Review Article | Open Access

# Kilonova/Macronova Emission from Compact Binary Mergers

**Academic Editor:**WeiKang Zheng

#### Abstract

We review current understanding of kilonova/macronova emission from compact binary mergers (mergers of two neutron stars or a neutron star and a black hole). Kilonova/macronova is emission powered by radioactive decays of -process nuclei and it is one of the most promising electromagnetic counterparts of gravitational wave sources. Emission from the dynamical ejecta of ~0.01 is likely to have a luminosity of ~10^{40}–10^{41} erg s^{−1} with a characteristic timescale of about 1 week. The spectral peak is located in red optical or near-infrared wavelengths. A subsequent accretion disk wind may provide an additional luminosity or an earlier/bluer emission if it is not absorbed by the precedent dynamical ejecta. The detection of near-infrared excess in short GRB 130603B and possible optical excess in GRB 060614 supports the concept of the kilonova/macronova scenario. At 200 Mpc distance, a typical peak brightness of kilonova/macronova with ejecta is about 22 mag and the emission rapidly fades to >24 mag within ~10 days. Kilonova/macronova candidates can be distinguished from supernovae by (1) the faster time evolution, (2) fainter absolute magnitudes, and (3) redder colors. Since the high expansion velocity () is a robust outcome of compact binary mergers, the detection of smooth spectra will be the smoking gun to conclusively identify the gravitational wave source.

#### 1. Introduction

Mergers of compact stars, that is, neutron star (NS) and black hole (BH), are promising candidates for direct detection of gravitational waves (GWs). On 2015 September 14, Advanced LIGO [1] has detected the first ever direct GW signals from a BH-BH merger (GW150914) [2]. This discovery marked the dawn of GW astronomy.

NS-NS mergers and BH-NS mergers are also important and leading candidates for the GW detection. They are also thought to be progenitors of short-hard gamma-ray bursts (GRBs [3–5]; see also [6, 7] for reviews). When the designed sensitivity is realized, Advanced LIGO [1], Advanced Virgo [8], and KAGRA [9] can detect the GWs from these events up to ~200 Mpc (for NS-NS mergers) and ~800 Mpc (for BH-NS mergers). Although the event rates are still uncertain, more than one GW event per year is expected [10].

Since localization only by the GW detectors is not accurate, for example, more than a few 10 deg^{2} [11–14], identification of electromagnetic (EM) counterparts is essentially important to study the astrophysical nature of the GW sources. In the early observing runs of Advanced LIGO and Virgo, the localization accuracy can be >100 deg^{2} [15–17]. In fact, the localization for GW150914 was about 600 deg^{2} (90% probability) [18].

To identify the GW source from such a large localization area, intensive transient surveys should be performed (see, e.g., [19–24] for the case of GW150914). NS-NS mergers and BH-NS mergers are expected to emit EM emission in various forms. One of the most robust candidates is a short GRB. However, the GRB may elude our detection due to the strong relativistic beaming. Other possible EM signals include synchrotron radio emission by the interaction between the ejected material and interstellar gas [25–27] or X-ray emission from a central engine [28–31].

Among variety of emission mechanisms, optical and infrared (IR) emission powered by radioactive decay of -process nuclei [32–37] is of great interest. This emission is called “kilonova” [34] or “macronova” [33] (we use the term of kilonova in this paper). Kilonova emission is thought to be promising: by advancement of numerical simulations, in particular numerical relativity [38–41], it has been proved that a part of the NS material is surely ejected from NS-NS and BH-NS mergers (e.g., [36, 42–49]). In the ejected material, -process nucleosynthesis undoubtedly takes place (e.g., [35, 36, 49–56]). Therefore the emission powered by -process nuclei is a natural outcome from these merger events.

Observations of kilonova will also have important implications for the origin of -process elements in the Universe. The event rate of NS-NS mergers and BH-NS mergers will be measured by the detection of GWs. In addition, as described in this paper, the brightness of kilonova reflects the amount of the ejected -process elements. Therefore, by combination of GW observations and EM observations, that is, “multimessenger” observations, we can measure the production rate of -process elements by NS-NS and BH-NS mergers, which is essential to understand the origin of -process elements. In fact, importance of compact binary mergers in chemical evolution has been extensively studied in recent years [72–82].

This paper reviews kilonova emission from compact binary mergers. The primal aim of this paper is providing a guide for optical and infrared follow-up observations for GW sources. For the physical processes of compact binary mergers and various EM emission mechanisms, see recent reviews by Rosswog [83] and Fernández and Metzger [84]. First, we give overview of kilonova emission and describe the expected properties of the emission in Section 2. Then, we compare kilonova models with currently available observations in Section 3. Based on the current theoretical and observational understanding, we discuss prospects for EM follow-up observations of GW sources in Section 4. Finally, we give summary in Section 5. In this paper, the magnitudes are given in the AB magnitude unless otherwise specified.

#### 2. Kilonova Emission

##### 2.1. Overview

The idea of kilonova emission was first introduced by Li and Paczyński [32]. The emission mechanism is similar to that of Type Ia supernova (SN). The main differences are the following: (1) a typical ejecta mass from compact binary mergers is only an order of ( for Type Ia SN), (2) a typical expansion velocity is as high as km s^{−1} (~10,000 km s^{−1} for Type Ia SN), and (3) the heating source is decay energy of radioactive -process nuclei ( for Type Ia SN).

Suppose spherical, homogeneous, and homologously expanding ejecta with a radioactive energy deposition. A typical optical depth in the ejecta is , where is the mass absorption coefficient or “opacity” (), is the density, and is the radius of the ejecta. Then, the diffusion timescale in the ejecta isby adopting (homogeneous ejecta) and (homologous expansion).

When the dynamical timescale of the ejecta () becomes comparable to the diffusion timescale, photons can escape from the ejecta effectively [85]. From the condition of , the characteristic timescale of the emission can be written as follows:

The radioactive decay energy of mixture of -process nuclei is known to have a power-law dependence [34, 35, 54, 86–88]. By introducing a fraction of energy deposition (), the total energy deposition rate (or the deposition luminosity) is . A majority (~90%) of decay energy is released by decay while the other is released by fission [34]. For the decay, about , , and of the energy are carried by neutrinos, electrons, and -rays, respectively. Among these, almost all the energy carried by electrons is deposited, and a fraction of the -ray energy is also deposited to the ejecta. Thus, the fraction is about 0.5 (see [89] for more details). The dashed line in Figure 1 shows the deposition luminosity for and .

Since the peak luminosity is approximated by the deposition luminosity at (so-called Arnett’s law [85]), the peak luminosity of kilonova can be written as follows:

An important factor in this analysis is the opacity in the ejected material from compact binary mergers. Previously, the opacity had been assumed to be similar to that of Type Ia SN, that is, (bound-bound opacity of iron-peak elements). However, recent studies [57, 90, 91] show that the opacity in the -process element-rich ejecta is as high as (bound-bound opacity of lanthanide elements). This finding largely revised our understanding of the emission properties of kilonova. As evident from (2) and (3), a higher opacity by a factor of 100 leads to a longer timescale by a factor of ~10 and a lower luminosity by a factor of ~20.

##### 2.2. NS-NS Mergers

When two NSs merge with each other, a small part of the NSs is tidally disrupted and ejected to the interstellar medium (e.g., [36, 42]). This ejecta component is mainly distributed in the orbital plane of the NSs. In addition to this, the collision drives a strong shock, and shock-heated material is also ejected in a nearly spherical manner (e.g., [48, 92]). As a result, NS-NS mergers have quasi-spherical ejecta. The mass of the ejecta depends on the mass ratio and the eccentricity of the orbit of the binary, as well as the radius of the NS or equation of state (EOS, e.g., [48, 92–96]): a more uneven mass ratio and more eccentric orbit lead to a larger amount of tidally disrupted ejecta and a smaller NS radius leads to a larger amount of shock-driven ejecta.

