Lanthanide Features in Near-infrared Spectra of Kilonovae

Domoto, Nanae; Tanaka, Masaomi; Kato, Daiji; Kawaguchi, Kyohei; Hotokezaka, Kenta; Wanajo, Shinya

doi:10.3847/1538-4357/ac8c36

Cited by 43 publications

(71 citation statements)

References 73 publications

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“…Due to their lower abundances, these lines are expected to be weaker compared to the Te line if collisional excitation dominates the excitation processes. However, as we make an implicit assumption that their E1 lines contribute to the opacity in the mid-IR, they may produce P-Cygni like features, see, e.g., [37,159]. For example, Ce III has a strong line at 2.07 µm with log gf = −1.67 [159].…”

Section: Spectral Analysis Modelingmentioning

confidence: 99%

“…However, as we make an implicit assumption that their E1 lines contribute to the opacity in the mid-IR, they may produce P-Cygni like features, see, e.g., [37,159]. For example, Ce III has a strong line at 2.07 µm with log gf = −1.67 [159]. We estimate that its line optical depth is ≲ 0.1 at 700 K with ∼ 0.05M ⊙ and ∼ 0.1c even if Ce is purely in Ce III.…”

Section: Spectral Analysis Modelingmentioning

confidence: 99%

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JWST detection of heavy neutron capture elements in a compact object merger

Levan,

Gompertz,

Salafia

et al. 2023

Preprint

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The mergers of binary compact objects such as neutron stars and black holes are of central interest to several areas of astrophysics, including as the progenitors of gamma-ray bursts (GRBs), sources of high-frequency gravitational waves and likely production sites for heavy element nucleosynthesis via rapid neutron capture (the r-process). These heavy elements include some of great geophysical, biological and cultural importance, such as thorium, iodine, and gold. Here we present observations of the exceptionally bright gamma-ray burst GRB230307A. We show that GRB 230307A belongs to the class of long-duration gamma-ray bursts associated with compact object mergers, and contains a kilonova similar to AT2017gfo, associated with the gravitational-wave merger GW170817. We obtained James Webb Space Telescope mid-infrared (mid-IR) imaging and spectroscopy 29 & 61 days after the burst. The spectroscopy shows an emission line at 2.1 microns which we interpret as tellurium (atomic mass A=130), and a very red source, emitting most of its light in the mid-IR due to the production of lanthanides. These observations demonstrate that nucleosynthesis in GRBs can create r-process elements across a broad atomic mass range and play a central role in heavy element nucleosynthesis across the Universe.

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Section: Spectral Analysis Modelingmentioning

confidence: 99%

Section: Spectral Analysis Modelingmentioning

confidence: 99%

JWST detection of heavy neutron capture elements in a compact object merger

Levan,

Gompertz,

Salafia

et al. 2023

Preprint

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show abstract

“…The location of the proposed Sr feature could also be explained by the He 10831 Å line, however, to have a noticeable effect on the spectrum, the required helium mass exceeds what is expected to be produced in merger simulations by about one order of magnitude (Perego et al 2022). In particular, no r-process elements of the second or third peaks have been unambiguously identified ( see however Domoto et al 2022, for tentative identifications of La and Ce ). Unsuccessful searches involve cesium/tellurium (Smartt et al 2017) and gold/platinum (Gillanders et al 2021).…”

mentioning

confidence: 91%

Opacities of Singly and Doubly Ionised Neodymium and Uranium for Kilonova Emission Modeling

Flörs¹,

Silva²,

Deprince³

et al. 2023

Preprint

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In 2017, the electromagnetic counterpart AT2017gfo to the binary neutron star merger GW170817 was observed by all major telescopes on Earth. While it was immediately clear that the transient following the merger event, is powered by the radioactive decay of r-process nuclei, only few tentative identifications of light r-process elements have been made so far. One of the major limitations for the identification of heavy nuclei based on light curves or spectral features is incomplete or missing atomic data. While some progress has been made on lanthanide atomic data over the last few years, for actinides very little atomic data is available. We perform atomic structure calculations of neodymium (𝑍 = 60) as well as the corresponding actinide uranium (𝑍 = 92). Using two different codes (FAC and HFR) for the calculation of the atomic data, we investigate the accuracy of the calculated data (energy levels and electric dipole transitions) and their effect on kilonova opacities. For the FAC calculations, we optimise the local central potential and the number of included configurations and use a dedicated calibration technique to improve the agreement between theoretical and available experimental atomic energy levels (AELs). For ions with vast amounts of experimental data available, the presented opacities agree quite well with previous estimations. On the other hand, the optimisation and calibration method cannot be used for ions with only few available AELs. For these cases, where no experimental nor benchmarked calculations are available, a large spread in the opacities estimated from the atomic data obtained with the various atomic structure codes is observed, most-likely due to the uncertainty in the density of low-lying levels predicted by theory. We find that the opacity of uranium is almost double the neodymium opacity.

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“…Recently, Domoto et al (2022) systematically studied the spectral features of kilonovae at NIR wavelengths. They identified several elements producing strong transitions in kilonovae, such as Ca, Sr, Y, Zr, Ba, La, and Ce.…”

Section: Introductionmentioning

confidence: 99%

Cerium Features in Kilonova Near-infrared Spectra: Implication from a Chemically Peculiar Star

Tanaka

Domoto

Aoki

et al. 2023

ApJ

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Observations of the kilonova from the neutron star merger event GW170817 opened a way to study r-process nucleosynthesis directly using neutron star mergers. It is, however, challenging to identify individual elements in kilonova spectra due to a lack of complete atomic data, in particular at near-infrared (NIR) wavelengths. In this paper, we demonstrate that spectra of chemically peculiar stars with enhanced heavy-element abundances can provide us with an excellent astrophysical laboratory for kilonova spectra. We show that the photosphere of the late B-type, chemically peculiar star HR 465 has similar lanthanide abundances and ionization degrees with those in the line-forming region in a kilonova at ∼2.5 days after the merger. The NIR spectrum of HR 465 taken with Subaru/IRD indicates that Ce iii lines give the strongest absorption feature around 16000 Å and there are no other comparably strong transitions around these lines. The Ce iii lines nicely match with the broad absorption feature at 14500 Å observed in GW170817 with a blueshift of v = 0.1 c, which supports recent identification of this feature as Ce iii by Domoto et al.

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Lanthanide Features in Near-infrared Spectra of Kilonovae

Cited by 43 publications

References 73 publications

JWST detection of heavy neutron capture elements in a compact object merger

JWST detection of heavy neutron capture elements in a compact object merger

Opacities of Singly and Doubly Ionised Neodymium and Uranium for Kilonova Emission Modeling

Cerium Features in Kilonova Near-infrared Spectra: Implication from a Chemically Peculiar Star

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