Two New Calcium-rich Gap Transients in Group and Cluster Environments

Lunnan, R.; Kasliwal, M. M.; Cao, Y.; Hangard, L.; Yaron, O.; Parrent, J.; McCully, C.; Gal‐Yam, A.; Mulchaey, John S.; Ben-Ami, Sagi; Filippenko, A. V.; Fremling, C.; Fruchter, A. S.; Howell, D. A.; Koda, Jin; Kupfer, Thomas; Kulkarni, S. R.; Laher, Russ R.; Masci, Frank J.; Nugent, P.; Ofek, E. O.; Yagi, Masafumi; Yan, Lin

doi:10.3847/1538-4357/836/1/60

Cited by 80 publications

(121 citation statements)

References 82 publications

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“…The lower panel of Fig. 9 shows the +12.9 and +19.6 d spectra of SN 2019bkc compared to the same sample of Ca-rich nebular phase spectra, with the addition of PTF12bho (Lunnan et al 2017). The emission lines at ∼7000 and ∼8400 Å seen in the spectra of SN 2019bkc look similar to those seen in the Ca-rich events (and associated with [Ca ii] and Ca ii, respectively).…”

Section: The Extraordinary Ca-rich Early Nebular Phasementioning

confidence: 73%

The rise and fall of an extraordinary Ca-rich transient

Prentice

Maguire

Flörs

et al. 2020

A&A

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This work presents the observations and analysis of ATLAS19dqr/SN 2019bkc, an extraordinary rapidly evolving transient event located in an isolated environment, tens of kpc from any likely host. Its light curves rise to maximum light in 5 − 6 d and then display an decline of ∆m 15 ∼ 5 mag. With such a pronounced decay, it has one of the most rapidly evolving light curves known for a stellar explosion. The early spectra show similarities to normal and "ultra-stripped" type Ic SNe but the early nebular phase spectra, reached just over two weeks after explosion, display prominent calcium lines, marking SN 2019bkc as a Ca-rich transient. The Ca emission lines at this phase show an unprecedented and unexplained blueshift of 10 000 -12 000 km s −1 . Modelling of the light curve and the early spectra suggests that the transient had a low ejecta mass of 0.2 − 0.4 M and a low kinetic energy of (2 − 5) × 10 50 erg, giving a specific kinetic energy E k /M ej around unity. The origin of this event cannot be unambiguously defined. While the abundance distribution used to model the spectra marginally favours a progenitor of white dwarf origin through the tentative identification of Ar ii, the specific kinetic energy, which is defined by the explosion mechanism, is found to be more similar to an ultra-stripped core-collapse events. SN 2019bkc adds to the diverse range of physical properties shown by Ca-rich events.

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Section: The Extraordinary Ca-rich Early Nebular Phasementioning

confidence: 73%

The rise and fall of an extraordinary Ca-rich transient

Prentice

Maguire

Flörs

et al. 2020

A&A

Self Cite

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“…The helium WD TDE light curves show similar timescales and luminosities to calcium-rich transients (Perets et al 2010;Kasliwal et al 2012;Valenti et al 2014;Lunnan et al 2017;Milisavljevic et al 2017;De et al 2018), .Ia explosions (Kasliwal et al 2010;Shen et al 2010), and rapid transients recently discovered by Drout et al (2014); Pursiainen et al (2018). We compare our models with observed transients of these classes.…”

Section: Possible Observational Counterpartsmentioning

confidence: 77%

Rapid Transients Originating from Thermonuclear Explosions in Helium White Dwarf Tidal Disruption Events

