Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Xiao Xue
Zi-Qing Xia
Xingjiang Zhu
Yue Zhao
Jing Shu
Qiang Yuan
N. D. Ramesh Bhat
Andrew D. Cameron
Shi Dai
Yi Feng
Boris Goncharov
George Hobbs
Eric Howard
Richard N. Manchester
Aditya Parthasarathy
Daniel J. Reardon
Christopher J. Russell
Ryan M. Shannon
Renée Spiewak
Nithyanandan Thyagarajan
Abstract： The nature of dark matter remains obscure in spite of decades of experimental efforts. The mass of dark matter candidates can span a wide range, and its coupling with the Standard Model sector remains uncertain. All these unknowns make the etection of dark matter extremely challenging. Ultralight dark matter, with $m \sim10^{-22}$ eV, is proposed to reconcile the disagreements between observations and predictions from simulations of small-scale structures in the cold dark matter paradigm, while remaining consistent with other observations. Because of its large de Broglie wavelength and large local occupation number within galaxies, ultralight dark matter behaves like a coherently oscillating background field with an oscillating frequency dependent on its mass. If the dark matter particle is a spin-1 dark photon, such as the $U(1)_B$ or $U(1)_{B-L}$ gauge boson, it can induce an external oscillating force and lead to displacements of test masses. Such an effect would be observable in the form of periodic variations in the arrival times of radio pulses from highly stable millisecond pulsars. In this study, we search for evidence of ultralight dark photon dark matter (DPDM) using 14-year high-precision observations of 26 pulsars collected with the Parkes Pulsar Timing Array. While no statistically significant signal is found, we place constraints on coupling constants for the $U(1)_B$ and $U(1)_{B-L}$ DPDM. Compared with other experiments, the limits on the dimensionless coupling constant $\epsilon$ achieved in our study are improved by up to two orders of magnitude when the dark photon mass is smaller than $3\times10^{-22}$~eV ($10^{-22}$~eV) for the $U(1)_{B}$ ($U(1)_{B-L}$) scenario.
Peer Review Status:
Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Xiao Xue
Ligong Bian
Jing Shu
Qiang Yuan
Xingjiang Zhu
N. D. Ramesh Bhat
Shi Dai
Yi Feng
Boris Goncharov
George Hobbs
Eric Howard
Richard N. Manchester
Christopher J. Russell
Daniel J. Reardon
Ryan M. Shannon
Renée Spiewak
Nithyanandan Thyagarajan
Jingbo Wang
Abstract： A cosmological first-order phase transition is expected to produce a stochastic gravitational wave background. If the phase transition temperature is on the MeV scale, the power spectrum of the induced stochastic gravitational waves peaks around nanohertz frequencies, and can thus be probed with high-precision pulsar timing observations. We search for such a stochastic gravitational wave background with the latest data set of the Parkes Pulsar Timing Array. We find no evidence for a Hellings-Downs spatial correlation as expected for a stochastic gravitational wave background. Therefore, we present constraints on first-order phase transition model parameters. Our analysis shows that pulsar timing is particularly sensitive to the low-temperature ($T \sim 1 - 100$ MeV) phase transition with a duration $(\beta/H_*)^{-1}\sim 10^{-2}-10^{-1}$ and therefore can be used to constrain the dark and QCD phase transitions.
Peer Review Status:Awaiting Review
Subjects: Astronomy >> Astrophysical processes submitted time 2023-02-19
Xiao Xue
Ligong Bian
Jing Shu
Qiang Yuan
Xingjiang Zhu
N. D. Ramesh Bhat
Shi Dai
Yi Feng
Boris Goncharov
George Hobbs
Eric Howard
Richard N. Manchester
Christopher J. Russell
Daniel J. Reardon
Ryan M. Shannon
Renée Spiewak
Nithyanandan Thyagarajan
Jingbo Wang
Abstract： A cosmological first-order phase transition is expected to produce a stochastic gravitational wave background. If the phase transition temperature is on the MeV scale, the power spectrum of the induced stochastic gravitational waves peaks around nanohertz frequencies, and can thus be probed with high-precision pulsar timing observations. We search for such a stochastic gravitational wave background with the latest data set of the Parkes Pulsar Timing Array. We find no evidence for a Hellings-Downs spatial correlation as expected for a stochastic gravitational wave background. Therefore, we present constraints on first-order phase transition model parameters. Our analysis shows that pulsar timing is particularly sensitive to the low-temperature ($T \sim 1 - 100$ MeV) phase transition with a duration $(\beta/H_*)^{-1}\sim 10^{-2}-10^{-1}$ and therefore can be used to constrain the dark and QCD phase transitions.
Peer Review Status:Awaiting Review
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