EFFECT OF A HIGH OPACITY ON THE LIGHT CURVES OF RADIOACTIVELY POWERED TRANSIENTS FROM COMPACT OBJECT MERGERS

By J. Barnes, D. Kasen. 2013

407 citations recorded by the source corpus.

The coalescence of compact objects is a promising astrophysical source of detectable gravitational wave signals. The ejection of r-process material from such mergers may lead to a radioactively powered electromagnetic counterpart signal which, if discovered, would enhance the science returns. As very little is known about the optical properties of heavy r-process elements, previous light-curve models have adopted opacities similar to those of iron group elements. Here we consider the effect of heavier elements, particularly the lanthanides, which increase the ejecta opacity by several orders of magnitude. We include these higher opacities in time-dependent, multi-wavelength radiative transport calculations to predict the broadband light curves of one-dimensional models over a range of parameters (ejecta masses ∼10−3–10−1 M☉ and velocities ∼0.1–0.3 c). We find that the higher opacities lead to much longer duration light curves which can last a week or more. The emission is shifted toward the infrared bands due to strong optical line blanketing, and the colors at later times are representative of a blackbody near the recombination temperature of the lanthanides (T ∼ 2500 K). We further consider the case in which a second mass outflow, composed of 56Ni, is ejected from a disk wind, and show that the net result is a distinctive two component spectral energy distribution, with a bright optical peak due to 56Ni and an infrared peak due to r-process ejecta. We briefly consider the prospects for detection and identification of these transients.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/aa2be146b40e295eb8540161bb6b7e354a7889a2

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Citations in the corpus

AN r-PROCESS KILONOVA ASSOCIATED WITH THE SHORT-HARD GRB 130603B (2013, methodology): “In the models of Barnes & Kasen (2013), the expected rest-frameB − J color at a rest-frame time of 7 days (corresponding to the observed F606W− F160W color at 9.4 days) is exceedingly red, B − J ≈ 12 mag, in agreement with the observed color.”
PRODUCTION OF ALL THE r-PROCESS NUCLIDES IN THE DYNAMICAL EJECTA OF NEUTRON STAR MERGERS (2014, background): “…“kilonova” emission from the r-processed ejecta can be a promising electromagnetic counterpart to the gravitational-wave signal from a CBM event (Li & Paczyński 1998; Metzger et al. 2010; Goriely et al. 2011; Kasen et al. 2013; Barnes & Kasen 2013; Tanaka & Hotokezaka 2013; Grossman et al. 2014).”
Production of the entire range of r-process nuclides by black hole accretion disc outflows from neutron star mergers (2016, background): “…decay of the r-process ejecta can power a thermal transient (a “kilonova”; e.g., Li & Paczyński 1998, Metzger et al. 2010, Roberts et al. 2011, Barnes & Kasen 2013, Tanaka & Hotokezaka 2013), which could serve as a promising electromagnetic counterpart to the gravitational waves (Metzger…”
Signatures of hypermassive neutron star lifetimes on r-process nucleosynthesis in the disc ejecta from neutron star mergers (2017, background): “…in most cases since the lanthaniderich material goes through a high-temperature phase and its outer layers let photons escape more freely (Barnes & Kasen 2013; Fernández et al. 2017) If we only consider the heating rates and lanthanide/actinide content from the disk outflow, we expect…”
The Electromagnetic Counterpart of the Binary Neutron Star Merger LIGO/Virgo GW170817. II. UV, Optical, and Near-infrared Light Curves and Comparison to Kilonova Models (2017, background): “…finally to a red SED, is strongly suggestive of both blue and red KN emission; this is consistent with lanthanide-poor and rich ejecta components, respectively (Metzger et al. 2010; Barnes & Kasen 2013; Tanaka & Hotokezaka 2013; Metzger & Fernández 2014; Kasen et al. 2015; Wollaeger et al. 2017).”
Neutrino-driven winds from neutron star merger remnants (2014, result): “The properties of this second detection are close to model predictions (Barnes & Kasen 2013; Kasen, Badnell & Barnes 2013; Tanaka & Hotokezaka 2013; Grossman et al. 2014; Rosswog et al. 2014a; Tanaka et al. 2014) for the so-called ‘macro-’ or ‘kilonovae’ (Li & Paczyński 1998; Kulkarni 2005;…”
RADIATIVE TRANSFER SIMULATIONS OF NEUTRON STAR MERGER EJECTA (2013, methodology): “This trend is also consistent with the results of Kasen et al. (2013) and Barnes & Kasen (2013).”
r-PROCESS LANTHANIDE PRODUCTION AND HEATING RATES IN KILONOVAE (2015, methodology): “Following Barnes & Kasen (2013), we adopt f = 0.3.”
DOUBLE COMPACT OBJECTS. II. COSMOLOGICAL MERGER RATES (2013, background): “Since this matter may be enriched in heavy elements through the r-process, the resulting radioactive decay may generate observable light, thereby providing a promising electromagnetic counterpart to the GW emission (Metzger & Berger 2012; Piran et al. 2013; Barnes & Kasen 2013).”
THE LIGHT CURVE OF THE MACRONOVA ASSOCIATED WITH THE LONG–SHORT BURST GRB 060614 (2015, background): “…is significantly lower than that of an SN at the same time scale, typically ∼ 0.5− 1 × 104 K (see e.g., Della Valle et al. 2006 and Cano et al. 2011), but it is similar to that expected at the photosphere for the recombination of Lanthanides (i.e., T ∼ 2500 K, see e.g., Barnes & Kasen 2013).”
Impact of ejecta morphology and composition on the electromagnetic signatures of neutron star mergers (2017, methodology): “These are often reasonable approximations for supernovae and macronovae (see Kasen et al. 2006; Barnes & Kasen 2013).”
Galactic r-process enrichment by neutron star mergers in cosmological simulations of a Milky Way-mass galaxy (2014, background): “…the decay of heavy elements produced during r-process nucleosynthesis powers isotropic electromagnetic emission that is predicted to be one of the most promising sources of electromagnetic emission coincident with a gravitational-wave detection (e.g. Metzger et al. 2010; Barnes & Kasen 2013).”
Neutron-powered precursors of kilonovae (2014, background): “Recent work suggests that matter containing even a small quantity of lanthanide or actinide elementspossesses an opacity at optical frequencies that can exceed by orders of magnitude that of normal supernovae (Kasen et al. 2013; Barnes & Kasen 2013).”
Short-Duration Gamma-Ray Bursts (2013, methodology): “In the opticalizy bands (0.7− 1 µm) the peak brightness is∼ 22− 24 AB mag and the timescale is∼ 1− 3 d (e.g.,Barnes & Kasen 2013).”
Kilonova from post-merger ejecta as an optical and near-infrared counterpart of GW170817 (2017, methodology): “Then, radioactive decays of r-process nuclei powers EM emission especially in the optical and near-infrared wavelengths (Li & Paczyński 1998; Kulkarni 2005; Metzger et al. 2010; Kasen et al. 2013; Barnes & Kasen 2013; Tanaka & Hotokezaka 2013).”
Follow Up of GW170817 and Its Electromagnetic Counterpart by Australian-Led Observing Programmes (2017, methodology): “…to generate a relatively rapidly evolving optical/infrared transient—referred to as kilonova or macronova (e.g., Li & Paczyński 1998; Metzger et al. 2010; Roberts et al. 2011; Barnes & Kasen 2013; Tanaka & Hotokezaka 2013; Kasen, Fernández, & Metzger 2015; Metzger et al. 2015; Barnes et al. 2016).”