Kawana

Maeda

Yoshida

et al. 2020

ApJL

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We study properties of the emission from thermonuclear explosions in a helium white dwarf (WD) tidal disruption event (TDE). The helium WD is not only tidally disrupted but is detonated by the tidal compression and by succeeding shocks. We focus on the emission powered by radioactive nuclei in the unbound ejecta of the TDE debris. We consider a TDE where a 0.2 M helium WD is disrupted by a 10 2.5 M intermediate-mass black hole (IMBH). We perform hydrodynamic simulations coupled with nuclear reactions, post-process detailed nucleosynthesis calculations, and then radiative transfer simulations. We thus derive multi-band light curves and spectra. The helium WD TDE shows rapid (∆t 1mag 5-10 d) and relatively faint (L peak 10 42 erg s −1 ) light curves, because the ejecta mass and 56 Ni mass are low (0.12 M and 0.03 M , respectively). The spectra show strong calcium and Fe-peak features and very weak silicon features, reflecting the peculiar elemental abundance. The key feature is the Doppler shift of the spectral lines up to ±12, 000 km s −1 , depending on the viewing angle, due to the bulk motion of the ejecta. Our model matches well with some rapid transients. The particular model presented here does not match with observed supernovae Iax, calcium-rich transients, nor .Ia explosion candidates, either in the spectra or light curves. However, we expect a large variety of the observational signatures once a wide range of the WD/BH masses and orbital parameters are considered. This study helps to search for WD TDEs with current and upcoming surveys, and to identify IMBHs as disrupters in the TDEs.

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“…Ivanova et al (2006) demonstrated similar results regarding the contribution of cluster WDs to the Type Ia SNe rate. WD-NS collisions in GCs have been proposed as a possible mechanism of calcium-rich gap transients observed at high radial off-sets in metal-poor galaxies (Kasliwal et al 2012;Lunnan et al 2017;De et al 2018;Shen et al 2019). Additionally, tidal disruptions of WDs by BHs (especially IMBHs) in GCs have been examined in several analyses (Rosswog et al 2009;MacLeod et al 2016;Fragione et al 2018b).…”

Section: White Dwarfs Collisions -Connecting To High-energy Transientsmentioning

confidence: 99%

Modeling Dense Star Clusters in the Milky Way and Beyond with the `CMC` Cluster Catalog

Kremer

Rui

et al. 2020

ApJS

205

322

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We present a set of 148 independent N -body simulations of globular clusters (GCs) computed using the code CMC (Cluster Monte Carlo). At an age of ∼ 10−13 Gyr, the resulting models cover nearly the full range of cluster properties exhibited by the Milky Way GCs, including total mass, core and half-light radii, metallicity, and galactocentric distance. We use our models to investigate the role that stellarmass black holes play in the process of core collapse. Furthermore, we study how dynamical interactions affect the formation and evolution of several important types of sources in GCs, including low-mass X-ray binaries, millisecond pulsars, blue stragglers, cataclysmic variables, Type Ia supernovae, calciumrich transients, and merging compact binaries. While our focus here is on old, low-metallicity GCs, our CMC simulations follow the evolution of clusters over a Hubble time, and they include a wide range of metallicities (up to solar), so that our results can also be used to study younger and higher-metallicity star clusters.2. METHODS 2.1. Summary of CMC

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Two New Calcium-rich Gap Transients in Group and Cluster Environments

Cited by 80 publications

References 82 publications

The rise and fall of an extraordinary Ca-rich transient

The rise and fall of an extraordinary Ca-rich transient

Rapid Transients Originating from Thermonuclear Explosions in Helium White Dwarf Tidal Disruption Events

Modeling Dense Star Clusters in the Milky Way and Beyond with the `CMC` Cluster Catalog

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Two New Calcium-rich Gap Transients in Group and Cluster Environments

Cited by 80 publications

References 82 publications

The rise and fall of an extraordinary Ca-rich transient

The rise and fall of an extraordinary Ca-rich transient

Rapid Transients Originating from Thermonuclear Explosions in Helium White Dwarf Tidal Disruption Events

Modeling Dense Star Clusters in the Milky Way and Beyond with the CMC Cluster Catalog

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Product

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Modeling Dense Star Clusters in the Milky Way and Beyond with the `CMC` Cluster Catalog