Efficiently Jet-powered Radiation in Intermediate-luminosity Optical Transients

Soker, Noam

doi:10.3847/1538-4357/ab7dbb

Cited by 26 publications

(27 citation statements)

References 69 publications

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“…M ej > M (η > 1) in which the entire mass of the donor is ejected, while a comparable number of events hover around η ∼ 1 (see also Soker 2020). A second point of tension is that the inferred ejecta velocities (estimated from Eq.…”

Section: Application To Individual Lrnementioning

confidence: 98%

“…SN light curves are powered by the initial thermal energy of the recently-shocked ejecta from the explosion or the radioactive decay of 56 Ni. Although the early-time peaks seen in many LRN light curves can be powered by the initial thermal energy of hot ejecta (MacLeod et al 2017;, the longer-lived plateau emission (sometimes manifesting as a second luminosity peak) is powered by hydrogen recombination energy or other forms of radially-distributed ejecta heating (e.g., shock interaction between the fast merger ejecta and circumbinary material from the pre-dynamical phase; Metzger & Pejcha 2017, or from an accretion-powered jet; e.g., Soker 2020;Soker & Kaplan 2021).…”

Section: Introductionmentioning

confidence: 99%

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Light Curve Model for Luminous Red Novae and Inferences about the Ejecta of Stellar Mergers

Matsumoto¹,

Metzger²

2022

Preprint

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The process of unstable mass transfer in a stellar binary can result in either a complete merger of the stars or successful removal of the donor envelope leaving a surviving more compact binary. "Luminous red nova" (LRN) are the class of optical transients believed to accompany such merger/common envelope events. Past works typically model LRNe using analytic formulae for supernova light curves which make assumptions (e.g., radiation dominated ejecta, neglect of hydrogen recombination energy) not justified in stellar mergers due to the lower velocities and specific thermal energy of the ejecta. We present a one-dimensional model of LRN light curves, which accounts for these effects. Consistent with observations, we find that LRNe typically possess two light curve peaks, an early phase powered by initial thermal energy of the hot, fastest ejecta layers and a later peak powered by hydrogen recombination from the bulk of the ejecta. We apply our model to a sample of LRNe to infer their ejecta properties (mass, velocity, and launching radius) and compare them to the progenitor donor star properties from pre-transient imaging. We define a maximum luminosity achievable for a given donor star in the limit that the entire envelope is ejected, finding that several LRNe violate this limit. Shock interaction between the ejecta and pre-dynamical mass-loss, may provide an additional luminosity source to alleviate this tension. Our model can also be applied to the merger of planets with stars or stars with compact objects.

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Section: Application To Individual Lrnementioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Light Curve Model for Luminous Red Novae and Inferences about the Ejecta of Stellar Mergers

Matsumoto¹,

Metzger²

2022

Preprint

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“…The LRN phenomenon can be comfortably explained in terms of post common envelope evolution and eventually co-alescence in binary systems whose components span a wide range of masses. However, the physical processes leading to the common envelope ejection and the path to coalescence are still debated (e.g" Ivanova et al 2013;Pejcha et al 2017;Segev et al 2019;MacLeod et al 2018;Soker 2020;Soker & Kaplan 2020). The characterization of this species of gap transients is also necessary to provide reliable estimates of their rates, both in the Galaxy and within a volume of universe, although it is now clear that the frequency of LRNe depends significantly on their luminosity and the total mass of the system (Kochanek et al 2014;Howitt et al 2020).…”