The red line in Figure 1 shows the expected luminosity of a NS-NS merger model (APR4-1215 from Hotokezaka et al. [48]). This model adopts a “soft” EOS APR4 [97], which gives the radius of 11.1 km for a NS. The gravitational masses of two NSs are and the ejecta mass is 0.01. The light curve does not have a clear peak since the energy deposited in the outer layer can escape earlier. Since photons kept in the ejecta by the earlier stage effectively escape from the ejecta at the characteristic timescale (2), the luminosity exceeds the energy deposition rate at ~5–8 days after the merger.

Figure 2 shows multicolor light curves of the same NS-NS merger model (red line; see the right axis for the absolute magnitudes). As a result of the high opacity and the low temperature [90], the optical emission is greatly suppressed, resulting in an extremely “red” color of the emission. The red color is more clearly shown in Figure 3, where the spectral evolution of the NS-NS merger model is compared with the spectra of a Type Ia SN and a broad-line Type Ic SN. In fact, the peak of the spectrum is located at near-IR wavelengths [57, 90, 91].

Because of the extremely high expansion velocities, NS-NS mergers show feature-less spectra (Figure 3). This is a big contrast to the spectra of SNe (black and gray lines), where Doppler-shifted absorption lines of strong features can be identified. Even broad-line Type Ic SN 1998bw (associated with long-duration GRB 980425) showed some absorption features although many lines are blended. Since the high expansion velocity is a robust outcome of dynamical ejecta from compact binary mergers, the confirmation of the smooth spectrum will be a key to conclusively identify the GW sources.

The current wavelength-dependent radiative transfer simulations assume the uniform element abundances. However, recent numerical simulations with neutrino transport show that the element abundances in the ejecta becomes nonuniform [54, 92, 95, 96]. Because of the high temperature and neutrino absorption, the polar region can have higher electron fractions ( or number of protons per nucleon), resulting in a wide distribution of in the ejecta. Interestingly the wide distribution of is preferable for reproducing the solar -process abundance ratios [54, 56]. This effect can have a big impact on the kilonova emission: if the synthesis of lanthanide elements is suppressed in the polar direction, the opacity there can be smaller, and thus, the emission to the polar direction can be more luminous with an earlier peak.

##### 2.3. BH-NS Mergers

Mergers of BH and NS are also important targets for GW detection (see [98] for a review). Although the event rate is rather uncertain [10], the number of events can be comparable to that of NS-NS mergers thanks to the stronger GW signals and thus larger horizon distances. BH-NS mergers in various conditions have been extensively studied by numerical simulations (e.g., [99–103]). In particular, for a low BH/NS mass ratio (or small BH mass) and a high BH spin, ejecta mass of BH-NS mergers can be larger than that of NS-NS mergers [59, 104–109]. Since the tidal disruption is the dominant mechanism of the mass ejection, a larger NS radius (or stiff EOS) gives a higher ejecta mass, which is opposite to the situation in NS-NS mergers, where shock-driven ejecta dominates.

Radiative transfer simulations in BH-NS merger ejecta show that kilonova emission from BH-NS mergers can be more luminous in optical wavelengths than that from NS-NS mergers [58]. The blue lines in Figure 2 show the light curve of a BH-NS merger model (APR4Q3a75 from Kyutoku et al. [59]), a merger of a 1.35 NS and a 4.05 BH with a spin parameter of . The mass of the ejecta is . Since BH-NS merger ejecta are highly anisotropic and confined to a small solid angle, the temperature of the ejecta can be higher for a given mass of the ejecta, and thus, the emission tends to be bluer than in NS-NS mergers. Therefore, even if the bolometric luminosity is similar, the optical luminosity of BH-NS mergers can be higher than that of NS-NS mergers.

It is emphasized that the mass ejection from BH-NS mergers has a much larger diversity compared with NS-NS mergers, depending on the mass ratio, the BH spin, and its orientation. As a result, the expected brightness also has a large diversity. See Kawaguchi et al. [110] for the expected kilonova brightness for a wide parameter space.

##### 2.4. Wind Components

After the merger of two NSs, a hypermassive NS is formed at the center, and it subsequently collapses to a BH. During this process, accretion disk surrounding the central remnant is formed. A BH-accretion disk system is also formed in BH-NS mergers. From such accretion disk systems, an outflow or disk “wind” can be driven by neutrino heating, viscous heating, or nuclear recombination [56, 111–117]. A typical velocity of the wind is km s^{−1}, slower than the precedent dynamical ejecta. Although the ejecta mass largely depends on the ejection mechanism, a typical mass is likely an order of or even larger.

This wind component is another important source of kilonova emission [112, 113, 118–120]. The emission properties depend on the element composition in the ejecta. In particular, if a high electron fraction () is realized by the neutrino emission from a long-lived hypermassive NS [118, 119] or shock heating in the outflow [115], synthesis of lanthanide elements can be suppressed in the wind. Then, the resulting emission can be bluer than the emission from the dynamical ejecta thanks to the lower opacity [57, 90]. This component can be called “blue kilonova” [84].

To demonstrate the effect of the low opacity, we show a simple wind model in Figures 1 and 2. In this model, we adopt a spherical ejecta of with a density structure of from to (with the average velocity of km s^{−1}). The elements in the ejecta are assumed to be lanthanide-free: only the elements of are included with the solar abundance ratios. As shown by previous works [119], the emission from such a wind can peak earlier than that from the dynamical ejecta (Figure 1) and the emission is bluer (Figure 2).

Note that this simple model neglects the presence of the dynamical ejecta outside of the wind component. The effect of the dynamical ejecta is in fact important, because it works as a “lanthanide curtain” [119] absorbing the emission from the disk wind. Interestingly, as described in Section 2.2, the polar region of the dynamical ejecta can have a higher , and the “lanthanide curtain” may not be present in the direction. Also, in BH-NS mergers, the dynamical ejecta is distributed in the orbital plane, and disk wind can be directly observed from most of the lines of sight. If the wind component is dominant for kilonova emission and can be directly observed, the spectra are not as smooth as the spectra of dynamical ejecta because of the slower expansion [119]. More realistic simulations capturing all of these situations will be important to understand the emission from the disk wind.

#### 3. Lessons from Observations

Since short GRBs are believed to be driven by NS-NS mergers or BH-NS mergers (see, e.g., [6, 7]), models of kilonova can be tested by the observations of short GRBs. As well known, SN component has been detected in the afterglow of long GRBs (see [121, 122] for reviews). If kilonova emission occurs, the emission can be in principle visible on top of the afterglow, but such an emission had eluded the detection for long time [123].

In 2013, a clear excess emission was detected in the near-IR afterglow of GRB 130603B [67, 68]. Interestingly, the excess was not visible in the optical data. Since this behavior nicely agrees with the expected properties of kilonova, the excess is interpreted to be the kilonova emission.

Figure 4(a) shows kilonova models compared with the observations of GRB 130603B. The observed brightness of the near-IR excess in GRB 130603B requires a relatively large ejecta mass of [67, 68, 73, 124]. As pointed out by Hotokezaka et al. [124], this favors a soft EOS for a NS-NS merger model (i.e., more shock-driven ejection) and a stiff EOS for a BH-NS merger model (i.e., more tidally driven ejection). Another possibility to explain the brightness may be an additional emission from the disk wind (green line in Figure 4; see [118, 119]).

**(a)**

**(b)**

Note that the excess was detected only at one epoch in one filter. Therefore, other interpretations are also possible, for example, emission by the external shock [125] or by a central magnetar [126, 127], or thermal emission from newly formed dust [128]. Importantly, a late-time excess is also visible in X-ray [129], and thus, the near-IR and X-ray excesses might be caused by the same mechanism, possibly the central engine [130, 131].

