primordial magnetic field
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2021 ◽  
Vol 104 (12) ◽  
Author(s):  
Motohiko Kusakabe ◽  
Atul Kedia ◽  
Grant J. Mathews ◽  
Nishanth Sasankan

2021 ◽  
Vol 2021 (6) ◽  
Author(s):  
Hajime Fukuda ◽  
Aneesh V. Manohar ◽  
Hitoshi Murayama ◽  
Ofri Telem

Abstract We explore the cosmological consequences of the superconductivity of QCD axion strings. Axion strings can support a sizeable chiral electric current and charge density, which alters their early universe dynamics. We examine the possibility that shrinking axion string loops can become effectively stable remnants called vortons, supported by the repulsive electromagnetic force of the string current. We find that vortons in our scenario are generically unstable, and so do not pose a cosmological difficulty. Furthermore, if a primordial magnetic field (PMF) exists in the early universe, a large current is induced on axion strings, creating a significant drag force from interactions with the surrounding plasma. As a result, the strings are slowed down, which leads to an orders of magnitude enhancement in the number of strings per Hubble volume. Finally, we study potential implications for the QCD axion relic abundance. The QCD axion window is shifted by orders of magnitude in some parts of our parameter space.


2021 ◽  
Vol 103 (10) ◽  
Author(s):  
Md Riajul Haque ◽  
Debaprasad Maity ◽  
Sourav Pal

2020 ◽  
Vol 497 (1) ◽  
pp. L35-L39 ◽  
Author(s):  
Pravin Kumar Natwariya ◽  
Jitesh R Bhatt

ABSTRACT We study the 21-cm differential brightness temperature in the presence of primordial helical magnetic fields for redshift z = 10–30. We argue that the α-effect that sets in at earlier time can be helpful in lowering the gas temperature to 3.2 K at z = 17. This effect can arise in the early Universe due to some parity-violating high-energy processes. Using the EDGES (Experiment to Detect the Global Epoch of Reionization Signature) results, we find the upper and lower limits on the primordial magnetic field to be 6 × 10−3 and 5 × 10−4 nG, respectively. We also discuss the effect of Ly α background on the bounds. Our results do not require any new physics in terms of dark matter.


2019 ◽  
Vol 486 (2) ◽  
pp. 1629-1640 ◽  
Author(s):  
Kanhaiya L Pandey ◽  
Shiv K Sethi ◽  
Bharat Ratra

Abstract We study the effect of magnetic braking due to a primordial magnetic field in the context of the formation of massive (≳104M⊙) direct-collapse black holes (DCBHs) at high redshifts. Under the assumption of axial symmetry, we analytically compute the effect of magnetic braking on the angular momentum of gas collapsing into the potential well of massive dark matter haloes (≃107−9M⊙) which are spun up by gravitational tidal torques. We find that a primordial magnetic field of strength B0 ≃ 0.1 nG (comoving) can remove the initial angular momentum gained by the in-falling gas due to tidal torques, thus significantly lowering the angular momentum barrier to the formation of DCBHs. These magnetic field strengths are consistent with the bounds on primordial fields from astrophysical and cosmological measurements and they are large enough to seed observed galactic magnetic fields.


2019 ◽  
Vol 872 (2) ◽  
pp. 172 ◽  
Author(s):  
Yudong Luo ◽  
Toshitaka Kajino ◽  
Motohiko Kusakabe ◽  
Grant J. Mathews

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