed FREmu, designed to provide rapid and precise forecasts of non-linear power spectra specifically for the Hu-Sawicki $f(R)$ gravity model across scales $0.0089 h \mathrm{Mpc}^{-1}<k<0.5 h \mathrm{Mpc}^{-1}$ and redshifts $0<z<3$. FREmu leverages Principal Component Analysis and Artificial Neural Networks to establish a mapping from parameters to power spectra, utilizing training data derived from the Quijote-MG simulation suite. With a parameter space encompassing 7 dimensions, including $\Omega_m$, $\Omega_b$, $h$, $n_s$, $\sigma_8$, $M_{\nu}$ and $f_{R_0}$, the emulator achieves an accuracy exceeding 95% for the majority of cases, thus proving to be highly efficient for constraining parameters.
Replacements for Fri, 10 May 24
- [14] arXiv:2311.03480 (replaced) [pdf, ps, other]
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Title: RFSoC Gen3-Based Software-Defined Radio Characterization for the Readout System of Low-Temperature BolometersAuthors: M. E. García Redondo, T. Muscheid, R. Gartmann, J. M. Salum, L. P. Ferreyro, N. A. Müller, J. D. Bonilla-Neira, J. M. Geria, J. J. Bonaparte, A. Almela, L. E. Ardila-Perez, M. R. Hampel, A. E. Fuster, M. Platino, O. Sander, M. Weber, A. EtchegoyenComments: 10 pages, peer reviewed, Journal of Low Temperature Physics special issue: LTD20Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Instrumentation and Detectors (physics.ins-det)
- [15] arXiv:2311.07805 (replaced) [pdf, ps, other]
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Title: Optimal Summary Statistics for X-ray PolarizationComments: 4 pages, accepted by the Open Journal of AstrophysicsSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Astrophysical Phenomena (astro-ph.HE)
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