Another interesting case is GRB 060614. This GRB was formally classified as a long GRB because the duration is about 100 sec. However, since no bright SN was accompanied, the origin was not clear [132–135]. Recently the existence of a possible excess in the optical afterglow was reported [69, 70]. Figure 4(b) shows the comparison between GRB 060614 and the same sets of the models. If this excess is caused by kilonova, a large ejecta mass of is required. This fact may favor a BH-NS merger scenario with a stiff EOS [69, 70]. It is however important to note that the emission from BH-NS merger has a large variation, and such an effective mass ejection requires a low BH/NS mass ratio and a high BH spin [110]. See also [136] for possible optical excess in GRB 050709, a genuine short GRB with a duration of 0.5 sec [137–140]. If the excess is attributed to kilonova, the required ejecta mass is .

Finally, an early brightening in optical data of GRB 080503 at days can also be attributed to kilonova [141] although the redshift of this object is unfortunately unknown. Kasen et al. [119] give a possible interpretation with the disk wind model. Note that a long-lasting X-ray emission was also detected in GRB 080503 at days, and it may favor a common mechanism for optical and X-ray emission [131, 142].

#### 4. Prospects for EM Follow-Up Observations of GW Sources

Figure 2 shows the expected brightness of compact binary merger models at 200 Mpc (left axis). All the models assume a canonical ejecta mass of , and therefore, the emission can be brighter or fainter depending on the merger parameters and the EOS (see Section 2). Keeping this caveat in mind, typical models suggest that the expected kilonova brightness at 200 Mpc is about 22 mag in red optical wavelengths (- or -bands) at days after the merger. The brightness quickly declines to >24 mag within days after the merger. To detect this emission, we ultimately need 8 m class telescopes. Currently the wide-field capability for 8 m class telescopes is available only at the 8.2 m Subaru telescope: Subaru/Hyper Suprime-Cam (HSC) has the field of view (FOV) of 1.77 deg^{2} [143, 144]. In future, the 8.4 m Large Synoptic Survey Telescope (LSST) with 9.6 deg^{2} FOV will be online [145, 146]. Note that targeted galaxy surveys are also effective to search for the transients associated with galaxies [147, 148].

It is again emphasized that the expected brightness of kilonova can have a large variety. If the kilonova candidates seen in GRB 130603B () and GRB 060614 () are typical cases (see Section 3), the emission can be brighter by ~1-2 mag. In addition, there are also possibilities of bright, precursor emission (e.g., [29, 130, 149]) which are not discussed in depth in this paper. And, of course, the emission is brighter for objects at closer distances. Therefore, surveys with small-aperture telescopes (typically with wider FOVs) are also important. See, for example, Nissanke et al. [13] and Kasliwal and Nissanke [16] for detailed survey simulations for various expected brightness of the EM counterpart.

A big challenge for identification of the GW source is contamination of SNe. NS-NS mergers and BH-NS mergers are rare events compared with SNe, and thus, much larger number of SNe are detected when optical surveys are performed over 10 deg^{2} (see [21–23] for the case of GW150914). Therefore, it is extremely important to effectively select the candidates of kilonova from a larger number of SNe.

To help the classification, color-magnitude and color-color diagrams for the kilonova models and Type Ia SNe are shown in Figure 5. The numbers attached with the models are days after the merger while dots for SNe are given with 5-day interval. According to the current understanding, the light curves of kilonova can be characterized as follows.(1)The timescale of variability should be shorter than that of SNe (Figure 2). This is robust since the ejecta mass from compact binary mergers is much smaller than SNe.(2)The emission is fainter than SNe. This is also robust because of the smaller ejecta mass and thus the lower available radioactive energy (Figure 1).(3)The emissions are expected to be redder than SNe. This is an outcome of a high opacity in the ejecta, but the exact color depends on the ejecta composition ([58, 90, 118, 119], Section 2).

**(a)**

**(b)**

Therefore, in order to effectively search for the EM counterpart of the GW source, multiple visits in a timescale of <10 days will be important so that the rapid time evolution can be captured. Surveys with multiple filters are also helpful to use color information. As shown in Figure 5, observed magnitudes of kilonovae at ~200 Mpc are similar to those of SNe at larger distances ( for Type Ia SNe). Therefore, if redshifts of the host galaxies are estimated, kilonova candidates can be further selected by the close distances and the intrinsic faintness.

#### 5. Summary

The direct detection of GWs from GW150914 opened GW astronomy. To study the astrophysical nature of the GW sources, the identification of the EM counterparts is essentially important. In this paper, we reviewed the current understanding of kilonova emission from compact binary mergers.

Kilonova emission from the dynamical ejecta of 0.01 has a typical luminosity is an order of with the characteristic timescale of about 1 week. Because of the high opacity and the low temperature, the spectral peak is located at red optical or near-IR wavelengths. In addition to the emission from the dynamical ejecta, a subsequent disk wind can cause an additional emission which may peak earlier with a bluer color if the emission is not absorbed by the precedent ejecta.

The detection of excess in GRB 130603B (and possibly GRB 060614) supports the kilonova scenario. If the excesses found in these objects are attributed to the kilonova emission, the required ejecta masses are and , respectively. The comparison between such observations and numerical simulations gives important insight to study the progenitor of compact binary mergers and EOS of NS.

At 200 Mpc distance, a typical peak brightness of kilonova emission is about 22 mag in the red optical wavelengths (- or -bands). The emission quickly fades to >24 mag within ~10 days. To distinguish GW sources from SNe, observations with multiple visits in a timescale of <10 days are important to select the objects with rapid temporal evolution. The use of multiple filters is also helpful to select red objects. Since the extremely high expansion velocities () are unique features of dynamical mass ejection from compact binary mergers, detection of extremely smooth spectrum will be the smoking gun to conclusively identify the GW sources.

#### Competing Interests

The author declares that there is no conflict of interests regarding the publication of this paper.

#### Acknowledgments

The author thanks Kenta Hotokezaka, Yuichiro Sekiguchi, Masaru Shibata, Kenta Kiuchi, Shinya Wanajo, Koutarou Kyutoku, Kyohei Kawaguchi, Keiichi Maeda, Takaya Nozawa, and Yutaka Hirai for fruitful discussion on compact binary mergers, nucleosynthesis, and kilonova emission. The author also thanks Nozomu Tominaga, Tomoki Morokuma, Michitoshi Yoshida, Kouji Ohta, and the J-GEM collaboration for valuable discussion on EM follow-up observations. Numerical simulations presented in this paper were carried out with Cray XC30 at Center for Computational Astrophysics, National Astronomical Observatory of Japan. This research has been supported by the Grant-in-Aid for Scientific Research of the Japan Society for the Promotion of Science (24740117, 15H02075) and Grant-in-Aid for Scientific Research on Innovative Areas of the Ministry of Education, Culture, Sports, Science and Technology (25103515, 15H00788).

