Constraining Ultralight Scalar Dark Matter in the Galactic Center with the S2 Orbit
Peking University（北京大学）；Kavli Institute for Astronomy and Astrophysics, Peking University（北京大学天体物理研究所）；Nanjing University（南京大学）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）
我们的银河系中心（GC）密集环境为探测超轻暗物质（ULDM）提供了独特实验室。我们探讨了通过其对S星星轨道动力学的影响来检测标量ULDM场的前景。我们考虑了标量场ϕ与标准模型粒子之间的线性和二次耦合，并分析了两种代表性的ULDM结构：标量引力原子和球形孤子。我们发现二次耦合导致非振荡扰动，引起长期 secular 轨道演化。我们利用观测到的S2星periastron进动率对GC中ULDM总质量及二次耦合常数施加严格限制。对于引力原子|211⟩态，我们限制ULDM质量与Sgr A*的质量比为β≈10^{-3}在m≈10^{-18} eV，而对于延伸到≈0.2 pc的球形孤子，质量比被限制为β≈1在m≈3×10^{-20} eV。值得注意的是，所得到的二次耦合常数限制在质量范围10^{-20} eV ≲ m ≲ 10^{-18} eV内超过了当前的界限。
英文摘要：
The dense environment of our Galactic Center (GC) offers a unique laboratory for probing ultralight dark matter (ULDM). We explore the prospect of detecting a scalar ULDM field through its effects on the orbital dynamics of S-stars around the supermassive black hole in the GC, Sgr A$^*$. We consider both linear and quadratic couplings between the real scalar field $ϕ$ and Standard Model particles, and analyze two representative ULDM structures: the scalar gravitational atom and the spherical soliton. We first find that quadratic coupling induces a non-oscillatory perturbation, leading to a long-term secular orbital evolution. We use the observed periastron precession rate of S2 star to put stringent constraints on the total ULDM mass in the GC and the quadratic coupling constant. For the gravitational atom $|211\rangle$ state, assuming an equatorial S2 orbit, we constrain the mass ratio of ULDM to Sgr A$^*$ to $β\lesssim 10^{-3}$ at $m \sim 10^{-18}$ eV, and for the spherical soliton which extends to $\sim 0.2\,$pc, the mass ratio is limited to $β\lesssim 1$ at $m \sim 3\times10^{-20}$ eV. Notably, over part of the mass range $10^{-20}\,\mathrm{eV}\lesssim m\lesssim10^{-18}\,\mathrm{eV}$, the S2 constraints are stronger than the corresponding bounds from Cassini and MICROSCOPE.
Constraining Ultralight Scalars with Black Hole Binary Mergers in Galactic Nuclei
Racah Institute of Physics, Hebrew University of Jerusalem（雷卡物理研究所，耶路撒冷希伯来大学）；Department of Astronomy, University of Wisconsin, Madison（威斯康星大学麦迪逊分校天文学系）
If ultralight $(\ll$ eV), bosonic dark matter couples to right handed neutrinos, active neutrino masses and mixing angles depend on the ambient dark matter density. When the neutrino Majorana mass, induced by the dark matter background, is small compared to the Dirac mass, neutrinos are "pseudo-Dirac" fermions that undergo oscillations between nearly degenerate active and sterile states. We present a complete cosmological history for such a scenario and find severe limits from a variety of terrestrial and cosmological observables. For scalar masses in the "fuzzy" dark matter regime ($\sim 10^{…
Pulsar Timing Arrays (PTAs) are exceptionally sensitive detectors in the frequency band $\text{nHz} \lesssim f \lesssim μ\text{Hz}$. Ultralight dark matter (ULDM), with mass in the range $10^{-23}\,\text{eV} \lesssim m_ϕ\lesssim 10^{-20}\,\text{eV}$, is one class of DM models known to generate signals in this frequency window. While purely gravitational signatures of ULDM have been studied previously, in this work we consider two signals in PTAs which arise in presence of direct couplings between ULDM and ordinary matter. These couplings induce variations in fundamental constants, i.e., partic…
Ultralight bosonic dark matter is expected to be able to form a cloud surrounding the supermassive black hole (SMBH) in the Galactic center. With increasing precision of the observations of the stellar kinematics around the SMBH, tiny effects from such a dark matter cloud, including its gravitational perturbation and the direct coupling with the ordinary matter may be detectable. In this work, we search for possible evidence of the scalar cloud using accurate orbital measurements of the S2 star around Sgr~A*. We solve the first order Post-Newtonian equation, considering simultaneously the exte…
Galactic magnetic fields seeded by ultralight dark photons
