Some New Possible Anticipated Signals for Existence of Magnetic Monopoles

TL;DR

This paper discusses potential astronomical signals indicating the presence of magnetic monopoles in supermassive objects like the Galactic Center, based on model predictions aligning with recent observations.

Contribution

It introduces specific predicted signals from magnetic monopoles in supermassive objects and compares them with recent astronomical data.

Findings

Predicted signals match recent observations quantitatively.

Magnetic monopoles may exist in supermassive objects like the Galactic Center.

Abstract

We summarize some predictions from the model of supermassive object with magnetic monopoles which match up with recent astronomical observations quantitatively. They may be the signals for existence of magnetic monopoles in the supermassive objects, such as one at the Galactic Center.

Equations

$$p+M\to M+e^{+}+{\pi }^0+\mathrm{debris}(85\%),$$

$$p+M\to M+e^{+}+{\mu }^{+}+{\mu }^{-}+\mathrm{debris}(15\%).$$

$$B\ge 8\left[\frac{RM}{66.960m^{-2}}\right]{\left[\frac{n_0}{26c{m}^{-3}}\right]}^{-1}mG,$$

$${\Phi }_m=n_m{v}_m=10^{-4}c{n}_B^{(0)}{\zeta }_m^{(0)}(\frac{v_m}{10^{-4}c})$$

$$\approx 7.5\times 10^{-19}(\frac{{\zeta }_m^{(0)}}{{\zeta }_S})(\frac{n_B^{(0)}}{1c{m}^3})(\frac{v_m}{10^{-4}c})c{m}^{-2}{s}^{-1}$$

$$\approx 2.5\times 10^{-4}(\frac{{\zeta }_m^{(0)}}{{\zeta }_S})(\frac{n_B^{(0)}}{1c{m}^3})(\frac{v_m}{10^{-4}c})\times (100m{)}^{-2}Y{r}^{-1},$$

$$N_m$$

$$L_m=N_m⟨\sigma v⟩n_B^{(c)}{m}_B{c}^2,$$

$$L_m$$

Full text

††slugcomment: Not to appear in Nonlearned J., 45.00footnotetext: Corresponding to Jing-Jing, Liu00footnotetext: Department of Astronomy, Nanjing University, Nanjing, Jiangshu 210000, China.00footnotetext: College of Marine Science and Technology, Hainan Tropical Ocean University, Sanya, Hainan 572022, China.00footnotetext: Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.

Keywords Galaxy: center — Galaxies: magnetic fields — Physical Date and Processes: black hole physics.

1 Introduction

Most of physicists believe that the existence of magnetic monopoles had been ruled out by experiments. However, experiments only indicated that the flux of magnetic monopoles on the earth is too low to be observed. In the primordial universe, the electromagnetic interaction between magnetic monopoles and plasma is so strong such that magnetic monopoles might store up in the center of quasars and active galactic nuclei (AGN) during the collapsing process of the original giant nebulae, including at the collapsed core of the Galactic Center (GC). Due to the Rubakov-Callan (RC) effect(Rubakov, 1981; Callan, 1983), magnetic monopoles may catalyze nucleon decay and is invoked as the energy source of quasars and AGN. The model of supermassive object with magnetic monopoles (SMOMM) (Peng & Chou, 2001), presented by one (QP) of the authors, gave five predictions, some of which match up with the recent astronomical observations quantitatively. It may be the signals for existence of magnetic monopoles in the supermassive objects.

From the symmetry and beauty of the Dirac equation, Dirac (Dirac, 1958) suggested the existence of magnetic monopoles which is the most natural explanation of the quantization of electric charge. It is a fundamental problem in physics whether magnetic monopoles exist or not.