#### References

- G. M. Harry and LIGO Scientific Collaboration, “Advanced LIGO: the next generation of gravitational wave detectors,”
*Classical and Quantum Gravity*, vol. 27, no. 8, Article ID 084006, 2010. View at: Publisher Site | Google Scholar | MathSciNet - B. P. Abbott, R. Abbott, T. D. Abbott et al. et al., “Observation of gravitational waves from a binary black hole merger,”
*Physical Review Letters*, vol. 116, no. 6, Article ID 061102, 2016. View at: Publisher Site | Google Scholar - S. I. Blinnikov, I. D. Novikov, T. V. Perevodchikova, and A. G. Polnarev, “Exploding neutron stars in close binaries,”
*Soviet Astronomy Letters*, vol. 10, no. 3, pp. 177–179, 1984. View at: Google Scholar - D. Eichler, M. Livio, T. Piran, and D. N. Schramm, “Nucleosynthesis, neutrino bursts and
*γ*-rays from coalescing neutron stars,”*Nature*, vol. 340, no. 6229, pp. 126–128, 1989. View at: Publisher Site | Google Scholar - B. Paczynski, “Gamma-ray bursters at cosmological distances,”
*The Astrophysical Journal*, vol. 308, pp. L43–L46, 1986. View at: Publisher Site | Google Scholar - E. Berger, “Short-duration gamma-ray bursts,”
*Annual Review of Astronomy and Astrophysics*, vol. 52, pp. 43–105, 2014. View at: Publisher Site | Google Scholar - E. Nakar, “Short-hard gamma-ray bursts,”
*Physics Reports*, vol. 442, no. 1–6, pp. 166–236, 2007. View at: Publisher Site | Google Scholar - F. Acernese, M. Agathos, K. Agatsuma et al. et al., “Focus issue: advanced interferometric gravitational wave detectors,”
*Classical and Quantum Gravity*, vol. 32, no. 2, Article ID 024001, 2015. View at: Google Scholar - K. Somiya, “Detector configuration of KAGRA–the Japanese cryogenic gravitational-wave detector,”
*Classical and Quantum Gravity*, vol. 29, no. 12, Article ID 124007, 2012. View at: Publisher Site | Google Scholar - J. Abadie, B. P. Abbott, R. Abbott et al., “Predictions for the rates of compact binary coalescences observable by ground-based gravitational-wave detectors,”
*Classical and Quantum Gravity*, vol. 27, Article ID 173001, 2010. View at: Publisher Site | Google Scholar - B. P. Abbott, R. Abbott, T. D. Abbott et al., “Prospects for observing and localizing gravitational-wave transients with advanced LIGO and advanced virgo,”
*Living Reviews in Relativity*, vol. 19, article 1, 2016. View at: Publisher Site | Google Scholar - L. Z. Kelley, I. Mandel, and E. Ramirez-Ruiz, “Electromagnetic transients as triggers in searches for gravitational waves from compact binary mergers,”
*Physical Review D*, vol. 87, no. 12, Article ID 123004, 16 pages, 2013. View at: Publisher Site | Google Scholar - S. Nissanke, M. Kasliwal, and A. Georgieva, “Identifying elusive electromagnetic counterparts to gravitational wave mergers: an end-to-end simulation,”
*The Astrophysical Journal*, vol. 767, no. 2, article 124, 2013. View at: Publisher Site | Google Scholar - S. Nissanke, J. Sievers, N. Dalal, and D. Holz, “Localizing compact binary inspirals on the sky using ground-based gravitational wave interferometers,”
*Astrophysical Journal*, vol. 739, no. 2, article 99, 2011. View at: Publisher Site | Google Scholar - R. Essick, S. Vitale, E. Katsavounidis, G. Vedovato, and S. Klimenko, “Localization of short duration gravitational-wave transients with the early advanced ligo and virgo detectors,”
*Astrophysical Journal*, vol. 800, no. 2, article 81, 2015. View at: Publisher Site | Google Scholar - M. M. Kasliwal and S. Nissanke, “On discovering electromagnetic emission from neutron star mergers: the early years of two gravitational wave detectors,”
*The Astrophysical Journal Letters*, vol. 789, no. 1, article L5, 2014. View at: Publisher Site | Google Scholar - L. P. Singer, L. R. Price, B. Farr et al., “The first two years of electromagnetic follow-up with advanced ligo and virgo,”
*Astrophysical Journal*, vol. 795, no. 2, article 105, 2014. View at: Publisher Site | Google Scholar - The LIGO Scientific Collaboration and the Virgo Collaboration, “Properties of the binary black hole merger GW150914,” 2016, https://arxiv.org/abs/1602.03840. View at: Google Scholar
- B. P. Abbott, R. Abbott, T. D. Abbott et al., “Localization and broadband follow-up of the gravitational-wave transient GW150914,” 2016, https://arxiv.org/abs/1602.08492. View at: Google Scholar
- P. A. Evans, J. A. Kennea, S. D. Barthelmy et al., “
*Swift*follow-up of the gravitational wave source GW150914,”*MNRAS Letters*, vol. 460, no. 1, pp. L40–L44, 2016. View at: Publisher Site | Google Scholar - M. M. Kasliwal, S. B. Cenko, L. P. Singer et al., “iPTF search for an optical counterpart to gravitational wave trigger GW150914,” http://arxiv.org/abs/1602.08764. View at: Google Scholar
- S. J. Smartt, K. C. Chambers, K. W. Smith et al., “Pan-STARRS and PESSTO search for the optical counterpart to the LIGO gravitational wave source GW150914,” http://arxiv.org/abs/1602.04156. View at: Google Scholar
- M. Soares-Santos, R. Kessler, E. Berger et al., “A dark energy camera search for an optical counterpart to the first advanced LIGO gravitational wave event GW150914,” http://arxiv.org/abs/1602.04198. View at: Google Scholar
- T. Morokuma, M. Tanaka, Y. Asakura et al., “J-GEM follow-up observations to search for an optical counterpart of the first gravitational wave source GW150914,” http://arxiv.org/abs/1605.03216. View at: Google Scholar
- E. Nakar and T. Piran, “Detectable radio flares following gravitational waves from mergers of binary neutron stars,”
*Nature*, vol. 478, no. 7367, pp. 82–84, 2011. View at: Publisher Site | Google Scholar - T. Piran, E. Nakar, and S. Rosswog, “The electromagnetic signals of compact binary mergers,”
*Monthly Notices of the Royal Astronomical Society*, vol. 430, no. 3, pp. 2121–2136, 2013. View at: Publisher Site | Google Scholar - K. Hotokezaka and T. Piran, “Mass ejection from neutron star mergers: different components and expected radio signals,”
*Monthly Notices of the Royal Astronomical Society*, vol. 450, no. 2, pp. 1430–1440, 2015. View at: Publisher Site | Google Scholar - T. Nakamura, K. Kashiyama, D. Nakauchi, Y. Suwa, T. Sakamoto, and N. Kawai, “Soft X-ray extended emissions of short gamma-ray bursts as electromagnetic counterparts of compact binary mergers: possible origin and detectability,”
*Astrophysical Journal*, vol. 796, no. 1, article 13, 2014. View at: Publisher Site | Google Scholar - B. D. Metzger and A. L. Piro, “Optical and X-ray emission from stable millisecond magnetars formed from the merger of binary neutron stars,”
*Monthly Notices of the Royal Astronomical Society*, vol. 439, no. 4, pp. 3916–3930, 2014. View at: Publisher Site | Google Scholar - S. Kisaka, K. Ioka, and T. Nakamura, “Isotropic detectable X-ray counterparts to gravitational waves from neutron star binary mergers,”
*The Astrophysical Journal Letters*, vol. 809, article L8, 2015. View at: Publisher Site | Google Scholar - D. M. Siegel and R. Ciolfi, “Electromagnetic emission from long-lived binary neutron star merger remnants. II. light curves and spectra,”