Colorado State University（科罗拉多州立大学）；University of Pittsburgh（匹兹堡大学）；Queen’s University（女王大学）；Arthur B. McDonald Canadian Astroparticle Physics Research Institute（阿瑟·B·麦克唐纳加拿大天体粒子物理研究所）；Perimeter Institute for Theoretical Physics（理论物理前沿研究所）；York University（约克大学）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）
We consider motion in spherically symmetric but time-dependent backgrounds. This problem is of interest, for example, in the context of ultralight dark matter, where galactic haloes produce a time-dependent and periodic gravitational potential. We study the properties of motion of stars in such spacetimes, for different field strengths and frequency, and including dissipative effects. We show that orbital resonances may occur and that spectroscopic emission lines from stars in these geometries exhibit characteristic, periodic modulation patterns. In addition, we work out a fully relativistic a…
Using the Pericentre Precession of LAGEOS II to Constrain Quadratically Coupled Ultralight Dark Matter
University of Nottingham（诺丁汉大学）；Leinweber Institute for Theoretical Physics, University of California, Berkeley（加州大学伯克利分校莱因韦伯理论物理研究所）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Università degli Studi di Torino（都灵大学）
We look for and place observational constraints on the imprint of ultralight dark matter (ULDM) soliton cores in rotation-dominated galaxies. Extending previous analyses, we find a conservative constraint which disfavors the soliton-host halo relation found in some numerical simulations over a broad range in the ULDM particle mass $m$. Combining the observational constraints with theoretical arguments for the efficiency of soliton formation via gravitational dynamical relaxation, and assuming that the soliton-halo relation is correct, our results disfavor ULDM from comprising 100\% of the tota…
We study the ultralight vector dark matter with a mass around $10^{-23}\,\mathrm{eV}$. The vector field oscillating coherently on galactic scales induces oscillations of the spacetime metric with a frequency around nHz, which is detectable by pulsar timing arrays. We find that the pulsar timing signal due to the vector dark matter has nontrivial angular dependence unlike the scalar dark matter and the maximal amplitude is three times larger than that of the scalar dark matter.
Gravitational lensing time delays offer an avenue to measure the Hubble parameter $H_0$, with some analyses suggesting a tension with early-type probes of $H_0$. The lensing measurements must mitigate systematic uncertainties due to the mass modelling of lens galaxies. In particular, a core component in the lens density profile would form an approximate local mass sheet degeneracy and could bias $H_0$ in the right direction to solve the lensing tension. We consider ultralight dark matter as a possible mechanism to generate such galactic cores. We show that cores of roughly the required propert…
Light halo dark matter (DM) particles upscattered by high-energy cosmic rays (CRs) can be energetic, and become detectable by conventional direct detection experiments. The current constraints derived from space-based direct CR measurements can reach $\mathcal{O}(10^{-31})\text{ cm}^{2}$ for a constant DM-nucleon scattering cross section. We show that if the CR energy spectrum follows a power law of type $\sim E^{-3}$, the derived constraints on the scattering cross section will be highly insensitive to DM particle mass. This suggests that ultrahigh-energy CRs (UHECRs) indirectly measured by g…
If high-energy neutrinos propagate in a background of ultralight scalar field particles of dark matter ($m_φ\sim 10^{-23}$eV), neutrino-dark matter interactions can play a role and affect the neutrino flux. In this work we analyse this effect using transport equations that account for the neutrino regeneration as well as absorption, and we consider the neutrino flux propagation in the extragalactic medium and also through the galactic halo of dark matter. We show the results for the final flux to arrive on Earth for different cases of point and diffuse neutrino fluxes. {We conclude that this t…