The plan of this letter is as follows. In section 2, we will sketch the model of SMOMM and its predictions. In Sections $3\sim 5$, we will show some predictions of our model in agreement quantitatively or basically with some new astrophysical observations: a strong magnetic field around the GC, the observation of the rate of the emitted positrons, and the frequency of the spectrum peak of the thermal radiation from the GC. In the last Section, we will discuss and try to explain two recent observations with the model of the stars with the magnetic monopoles: the highly super-luminous supernova ASASSN-15lh and the gravitational waves GW150914.

2 The model of SMOMM

The model of SMOMM (Peng & Chou, 2001) suggested that an amount of magnetic monopoles stored up in the center of quasars and AGNs, including at the collapsed core of the GC during the collapsing process of the original giant nebulae in the primordial universe because the electromagnetic interaction between magnetic monopoles and plasma was so strong. Due to the RC effect (Rubakov, 1981; Callan, 1983), nucleon decay may be catalyzed by magnetic monopoles,

[TABLE]

[TABLE]

In this model, the RC effect is invoked as the energy source. In the case of GC, the SMOMM is located at the center with the radius of about $8.1\times 10^{15}cm\sim 1.2\times 10^{4}R_{S}$ ($R_{S}$ is its Schwarzschild radius). The total mass of the SMOMM is derived to be $2.5\times 10^{6}M_{\bigodot}$ (now taken as $4.6\times 10^{6}M_{\bigodot}$) from the observed luminosity of Sgr A${}^{*}(1\times 10^{37}$ ergs ${\rm s}^{-1}$).

The gravitational effect around SMOMM in the GC is similar to the model of supermassive black holes. In the black hole model, accretion of matter results in the huge luminosity, but the energy source in the model of SMOMM is supplied by the RC effect.

The main predictions of the model of SMOMM are as follows (Peng & Chou, 2001).

1. The production rate of positrons emitted from the SMOMM in the model is $\sim 6.5\times 10^{42}e^{+}/sec$.

2. High-energy gamma-ray radiation has energy higher than 0.5 MeV. The integrated energy of these radiations would be much greater than both the bolometric luminosity and the energy of positron annihilation line.

3. The radial magnetic field at the surface of the SMOMM is estimated to be $H(R)\sim(20-100)G$.

4. The strong radial magnetic fields of the high-speed rotating SMOMM transforms a strong electric field for a distant observer in the rest frame. A variety of produced particles ($e^{+}$, $\mu^{\pm}$, $\pi^{\pm}$) would be accelerated by the strong electric field to very high energy, say $E_{\gamma}\sim 10^{21}$eV or greater. We predict that these could just be the observed ultra-high-energy cosmic rays which have an initial energy of several hundred MeV produced from the SMOMM.

5. The surface temperature of the SMOMM is derived to be about 121 K and the corresponding spectrum peak of the thermal radiation is at $10^{13}Hz$ in the sub-mm wavelength regime.

3 A strong magnetic field around the galactic center

The recent observation (Eatough et al., 2013) in 2013 indicated that there is a dynamically important magnetic field near the black hole. In particular, at $r=0.12pc$ the lower limit of the outward radial magnetic field near the GC is

[TABLE]

where $n_{0}$ is the number density of electrons there, and RM denotes the measurement of the Faraday rotation near the GC. The lower limit of the observed data is in agreement with the the prediction 3 in the model of SMOMM because the magnetic field strength decreases as the inverse square of the distance from the source and has $B\approx(10-50)mG$ at $r=0.12pc$. Up to now no other physical mechanism can produce this strong radial magnetic field.

As analyzed in (Zamaninasab et al., 2014), “jet magnetic field and accretion disk luminosity are tightly correlated over seven orders of magnitude for sample of 76 radio-loud active galaxies”. They pointed out that the black hole models “may require significant changes”, and “models of the Galactic Center accretion disk may also need to be revised, as a dynamically important magnetic field has been reported (Eatough et al., 2013) within a distance of $\sim 3\times 10^{7}r_{g}$ from the central black hole.”