*The Astrophysical Journal*, vol. 819, no. 1, p. 15, 2016. View at: Publisher Site | Google Scholar - L.-X. Li and B. Paczyński, “Transient events from neutron star mergers,”
*The Astrophysical Journal*, vol. 507, no. 1, pp. L59–L62, 1998. View at: Publisher Site | Google Scholar - S. R. Kulkarni, “Modeling supernova-like explosions associated with gamma-ray bursts with short durations,” 2005, http://arxiv.org/abs/astro-ph/0510256. View at: Google Scholar
- B. D. Metzger, G. Martínez-Pinedo, S. Darbha et al., “Electromagnetic counterparts of compact object mergers powered by the radioactive decay of
*r*-process nuclei,”*Monthly Notices of the Royal Astronomical Society*, vol. 406, no. 4, pp. 2650–2662, 2010. View at: Publisher Site | Google Scholar - L. F. Roberts, D. Kasen, W. H. Lee, and E. Ramirez-Ruiz, “Electromagnetic transients powered by nuclear decay in the tidal tails of coalescing compact binaries,”
*The Astrophysical Journal Letters*, vol. 736, no. 1, article L21, 2011. View at: Publisher Site | Google Scholar - S. Goriely, A. Bauswein, and H.-T. Janka, “R-process nucleosynthesis in dynamically ejected matter of neutron star mergers,”
*Astrophysical Journal Letters*, vol. 738, no. 2, article L32, 2011. View at: Publisher Site | Google Scholar - B. D. Metzger and E. Berger, “What is the most promising electromagnetic counterpart of a neutron star binary merger?”
*The Astrophysical Journal*, vol. 746, no. 1, p. 48, 2012. View at: Publisher Site | Google Scholar - M. Shibata and K. Uryū, “Simulation of merging binary neutron stars in full general relativity: $\Gamma =2$ case,”
*Physical Review D*, vol. 61, no. 6, Article ID 064001, 18 pages, 2000. View at: Publisher Site | Google Scholar - M. Shibata, K. Taniguchi, and K. Uryū, “Merger of binary neutron stars with realistic equations of state in full general relativity,”
*Physical Review D*, vol. 71, no. 8, Article ID 084021, 2005. View at: Publisher Site | Google Scholar - M. D. Duez, “Numerical relativity confronts compact neutron star binaries: a review and status report,”
*Classical and Quantum Gravity*, vol. 27, no. 11, Article ID 114002, 2010. View at: Publisher Site | Google Scholar - J. A. Faber and F. A. Rasio, “Binary neutron star mergers,”
*Living Reviews in Relativity*, vol. 15, article 8, 2012. View at: Publisher Site | Google Scholar - S. Rosswog, M. Liebendörfer, F.-K. Thielemann, M. B. Davies, W. Benz, and T. Piran, “Mass ejection in neutron star mergers,”
*Astronomy and Astrophysics*, vol. 341, no. 2, pp. 499–526, 1999. View at: Google Scholar - S. Rosswog, M. B. Davies, F.-K. Thielemann, and T. Piran, “Merging neutron stars: asymmetric systems,”
*Astronomy & Astrophysics*, vol. 360, pp. 171–184, 2000. View at: Google Scholar - M. Ruffert and H.-T. Janka, “Coalescing neutron stars—a step towards physical models III. Improved numerics and different neutron star masses and spins,”
*Astronomy and Astrophysics*, vol. 380, no. 2, pp. 544–577, 2001. View at: Publisher Site | Google Scholar - S. Rosswog, “Mergers of neutron star-black hole binaries with small mass ratios: nucleosynthesis, gamma-ray bursts, and electromagnetic transients,”
*Astrophysical Journal*, vol. 634, no. 2, pp. 1202–1213, 2005. View at: Publisher Site | Google Scholar - W. H. Lee and E. Ramirez-Ruiz, “The progenitors of short gamma-ray bursts,”
*New Journal of Physics*, vol. 9, article A17, 2007. View at: Publisher Site | Google Scholar - S. Rosswog, “The dynamic ejecta of compact object mergers and eccentric collisions,”
*Royal Society of London Philosophical Transactions Series A*, vol. 371, no. 1992, Article ID 20272, 2013. View at: Publisher Site | Google Scholar - K. Hotokezaka, K. Kiuchi, K. Kyutoku et al., “Mass ejection from the merger of binary neutron stars,”
*Physical Review D—Particles, Fields, Gravitation and Cosmology*, vol. 87, no. 2, Article ID 024001, 2013. View at: Publisher Site | Google Scholar - A. Bauswein, S. Goriely, and H.-T. Janka, “Systematics of dynamical mass ejection, nucleosynthesis, and radioactively powered electromagnetic signals from neutron-star mergers,”
*Astrophysical Journal*, vol. 773, no. 1, article 78, 2013. View at: Publisher Site | Google Scholar - J. M. Lattimer and D. N. Schramm, “Black-hole-neutron-star collisions,”
*Astrophysical Journal*, vol. 192, part 2, pp. L145–L147, 1974. View at: Google Scholar - J. M. Lattimer and D. N. Schramm, “The tidal disruption of neutron stars by black holes in close binaries,”
*The Astrophysical Journal*, vol. 210, pp. 549–567, 1976. View at: Publisher Site | Google Scholar - C. Freiburghaus, S. Rosswog, and F.-K. Thielemann, “
*r*-process in neutron star mergers,”*The Astrophysical Journal*, vol. 525, no. 2, pp. L121–L124, 1999. View at: Publisher Site | Google Scholar - O. Korobkin, S. Rosswog, A. Arcones, and C. Winteler, “On the astrophysical robustness of the neutron star merger r-process,”
*Monthly Notices of the Royal Astronomical Society*, vol. 426, no. 3, pp. 1940–1949, 2012. View at: Publisher Site | Google Scholar - S. Wanajo, Y. Sekiguchi, N. Nishimura, K. Kiuchi, K. Kyutoku, and M. Shibata, “Production of all the r-process nuclides in the dynamical ejecta of neutron star mergers,”
*The Astrophysical Journal Letters*, vol. 789, no. 2, article L39, 2014. View at: Publisher Site | Google Scholar - J. de Jesús Mendoza-Temis, M.-R. Wu, K. Langanke, G. Martínez-Pinedo, A. Bauswein, and H.-T. Janka, “Nuclear robustness of the
*r*process in neutron-star mergers,”*Physical Review C*, vol. 92, no. 5, Article ID 055805, 16 pages, 2015. View at: Publisher Site | Google Scholar - O. Just, A. Bauswein, R. A. Pulpillo, S. Goriely, and H. T. Janka, “Comprehensive nucleosynthesis analysis for ejecta of compact binary mergers,”
*Monthly Notices of the Royal Astronomical Society*, vol. 448, no. 1, pp. 541–567, 2015. View at: Publisher Site | Google Scholar - M. Tanaka and K. Hotokezaka, “Radiative transfer simulations of neutron star merger ejecta,”
*The Astrophysical Journal*, vol. 775, no. 2, article 113, 2013. View at: Publisher Site | Google Scholar - M. Tanaka, K. Hotokezaka, K. Kyutoku et al., “Radioactively powered emission from black hole-neutron star mergers,”
*Astrophysical Journal*, vol. 780, no. 1, article 31, 2014. View at: Publisher Site | Google Scholar - K. Kyutoku, K. Ioka, and M. Shibata, “Anisotropic mass ejection from black hole-neutron star binaries: diversity of electromagnetic counterparts,”
*Physical Review D*, vol. 88, no. 4, Article ID 041503, 2013. View at: Publisher Site | Google Scholar - A. Pastorello, S. Taubenberger, N. Elias-Rosa et al., “ESC observations of SN 2005cf -I. Photometric evolution of a normal Type Ia supernova,”
*Monthly Notices of the Royal Astronomical Society*, vol. 376, no. 3, pp. 1301–1316, 2007. View at: Publisher Site | Google Scholar - G. Garavini, S. Nobili, S. Taubenberger et al., “ESC observations of SN 2005cf. II. Optical spectroscopy and the high-velocity features,”
*Astronomy & Astrophysics*, vol. 471, no. 2, pp. 527–535, 2007. View at: Publisher Site | Google Scholar - X. Wang, W. Li, A. V. Filippenko et al., “The golden standard type ia supernova 2005cf: observations from the ultraviolet to the near-infrared wavebands,”