Ultralight-axion (ULA) dark matter is one of the possible solutions to resolve small-scale problems, especially the core-cusp problem. This is because ULA dark matter can create a central soliton core in all dark matter haloes stemmed from the quantum pressure against gravity below the de Broglie wavelength, which becomes manifest on astrophysical scales with axion mass range $\sim10^{-22}$ eV. In this work, we apply our non-spherical dynamical models to the kinematic data of eight classical dwarf spheroidals (dSphs) to obtain more reliable and realistic limits on ULA particle mass. This is mo…
Ultralight bosons and axion-like particles appear naturally in different scenarios and could solve some long-standing puzzles. Their detection is challenging, and all direct methods hinge on unknown couplings to the Standard Model of particle physics. However, the universal coupling to gravity provides model-independent signatures for these fields. We explore here the superradiant instability of spinning black holes triggered in the presence of such fields. The instability taps angular momentum from and limits the maximum spin of astrophysical black holes. We compute, for the first time, the s…
Potential of constraining the Fifth Force Using the Earth as a Spin and Mass Source from space
Beihang University（北京航空航天大学）；École Centrale de Pékin（巴黎中央理工学院北京校区）；Sino-French Carbon Neutrality Research Center（中法碳中和研究中心）；Peng Huanwu Collaborative Center for Research and Education（彭桓武科教协同中心）；Beijing Key Laboratory of Advanced Nuclear Materials and Physics（先进核材料物理北京市重点实验室）；Southern Center for Nuclear-Science Theory (SCNT)（南方核科学理论中心）；Institute of Modern Physics, Chinese Academy of Sciences（中国科学院近代物理研究所）；Johannes Gutenberg University（约翰内斯·古腾堡大学）；Helmholtz Institute Mainz（亥姆霍兹美因茨研究所）
Probing Fundamental Constant Oscillation in the Galactic Center with S-Star Spectroscopy
Weizmann Institute of Science（魏茨曼科学研究所）；Tsung-Dao Lee Institute, Shanghai Jiao Tong University（上海交通大学李政道研究所）；University of California, Los Angeles（加州大学洛杉矶分校）；Observatoire de Paris, Université PSL（巴黎天文台，巴黎文理研究大学）；University of Chicago（芝加哥大学）；Fermilab（费米国家加速器实验室）
Identifying Monochromatic Signals in LISA and Taiji via Spectral Split: Gravitational Waves versus Ultralight Dark Matter
University of Chinese Academy of Sciences (UCAS)（中国科学院大学）；Hangzhou Institute for Advanced Study, UCAS（杭州高等研究院，中国科学院大学）；Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；International Center for Theoretical Physics Asia-Pacific（亚太理论物理中心）；School of Astronomy and Space Science, UCAS（天文学与空间科学学院，中国科学院大学）
Ultralight scalar dark matter has been proposed to constitute a component of dark matter, though the minimal scenarios have increasingly become constrained. In this work, we analyze scenarios where the dark matter consists of more than one ultralight boson, each with different masses. This potentially leads to formation of gravitationally-bound Bose-Einstein condensates with structures that are very different from condensates composed of a single scalar field. By generalizing from the well-understood single-flavor case, we explore a large range of input parameters, subject to stability criteri…
We study some possible astrophysical implications of a very weakly coupled ultralight dilaton-type scalar field. Such a field may develop an (approximately stable) network of domain walls. The domain wall thickness is assumed to be comparable with the thickness of the luminous part of the spiral galaxies. The walls provide trapping for galactic matter. This is used to motivate the very existence of the spiral galaxies. A zero mode existing on the domain wall is a massless scalar particle confined to 1+2 dimensions. At distances much larger than the galaxy/wall thickness, the zero-mode exchange…
High energy protons produced by various sources of cosmic rays, {\it e.g.} supernova remnants, pulsar wind nebulae, active galactic nuclei and gamma-ray bursts participate in $pγ$ and $pp$ interactions. Although $pp$ interactions may be the dominant mechanism in our Galaxy, it is unclear how important $pγ$ process is. We show that the upper bound on the fraction of protons participating in $pγ$ interactions inside all Galactic astrophysical sources of cosmic rays is 10%.
