Publications of the Astronomical Society of the Pacific最新文献

{"title":"Time Variability of FUV Emission from Cool Stars on Multi-year Timescales","authors":"Leo Kamgar, Kevin France, Allison Youngblood","doi":"10.1088/1538-3873/ad119f","DOIUrl":"https://doi.org/10.1088/1538-3873/ad119f","url":null,"abstract":"The physical and chemical properties of planetary atmospheres are affected by temporal evolution of ultraviolet (UV) radiation inputs from their host stars at all time scales. While studies of X-ray/UV flare properties and long-term stellar evolution of exoplanet host stars have provided new constraints regarding stellar inputs to exoplanetary systems, the UV temporal variability of cool stars on the timescale of stellar cycles remains largely unexplored. To address this gap in our understanding of the UV temporal variability of cool stars, we analyze far-ultraviolet (FUV) emission lines of ions that trace the chromosphere and transition region of nearby stars (C <sc>ii</sc>, Si <sc>iii</sc>, Si <sc>iv</sc>, and N <sc>v</sc>; formation temperatures ∼ 20–150 kK) using data from the Hubble Space Telescope (HST) and International Ultraviolet Explorer (IUE) archives spanning temporal baselines of months to years. We select 33 unique stars of spectral types F-M with observing campaigns spanning over a year, and create ionic light curves to evaluate the characteristic variability of cool stars on such timescales. Screening for large flare events, we observe that the relative variability of FUV light curves decreases with increasing stellar effective temperature, from 30% to 70% variability for M-type stars to <30% variability for F and G-type stars. We also observe a weak trend in the temporal variability with the Ca <sc>ii</sc>\u0000<inline-formula>\u0000<tex-math>\u0000<?CDATA ${R}_{mathrm{HK}}^{{prime} }$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msubsup><mml:mrow><mml:mi>R</mml:mi></mml:mrow><mml:mrow><mml:mi>HK</mml:mi></mml:mrow><mml:mrow><mml:mo accent=\"true\">′</mml:mo></mml:mrow></mml:msubsup></mml:math>\u0000<inline-graphic xlink:href=\"paspad119fieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> stellar activity indicator, suggesting that stars with lower Ca <sc>ii</sc> activity exhibit a smaller range of FUV flux variability. Screening for data sets with optimal temporal spread, and a sufficient number of individual observations, we select 5 data sets for further periodicity analysis (HST <italic toggle=\"yes\">α</italic> Centauri A, HST <italic toggle=\"yes\">α</italic> Centauri B, IUE <italic toggle=\"yes\">α</italic> Centauri B, IUE <italic toggle=\"yes\">ϵ</italic> Eri, IUE <italic toggle=\"yes\">ξ</italic> Boo). Various periodic structures within the FUV flux were detected, with most significant being a 79 days frequency present within the IUE observations of <italic toggle=\"yes\">ξ</italic> Boo, with a significance of 6<italic toggle=\"yes\">σ</italic>, and a periodic signal in the FUV observations of <italic toggle=\"yes\">α</italic> Centauri B, for both HST and IUE measurements, at ≈210 days frequency with significance of 3<italic toggle=\"yes\">σ</italic> and 3.7<italic toggle=\"yes\">σ</italic>, respectively. Our results suggest that extreme ultraviolet flux from cool stars varies by less than a factor of two on decade timescales, significantly sm","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"46 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140009714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ambipolar Diffusion with a Polytropic Equation of State","authors":"Blake J. Bottesi, Marco Fatuzzo, Lisa Holden, Kendra Herweck","doi":"10.1088/1538-3873/ad1f3d","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1f3d","url":null,"abstract":"Ambipolar diffusion is the mechanism believed to be responsible for the loss of magnetic support in dense molecular cloud cores, and is therefore likely to play a key role in the star formation process. As such, this mechanism has been studied extensively both semianalytically and numerically. We build upon this existing body of work by considering a one-dimensional self-gravitating gas with a polytropic equation of state (<italic toggle=\"yes\">P</italic> ∝ <italic toggle=\"yes\">ρ</italic>\u0000^{\u0000<italic toggle=\"yes\">ϵ</italic>\u0000}), and consider cases that range from softer (<italic toggle=\"yes\">ϵ</italic> &lt; 1) to stiffer (<italic toggle=\"yes\">ϵ</italic> &gt; 1) than isothermal. Our results indicate that the diffusion time is not very sensitive to the polytropic exponent <italic toggle=\"yes\">ϵ</italic> when stiffer than isothermal, but is sensitive to the exponent when softer than isothermal. Additionally, the presence of magnetic and density fluctuations causes the ambipolar diffusion process to speed up, with the shortest diffusion times obtained for gases with large initial magnetic to gas pressure ratios and fairly soft equations of state. However, the diffusion time starts to increase significantly for <italic toggle=\"yes\">ϵ</italic> ≲ 0.5, indicating that such soft equations of state are inconsistent with observations.