*The Astrophysical Journal*, vol. 697, no. 1, pp. 380–408, 2009. View at: Publisher Site | Google Scholar - K. Iwamoto, P. A. Mazzali, K. Nomoto et al., “A hypernova model for the supernova associated with the
*γ*-ray burst of 25 April 1998,”*Nature*, vol. 395, no. 6703, pp. 672–674, 1998. View at: Publisher Site | Google Scholar - K. Iwamoto, P. A. Mazzali, K. Nomoto et al., “A hypernova model for the supernova associated with the
*γ*-ray burst of 25 April 1998,”*Nature*, vol. 395, no. 6703, pp. 672–674, 1998. View at: Publisher Site | Google Scholar - N. K. Glendenning and S. A. Moszkowski, “Reconciliation of neutron-star masses and binding of the Λ in hypernuclei,”
*Physical Review Letters*, vol. 67, p. 2414, 1991. View at: Publisher Site | Google Scholar - B. D. Lackey, M. Nayyar, and B. J. Owen, “Observational constraints on hyperons in neutron stars,”
*Physical Review D*, vol. 73, no. 2, Article ID 024021, 2006. View at: Publisher Site | Google Scholar - N. R. Tanvir, A. J. Levan, A. S. Fruchter et al., “A ‘kilonova’ associated with the short-duration
*γ*-ray burst GRB 130603B,”*Nature*, vol. 500, no. 7464, pp. 547–549, 2013. View at: Publisher Site | Google Scholar - E. Berger, W. Fong, and R. Chornock, “An r-process kilonova associated with the short-hard GRB 130603B,”
*The Astrophysical Journal Letters*, vol. 774, no. 2, article L23, 2013. View at: Publisher Site | Google Scholar - B. Yang, Z.-P. Jin, X. Li et al., “A possible macronova in the late afterglow of the long-short burst GRB 060614,”
*Nature Communications*, vol. 6, article 7323, 2015. View at: Publisher Site | Google Scholar - Z.-P. Jin, X. Li, Z. Cano, S. Covino, Y.-Z. Fan, and D.-M. Wei, “The light curve of the macronova associated with the long-short burst GRB 060614,”
*Astrophysical Journal Letters*, vol. 811, no. 2, article L22, 2015. View at: Publisher Site | Google Scholar - P. Nugent, A. Kim, and S. Perlmutter, “K-corrections and extinction corrections for type Ia supernovae,”
*Publications of the Astronomical Society of the Pacific*, vol. 114, no. 798, pp. 803–819, 2002. View at: Publisher Site | Google Scholar - D. Argast, M. Samland, F.-K. Thielemann, and Y.-Z. Qian, “Neutron star mergers versus core-collapse supernovae as dominant r-process sites in the early Galaxy,”
*Astronomy and Astrophysics*, vol. 416, no. 3, pp. 997–1011, 2004. View at: Publisher Site | Google Scholar - T. Piran, O. Korobkin, and S. Rosswog, “Implications of GRB 130603B and its macronova for r-process nucleosynthesis,” http://arxiv.org/abs/1401.2166. View at: Google Scholar
- F. Matteucci, D. Romano, A. Arcones, O. Korobkin, and S. Rosswog, “Europium production: neutron star mergers versus core-collapse supernovae,”
*Monthly Notices of the Royal Astronomical Society*, vol. 438, no. 3, Article ID stt2350, pp. 2177–2185, 2014. View at: Publisher Site | Google Scholar - T. Tsujimoto and T. Shigeyama, “Enrichment history of r-process elements shaped by a merger of neutron star pairs,”
*Astronomy and Astrophysics*, vol. 565, article L5, 2014. View at: Publisher Site | Google Scholar - Y. Komiya, S. Yamada, T. Suda, and M. Y. Fujimoto, “The new model of chemical evolution of
*r*-process elements based on the hierarchical galaxy formation. I. Ba and Eu,”*The Astrophysical Journal*, vol. 783, no. 2, p. 132, 2014. View at: Publisher Site | Google Scholar - G. Cescutti, D. Romano, F. Matteucci, C. Chiappini, and R. Hirschi, “The role of neutron star mergers in the chemical evolution of the Galactic halo,”
*Astronomy & Astrophysics*, vol. 577, article A139, 10 pages, 2015. View at: Publisher Site | Google Scholar - B. Wehmeyer, M. Pignatari, and F.-K. Thielemann, “Galactic evolution of rapid neutron capture process abundances: the inhomogeneous approach,”
*Monthly Notices of the Royal Astronomical Society*, vol. 452, no. 2, pp. 1970–1981, 2015. View at: Publisher Site | Google Scholar - Y. Ishimaru, S. Wanajo, and N. Prantzos, “Neutron star mergers as the origin of r-process elements in the galactic halo based on the sub-halo clustering scenario,”
*The Astrophysical Journal Letters*, vol. 804, no. 2, article L35, 2015. View at: Publisher Site | Google Scholar - S. Shen, R. J. Cooke, E. Ramirez-Ruiz, P. Madau, L. Mayer, and J. Guedes, “The history of r-process enrichment in the milky way,”
*Astrophysical Journal*, vol. 807, no. 2, article 115, 2015. View at: Publisher Site | Google Scholar - F. van de Voort, E. Quataert, P. F. Hopkins, D. Kereš, and C. Faucher-Giguere, “Galactic r-process enrichment by neutron star mergers in cosmological simulations of a Milky Way-mass galaxy,”
*Monthly Notices of the Royal Astronomical Society*, vol. 447, no. 1, pp. 140–148, 2015. View at: Publisher Site | Google Scholar - Y. Hirai, Y. Ishimaru, T. R. Saitoh, M. S. Fujii, J. Hidaka, and T. Kajino, “Enrichment of r-process elements in dwarf spheroidal galaxies in chemo-dynamical evolution model,”
*The Astrophysical Journal*, vol. 814, no. 1, p. 41, 2015. View at: Publisher Site | Google Scholar - S. Rosswog, “The multi-messenger picture of compact binary mergers,”
*International Journal of Modern Physics. D. Gravitation, Astrophysics, Cosmology*, vol. 24, no. 5, Article ID 1530012, 2015. View at: Publisher Site | Google Scholar | MathSciNet - R. Fernández and B. D. Metzger, “Electromagnetic signatures of neutron star mergers in the advanced LIGO era,” 2015, http://arxiv.org/abs/1512.05435. View at: Google Scholar
- W. D. Arnett, “Type I supernovae. I—analytic solutions for the early part of the light curve,”
*The Astrophysical Journal*, vol. 253, no. 2, pp. 785–797, 1982. View at: Publisher Site | Google Scholar - S. Rosswog, O. Korobkin, A. Arcones, F.-K. Thielemann, and T. Piran, “The long-term evolution of neutron star merger remnants—I. The impact of r-process nucleosynthesis,”
*Monthly Notices of the Royal Astronomical Society*, vol. 439, no. 1, pp. 744–756, 2014. View at: Publisher Site | Google Scholar - D. Grossman, O. Korobkin, S. Rosswog, and T. Piran, “The long-term evolution of neutron star merger remnants—II. Radioactively powered transients,”
*Monthly Notices of the Royal Astronomical Society*, vol. 439, no. 1, pp. 757–770, 2014. View at: Publisher Site | Google Scholar - J. Lippuner and L. F. Roberts, “r-Process lanthanide production and heating rates in kilonovae,”
*The Astrophysical Journal*, vol. 815, no. 2, p. 82, 2015. View at: Publisher Site | Google Scholar - K. Hotokezaka, S. Wanajo, M. Tanaka, A. Bamba, Y. Terada, and T. Piran, “Radioactive decay products in neutron star merger ejecta: heating efficiency and
*γ*-ray emission,”*Monthly Notices of the Royal Astronomical Society*, vol. 459, no. 1, pp. 35–43, 2016. View at: Publisher Site | Google Scholar - D. Kasen, N. R. Badnell, and J. Barnes, “Opacities and spectra of the r-process ejecta from neutron star mergers,”
*Astrophysical Journal*, vol. 774, no. 1, article 25, 2013. View at: Publisher Site | Google Scholar - J. Barnes and D. Kasen, “Effect of a high opacity on the light curves of radioactively powered transients from compact object mergers,”