Scenarios with axion-like particles of variable masses, from the milli-eV range to ultralight, can be generated in a natural way in the context of effective field theory models with anomalous $U(1)$ gauge symmetries. They include dimension-5 operators which define a coupling of the axion to the gauge anomaly. They provide a realization, in the domain of ordinary gauge theories, of models for such particles, which evade the usual mass/coupling constraint of ordinary (Peccei-Quinn) axions and are natural dark matter candidates. As an illustration of these models, we present an overview of two of…
Ultralight dark photons predicted in several Standard Model extensions can trigger the superradiant instability around rotating black holes if their Compton wavelength is comparable to the Blackhole radius. Consequently, the angular momentum of the black hole is reduced to a value which depends upon the mass and spin of the black hole as well as the mass of the dark photon. We use the mass and spin measurements of the primary black holes in two recently observed binary black hole systems: GW190517 and GW190426_152155 to constrain dark photon mass in the ranges $1.7\times 10^{-14}{\rm\ eV}<m_{A…
Enhancing Constraints on Ultralight Axion Dark Matter from Gravitational Capture
University of California Santa Cruz（加州大学圣克鲁兹分校）；Princeton University（普林斯顿大学）；Argonne National Laboratory（阿贡国家实验室）；University of Illinois Urbana-Champaign（伊利诺伊大学厄巴纳-香槟分校）；The University of Tokyo（东京大学）
Measurements of the dynamical environment of supermassive black holes (SMBHs) are becoming abundant and precise. We use such measurements to look for ultralight dark matter (ULDM), which is predicted to form dense cores ("solitons") in the centre of galactic halos. We search for the gravitational imprint of an ULDM soliton on stellar orbits near Sgr A* and by combining stellar velocity measurements with Event Horizon Telescope imaging of M87*. Finding no positive evidence, we set limits on the soliton mass for different values of the ULDM particle mass $m$. The constraints we derive exclude th…
Ultralight axion-like particles $m_a \sim 10^{-22}$ eV, or Fuzzy Dark Matter (FDM), behave comparably to cold dark matter (CDM) on cosmological scales and exhibit a kpc-size de Broglie wavelength capable of alleviating established (sub-)galactic-scale problems of CDM. Substructures inside an FDM halo incur gravitational potential perturbations, resulting in stellar heating sufficient to account for the Galactic disc thickening over a Hubble time, as first demonstrated by Church et al. We present a more sophisticated treatment that incorporates the full baryon and dark matter distributions of t…
Axion particles can form macroscopic condensates, whose size can be galactic in scale for models with very small axion masses $m\sim10^{-22}$ eV, and which are sometimes referred to under the name of Fuzzy Dark Matter. Many analyses of these condensates are done in the non-interacting limit, due to the weakness of the self-interaction coupling of axions. We investigate here how certain results change upon inclusion of these interactions, finding a decreased maximum mass and a modified mass-radius relationship. Further, these condensates are, in general, unstable to decay through number-changin…
Models in which dark matter consists entirely of primordial black holes (PBHs) with masses around $10^{17}$ g are currently unconstrained. However, if PBHs are a component of the Galactic dark matter density, they will inject a large flux of energetic particles into the Galaxy as they radiate. Positrons produced by these black holes will subsequently propagate throughout the Galaxy and annihilate, contributing to the Galactic 511 keV line. Using measurements of this line by the INTEGRAL satellite as a constraint on PBH positron injection, we place new limits on PBH abundance in the mass range …
The mass of ultralight axions is determined in order to get the explicit U(1)$_A$ symmetry breaking scale $ Λ$ at a Peccei-Quinn scale of the magnitude of the Planck mass. It is assumed that the dominant contribution to the mass of a galaxy with low surface brightness is only determined by one axionic species in the sense of fuzzy dark matter (lumps). For rotation curve fits to galactic rotation curves, therefore the Soliton-Navarro-Frenk-White model is used, which assumes a condensate core plus correlated axions in the halo according to the solution of the Poisson-Schrödinger system. In addit…
Scalar fields can give rise to confined structures, such as boson stars or Q-balls. These objects are interesting hypothetical new "dark matter stars," but also good descriptions of dark matter haloes when the fields are ultralight. Here, we study the dynamical response of such confined bosonic structures when excited by external matter (stars, planets or black holes) in their vicinities. Such perturbers can either be plunging through the bosonic configuration or simply act as periodic sources. Our setup can also efficiently describe the interaction between a massive black hole and the surroun…