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"169 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764453","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Global Parameters of Eight W UMa-type Binary Systems","authors":"Atila Poro, Mehmet Tanriver, Raul Michel, Ehsan Paki","doi":"10.1088/1538-3873/ad1ed3","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1ed3","url":null,"abstract":"Multiband photometric investigations for eight binary systems of the W Ursae Majoris-type are presented. Six systems are presented for the first time to analyze their light curves. All the analyzed systems have a temperature below 5000 K and an orbital period of less than 0.28 days. We extracted primary and secondary minima from the ground-based observations of these systems. According to a few observations reported in the literature, linear fits were considered in the <italic toggle=\"yes\">O</italic> − <italic toggle=\"yes\">C</italic> diagrams, and new ephemerides were presented. Light curve solutions were performed using the PHysics Of Eclipsing BinariEs code. The results of the mass ratio and fillout factor indicate that the systems are contact binary stars. Six of them showed the O’Connell effect, and a cold starspot on each companion was required for light curve solutions. Their absolute parameters were estimated and evaluated by two other methods. In this study, the empirical relationship between the orbital period and semimajor axis was updated using a sample consisting of 414 contact binary systems and the Monte Carlo Markov Chain approach. Also, using Machine Learning and the Artificial Neural Network model, the relationship between <italic toggle=\"yes\">P</italic>–<italic toggle=\"yes\">T</italic>\u0000₁–<italic toggle=\"yes\">M</italic>\u0000₁ was updated for a better estimation of the mass of the primary star.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"7 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Algorithm to Mitigate Charge Migration Effects in Data from the Near Infrared Imager and Slitless Spectrograph on the James Webb Space Telescope* * This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with programs #1083, 1093, 1094, and 1096.","authors":"Paul Goudfrooij, David Grumm, Kevin Volk, Howard Bushouse","doi":"10.1088/1538-3873/ad1c98","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1c98","url":null,"abstract":"We present an algorithm that mitigates the effects of charge migration due to the “brighter-fatter effect” (BFE) that occurs for highly illuminated stars in the Teledyne HAWAII-2RG detectors used in the NIRCam, NIRISS, and NIRSpec science instruments aboard the James Webb Space Telescope (JWST). The impact of this effect is most significant for photometry and spectrophotometry of bright stars in data for which the point-spread function (PSF) is undersampled, which is the case for several observing modes of the NIRISS instrument. The main impact of BFE to NIRISS data is incorrect count rate determinations for pixels in the central regions of PSFs of bright stars due to jump detections that are caused by charge migration from peak pixels to surrounding pixels. The effect is especially significant for bright compact sources in resampled, distortion-free images produced by the drizzle algorithm: quantitatively, apparent flux losses of &gt;50% can occur in such images due to BFE. We describe the algorithm of the “<monospace>charge</monospace>_<monospace>migration</monospace>” mitigation step that has been implemented in version 10.0 of the operational JWST calibration pipeline as of 2023 December 5. We illustrate the impact of this step in terms of the resulting improvements of the precision of imaging photometry of point sources. The algorithm renders the effects of BFE on photometry and surface brightness measurements to stay within 1%.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"25 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764360","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"WARP: The Data Reduction Pipeline for the WINERED Spectrograph","authors":"Satoshi Hamano, Yuji Ikeda, Shogo Otsubo, Haruki Katoh, Kei Fukue, Noriyuki Matsunaga, Daisuke Taniguchi, Hideyo Kawakita, Keiichi Takenaka, Sohei Kondo, Hiroaki Sameshima","doi":"10.1088/1538-3873/ad1b38","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1b38","url":null,"abstract":"We present a data reduction pipeline written in Python for data obtained with the near-infrared cross-dispersed echelle spectrograph, WINERED, which yields a 0.91–1.35 <italic toggle=\"yes\">μ</italic>m spectrum with the resolving power of <inline-formula>\u0000<tex-math>\u0000<?CDATA ${R}_{max }equiv lambda /{rm{Delta }}lambda ={rm{28,000}}$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mrow><mml:mi>R</mml:mi></mml:mrow><mml:mrow><mml:mi>max</mml:mi></mml:mrow></mml:msub><mml:mo>≡</mml:mo><mml:mi>λ</mml:mi><mml:mrow><mml:mo stretchy=\"true\">/</mml:mo></mml:mrow><mml:mi mathvariant=\"normal\">Δ</mml:mi><mml:mi>λ</mml:mi><mml:mo>=</mml:mo><mml:mi mathvariant=\"normal\">28,000</mml:mi></mml:math>\u0000<inline-graphic xlink:href=\"paspad1b38ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> or 70,000 depending on the observing mode. The pipeline was developed to efficiently extract the spectrum from the raw data with high quality. It comprises two modes: the calibration and the science mode. The calibration mode automatically produces the flat-fielding image, bad pixel map, echellogram distortion map and the dispersion solution from the set of the calibration data. Using calibration images and parameters, the science data of astronomical objects can be reduced automatically using the science mode. The science mode is also used for the real-time quick look at the data during observations. An example of the spectra reduced with WARP is presented. The effect of the highly inclined slit image on the spectral resolution is discussed.