Kilonova from post-merger ejecta as an optical and near-Infrared counterpart of GW170817

Tanaka, Masaomi; Utsumi, Yousuke; Mazzali, Paolo A.; Tominaga, Nozomu; Yoshida, Michitoshi; Sekiguchi, Y.; Morokuma, Tomoki; Motohara, Kentaro; Ohta, Kouji; Kawabata, Miho; Abe, F.; Aoki, Kentaro; Asakura, Y.; Baar, Stefan; Barway, Sudhanshu; Bond, I. A.; Doi, Mamoru; Fujiyoshi, Takuya; Furusawa, Hisanori; Honda, Satoshi; Itoh, Yoichi; Kawai, N.; Kim, Ji Hoon; Lee, Chien‐Hsiu; Miyazaki, Shota; Morihana, K.; Nagashima, Hiroki; Nagayama, Takahiro; Nakaoka, Tatsuya; Nakata, Fumiaki; Ohsawa, Ryou; Ohshima, Tomohito; Okita, Hirofumi; Saito, Tomoki; Sumi, T.; Tajitsu, Akito; Takahashi, Jun; Takayama, Masaki; Tamura, Motohide; Tanaka, Ichi; Terai, Tsuyoshi; Tristram, P. J.; Yasuda, Naoki; Zenko, Tetsuya

doi:10.1093/pasj/psx121

Cited by 284 publications

(208 citation statements)

References 50 publications

Supporting

Mentioning

186

Contrasting

Unclassified

Order By: Relevance

“…A fit of AT2017gfo light curves to a semianalytical two-components spherical model indicates a lanthanide poor (rich) blue (red) component of mass 2.5×10 −2 M (5.0×10 −2 M ) and velocity 0.27c (0.15c) [4,16] (See however [17] for an alternative interpretation.) Similar results are obtained using more sophisticated 1D simulations of radiation transport along spherical shells of mass ejecta [5,6].…”

Section: Introductionsupporting

confidence: 81%

Spiral-wave Wind for the Blue Kilonova

Nedora

Bernuzzi

Radice

et al. 2019

ApJL

132

View full text Add to dashboard Cite

The AT2017gfo kilonova counterpart of the binary neutron star merger event GW170817 was characterized by an early-time bright peak in optical and UV bands. Such blue kilonova is commonly interpreted as a signature of weak r-process nucleosynthesis in a fast expanding wind whose origin is currently debated. Numerical-relativity simulations with microphysical equations of state, approximate neutrino transport, and turbulent viscosity reveal a new mechanism that can power the blue kilonova. Spiral density waves in the remnant generate a characteristic wind of mass ∼10 −2 M and velocity ∼0.2c. The ejected material has electron fraction mostly distributed above 0.25 being partially reprocessed by hydrodynamic shocks in the expanding arms. The combination of dynamical ejecta and spiral-wave wind can account for solar system abundances of r-process elements and early-time observed light curves.PACS numbers: 04.25.D-, 04.30.Db, 95.30.Sf, 95.30.Lz, 97.60.Jd arXiv:1907.04872v1 [astro-ph.HE]

show abstract

Section: Introductionsupporting

confidence: 81%

Spiral-wave Wind for the Blue Kilonova

Nedora

Bernuzzi

Radice

et al. 2019

ApJL

132

View full text Add to dashboard Cite

show abstract

“…Temperatures of the ejecta are evaluated with an equation of state (Blinnikov et al 1996), taking into account the energy generation through nuclear reactions (Rosswog et al 2017). The model has four parameters; the mass of the ejecta (Mej), the expansion velocity (vex), the electron fraction (Ye), and entropy per baryon (s), where Ye and s are evaluated when the temperature is equal to 9 × 10 9 K. We have performed calculations for parameters of Ye = 0.1, 0.15, 0.2, 0.25, and 0.3, and vex/c = 0.05, 0.1, and 0.2 with fixed parameters Mej = 0.03M⊙, which is comparable to masses adopted in kilonova models for GW170817 (Tanaka et al 2017;Kasen et al 2017), and s = 10kB, where kB is the Boltzmann constant. We investigate the following three cases; (a) the nine nuclei ( 121,123,125,127 Sn,128,129 Sb,129,131 Te, and 134 I) are assumed to be always stayed in their GSs: (b) the nine nuclei in their ISs with 100% β − BRs: and (c) the four nuclei, 123,125,127 Sn, and 128 Sb, whose IS largely dominates over its GS even when IS is not excited from GS (Appendix A), are assumed to be always stayed in their ISs with 100% β − BRs.…”

