Spitzer + VLTI-GRAVITY Measure the Lens Mass of a Nearby Microlensing Event

Zang, Weicheng; Dong, Subo; Gould, Andrew; Novati, S. Calchi; Chen, Ping; Yang, Hongjing; Li, Shun-Sheng; Mao, Shude; Alton, Kevin B.; Brimacombe, J.; Carey, Sean; Christie, Grant; Delplancke-Ströbele, F.; Feliz, Dax L.; Gaudi, B. Scott; Green, J.; Hu, Shaoming; Jayasinghe, T.; Koff, R. A.; Kurtenkov, A.; Mérand, A.; Minev, M.; Mutel, R. L.; Natusch, T.; Roth, T.; Shvartzvald, Yossi; Sun, Fengwu; Vanmunster, Tonny; Zhu, Wei

doi:10.3847/1538-4357/ab9749

Cited by 22 publications

(19 citation statements)

References 68 publications

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“…Because it requires very bright targets, successful observations have been conducted only twice so far. For the Kojima event (Nucita et al 2018;Fukui et al 2019;Zang et al 2020) the interferometric measurements led to the separation of images using the GRAVITY instrument on ESO VLTI (Dong et al 2019). The second was the Gaia19bld event, for which the photometric analysis is presented in this paper, while the interferometric measurements are described in companion paper (Cassan et al 2021, hereafter C21).…”

Section: Introductionmentioning

confidence: 90%

“…For the Spitzer-"only" determination, we follow the method developed and described in detail by Gould et al (2020) for KMT-2018-BLG-0029 and subsequently applied by Hirao et al (2020) and Zang et al (2020) to OGLE-2017-BLG-0406 and OGLE-2018-BLG-799, respectively. We first fix the Paczynski (1986) parameters (t 0 , u 0 , t E ) at their ground-based values.…”

Section: Microlensing Parallax Analysismentioning

confidence: 99%

“…Because it is not a joint fit, the resulting parallax measurement will not be as affected by systematic errors in the ground-based data, whereas it might be in a global fit to all data sets. In previous applications of this method (Gould et al 2020;Hirao et al 2020;Zang et al 2020) it has been important for isolating and evaluating potential effects due to systematic errors in the Spitzer photometry. In these three cases, the Spitzer detection was weak and the photometry only covered the falling wing of the light curve.…”

Section: Gould 1994amentioning

confidence: 99%

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Single-lens mass measurement in the high-magnification microlensing event Gaia19bld located in the Galactic disc

Rybicki

Wyrzykowski

Bachelet

et al. 2021

A&A

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Context. Microlensing provides a unique opportunity to detect non-luminous objects. In the rare cases that the Einstein radius θE and microlensing parallax πE can be measured, it is possible to determine the mass of the lens. With technological advances in both ground- and space-based observatories, astrometric and interferometric measurements are becoming viable, which can lead to the more routine determination of θE and, if the microlensing parallax is also measured, the mass of the lens. Aims. We present the photometric analysis of Gaia19bld, a high-magnification (A ≈ 60) microlensing event located in the southern Galactic plane, which exhibited finite source and microlensing parallax effects. Due to a prompt detection by the Gaia satellite and the very high brightness of I = 9.05 mag at the peak, it was possible to collect a complete and unique set of multi-channel follow-up observations, which allowed us to determine all parameters vital for the characterisation of the lens and the source in the microlensing event. Methods. Gaia19bld was discovered by the Gaia satellite and was subsequently intensively followed up with a network of ground-based observatories and the Spitzer Space Telescope. We collected multiple high-resolution spectra with Very Large Telescope (VLT)/X-shooter to characterise the source star. The event was also observed with VLT Interferometer (VLTI)/PIONIER during the peak. Here we focus on the photometric observations and model the light curve composed of data from Gaia, Spitzer, and multiple optical, ground-based observatories. We find the best-fitting solution with parallax and finite source effects. We derived the limit on the luminosity of the lens based on the blended light model and spectroscopic distance. Results. We compute the mass of the lens to be 1.13 ± 0.03 M⊙ and derive its distance to be 5.52−0.64+0.35 kpc. The lens is likely a main sequence star, however its true nature has yet to be verified by future high-resolution observations. Our results are consistent with interferometric measurements of the angular Einstein radius, emphasising that interferometry can be a new channel for determining the masses of objects that would otherwise remain undetectable, including stellar-mass black holes.

