M. C. Bersten, G. Folatelli, F. García, S. D. Van Dyk, O. G. Benvenuto, M. Orellana, V. Buso, J. L. Sánchez, M. Tanaka, K. Maeda, A. V. Filippenko, W. Zheng, T.… 展开作者
M. C. Bersten, G. Folatelli, F. García, S. D. Van Dyk, O. G. Benvenuto, M. Orellana, V. Buso, J. L. Sánchez, M. Tanaka, K. Maeda, A. V. Filippenko, W. Zheng, T. G. Brink, S. B. Cenko, T. de Jaeger, S. Kumar, T. J. Moriya, K. Nomoto, D. A. Perley, I. Shivvers, N. Smith
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Published in Nature on Feb. 22 Three main figures, six extended data Figures, four tables
It is difficult to establish the properties of massive stars that explode as supernovae. The electromagnetic emission during the first minutes to hours after the emergence of the shock from the stellar surface conveys important information about the final evolution and structure of the exploding star. However, the unpredictable nature of supernova events hinders the detection of this brief initial phase. Here we report the serendipitous discovery of a newly born, normal type IIb supernova (SN 2016gkg), which reveals a rapid brightening at optical wavelengths of about 40 magnitudes per day. The very frequent sampling of the observations allowed us to study in detail the outermost structure of the progenitor of the supernova and the physics of the emergence of the shock. We develop hydrodynamical models of the explosion that naturally account for the complete evolution of the supernova over distinct phases regulated by different physical processes. This result suggests that it is appropriate to decouple the treatment of the shock propagation from the unknown mechanism that triggers the explosion.
Following an initial explosion that might be launched either by magnetic interactions or neutrinos, a rotating magnetar radiating according to the classic dipole formula could power a very luminous supernova. While some 56Ni might be produced in the initial explosion, the peak of the light curve in a Type I supernova would not be directly related to its mass. In fact, the peak luminosity would be most sensitive to the dipole field strength of the magnetar. The tail of the light curve could resemble radioactive decay for some time but, assuming complete trapping of the pulsar emission, would ev…
Published X-ray emission properties for a sample of 50 supernova remnants (SNRs) in the LMC are used as input for SNR evolution modelling calculations. The forward shock emission is modelled to obtain the initial explosion energy, age, and circumstellar medium density for each SNR in the sample. The resulting age distribution yields a SNR birthrate of 1/(500 yr) for the LMC. The explosion energy distribution is well fit by a log-normal distribution, with most-probable explosion energy of $0.5\times10^{51}$erg, with a 1-$σ$ dispersion by factor 3 in energy. The circumstellar medium density dist…
We propose a new type of electromagnetic transients associated with the birth of binary black holes (BBHs), which may lead to merger events accompanied by gravitational waves in $\sim0.1-1$ Gyr. We consider the newborn BBHs formed through the evolution of isolated massive stellar binaries. For a close massive binary, consisting of a primary black hole (BH) and a secondary Wolf-Rayet (WR) star that are orbiting around each other, the spin period of the WR star can be tidally synchronized to its orbital period. Then, the angular momentum of the outer material of the WR star is large enough to fo…
(shortened) The SMC is ideally suited to investigating the recent star formation history from X-ray source population studies. It harbours a large number of Be/X-ray binaries, and the supernova remnants can be easily resolved with imaging X-ray instruments. We search for new supernova remnants in the SMC and in particular for composite remnants with a central X-ray source. We study the morphology of newly found candidate supernova remnants using radio, optical and X-ray images and investigate their X-ray spectra. Here we report on the discovery of the new supernova remnant around the recently …
The origin of rapid neutron capture (r-process) nuclei remains one of the longest standing mysteries in nuclear astrophysics. Core collapse supernovae (SNe) and neutron star binary mergers are likely r-process sites, but little evidence yet exists for their in situ formation in such environments. Motivated by the advent of sensitive new or planned X-ray telescopes such as the Nuclear Spectroscopic Telescope Array (NuSTAR) and the Large Observatory for X-ray Timing (LOFT), we revisit the prospects for the detection of X-ray decay lines from r-process nuclei in young or nearby supernova remnants…