Section: Introductionmentioning

confidence: 99%

The luminous red nova variety: AT 2020hat and AT 2020kog

Pastorello,

Valerin,

Fraser

et al. 2020

Preprint

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We present the results of our monitoring campaigns of the Luminous Red Novae (LRNe) AT 2020hat in NGC 5068 and AT 2020kog in NGC 6106. The two objects were imaged (and detected) before their discovery by routine survey operations. They show a general trend of slow luminosity rise lasting at least a few months. The subsequent major LRN outbursts were extensively followed in photometry and spectroscopy. The light curves present an initial short-duration peak, followed by a redder plateau phase. AT 2020kog is a moderately luminous event peaking at ∼ 7 × 10 40 erg s −1 , while AT 2020hat is almost one order of magnitude fainter than AT 2020kog, although still more luminous than V838 Mon. In analogy with other LRNe, the spectra of AT 2020kog change significantly with time. They resemble those of Type IIn supernovae at early phases, then they become similar to those of K-type stars during the plateau, and to M-type stars at very late phases. In contrast, AT 2020hat shows a redder continuum already at early epochs, and its spectrum shows the late appearance of molecular bands. A moderate-resolution spectrum of AT 2020hat taken at +37 d after maximum shows a forest of narrow P Cygni lines of metals with velocities of 180 km s −1 , along with an Hα emission with a full-width at half-maximum velocity of 250 km s −1 . For AT 2020hat, a robust constraint on its quiescent progenitor is provided by archival images of the Hubble Space Telescope. The progenitor is clearly detected as a mid-K type star, with an absolute magnitude M F606W = −3.33 ± 0.09 mag and a colour F606W − F814W = 1.14 ± 0.05 mag, which are inconsistent with the expectations from a massive star that could later produce a core-collapse supernova. Although quite peculiar, the two objects well match the progenitor vs. light curve absolute magnitude correlations discussed in the literature.

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“…Kulkarni & Kasliwal 2009;Kasliwal 2012; or even intermediate-luminosity optical transients (e.g. Berger et al 2009a;Soker & Kashi 2012;Soker 2020;Soker & Kaplan 2021).…”

Section: Introductionmentioning

confidence: 99%

Intermediate-luminosity red transients: Spectrophotometric properties and connection to electron-capture supernova explosions

Cai,

Pastorello,

Fraser

et al. 2021

Preprint

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We present the spectroscopic and photometric study of five intermediate-luminosity red transients (ILRTs), namely AT 2010dn, AT 2012jc, AT 2013la, AT 2013lb, and AT 2018aes. They share common observational properties and belong to a family of objects similar to the prototypical ILRT SN 2008S. These events have a rise time that is less than 15 days and absolute peak magnitudes of between −11.5 and −14.5 mag. Their pseudo-bolometric light curves peak in the range 0.5 -9.0 × 10 40 erg s −1 and their total radiated energies are on the order of (0.3 -3) × 10 47 erg. After maximum brightness, the light curves show a monotonic decline or a plateau, resembling those of faint supernovae IIL or IIP, respectively. At late phases, the light curves flatten, roughly following the slope of the 56 Co decay. If the late-time power source is indeed radioactive decay, these transients produce 56 Ni masses on the order of 10 −4 to 10 −3 M . The spectral energy distribution of our ILRT sample, extending from the optical to the mid-infrared (MIR) domain, reveals a clear IR excess soon after explosion and non-negligible MIR emission at very late phases. The spectra show prominent H lines in emission with a typical velocity of a few hundred km s −1 , along with Ca II features. In particular, the [Ca ii] λ7291,7324 doublet is visible at all times, which is a characteristic feature for this family of transients. The identified progenitor of SN 2008S, which is luminous in archival Spitzer MIR images, suggests an intermediate-mass precursor star embedded in a dusty cocoon. We propose the explosion of a super-asymptotic giant branch star forming an electron-capture supernova as a plausible explanation for these events.

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Efficiently Jet-powered Radiation in Intermediate-luminosity Optical Transients

Cited by 26 publications

References 69 publications

Light Curve Model for Luminous Red Novae and Inferences about the Ejecta of Stellar Mergers

Light Curve Model for Luminous Red Novae and Inferences about the Ejecta of Stellar Mergers

The luminous red nova variety: AT 2020hat and AT 2020kog

Intermediate-luminosity red transients: Spectrophotometric properties and connection to electron-capture supernova explosions

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