Triaxial phase of a compact object is an unusual state rather than our known states such as spheroid, ellipsoid and cylindrical. In 1967 S. Chandrasekhar [1] first discussed the possibility of such phase to exist in realistic cases, particularly in astronomical compact objects. White dwarf was the one and only known compact object at that time (better it was known as Chandrasekhar limit i.e. 1.4 M_o is the maximum mass of a white dwarf, M_o being the mass of the Sun). To define the triaxiality in physical shaped objects it was stated in the form of ratio i.e. Kinetic Energy (T) / Gravitational Energy (W) such that T/ |W| = 0.14 is a bifurcation point. This means that an object with its spheroidal shape can be transformed into ellipsoidal shape i.e. deformation when its T/ |W| > 0.14. Triaxiality therefore associated (due rotation) with the ellipsoid shape in the form of ellipticity. This implies that the triaxiality puts constraint on the limitation of ellipticity i.e. triaxiality phase exist till the object maintain its ellipticity within the certain range of ellipticity value beyond which this object can be treated as ellipsoidal shape.

Based on the characteristic of triaxiality of cosmic baby it can be possible to search in four invaluable areas: i) triaxial nature (i.e. Triaxial Star) of the secondary component mass of the GW190814 event before coalescence, ii) the Neo-Natal triaxial star, iii) possible existence of a compact object having gold nanostars or in the form of a Hybrid Star (?)

The detection of the event GW190814 [2] created a puzzle on the identification of the secondary or companion object with estimated mass 2.5 – 2.67 M_o i.e. whether it was a heaviest neutron star or the lowest mass black hole or any other compact object.

Astronomers tried to resolve this problem using the earlier measured and estimated data of GW170817 as well as the observed pulsar data as reference:

1. Inferring from the measurement of electromagnetic (EM) and gravitational waves (GW) spectra of GW170817 [3] suggests that it was maximum mass of a neutron star [4,5].
2. Broekgaareden and Berger [6] found a significant result, using the observed parameters of the black hole – neutron star (i.e. BH – NS) event GW190425, that the properties of GW190425 and GW190814 do not match with the prediction of (BH – NS) population implying that the GW190814 most likely to be a (BH – BH) merger.
3. Dexheimer et al. [7] suggested that the secondary component of GW190814 was a massive rapidly rotating neutron star with exotic degrees of freedom.
4. Bombaci et al. [8], on the other hand, suggested that the secondary companion was most probably a strange quark star, i.e. the event GW190814 was a black hole – strange quark star system.
5. Considering black hole Battery powered magnetosphere model [9] recently D’Orazio et al. [10]. studied the multi-messenger constraints on the magnetic fields in (BH – NS) binaries concentrating on the overlooked area mainly the lack of neutron star disruption as the lack of brightness in the electro-magnetic (EM) counterparts and found that a bright electromagnetic (EM) emission is possible and even also possible from a non-disrupting binary system. As a possible reason they explained that locking up of magnetic energy in the neutron star’s magnetosphere can arise without breaking apart the neutron star.

The significant results they found are:

1. The upper limit for future detection of GW plus gamma ray flux constraints to as low as ~ 10¹³ – 10¹⁴ G, depending upon distance, battery parameters, and EM flux upper limit.
2. The strength of surface dipolar magnetic field of neutron star is constrained to be ≤  10¹⁵ G.
3. In the case of joint detection of GW and EM, the upper limit for neutron star surface dipolar magnetic field >~ 10¹⁵ G until the merger is ruled out.

Assuming that magnetar can be formed in a binary system [11] and neutron star can only hold large magnetic fields for the magnetar’s life time (i.e. ~ 10³ – 10⁴ years) they estimated the maximum allowed neutron star surface magnetic field (i.e. the optimistic value “opt”) for flux upper limit and black hole spin for different GW sources as:

GW190814 ---- 1.3 x 10¹⁵ G

GW200105 ---- 6.3 x 10¹⁴ G

GW200115 ---- 4.4 x 10¹⁴ G

Using this “opt” values in the best fitting relation for ellipticity (? ) estimation ( for details see Parui [12] ) i.e.

 log ? = – 22.50^+2.15_{- 2.22} + (1.29^+0.15_-0.14) log B_dipole   (1)

this author found the internal magnetic field and ellipticity as 1.861526 x 10¹⁸ G and 1.0069 x 10 ^{– 3,} respectively, implying that the estimated values satisfy the condition for being a triaxial star.

Thus, the secondary or companion compact object of GW190814 can be considered as a triaxial star i.e. it was a “Triaxial Star”.

Re-analyzing the earlier observed parameters of GRB130310A Zhang et al. [13] estimated the age of the magnetar associated with this gamma ray burst (GRB) is only two weeks.

Considering the two observational facts for a new born magnetar that

1. The long lasting / stable survive remnant of binary neutron star merger is a millisecond magnetar (i.e. the source of short GRBs and Kilonovae), and
2. The overall light curves of GRB exhibits a plateau shape in the afterglow phase,

this author (i.e. Parui [14]) has estimated the interior magnetic field strength and ellipticity (?) of the millisecond magnetar associated with this GRB130310A as 3.95 x 10¹⁷ G and ~ 4 x 10^–3, respectively. This author has also calculated the interior magnetic field and ellipticity of the recently detected magnetar, i.e. Swift J1818.0 – 1607 (now known as Cosmic Baby) as given below:

Note that for quantitative analysis only 73 millisecond magnetars are considered. It is found that out of these only 6 magnetars (3 in long GRBs i.e. GRB 061222A, GRB 120907A and GRB 180626A, and 3 in short GRBs i.e. GRB 070810A, GRB 090428, GRB 090510) are of 2 weeks aged and possess ellipticities of ~ 10^{– 3} – 10^{– 4} (which is within the limit of ellipticity ? ~ 0.004 – 0.007 for being a real triaxial star whose physical existence is possible. As the magnetar associated with the GRB 130310A possesses the required values of ellipticity and magnetic field strength, it is proposed that the associated magnetar of GRB130310A was a “Neo-Natal Triaxial Star”.