4 Rate of emitted positrons

New observation (Knödlseder et al., 2003) reported that the measured 511 keV line flux located at the GC at a distance of $8.5kpc$ converts into an annihilation rate of $(3.4-6.3)\times 10^{42}s^{-1}$. “The observed flux is compatible with previous measurements (Share et al., 1990; Cheng et al., 1997; Purcell et al., 1997; Milne et al., 2000, 2001) that have been obtained using telescopes with small or moderate fields-of-view, yet it is on the low side when compared to OSSE measurements.” (Knödlseder et al., 2003) Those observations are in agreement with the the prediction 1 in the model of SMOMM quantitatively.

5 Frequency of spectrum peak of the thermal radition from the galactic center

A review paper (Falcke & Markoff, 2013) pointed out that the radio flux density $S_{\nu}$ from the GC shows a flat-to-inverted spectrum. i.e., it raised slowly with frequency of the power peaking around $10^{12}$ Hz in the sub-mm band. The observed power peak is in agreement basically with the prediction 5 in the model of SMOMM.

6 Conclusions and discussions

The agreement of the predictions of our model of the SMOMM with three new astrophysical observations quantitatively or basically issues the signals for existence of magnetic monopoles. We are looking forward to seeing more astrophysical observation which will meet the predictions of our model.

At the beginning of this year two important astrophysical observations were reported: The highly super-luminous supernova ASASSN-15lh and the gravitational waves GW150914. We believe that our model and its development can be suitable to meet the new observations.

The recent observation (Dong et al., 2016) reported the discovery of ASASSN-15lh (SN 2015L), which was interpreted as the most luminous supernova to be found. “At redshift $z-0.2326$, ASASSN-15lh reached an absolute magnitude of $M_{u,AB}=-23.5\pm 0.1$ and bolometric luminosity $L_{bol}=(2.2\pm 0.2)\times 10^{45}$ erg s*-1*, which is more than twice as luminous as any previously known supernova”. “In the 4 months since first detection, ASASSN-15lh radiated $(1.1\pm 0.2)\times 10^{52}$ ergs, challenging the magnetar model for its engine”.

Up to now, the supernova explosion mechanism has not been solved. In a model of a supermassive star with magnetic monopoles, the phenomena of ASASSN-15lh and the super-luminous supernova (SLSN) may be explained naturally. Although a few magnetic monopoles may be stored in the core of stars during the process of star formation from a neutral hydrogen nebulae due to very weak interaction between magnetic monopoles and neutral hydrogens, the stars may capture some flight magnetic monopoles in the space (Peng et al., 1985). The flux of the flight magnetic monopoles is

[TABLE]

where $n_{m}$ is the number density of the magnetic monopoles, $v_{m}$ is the average velocity of the flight magnetic monopoles in space, $n_{B}^{(0)}$ is the number density of the baryons in the interstellar space, and $\zeta_{S}=Gm_{B}m_{m}/g_{m}^{2}\simeq 1.9\times 10^{-25}$ denotes the Newton saturation value of $\zeta_{m}=N_{m}/N_{B}$, where $N_{m}$ is the total number of the flight magnetic monopoles and $N_{B}$ is the total number of nucleons. $\zeta_{m}^{(0)}$ is the value of $\zeta_{m}$ in the interstellar space, and its upper limit is $\zeta_{m}^{0}\leq 10^{-20\pm 1}$ (Parker, 1970; Lazarides et al., 1981). After formation of stars the total number of the magnetic monopoles captured by the stars from space is estimated to be

[TABLE]

where $R$ is the radius of the star, $T$ is the age of the progenitor of the supernova. The captured superheavy monopoles are gathered at the core of the stars.

Due to the RC effect, the luminosity produced by the nucleon decay catalyzed by magnetic monopoles in the core of the stars is

[TABLE]

where $\sigma\sim 10^{-25}-10^{-26}$ cm2 is the cross section of the RC effect (Rubakov, 1981; Callan, 1983), $v$ is the thermal velocity of the nucleons, and $n_{B}^{(c)}$ is the central number density of the baryons for the star. The temperature would reach $10^{11}$K in the collapsed core of the supernova, i.e., $v/c\geq 0.1$. Thus,

[TABLE]

This luminosity is enough to explain the supernova explosion, when the density of the supernova core is greater than the nuclear density ($n_{nuc}$).