Section: Evolution Of Abundances and Energy Generation Rates Of Ejectamentioning

confidence: 99%

“…A gravitational wave source, GW170817, has been identified to be a neutron star merger (NSM) (Abbott et al 2017) and the association was observationally confirmed with a kilonova, AT2017gfo, whose light curve has been modeled with two components; early blue and later red ones (Cowperthwaite et al 2017;Tanaka et al 2017;Tanvir et al 2017;Kasen et al 2017;Villar et al 2017;Smartt et al 2017). In the scenario, the kilonova is possibly powered by the radioactive decay of neutron(n)-rich matter freshly synthesized in ejecta from NSM through r-process nucleosynthesis (Li & Paczyński 1998;Wanajo et al 2014).…”

Section: Introductionmentioning

confidence: 97%

The impact of isomers on a kilonova associated with neutron star mergers

Fujimoto

Hashimoto

2020

Monthly Notices of the Royal Astronomical Society: Letters

View full text Add to dashboard Cite

We investigate the significance of isomers on a kilonova associated with neutron star mergers (NSMs) for the first time. We calculate the evolution of abundances and energy generation rates (ǫ nuc ) of ejecta from NSMs, taking into account β − decay through isomers. We find that for ejecta with electron fraction (Y e ) of 0.2 − 0.3,ǫ nuc is appreciably changed from those without isomers, due to the large change in timing of β − decay through the isomeric states of 123,125,127 Sn and 128 Sb. In particular, the effects of the isomers onǫ nuc are prominent for ejecta of Y e ∼ 0.25, which could emit a fraction of an early, blue component of a kilonova observed in GW170817. When the excitation from a ground state to its isomeric state is important, the isomers of 129 Sb and 129,131 Te also cause additional and appreciable change inǫ nuc . Furthermore, we demonstrate that larger amounts of lanthanide-free ejecta result in a better fit of an observed light curve of the kilonova in GW170817 if the isomers are taken into account.

show abstract

“…As a comparison, the mass of the dynamical ejecta of double NS mergers is typically ∼10 −4 -10 −2 M e (Rosswog 2007;Bauswein et al 2013;Hotokezaka et al 2013a). It also does not conflict with the estimation of M ej ∼10 −3 -10 −2 M e for the dynamical ejecta of GW170817 (Abbott et al 2017d;Utsumi et al 2017;Tanaka et al 2017;Matsumoto et al 2018). In a few recent studies, a more precise ejecta mass of M ej ∼0.05M e was estimated when modeling the GW170817 kilonova (Cowperthwaite et al 2017;Drout et al 2017;Kasliwal et al 2017;Kasen et al 2017;Villar et al 2017;Waxman et al 2017).…”

Section: Numerical Resultsmentioning

confidence: 83%

Continued Brightening of the Afterglow of GW170817/GRB 170817A as Being Due to a Delayed Energy Injection

Huang

et al. 2018

ApJL

View full text Add to dashboard Cite

The brightness of the multi-wavelength afterglow of GRB 170817A is increasing unexpectedly even ∼160 days after the associated gravitational burst. Here we suggest that the brightening can be caused by a late-time energy injection process. We use an empirical expression to mimic the evolution of the injection luminosity, which consists of a power-law rising phase and a power-law decreasing phase. It is found that the power-law indices of the two phases are 0.92 and −2.8, respectively, with the peak time of the injection being ∼110days. The energy injection could be due to some kind of accretion, with the total accreted mass being ∼0.006M e . However, normal fall-back accretion, which usually lasts for a much shorter period, cannot provide a natural explanation. Our best-fit decay index of −2.8 is also at odds with the expected value of −5/3 for normal fall-back accretion. Noting that the expansion velocities of the kilonova components associated with GW170817 are 0.1-0.3 c, we argue that there should also be some ejecta with correspondingly lower velocities during the coalescence of the double neutron star (NS) system. They are bound by the gravitational well of the remnant central compact object and might be accreted at a timescale of about 100 days, providing a reasonable explanation for the energy injection. Detailed studies on the long-lasting brightening of GRB 170817A thus may provide useful information on matter ejection during the merger process of binary neutron stars.

show abstract

Kilonova from post-merger ejecta as an optical and near-Infrared counterpart of GW170817

Cited by 284 publications

References 50 publications

Spiral-wave Wind for the Blue Kilonova

Spiral-wave Wind for the Blue Kilonova

The impact of isomers on a kilonova associated with neutron star mergers

Continued Brightening of the Afterglow of GW170817/GRB 170817A as Being Due to a Delayed Energy Injection

Contact Info

Product

Resources

About