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"77 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764562","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"JWST’s PEARLS: Improved Flux Calibration for NIRCam","authors":"Zhiyuan Ma, Haojing Yan, Bangzheng Sun, Seth H. Cohen, Rolf A. Jansen, Jake Summers, Rogier A. Windhorst, Jordan C. J. D’Silva, Anton M. Koekemoer, Dan Coe, Christopher J. Conselice, Simon P. Driver, Brenda Frye, Norman A. Grogin, Madeline A. Marshall, Mario Nonino, Rafael Ortiz, Nor Pirzkal, Aaron Robotham, Russell E. Ryan, Christopher N. A. Willmer, Heidi B. Hammel, Stefanie N. Milam, Nathan J. Adams, Cheng Cheng, Nimish P. Hathi","doi":"10.1088/1538-3873/ad1f3e","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1f3e","url":null,"abstract":"The Prime Extragalactic Areas for Reionization and Lensing Science, a James Webb Space Telescope (JWST) GTO program, obtained a set of unique NIRCam observations that have enabled us to significantly improve the default photometric calibration across both NIRCam modules. The observations consisted of three epochs of 4-band (F150W, F200W, F356W, and F444W) NIRCam imaging in the Spitzer IRAC Dark Field (IDF). The three epochs were six months apart and spanned the full duration of Cycle 1. As the IDF is in the JWST continuous viewing zone, we were able to design the observations such that the two modules of NIRCam, modules A and B, were flipped by 180° and completely overlapped each other’s footprints in alternate epochs. We were therefore able to directly compare the photometry of the same objects observed with different modules and detectors, and we found significant photometric residuals up to ∼0.05 mag in some detectors and filters, for the default version of the calibration files that we used (<monospace>jwst</monospace>_<monospace>1039.pmap</monospace>). Moreover, there are multiplicative gradients present in the data obtained in the two long-wavelength bands. The problem is less severe in the data reduced using the latest pmap (<monospace>jwst</monospace>_<monospace>1130.pmap</monospace> as of 2023 September), but it is still present, and is non-negligible. We provide a recipe to correct for this systematic effect to bring the two modules onto a more consistent calibration, to a photometric precision better than ∼0.02 mag.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"17 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764545","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"ESPRESSO Observations of Gaia BH1: High-precision Orbital Constraints and no Evidence for an Inner Binary","authors":"Pranav Nagarajan, Kareem El-Badry, Amaury H. M. J. Triaud, Thomas A. Baycroft, David Latham, Allyson Bieryla, Lars A. Buchhave, Hans-Walter Rix, Eliot Quataert, Andrew Howard, Howard Isaacson, Melissa J. Hobson","doi":"10.1088/1538-3873/ad1ba7","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1ba7","url":null,"abstract":"We present high-precision radial velocity observations of Gaia BH1, the nearest known black hole (BH). The system contains a solar-type G star orbiting a massive dark companion, which could be either a single BH or an inner BH + BH binary. A BH + BH binary is expected in some models where Gaia BH1 formed as a hierarchical triple, which is attractive because they avoid many of the difficulties associated with forming the system through isolated binary evolution. Our observations test the inner binary scenario. We have measured 115 precise RVs of the G star, including 40 from ESPRESSO with a precision of 3–5 m s⁻¹, and 75 from other instruments with a typical precision of 30–100 m s⁻¹. Our observations span 2.33 orbits of the G star and are concentrated near a periastron passage, when perturbations due to an inner binary would be largest. The RVs are well-fit by a Keplerian two-body orbit and show no convincing evidence of an inner binary. Using <monospace>REBOUND</monospace> simulations of hierarchical triples with a range of inner periods, mass ratios, eccentricities, and orientations, we show that plausible inner binaries with periods <italic toggle=\"yes\">P</italic>\u0000_inner ≳ 1.5 days would have produced larger deviations from a Keplerian orbit than observed. Binaries with <italic toggle=\"yes\">P</italic>\u0000_inner ≲ 1.5 days are consistent with the data, but these would merge within a Hubble time and would thus imply fine-tuning. We present updated parameters of Gaia BH1's orbit. The RVs yield a spectroscopic mass function <inline-formula>\u0000<tex-math>\u0000<?CDATA $fleft({M}_{mathrm{BH}}right)=3.9358pm 0.0002,{M}_{odot }$?