A Method to Characterize the Wide-angle Point-Spread Function of Astronomical Images

Liu, Qing; Abraham, Roberto; Gilhuly, Colleen; Dokkum, Pieter van; Martín, P. G.; Li, Jiaxuan; Greco, Johnny P.; Lokhorst, Deborah; Chen, Seery; Danieli, Shany; Keim, Michael A.; Merritt, Allison; Miller, Tim B.; Pasha, I. I.; Polzin, Ava; Shen, Zili; Zhang, Jielai

doi:10.3847/1538-4357/ac32c6

Cited by 11 publications

(23 citation statements)

References 63 publications

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“…Finally, the remaining artifacts brighter than a magnitude of 16 are masked. Further details are provided in van Dokkum et al (2020) and Liu et al (2022).…”

Section: Multiresolution Filteringmentioning

confidence: 99%

“…In Figure 16, we give the complete subtracted model, including that generated by the MRF procedure. wings Liu et al 2022). To ensure that the tidal break is not the result of Dragonfly's PSF, in Figure 18 we convolve 2D Sérsic models of each galaxy without the break with Dragonfly's wide-angle PSF (as utilized in Section 3.2), and compare to the observed surface brightness profile.…”

Section: Appendix C Isophote Fitting and Model Subtractionmentioning

confidence: 99%

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Tidal Distortions in NGC1052-DF2 and NGC1052-DF4: Independent Evidence for a Lack of Dark Matter

Keim

Dokkum

Danieli

et al. 2022

ApJ

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Two ultra-diffuse galaxies in the same group, NGC1052-DF2 and NGC1052-DF4, have been found to have little or no dark matter and to host unusually luminous globular cluster populations. Such low-mass diffuse objects in a group environment are easily disrupted and are expected to show evidence of tidal distortions. In this work, we present deep new imaging of the NGC1052 group, obtained with the Dragonfly Telephoto Array, to test this hypothesis. We find that both galaxies show strong position-angle twists and are significantly more elongated at their outskirts than in their interiors. The group’s central massive elliptical NGC1052 is the most likely source of these tidal disturbances. The observed distortions imply that the galaxies have a low total mass or are very close to NGC1052. Considering constraints on the galaxies’ relative distances, we infer that the dark matter halo masses of these galaxies cannot be much greater than their stellar masses. Calculating pericenters from the distortions, we find that the galaxies are on highly elliptical orbits, with a ratio of pericenter to present-day radius R peri/R 0 ∼ 0.1 if the galaxies are dark matter–free and R peri/R 0 ∼ 0.01 if they have a normal dark halo. Our findings provide strong evidence, independent of kinematic constraints, that both galaxies are dark matter–deficient. Furthermore, the similarity of the tidal features in NGC1052-DF2 and NGC1052-DF4 strongly suggests that they arose at comparable distances from NGC1052. In Appendix A, we describe sbcontrast, a robust method for determining the surface brightness limits of images.

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“…Finally, the remaining artifacts brighter than a magnitude of 16 are masked. Further details are provided in van Dokkum et al (2020) and Liu et al (2022).…”

Section: Multiresolution Filteringmentioning

confidence: 99%

Section: Appendix C Isophote Fitting and Model Subtractionmentioning

confidence: 99%

Tidal Distortions in NGC1052-DF2 and NGC1052-DF4: Independent Evidence for a Lack of Dark Matter

Keim

Dokkum

Danieli

et al. 2022

ApJ

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“…Scattered light is the perennial bane of low surface brightness photometry, and edge-on galaxies are especially susceptible to scattered light contamination along the minor axis where the true light distribution may drop off very steeply (de Jong 2008; Sandin 2014Sandin , 2015. The elderflower package 16 (Liu et al 2022) was used to fit a three-component power-law PSF with a Moffat core within a 0°.42 × 0°.42 central cutout of each g-and r-band image. The PSF model was extrapolated to a radius of 0°.…”

Section: Discussionmentioning

confidence: 99%

“…It is advantageous to measure the PSF on the science images themselves, because the PSF is not constant over time. For example, by comparing the PSFs of the M44 field observed on two clear nights immediately before and after the lenses were cleaned, Liu et al (2022) showed that the Dragonfly wide angle PSF is measurably impacted by the cleanliness of the lenses. The pre-cleaning PSF was much shallower than the post-cleaning PSF beyond ¢ 3 , with fitted power-law indices of 1.35 and 1.9 respectively.…”

Section: Discussionmentioning

confidence: 99%

Stellar Halos from the The Dragonfly Edge-on Galaxies Survey

Gilhuly

Merritt

Abraham

et al. 2022

ApJ

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We present the primary results from the Dragonfly Edge-on Galaxies Survey, an exploration of the stellar halos of twelve nearby (d < 25 Mpc) edge-on disk galaxies with the Dragonfly Telephoto Array. The edge-on orientation of these galaxies allows their stellar halos to be explored with minimal obscuration by or confusion with the much brighter disk light. Galaxies in the sample span a range of stellar masses from 109.68 to 1010.88 M ⊙. We confirm that the wide range of stellar halo mass fractions previously seen for Milky Way–mass galaxies is also found among less massive spiral galaxies. The scatter in stellar halo mass fraction is large, but we do find a significant positive correlation between stellar halo mass fraction and total stellar mass when the former is measured beyond five half-mass radii. Reasonably good agreement is found with predictions from cosmological hydrodynamical simulations, although observed stellar halo fractions appear to be somewhat lower than expected from these simulations.

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“…Indeed, the characterization of the wide-angle PSF may be sensitive to sky subtraction, particularly in crowded regions (cf. Liu et al 2022). We will improve the telescope's PSF model analysis in future work.…”

Section: Scattering and Reflectionmentioning

confidence: 99%

Performance Assessment of the KASI-Deep Rolling Imaging Fast-optics Telescope Pathfinder

Byun¹,

Ko²,

Kim³

et al. 2022

PASP

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In a ΛCDM universe, most galaxies evolve by mergers and accretions, leaving faint and/or diffuse structures, such as tidal streams and stellar halos. Although these structures are a good indicator of galaxies’ recent mass assembly history, they have the disadvantage of being difficult to observe due to their low surface brightness (LSB). To recover these LSB features by minimizing the photometric uncertainties introduced by the optical system, we developed a new optimized telescope named K-DRIFT pathfinder, adopting a linear astigmatism free-three mirror system. Thanks to the off-axis design, it is expected to avoid the loss and scattering of light on the optical path within the telescope. To assess the performance of this prototype telescope, we investigate the photometric depth and capability to identify LSB features. We find that the surface brightness limit reaches down to μ r,1σ ∼ 28.5 mag arcsec−2 in 10″ × 10″ boxes, enabling us to identify a single stellar stream to the east of NGC 5907. We also examine the characteristics of the point-spread function (PSF) and find that the PSF wing reaches a very low level. Still, however, some internal reflections appear within a radius of ∼6′ from the center of sources. Despite a relatively small aperture (0.3 m) and short integration time (2 hr), this result demonstrates that our telescope is highly efficient in LSB detection.

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A Method to Characterize the Wide-angle Point-Spread Function of Astronomical Images

Cited by 11 publications

References 63 publications

Tidal Distortions in NGC1052-DF2 and NGC1052-DF4: Independent Evidence for a Lack of Dark Matter

Tidal Distortions in NGC1052-DF2 and NGC1052-DF4: Independent Evidence for a Lack of Dark Matter

Stellar Halos from the The Dragonfly Edge-on Galaxies Survey

Performance Assessment of the KASI-Deep Rolling Imaging Fast-optics Telescope Pathfinder

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