Dark matter (DM) can consist of very light bosons behaving as a classical scalar field that experiences coherent oscillations. The presence of this DM field would perturb the dynamics of celestial bodies, either because the (oscillating) DM stress tensor modifies the gravitational potentials of the galaxy, or if DM is directly coupled to the constituents of the body. We study secular variations of the orbital parameters of binary systems induced by such perturbations. Two classes of effects are identified. Effects of the first class appear if the frequency of DM oscillations is in resonance wi…
Ultralight bosons can induce superradiant instabilities in spinning black holes, tapping their rotational energy to trigger the growth of a bosonic condensate. Possible observational imprints of these boson clouds include (i) direct detection of the nearly monochromatic (resolvable or stochastic) gravitational waves emitted by the condensate, and (ii) statistically significant evidence for the formation of "holes" at large spins in the spin versus mass plane (sometimes also referred to as "Regge plane") of astrophysical black holes. In this work, we focus on the prospects of LISA and LIGO dete…
High energy cosmic ray electrons and positrons, during propagation in the Galaxy, mainly lose energy through either the inverse Compton scattering (ICS) off of the interstellar radiation field (ISRF) or emitting synchrotron radiation in the Galactic magnetic field (GMF). Emitted photons by these two main energy loss mechanisms contribute to, respectively, diffuse Galactic gamma rays and radio waves. The variation of the distribution of the ISRF and the GMF has a sizable impact on the spectrum of cosmic ray electrons and positrons throughout the Galaxy. This impact is revealed both locally thro…
A high-statistics measurement of the neutrinos from a galactic core-collapse supernova is extremely important for understanding the explosion mechanism, and studying the intrinsic properties of neutrinos themselves. In this paper, we explore the possibility to constrain the absolute scale of neutrino masses $m^{}_ν$ via the detection of galactic supernova neutrinos at the Jiangmen Underground Neutrino Observatory (JUNO) with a 20 kiloton liquid-scintillator detector. In assumption of a nearly-degenerate neutrino mass spectrum and a normal mass ordering, the upper bound on the absolute neutrino…
In this work we confront dark matter models to constraints that may be derived from radio synchrotron radiation from the Galaxy, taking into account the astrophysical uncertainties and we compare these to bounds set by accelerator and complementary indirect dark matter searches. Specifically we apply our analysis to three popular particle physics models. First, a generic effective operator approach, in which case we set bounds on the corresponding mass scale, and then, two specific UV completions, the Z' and Higgs portals. We show that for many candidates, the radio synchrotron limits are comp…
It is widely accepted that dark matter contributes about a quarter of the critical mass-energy density in our Universe. The nature of dark matter is currently unknown, with the mass of possible constituents spanning nearly one hundred orders of magnitude. The ultralight scalar field dark matter, consisting of extremely light bosons with $m \sim 10^{-22}$ eV and often called "fuzzy" dark matter, provides intriguing solutions to some challenges at sub-Galactic scales for the standard cold dark matter model. As shown by Khmelnitsky and Rubakov, such a scalar field in the Galaxy would produce an o…
Probing Extragalactic Ultralight Axion Dark Matter with Decade-long Blazar Optical Polarimetry of 1ES 1959+650
Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；School of Astronomy and Space Sciences, University of Science and Technology of China（中国科学技术大学天文与空间科学学院）
If the gamma-ray excess from the galactic center reported by Fermi-LAT is a signal from annihilating dark matter, one must question why a similar excess has not been observed in dwarf spheroidal galaxies. We use this observation to place constraints on the density profile of dwarf spheroidal galaxies under the assumption that the galactic center excess is in fact a signal from annihilating dark matter. We place constraints on the generalized NFW parameter $γ$ and the Einasto profile parameter $α$ which control the logarithmic slope of the inner regions of the halo's density profile. We determi…
Models which associate the origin of the ultra-high energy cosmic rays (UHECR) with decays of relic superheavy particles predict the anisotropy of UHECR flux toward the Galactic center. We use the existing SUGAR data, which covered the Galactic center best so far, to look for such a signal and limit the fraction of UHECR produced by this mechanism. The absence of anisotropy toward the Galactic center in the SUGAR data implies at 95% confidence level that the fraction of SHDM-related cosmic rays should be less than 20% at $E>1\times10^{19}$ eV and less than 50% at $E>4\times10^{19}$ eV.