We study optical counterparts of a new-born pulsar in a double neutron star system like PSR J0737-3039A/B. This system is believed to eject a small amount of mass of $\mathcal{O}(0.1M_{\odot})$ at the second core-collapse supernova. We argue that the initial spin of the new-born pulsar can be determined by the orbital period at the time when the second supernova occurs. The spin angular momentum of the progenitor is expected to be similar to that of the He-burning core, which is tidally synchronized with the orbital motion, and then the second remnant may be born as a millisecond pulsar. If th…
The inferred parameters of the binary black hole GW151226 are consistent with nonzero spin for the most massive black hole, misaligned from the binary's orbital angular momentum. If the black holes formed through isolated binary evolution from an initially aligned binary star, this misalignment would then arise from a natal kick imparted to the first-born black hole at its birth during stellar collapse. We use simple kinematic arguments to constrain the characteristic magnitude of this kick, and find that a natal kick $v_k \gtrsim 50$ km/s must be imparted to the black hole at birth to produce…
The white dwarf (WD) + helium (He) star binary channel plays an important role in the single degenerate scenario for the progenitors of type Ia supernovae (SNe Ia). Previous studies on the WD + main sequence star evolution have shown that the magnetic fields of WDs may significantly influence their accretion and nuclear burning processes. In this work we focus on the evolution of magnetized WD + He star binaries with detailed stellar evolution and binary population synthesis (BPS) calculations. In the case of magnetized WDs, the magnetic fields may disrupt the inner regions of the accretion di…
The abundances of 92Nb and 146Sm in the early Solar System are determined from meteoritic analysis and their stellar production is attributed to the p process. We investigate if their origin from thermonuclear supernovae deriving from the explosion of white dwarfs with mass above the Chandrasekhar limit is in agreement with the abundance of 53Mn, another radionuclide present in the early Solar System and produced in the same events. A consistent solution for 92Nb and 53Mn cannot be found within the current uncertainties and requires that the 92Nb/92Mo ratio in the early Solar System is at leas…
The birth properties of neutron stars yield important information on the still debated physical processes that trigger the explosion and on intrinsic neutron-star physics. These properties include the high space velocities of young neutron stars with average values of several 100 km/s, whose underlying "kick" mechanism is not finally clarified. There are two competing possibilities that could accelerate NSs during their birth: anisotropic ejection of either stellar debris or neutrinos. We here present new evidence from X-ray measurements that chemical elements between silicon and calcium in si…
We consider fallback accretion after an ultra-stripped supernova (USSN) that accompanies formation of a binary neutron star (BNS) or a neutron star-black hole binary (NS-BH). The fallback matter initially accretes directly to the nascent NS, while it starts to accrete to the circumbinary disk, typically $0.1\mbox{-}1\, \mathrm{day}$ after the onset of the USSN explosion. The circumbinary disk mass further accretes, forming mini disks around each compact object, with a super-Eddington rate up to a few years. We show that such a system constitutes a binary ultraluminous X-ray source (ULX), and a…
We give in this Chapter an overview of the problem of neutron star mass distribution, the issue of the maximum mass as inferred from the existing sample and the new gravitational wave events, and the connection with the formation events. It is shown that at least two different mass-scales (and possibly three) are favored by Bayesian and frequentist analysis, and the resulting maximum mass on empirical grounds only is $\sim 2.5 M_{\odot}$, making room for an interpretation of the lighter component of the GW190408 merger as a neutron star (as suggested by the GW event population analysis). We di…
In this paper we show that the most luminous supernova discovered very recently, ASASSN-15lh, could have been powered by a newborn ultra-strongly-magnetized pulsar, which initially rotates near the Kepler limit. We find that if this pulsar is a neutron star, its rotational energy could be quickly lost as a result of gravitational-radiation-driven r-mode instability; if it is a strange quark star, however, this instability is highly suppressed due to a large bulk viscosity associated with the nonleptonic weak interaction among quarks and thus most of its rotational energy could be extracted to …