>\u0000</tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mi>f</mml:mi><mml:mfenced close=\")\" open=\"(\"><mml:mrow><mml:msub><mml:mrow><mml:mi>M</mml:mi></mml:mrow><mml:mrow><mml:mi>BH</mml:mi></mml:mrow></mml:msub></mml:mrow></mml:mfenced><mml:mo>=</mml:mo><mml:mn>3.9358</mml:mn><mml:mo>±</mml:mo><mml:mn>0.0002</mml:mn><mml:mspace width=\"0.25em\"></mml:mspace><mml:msub><mml:mrow><mml:mi>M</mml:mi></mml:mrow><mml:mrow><mml:mo>⊙</mml:mo></mml:mrow></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"paspad1ba7ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula>—about 7000<italic toggle=\"yes\">σ</italic> above the ∼2.5 <italic toggle=\"yes\">M</italic>\u0000_⊙ maximum neutron star mass. Including the inclination constraint from Gaia astrometry, this implies a BH mass of <italic toggle=\"yes\">M</italic>\u0000_BH = 9.27 ± 0.10 <italic toggle=\"yes\">M</italic>\u0000_⊙.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"7 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NSClean: An Algorithm for Removing Correlated Noise from JWST NIRSpec Images","authors":"Bernard J. Rauscher","doi":"10.1088/1538-3873/ad1b36","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1b36","url":null,"abstract":"NSClean is an algorithm and python package for removing faint vertical banding and “picture frame noise” from JWST Near Infrared Spectrograph (NIRSpec) images. NSClean uses known dark areas to fit a background model to each exposure in Fourier space. When the model is subtracted, it removes nearly all correlated noise. Compared to simpler strategies like subtracting the rolling median, NSClean is more thorough and uniform. NSClean has been developed and tested for NIRSpec IFU mode data, although it can be used on other NIRSpec modes as well. NSClean is computationally undemanding, requiring only a few seconds to clean an image on a typical laptop. The NSClean package is freely available from the NASA JWST website.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"24 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764559","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Novel Eccentricity Parameterization for Transit-only Models","authors":"Jason D. Eastman","doi":"10.1088/1538-3873/ad1412","DOIUrl":"https://doi.org/10.1088/1538-3873/ad1412","url":null,"abstract":"We present a novel eccentricity parameterization for transit-only fits that allows us to efficiently sample the eccentricity and argument of periastron, while being able to generate a self-consistent model of a planet in a Keplerian orbit around its host star. With simulated fits of 330 randomly generated systems, we demonstrate that typical parameterizations often lead to inaccurate and overly precise determinations of the planetary eccentricity. However, our proposed parameterization allows us to accurately—and often precisely—recover the eccentricity for the simulated planetary systems with only transit data available.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"11 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139764447","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Optimal Photometry of Point Sources: Joint Source Flux and Background Determination on Array Detectors—from Theory to Practical Implementation","authors":"Mario L. Vicuña, Jorge F. Silva, Rene A. Mendez, Marcos E. Orchard, Sebastian Espinosa, Jeremy Tregloan-Reed","doi":"10.1088/1538-3873/ad0ca3","DOIUrl":"https://doi.org/10.1088/1538-3873/ad0ca3","url":null,"abstract":"In this paper we study the joint determination of source and background flux for point sources as observed by digital array detectors. We explicitly compute the two-dimensional Cramér–Rao absolute lower bound (CRLB) as well as the performance bounds for high-dimensional implicit estimators from a generalized Taylor expansion. This later approach allows us to obtain computable prescriptions for the bias and variance of the joint estimators. We compare these prescriptions with empirical results from numerical simulations in the case of the weighted least squares estimator (introducing an improved version, denoted stochastic weighted least-squares) as well as with the maximum likelihood estimator, finding excellent agreement. We demonstrate that these estimators provide quasi-unbiased joint estimations of the flux and background, with a variance that approaches the CRLB very tightly and are, hence, optimal, unlike the case of sequential estimation used commonly in astronomical photometry which is sub-optimal. We compare our predictions with numerical simulations of realistic observations, as well as with observations of a bona fide non-variable stellar source observed with TESS, and compare it to the results from the sequential estimation of background and flux, confirming our theoretical expectations. Our practical estimators can be used as benchmarks for general photometric pipelines, or for applications that require maximum precision and accuracy in absolute photometry.","PeriodicalId":20820,"journal":{"name":"Publications of the Astronomical Society of the Pacific","volume":"4 1","pages":""},"PeriodicalIF":3.5,"publicationDate":"2024-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139507094","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}