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Section: Introductionmentioning

confidence: 90%

Section: Microlensing Parallax Analysismentioning

confidence: 99%

Section: Gould 1994amentioning

confidence: 99%

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Single-lens mass measurement in the high-magnification microlensing event Gaia19bld located in the Galactic disc

Rybicki

Wyrzykowski

Bachelet

et al. 2021

A&A

Self Cite

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“…Two possible values were actually found [8], depending on the chosen model θ E = 1.850 ± 0.014 mas and θ E = 1.891 ± 0.014 mas (or θ E = 1.87 ± 0.03 mas considering both models). Further follow-up studies [18,19] using complementary ground-based data, Gaia and Spitzer space data, as well as Keck adaptive-optics images and spectroscopic data were used to break the degeneracy in the models, yielding a determination of the microlens mass to a relative uncertainty of about 6%.…”

Section: Main Textmentioning

confidence: 99%

“…1, 2 and 3). For 'Kojima-1', the relative uncertainty on θ E combines interferometry, high-resolution imaging, spectroscopy and space parallax [8,18,19], while in the case of Gaia19bld, this uncertainty comes from interferometry alone.…”

Section: Figure Legends/captions (For Main Text Figures)mentioning

confidence: 99%

Microlensing mass measurement from images of rotating gravitational arcs

et al. 2021

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Introductory paragraph, referencedGravitational microlensing [1] is a powerful technique for measuring the mass of isolated, faint or non-luminous objects in the Milky Way [2,3]. In most cases however, additional observations to the photometric light curve are required to measure accurately the mass of the microlens. Long-baseline optical/infrared interferometry provides a new and efficient way to deliver such independent constraints [4,5,6,7], as it was recently demonstrated by first interferometric observations in microlensing event TCP J05074264+2447555 ('Kojima-1') [8]. Here, we report real-time observations of gravitationally-lensed arcs in rotation around a microlens, Gaia19bld[9], made with the PIONIER instrument[10] at the Very Large Telescope Interferometer (VLTI). Our data allowed us to determine the angular separation and length of the arcs, as well as their rotation rate. Combining these measurements with ground-based photometric data enabled the determination of the microlens mass to a very high accuracy, M = 1.147 ± 0.029 M . We anticipate interferometric microlensing to play an important future role in the mass and distance determination of isolated stellar-mass black holes [11,12,13] in the Galaxy, which cannot be addressed by any other technique.

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A Light‐Responsive Injectable Hydrogel with Remodeling Tumor Microenvironment for Light‐Activated Chemodynamic Therapy

Liu

Chen

Huang

et al. 2022

Macromolecular Bioscience

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Chemodynamic therapy (CDT) based on Fenton-like reaction is often limited by the tumor microenvironment (TME), which has insufficient hydrogen peroxide, and single CDT treatment is often less efficacious. To overcome these limitations, a hydrogel-based system is designed to enhance the redox stress (EOH) by loading the composite nanomaterial Cu-Hemin-Au, into the agarose hydrogels. The hydrogels can reach the tumor site upon intratumoral injection, and then coagulate and stay for extended period. Once irradiated with near-infrared light, the Cu-Hemin-Au act as a photothermal agent to convert the light energy into heat, and the EOH gradually heated up and softened, releasing the Cu-Hemin-Au residing in it to achieve photothermal therapy (PTT). Benefiting from the glucose oxidase (GOx)-like activity of the Au nanoparticles, glucose in the tumor cells is largely consumed, and hydrogen peroxide (H 2 O 2 ) is generated in situ, and then Cu-Hemin-Au react with sufficient H 2 O 2 to generate a large amount of reactive oxygen species, which promote the complete inhibition of tumor growth in mice during the treatment cycle. The hydrogel system for the synergistic enhancement of oxidative stress achieves good PTT/CDT synergy, providing a novel inspiration for the next generation of hydrogels for application in antitumor therapy.

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Spitzer + VLTI-GRAVITY Measure the Lens Mass of a Nearby Microlensing Event

Cited by 22 publications

References 68 publications

Single-lens mass measurement in the high-magnification microlensing event Gaia19bld located in the Galactic disc

Single-lens mass measurement in the high-magnification microlensing event Gaia19bld located in the Galactic disc

Microlensing mass measurement from images of rotating gravitational arcs

A Light‐Responsive Injectable Hydrogel with Remodeling Tumor Microenvironment for Light‐Activated Chemodynamic Therapy

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