Cosmic strings in generalized hybrid metric-Palatini gravity

Abstract We demonstrate that all rigidly rotating strings with center of mass at the origin of the dS3 static patch satisfy the Higuchi bound. This extends the observation of Noumi et al. for the open GKP-like string to all solutions of the Larsen-Sanchez class. We argue that strings violating the bound end up expanding towards the horizon and provide a numerical example. Adding point masses to the open string only increases the mass/spin ratio. For segmented strings, we write the conserved quantities, invariant under Gubser’s algebraic evolution equation, in terms of discrete lightcone coordinates describing kink collisions. Randomly generated strings are found to have a tendency to escape through the horizon that is mostly determined by their energy. For rapidly rotating segmented strings with mass/spin < 1, the kink collisions eventually become causally disconnected. Finally we consider the scenario of cosmic strings captured by a black hole in dS and find that horizon friction can make the strings longer.

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Primordial monopoles and strings, inflation, and gravity waves

Journal of High Energy Physics ◽

10.1007/jhep02(2021)114 ◽

2021 ◽

Vol 2021 (2) ◽

Author(s):

Joydeep Chakrabortty ◽

George Lazarides ◽

Rinku Maji ◽

Qaisar Shafi

Keyword(s):

Symmetry Breaking ◽

Gravity Waves ◽

Cosmic Strings ◽

Wave Spectrum ◽

Gauge Coupling ◽

String Tension ◽

Magnetic Monopoles ◽

Intermediate Scale ◽

Tension Parameter ◽

The Universe

Abstract We consider magnetic monopoles and strings that appear in non-supersymmetric SO(10) and E6 grand unified models paying attention to gauge coupling unification and proton decay in a variety of symmetry breaking schemes. The dimensionless string tension parameter Gμ spans the range 10−6− 10−30, where G is Newton’s constant and μ is the string tension. We show how intermediate scale monopoles with mass ∼ 1013− 1014 GeV and flux ≲ 2.8 × 10−16 cm−2s−1sr−1, and cosmic strings with Gμ ∼ 10−11− 10−10 survive inflation and are present in the universe at an observable level. We estimate the gravity wave spectrum emitted from cosmic strings taking into account inflation driven by a Coleman-Weinberg potential. The tensor-to-scalar ratio r lies between 0.06 and 0.003 depending on the details of the inflationary scenario.

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Searching for gravitational-wave bursts from cosmic string cusps with the Parkes Pulsar Timing Array

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3721 ◽

2020 ◽

Vol 501 (1) ◽

pp. 701-712

Author(s):

N Yonemaru ◽

S Kuroyanagi ◽

G Hobbs ◽

K Takahashi ◽

X-J Zhu ◽

...

Keyword(s):

False Alarm ◽

Gravitational Wave ◽

Cosmic String ◽

Cosmic Strings ◽

False Alarm Probability ◽

String Tension ◽

Detection Algorithm ◽

Pulsar Timing ◽

Upper Limits ◽

Pulsar Timing Array

ABSTRACT Cosmic strings are potential gravitational-wave (GW) sources that can be probed by pulsar timing arrays (PTAs). In this work we develop a detection algorithm for a GW burst from a cusp on a cosmic string, and apply it to Parkes PTA data. We find four events with a false alarm probability less than 1 per cent. However further investigation shows that all of these are likely to be spurious. As there are no convincing detections we place upper limits on the GW amplitude for different event durations. From these bounds we place limits on the cosmic string tension of Gμ ∼ 10−5, and highlight that this bound is independent from those obtained using other techniques. We discuss the physical implications of our results and the prospect of probing cosmic strings in the era of Square Kilometre Array.

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INHERITING SPACELIKE CONFORMAL KILLING VECTORS IN STRING COSMOLOGY

International Journal of Modern Physics D ◽

10.1142/s0218271803003360 ◽

2003 ◽

Vol 12 (05) ◽

pp. 885-892 ◽

Cited By ~ 1

Author(s):

HÜSNÜ BAYSAL

Keyword(s):

General Relativity ◽

Cosmic Strings ◽

String Cosmology ◽

Conformal Killing ◽

Killing Vectors ◽

Conformal Killing Vectors

We study the consequences of the existence of spacelike conformal Killing vectors (SpCKV) parallel to xa for cosmic strings and string fluid in the context of general relativity. The inheritance symmetries of the cosmic strings and string fluid are discussed in the case of SpCKV. Furthermore we examine proper homothetic spacelike Killing vectors for the cosmic strings and string fluid.

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