Neutrino signals from Neutron Star implosions to Black Holes

Abstract

We calculate the neutrino luminosity in an astrophysical scenario where dark matter is captured by a neutron star which eventually implodes to form a low mass black hole. The Trojan horse scenario involves the collapse of a neutron star (NS) due to the accumulation of a critical amount of dark matter (DM) during its lifetime. As a result, a central disk forms out of the ejected material with a finite radial extension, density, temperature, and lepton fraction, producing fainter neutrino luminosities and colder associated spectra than found in a regular core-collapse supernova. The emitted gravitational wave (GW) signal from the imploding NS should be detectable at ultra-high $\gtrsim 0.1$ GHz frequencies.

Figures (4)

• Figure 1: Cartoon showing (left) the NS implosion due to a critical accumulation of an inner core of DM, from a generic massive candidate $\chi$. Following this event, a BH with an accretion disk (right) of mostly ordinary matter and radial extension $R_{disk}$ may be formed. A BH face-on view is shown.
• Figure 2: (Top to bottom) Electron fraction, mass density normalized to $10^9$$\rm g/cm^3$, temperature normalized to $10^{11}$ K as functions of radial coordinate in $r_{g}$ units at $t = 1\ ms$ after the collapse event.
• Figure 3: (Left) Neutrino emissivities per unit volume in the disk as a function of radial distance (in $r_g$ units) for the different processes considered i.e. Nucleon-electron (positron) $Ne$, electron-positron pair annihilation $e^+e^-$, NN bremstrahlung, ${NNBrems}$, and plasmon decay $(\gamma)$ up to $r=10r_g$. (Right) The luminosity due to the different neutrino species as a function of radius in $r_{g}$ units at $\rm t = 1\ ms$ after the NS collapse with initial $\rm B=0.5B_{16}$ where, $\rm B_{16} = 10^{16}G$.
• Figure 4: (Left) Time evolution of neutrino luminosities after collapse and formation of a BH $\rm M_{BH}= 1M_\odot$, for flavors $\nu_e$, $\bar{\nu}_{e}$, and $\nu_{x}$ (in units of $10^{53}\ erg\ s^{-1}$). We show the limiting curves for cases $[9.6,\rm 18] M_{\odot}$ CCSN ChakrabortyPRD+14 (Right) The neutrino luminosities for flavors $\nu_e$, $\bar{\nu}_{e}$, and $\nu_{x}$ (in units of $10^{51}\ erg\ s^{-1}$) evolution with time after bounce (in seconds) of the prompt collapse of NS to BH driven by DM capture. The solid and dashed line elucidate a $\rm M_{BH}= 1M_\odot$ and a $\rm M_{BH}= 2 M_\odot$, respectively.