In general, nanostars are a type of nano particles consisting of a sphere core and multiple branches, resembling or looking like a star, having sizes 1–100 nm. These nanostars, have been produced in the laboratory on earth, consisting entirely of a mixture of gold, silver, platinum, palladium, and rhodium among other materials. At the center, in fact, silica is one of the important other materials, it may coat the nanostar, acting as the spherical core from which metallic branches are grown [15]. This gold nanostar, produced at the laboratory on the earth, offer a challenge to the astronomers, scientists to search for the production of such gold nanostar in space i.e. whether this gold nanostars are formed in the ISM or not? If yes, whether any possibility of existence of a compact star made of gold nanostar?

Laboratory experiment performed on plasmonic colloids [16,17] showed the nanostructured gold colloids are capable of exhibiting large electromagnetic fields effect (i.e. localized surface plasmon resonance (LSPR) at their surface upon excitation. Precisely, tipped nanoparticles show an uneven distribution of LSPR forming cubes –, rod –, plates – like structures over their surface depending upon the concentration of light in certain regions where the tips in their structure.

A similar type shapes / structures, such as exotic shapes of rod – like, slab – like are expected in the supernova cores and neutron star crusts [18,19] at high density in the presence of strong surface magnetic field.

The main question arises: Is there any link between the formation of uneven shapes or structures in laboratory available nanostar and exotic materials in neutron star crust through the element gold? i.e. nano structured gold may present in Neutron Star?

In searching the answer of these two questions first we have to know the origin of gold in space. Our present knowledge indicates two main sources, responsible for production of gold in space are: (1) r-process nucleosynthesis during the evolution period from birth of a star to formation of supernova and after then supernova explosions, and (2) coalescence of two neutron stars in a binary system i.e. merger of binary neutron stars in gravitational wave event (i.e.GW event).

Birth of a star takes place in the interstellar medium (ISM) through contraction of dust, gas clouds containing hydrogen (H), and other gas molecules. Due to contraction temperature increases and after a certain temperature fusion process becomes active among hydrogen gas molecules, hydrogen converted into helium (He), helium gradually then converted into Li, C, N, O, …… Neutrons are released during the fusion reactions, which then combines with the produced elements and ultimately turns into higher atomic mass elements up to iron (Fe). i.e. massive stars (i.e. > 8 M_o) continued nuclear fusion beyond that of helium core, the carbon – oxygen core is formed. When all of the helium in the core is exhausted, carbon – oxygen begins to fuse. This fusion thus yields neon, magnesium, silicon, and sulphur [20]. Further, silicon and sulphur fuses in the star’s core form iron (Fe), nickel (Ni) and other elements of similar atomic weight. Note that, the star’s structure now resembles an onion structure i.e. the central core of the onion (i.e. star) consists of iron, surrounded by a shell where silicon and sulphur fuse and adds more iron-to-iron core.

In this stage at sufficient temperature and presence of excess neutrons r – process nucleosynthesis begins to form heavy elements (higher than Fe) including gold, platinum, uranium, etc. Thus, the elements (less than Fe) produced through s-process neutron capture, and the heavy elements (higher than Fe) including gold produced through the r-process are present in the supernova.

Supernova explosion thus offers two facts — central part, consisting of iron and other heavy elements including gold, platinum, implodes forming a neutron star while shell part, surrounding the central part, explodes scattering all of its constituents into the ISM. Figure 1 shows the possible path of gold, platinum and other heavy elements (> Fe) reaching both in ISM and on the earth (orange color arrow).

In the case of coalescence of two neutron stars, i.e. merger of a binary neutron stars the event generates gravitational waves (GW) as well as produces many heavy elements including gold [21].

Analysis of Meteorites, using the LASER desorption / controlled condensations method, shows that meteorite contains nano particles [22] implying that these particles are formed from materials that were formed originally from interstellar / nebula dust. Nano particles, produced in our experimental laboratory, aggregates the web-like morphologies similar to interstellar dust grains. This means that the used materials with a composition in the laboratory have a link similar to the interstellar and interplanetary materials. Therefore, parent asteroids were formed from interstellar dust particles that coagulated in the Solar Nebula, (i.e. a relatively mild processing in the Nebula but no igneous transformation) and have been frozen since then until impact on the Earth [23]. In other words, it provides a link between the chemical complexity of such region in ISM when the dust and first star formation take place, and the molecules and surface reactions of many small hydrogen rich species which are formed by atomic recombination of grains available in the cold, dense, and dusty region of our galaxy [24]. The key point is — it is inevitable that laboratory investigation of gold nanostar can be a tool to understand how short-wave lengths photons (VUV, X-ray and γ-ray), and Cosmic Rays or Shock Waves [25] converts the nano particles into chemical complexes in space, in the interior of compact objects like neutron star, magnetar, resulting which interior of them contains superfluids, superconductor [26], in the core sheet like structure formation [27].

The author is greatly indebted to the editorial team of Journal of Nanotechnology and Nanomaterials for their kind invitation. He wishes to thank Prof. H. N. K. Sarma, Dept. of Physics, Manipur University; Mr B. K. Ganguly, Airports Authority of India, Kolkata; Mrs. Tapati Parui and Sri Rajarshi Parui for their kind encouragement and help.

No new data used.

Not applicable.