Neutron star X-ray binaries (NS XRBs) associated with supernova remnants (SNRs) are the youngest X-ray binaries that can provide insights into the early evolution of X-ray binaries and the formation properties of neutron stars. There are an increasing number of NS XRBs discovered to be harbored in SNRs in our and nearby galaxies. In this work, we perform binary population synthesis calculations to simulate the population of NS XRBs associated with SNRs for different types of companions, including Roche-lobe overfilling main-sequence stars, Be stars and supergiants. We estimate their birthrates…
The fraction of long duration gamma ray bursts (GRBs) without an associated bright supernovae (SNe) at small redshifts $(z<0.15)$ is comparable to that of GRBs associated with SNe. We show, that their X-ray afterglow and the X-ray afterglow of most of the nearby $(z<1)$ GRBs without a confirmed association with SNe, are well reproduced by the launch of highly relativistic jets in the SN-less birth of millisecond pulsars in neutron star mergers or through phase transition of neutron stars to quark stars following mass accretion in compact binaries. Such a large fraction of GRBs with pulsar-like…
A subpopulation of neutron stars (NSs), known as central compact objects (CCOs) in supernova remnants, are suspected to be low-field objects basing on $P$-$\dot P$ measurements for three of them. The birth rate of low-field NSs is probably comparable with the birth rate of normal radio pulsars. However, among compact objects in High-Mass X-ray Binaries (HMXBs) we do not see robust candidates for low-field NSs. We propose that this contradiction can be solved if magnetic fields of CCOs was buried due to strong fall-back, and then the field emerges on the time scale $10^4$-$10^5$ yrs.
Using simulations of non-rotating supernova progenitors, we explore the kicks imparted to and the spins induced in the compact objects birthed in core collapse. We find that the recoil due to neutrino emissions can be a factor affecting core recoil, comparable to and at times larger than the corresponding kick due to matter recoil. This result would necessitate a revision of the general model of the origin of pulsar proper motions. In addition, we find that the sign of the net neutrino momentum can be opposite to the sign of the corresponding matter recoil. As a result, at times the pulsar rec…
Massive stars (M> 10Msun) end their lives with spectacular explosions due to gravitational collapse. The collapse turns the stars into compact objects such as neutron stars and black holes with the ejection of cosmic rays and heavy elements. Despite the importance of these astrophysical events, the mechanism of supernova explosions has been an unsolved issue in astrophysics. This is because clarification of the supernova dynamics requires the full knowledge of nuclear and neutrino physics at extreme conditions, and large-scale numerical simulations of neutrino radiation hydrodynamics in multi-…
Blue-supergiant stars develop into core-collapse supernovae --- one of the most energetic outbursts in the universe --- when all nuclear burning fuel is exhausted in the stellar core. Previous attempts failed to explain observed explosions of such stars which have a zero-age main sequence mass of 50~M$_\odot$ or more. Here we exploit the largely uncertain state of matter at high density, and connect the modeling of such stellar explosions with a first-order phase transition from nuclear matter to the quark-gluon plasma. The resulting energetic supernova explosions can account for a large varie…
We investigate the distribution of neutron star masses in different populations of binaries, employing Bayesian statistical techniques. In particular, we explore the differences in neutron star masses between sources that have experienced distinct evolutionary paths and accretion episodes. We find that the distribution of neutron star masses in non-recycled eclipsing high-mass binaries as well as of slow pulsars, which are all believed to be near their birth masses, has a mean of 1.28 M_solar and a dispersion of 0.24 M_solar. These values are consistent with expectations for neutron star forma…
We show that the nonzero electron mass plays a critical role in determining the magnetic properties of neutron stars, making it impossible to generate the chiral charge density needed to trigger a strong chiral magnetic instability during the core collapse of supernovae. This instability has been proposed as a plausible mechanism for generating extremely large helical magnetic fields in neutron stars at their birth; the mechanism relies on the generation of a large non-equilibrium chiral charge density via electron capture reactions that selectively deplete left-handed electrons during core-co…