*The Astrophysical Journal*, vol. 775, no. 1, p. 18, 2013. View at: Publisher Site | Google Scholar - D. Radice, F. Galeazzi, J. Lippuner, L. F. Roberts, C. D. Ott, and L. Rezzolla, “Dynamical mass ejection from binary neutron star mergers,” 2016, http://arxiv.org/abs/1601.02426. View at: Google Scholar
- S. Rosswog, T. Piran, and E. Nakar, “The multimessenger picture of compact object encounters: binary mergers versus dynamical collisions,”
*Monthly Notices of the Royal Astronomical Society*, vol. 430, no. 4, pp. 2585–2604, 2013. View at: Publisher Site | Google Scholar - C. Palenzuela, S. L. Liebling, D. Neilsen et al., “Effects of the microphysical equation of state in the mergers of magnetized neutron stars with neutrino cooling,”
*Physical Review D*, vol. 92, no. 4, Article ID 044045, 23 pages, 2015. View at: Publisher Site | Google Scholar - Y. Sekiguchi, K. Kiuchi, K. Kyutoku, and M. Shibata, “Dynamical mass ejection from binary neutron star mergers: radiation-hydrodynamics study in general relativity,”
*Physical Review D*, vol. 91, no. 5, Article ID 064059, 2015. View at: Publisher Site | Google Scholar - Y. Sekiguchi, K. Kiuchi, K. Kyutoku, M. Shibata, and K. Taniguchi, “Dynamical mass ejection from the merger of asymmetric binary neutron stars: radiation-hydrodynamics study in general relativity,” http://arxiv.org/abs/1603.01918. View at: Google Scholar
- A. Akmal, V. R. Pandharipande, and D. G. Ravenhall, “Equation of state of nucleon matter and neutron star structure,”
*Physical Review C—Nuclear Physics*, vol. 58, no. 3, pp. 1804–1828, 1998. View at: Publisher Site | Google Scholar - M. Shibata and K. Taniguchi, “Coalescence of black hole-neutron star binaries,”
*Living Reviews in Relativity*, vol. 14, article 6, 2011. View at: Publisher Site | Google Scholar - M. Shibata and K. Taniguchi, “Merger of binary neutron stars to a black hole: Disk mass, short gamma-ray bursts, and quasinormal mode ringing,”
*Physical Review D*, vol. 73, Article ID 064027, 2006. View at: Publisher Site | Google Scholar - Z. B. Etienne, J. A. Faber, Y. T. Liu, S. L. Shapiro, K. Taniguchi, and T. W. Baumgarte, “Fully general relativistic simulations of black hole-neutron star mergers,”
*Physical Review D*, vol. 77, no. 8, Article ID 084002, 2008. View at: Publisher Site | Google Scholar - M. D. Duez, F. Foucart, L. E. Kidder, H. P. Pfeiffer, M. A. Scheel, and S. A. Teukolsky, “Evolving black hole-neutron star binaries in general relativity using pseudospectral and finite difference methods,”
*Physical Review D—Particles, Fields, Gravitation and Cosmology*, vol. 78, no. 10, Article ID 104015, 2008. View at: Publisher Site | Google Scholar - K. Kyutoku, M. Shibata, and K. Taniguchi, “Gravitational waves from nonspinning black hole-neutron star binaries: dependence on equations of state,”
*Physical Review D*, vol. 82, Article ID 044049, 2010. View at: Publisher Site | Google Scholar - K. Kyutoku, H. Okawa, M. Shibata, and K. Taniguchi, “Gravitational waves from spinning black hole-neutron star binaries: dependence on black hole spins and on neutron star equations of state,”
*Physical Review D*, vol. 84, no. 6, Article ID 064018, 2011. View at: Publisher Site | Google Scholar - M. B. Deaton, M. D. Duez, F. Foucart et al., “Black hole-neutron star mergers with a hot nuclear equation of state: outflow and neutrino-cooled disk for a low-mass, high-spin case,”
*Astrophysical Journal*, vol. 776, no. 1, article 47, 2013. View at: Publisher Site | Google Scholar - F. Foucart, M. B. Deaton, M. D. Duez et al., “Black-hole-neutron-star mergers at realistic mass ratios: equation of state and spin orientation effects,”
*Physical Review D—Particles, Fields, Gravitation and Cosmology*, vol. 87, no. 8, Article ID 084006, 2013. View at: Publisher Site | Google Scholar - G. Lovelace, M. D. Duez, F. Foucart et al., “Massive disc formation in the tidal disruption of a neutron star by a nearly extremal black hole,”
*Classical and Quantum Gravity*, vol. 30, no. 13, Article ID 135004, 2013. View at: Publisher Site | Google Scholar | MathSciNet - F. Foucart, M. B. Deaton, M. D. Duez et al., “Neutron star-black hole mergers with a nuclear equation of state and neutrino cooling: dependence in the binary parameters,”
*Physical Review D*, vol. 90, no. 2, Article ID 024026, 2014. View at: Publisher Site | Google Scholar - K. Kyutoku, K. Ioka, H. Okawa, M. Shibata, and K. Taniguchi, “Dynamical mass ejection from black hole-neutron star binaries,”
*Physical Review D—Particles, Fields, Gravitation and Cosmology*, vol. 92, no. 4, Article ID 044028, 2015. View at: Publisher Site | Google Scholar - K. Kawaguchi, K. Kyutoku, H. Nakano, H. Okawa, M. Shibata, and K. Taniguchi, “Black hole-neutron star binary merger: dependence on black hole spin orientation and equation of state,”
*Physical Review D*, vol. 92, no. 2, Article ID 024014, 2015. View at: Publisher Site | Google Scholar - K. Kawaguchi, K. Kyutoku, M. Shibata, and M. Tanaka, “Models of Kilonova/macronova emission from black hole-neutron star mergers,” http://arxiv.org/abs/1601.07711. View at: Google Scholar
- L. Dessart, C. D. Ott, A. Burrows, S. Rosswog, and E. Livne, “Neutrino signatures and the neutrino-driven wind in binary neutron star mergers,”
*Astrophysical Journal*, vol. 690, no. 2, pp. 1681–1705, 2009. View at: Publisher Site | Google Scholar - R. Fernández and B. D. Metzger, “Delayed outflows from black hole accretion tori following neutron star binary coalescence,”
*Monthly Notices of the Royal Astronomical Society*, vol. 435, no. 1, p. 502, 2013. View at: Publisher Site | Google Scholar - A. Perego, S. Rosswog, R. M. Cabezón et al., “Neutrino-driven winds from neutron star merger remnants,”
*Monthly Notices of the Royal Astronomical Society*, vol. 443, no. 4, pp. 3134–3156, 2014. View at: Publisher Site | Google Scholar - K. Kiuchi, K. Kyutoku, Y. Sekiguchi, M. Shibata, and T. Wada, “High resolution numerical relativity simulations for the merger of binary magnetized neutron stars,”
*Physical Review D—Particles, Fields, Gravitation and Cosmology*, vol. 90, no. 4, Article ID 041502, 2014. View at: Publisher Site | Google Scholar - K. Kiuchi, Y. Sekiguchi, K. Kyutoku, M. Shibata, K. Taniguchi, and T. Wada, “High resolution magnetohydrodynamic simulation of black hole-neutron star merger: mass ejection and short gamma ray bursts,”
*Physical Review D*, vol. 92, no. 6, Article ID 064034, 8 pages, 2015. View at: Publisher Site | Google Scholar - R. Fern, D. Kasen, B. D. Metzger, and E. Quataert, “Outflows from accretion discs formed in neutron star mergers: effect of black hole spin,”
*Monthly Notices of the Royal Astronomical Society*, vol. 446, no. 1, pp. 750–758, 2015. View at: Publisher Site | Google Scholar - R. Fernández, E. Quataert, J. Schwab, D. Kasen, and S. Rosswog, “The interplay of disc wind and dynamical ejecta in the aftermath of neutron star-black hole mergers,”
*Monthly Notices of the Royal Astronomical Society*, vol. 449, no. 1, pp. 390–402, 2015. View at: Publisher Site | Google Scholar - B. D. Metzger and R. Fernández, “Red or blue? A potential kilonova imprint of the delay until black hole formation following a neutron star merger,”