As long as we assume that the initial mass of the progenitor of the SLSN is greater than $150m_{\bigodot}$, then its radius before the supernova explosion was greater than $10^{4}R_{\bigodot}$, and the life of the super-massive star is only $10^{5}-10^{6}Yr$. Thus, the luminosity produced from the nucleon decay catalyzed by the magnetic monopoles in the collapsed core of the supernova, where the density of the core is much greater than the nuclear density, will be greater than $10^{42}-10^{43}$ ergs. This luminosity is enough to make the SLSN exploding, so that the SLSN is explained naturally.

On September 14, 2015 two detectors of the Laser Interferometer Gravitational-Wave Observatory (LIGO) simultaneously observed a transient gravitational-wave signal (GW150914) (Abbott et al., 2016). This is the first direct detection of gravitational waves which was commonly explained as the first observation of a binary black hole system mergering to form a single black hole. On December 26, 2015, a second gravitational-wave event, GW151226, was observed by the twin detectors of LIGO(Abbott et al., 2016).

On February 16, 2016, Connaughton et al. (2016) reported that the Fermi Gamma-ray Burst Monitor (GBM) had revealed the presence of a weak transient source above 50 keV, 0.4 s after the GW event: “This weak transient lasting 1 s does not appear connected with other previously known astrophysical, solar, terrestrial, or magnetospheric activity. Its localization is ill-constrained but consistent with the direction of GW150914”(Connaughton et al., 2016). They also note that the electromagnetic signal from a stellar mass black hole binary merger is not expected if the GBM transient is associated with GW150914. Based on their measurement of the fluence seen by GMB, a luminosity of $1.8^{+1.5}_{-1.0}\times 10^{49}$ erg s*-1* is derived in hard X-ray emission between 1 keV and 10 MeV.

In another paper (Lyutikov, 2016) Lyutikov analyzed the physical requirements in some detail that the possible observation of the electromagnetic signal contemporaneous with GW150914 imposes on the circum-merger environment, and found that the required physical parameters at the source exceed by many orders of magnitude what is expected in realistic astrophysical scenarios. He concluded that Fermi GMB signal contemporaneous with GW150914 is unrelated to the black hole merger.

The merger of two black holes can produce the GW only, not the gamma-ray burst simultaneously. However, in our model of stars with magnetic monopoles, the merger of two supermassive neutron stars with the magnetic monopoles, (They cannot collapse to black holes through the RC effect), whose mass density reaches to $(10^{5}-10^{6})\rho_{nuc}$ at the center core, not only produces the GW, but also produces the gamma-ray burst whose luminosity may reach $10^{49}ergs/s$ through the RC effect. After we have finished this paper, Racusin et al. (2016) reported on June 15, 2016 that they had made observations of the event GW151226 and candidate LVT151012 with both the Fermi Gamma-ray Burst Monitor and the Large Area Telescope (LAT). No electromagnetic counterparts were detected by either GBM or LAT. We are looking forward to the future detections of the GW which may accompany with the gamma-ray burst. If yes, it will verify the existence of magnetic monopoles.

Acknowledgements We would like to thank Prof. Daniel Wang, Prof. Y.F. Huang, Prof. P.F. Chen and Prof. J. L. Han for their help to inform us some new information of observations. This work was supported in part by the National Natural Science Foundation of China under grants 10773005, 11565020, and the Counterpart Foundation of Sanya under grant 2016PT43, the Special Foundation of Science and Technology Cooperation for Advanced Academy and Regional of Sanya under grant 2016YD28, and the Natural Science Foundation of Hainan province under grant 114012.