*Monthly Notices of the Royal Astronomical Society*, vol. 441, no. 4, pp. 3444–3453, 2014. View at: Publisher Site | Google Scholar - D. Kasen, R. Fernández, and B. D. Metzger, “Kilonova light curves from the disc wind outflows of compact object mergers,”
*Monthly Notices of the Royal Astronomical Society*, vol. 450, no. 2, pp. 1777–1786, 2015. View at: Publisher Site | Google Scholar - D. Martin, A. Perego, A. Arcones, F.-K. Thielemann, O. Korobkin, and S. Rosswog, “Neutrino-driven winds in the aftermath of a neutron star merger: nucleosynthesis and electromagnetic transients,”
*The Astrophysical Journal*, vol. 813, no. 1, p. 2, 2015. View at: Publisher Site | Google Scholar - S. E. Woosley and J. S. Bloom, “The supernova-gamma-ray burst connection,”
*Annual Review of Astronomy and Astrophysics*, vol. 44, pp. 507–556, 2006. View at: Publisher Site | Google Scholar - Z. Cano, S.-Q. Wang, Z.-G. Dai, and X.-F. Wu, “The observer's guide to the gamma-ray burst-supernova connection,” https://arxiv.org/abs/1604.03549. View at: Google Scholar
- D. A. Kann, S. Klose, B. Zhang et al., “The afterglows of
*Swift*-era gamma-ray bursts. II. Type I GRB versus type II GRB optical afterglows,”*The Astrophysical Journal*, vol. 734, no. 2, article 96, 2011. View at: Publisher Site | Google Scholar - K. Hotokezaka, K. Kyutoku, M. Tanaka et al., “Progenitor models of the electromagnetic transient associated with the short gamma ray burst 130603B,”
*Astrophysical Journal Letters*, vol. 778, no. 1, article L16, 2013. View at: Publisher Site | Google Scholar - Z.-P. Jin, D. Xu, Y.-Z. Fan, X.-F. Wu, and D.-M. Wei, “Is the late near-infrared bump in short-hard grb 130603B due to the Li-Paczynski kilonova?”
*The Astrophysical Journal*, vol. 775, no. 1, p. L19, 2013. View at: Publisher Site | Google Scholar - Y.-W. Yu, B. Zhang, and H. Gao, “Bright “Merger-nova” from the remnant of a neutron star binary merger: a signature of a newly born, massive, millisecond magnetar,”
*The Astrophysical Journal*, vol. 776, no. 2, p. L40, 2013. View at: Publisher Site | Google Scholar - Y.-Z. Fan, Y.-W. Yu, D. Xu et al., “A supramassive magnetar central engine for GRB 130603B,”
*The Astrophysical Journal*, vol. 779, no. 2, p. L25, 2013. View at: Publisher Site | Google Scholar - H. Takami, T. Nozawa, and K. Ioka, “Dust formation in macronovae,”
*The Astrophysical Journal Letters*, vol. 789, article L6, 2014. View at: Publisher Site | Google Scholar - W. Fong, E. Berger, B. D. Metzger et al., “Short GRB 130603B: discovery of a jet break in the optical and radio afterglows, and a mysterious late-time X-ray excess,”
*Astrophysical Journal*, vol. 780, no. 2, article 118, 2014. View at: Publisher Site | Google Scholar - S. Kisaka, K. Ioka, and H. Takami, “Energy sources and light curves of macronovae,”
*Astrophysical Journal*, vol. 802, no. 2, article 119, 2015. View at: Publisher Site | Google Scholar - S. Kisaka, K. Ioka, and E. Nakar, “X-ray-powered macronovae,”
*The Astrophysical Journal*, vol. 818, no. 2, p. 104, 2016. View at: Publisher Site | Google Scholar - N. Gehrels, J. P. Norris, S. D. Barthelmy et al., “A new
*γ*-ray burst classification scheme from GRB 060614,”*Nature*, vol. 444, no. 7122, pp. 1044–1046, 2006. View at: Publisher Site | Google Scholar - J. P. U. Fynbo, D. Watson, C. C. Thöne et al., “No supernovae associated with two long-duration
*γ*-ray bursts,”*Nature*, vol. 444, no. 7122, pp. 1047–1049, 2006. View at: Publisher Site | Google Scholar - M. D. Valle, G. Chincarini, N. Panagia et al., “An enigmatic long-lasting
*γ*-ray burst not accompanied by a bright supernova,”*Nature*, vol. 444, no. 7122, pp. 1050–1052, 2006. View at: Publisher Site | Google Scholar - A. Gal-Yam, D. B. Fox, P. A. Price et al., “A novel explosive process is required for the
*γ*-ray burst GRB 060614,”*Nature*, vol. 444, no. 7122, pp. 1053–1055, 2006. View at: Publisher Site | Google Scholar - Z.-P. Jin, K. Hotokezaka, X. Li et al., “The 050709 macronova and the GRB/macronova connection,” https://arxiv.org/abs/1603.07869. View at: Google Scholar
- J. S. Villasenor, D. Q. Lamb, G. R. Ricker et al., “Discovery of the short
*γ*-ray burst GRB 050709,”*Nature*, vol. 437, no. 7060, pp. 855–858, 2005. View at: Publisher Site | Google Scholar - J. Hjorth, D. Watson, J. P. U. Fynbo et al., “The optical afterglow of the short
*γ*-ray burst GRB 050709,”*Nature*, vol. 437, no. 7060, pp. 859–861, 2005. View at: Publisher Site | Google Scholar - D. B. Fox, D. A. Frail, P. A. Price et al., “The afterglow of GRB 050709 and the nature of the short-hard
*γ*-ray bursts,”*Nature*, vol. 437, no. 7060, pp. 845–850, 2005. View at: Publisher Site | Google Scholar - S. Covino, D. Malesani, G. L. Israel et al., “Optical emission from GRB 050709: a short/hard GRB in a star-forming galaxy,”
*Astronomy & Astrophysics*, vol. 447, no. 2, pp. L5–L8, 2006. View at: Publisher Site | Google Scholar - D. A. Perley, B. D. Metzger, J. Granot et al., “GRB 080503: implications of a naked short gamma-ray burst dominated by extended emission,”
*Astrophysical Journal*, vol. 696, no. 2, pp. 1871–1885, 2009. View at: Publisher Site | Google Scholar - H. Gao, X. Ding, X.-F. Wu, Z.-G. Dai, and B. Zhang, “GRB 080503 late afterglow re-brightening: signature of a magnetar-powered merger-nova,”
*The Astrophysical Journal*, vol. 807, no. 2, p. 163, 2015. View at: Publisher Site | Google Scholar - S. Miyazaki, Y. Komiyama, H. Nakaya et al., “HyperSuprime: project overview,” in
*Ground-based and Airborne Instrumentation for Astronomy*, vol. 6269 of*Proceedings of SPIE*, May 2006. View at: Publisher Site | Google Scholar - S. Miyazaki, Y. Komiyama, H. Nakaya et al., “Hyper suprime-cam,” in
*Ground-based and Airborne Instrumentation for Astronomy IV*, vol. 8446 of*Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series*, 2012. View at: Google Scholar - Z. Ivezic, J. A. Tyson, E. Acosta et al., “LSST: from science drivers to reference design and anticipated data products,” 2008, https://arxiv.org/abs/0805.2366. View at: Google Scholar
- P. A. Abell, J. Allison, S. F. Anderson et al., “LSST science book, version 2.0,” http://arxiv.org/abs/0912.0201. View at: Google Scholar
- N. Gehrels, J. K. Cannizzo, J. Kanner, M. M. Kasliwal, S. Nissanke, and L. P. Singer, “Galaxy strategy for ligo-virgo gravitational wave counterpart searches,”
*The Astrophysical Journal*, vol. 820, no. 2, p. 136, 2016. View at: Publisher Site | Google Scholar - L. P. Singer, H.-Y. Chen, D. E. Holz et al., “Going the distance: mapping host galaxies of LIGO and virgo sources in three dimensions using local cosmography and targeted follow-up,” http://arxiv.org/abs/1603.07333. View at: Google Scholar
- B. D. Metzger, A. Bauswein, S. Goriely, and D. Kasen, “Neutron-powered precursors of kilonovae,”
*Monthly Notices of the Royal Astronomical Society*, vol. 446, no. 1, pp. 1115–1120, 2014. View at: Publisher Site | Google Scholar

#### Copyright

Copyright © 2016 Masaomi Tanaka. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.