Detecting chameleons: The astronomical polarization produced by chameleonlike scalar fields

Burrage, Clare; Davis, Anne-Christine; Shaw, Douglas J.

doi:10.1103/physrevd.79.044028

Cited by 90 publications

(123 citation statements)

References 111 publications

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“…For example, observations of circularly-polarized starlight in the wavelength range 1 − 10 3Å could be a strong indication of mixing between chameleons and photons [876]. A difference in the ratio of the electron to proton mass between laboratories on Earth and in space can be measured and would indicate the presence of a chameleon-like scalar particle [898].…”

Section: Galaxies In the Nearby Universementioning

confidence: 99%

“…A difference in the ratio of the electron to proton mass between laboratories on Earth and in space can be measured and would indicate the presence of a chameleon-like scalar particle [898]. In [876,898], it was shown that the scatter in the luminosity of astrophysical objects can be used to search for chameleons, particularly through observing active galactic nuclei.…”

Section: Galaxies In the Nearby Universementioning

confidence: 99%

“…Similarly, the Axion Dark Matter eXperiment (ADMX) resonant microwave cavity was used recently to search for chameleons [874]. Photon-chameleon mixing can also occur deep inside the Sun [875] and affect the spectrum of distant astrophysical objects [876].…”

Section: Laboratory and Solar System Tests Of Chameleon Theoriesmentioning

confidence: 99%

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Beyond the cosmological standard model

et al. 2015

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After a decade and a half of research motivated by the accelerating universe, theory and experiment have a reached a certain level of maturity. The development of theoretical models beyond Λ or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests.We begin by reviewing recent attempts to consistently modify Einstein gravity in the infrared, focusing on the notion that additional degrees of freedom introduced by the modification must "screen" themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives of the field become important, and those for which second derivatives of the field are important. Examples of the first class, such as f (R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories and discuss prospects for completion in a more fundamental theory. We describe experimental tests of each class of theories, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. Finally, we discuss prospects for future tests which will be sensitive to different signatures of new physics in the gravitational sector.The review is structured so that those parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

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Section: Galaxies In the Nearby Universementioning

confidence: 99%

Section: Galaxies In the Nearby Universementioning

confidence: 99%

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Beyond the cosmological standard model

et al. 2015

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“…Early examples of dark energy in the form of a scalar field with a self-interaction potential can be found in a review by Peebles & Ratra (2003). To explain the nature of dark energy, many sophisticated models have been suggested (see, e.g., Caldwell et al 1998), and among them the scalar fields that are ultralight in the cosmic vacuum but that possess a high mass locally when they are coupled to ordinary matter by the so-called chameleon mechanism A&A 524, A32 (2010) (Khoury & Weltman 2004a,b;Brax et al 2004;Avelino 2008;Burrage et al 2009;Davis et al 2009;Brax 2009;Upadhye et al 2010;Brax & Zioutas 2010). A subclass of such models considered by Olive & Pospelov (2008) predicts that fundamental physical quantities, such as elementary particle masses and lowenergy coupling constants, may also depend on the local matter density.…”

Section: Introductionmentioning

confidence: 99%

Searching for chameleon-like scalar fields with the ammonia method

Levshakov

Lapinov

Henkel

et al. 2010

A&A

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Context. In our previous work we found a statistically significant offset ΔV ≈ 27 m s −1 between the radial velocities of the HC 3 N J = 2−1 and NH 3 (J, K) = (1, 1) transitions observed in molecular cores from the Milky Way. This may indicate that the electron-toproton mass ratio, μ ≡ m e /m p , increases by ∼3 × 10 −8 when measured under interstellar conditions with matter densities of more than 10 orders of magnitude lower than with laboratory (terrestrial) environments. Aims. We map four molecular cores L1498, L1512, L1517, and L1400K selected from our previous sample to estimate systematic effects in ΔV due to possible velocity gradients or other sources across the cloud and to check the reproducibility of the velocity offsets on the year-to-year time base. Methods. We use the ammonia method, which involves observations of inversion lines of NH 3 complemented by rotational lines of other molecular species and allows us to test changes in μ caused by a higher sensitivity of the inversion frequencies to the μ-variation than with the rotational frequencies. Results. We find that in two cores L1498 and L1512 the NH 3 (1, 1) and HC 3 N (2-1) transitions closely trace the same material and show an offset of ΔV ≡ V lsr (HC 3 N) -V lsr (NH 3 ) = 26.9 ± 1.2 stat ± 3.0 sys m s −1 throughout the entire clouds. The offsets measured in L1517B and L1400K are 46.9 ± 3.3 stat ± 3.0 sys m s −1 and 8.5 ± 3.4 stat ± 3.0 sys m s −1 , respectively, and are, probably, subject to Doppler shifts due to spatial segregation of HC 3 N versus NH 3 . We also determine frequency shifts caused by external electric and magnetic fields and by the cosmic black body radiation-induced Stark effect and find that they are less than 1 m s −1 . Conclusions. The measured velocity offset in L1498 and L1512, when interpreted in terms of Δμ/μ ≡ (μ obs − μ lab )/μ lab , gives Δμ/μ = (26 ± 1 stat ± 3 sys ) × 10 −9 . Although this estimate is based on a limited number of sources and molecular pairs used in the ammonia method, it demonstrates a high accuracy with which the fundamental physics can be tested by means of radio observations. The non-zero signal in Δμ/μ should be further examined as larger and more accurate data sets become available.

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“…The present paper deals with one such astronomical test based on spectral observations of molecular clouds in the Milky Way disk. Additional tests employing polarization of the light from the stars and a modification of the Sunyaev-Zel'dovich effect in the cosmic microwave background due to a coupling between a chameleon-like scalar field and photons are described, respectively, in Burrage et al (2009) and Davis et al (2009).…”

Section: Introductionmentioning

confidence: 99%

Searching for chameleon-like scalar fields with the ammonia method

Levshakov

Molaro

Lapinov

et al. 2010

A&A

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Aims. We probe the dependence of the electron-to-proton mass ratio, μ = m e /m p , on the ambient matter density by means of radio astronomical observations. Methods. The ammonia method, which has been proposed to explore the electron-to-proton mass ratio, is applied to nearby dark clouds in the Milky Way. This ratio, which is measured in different physical environments of high (terrestrial) and low (interstellar) densities of baryonic matter is supposed to vary in chameleon-like scalar field models, which predict strong dependences of both masses and coupling constant on the local matter density. High resolution spectral observations of molecular cores in lines of NH 3 (J, K) = (1, 1), HC 3 N J = 2−1, and N 2 H + J = 1−0 were performed at three radio telescopes to measure the radial velocity offsets, ΔV ≡ V rot − V inv , between the inversion transition of NH 3 (1,1) and the rotational transitions of other molecules with different sensitivities to the parameter Δμ/μ ≡ (μ obs − μ lab )/μ lab . Results. The measured values of ΔV exhibit a statistically significant velocity offset of 23 ± 4 stat ± 3 sys m s −1 . When interpreted in terms of the electron-to-proton mass ratio variation, this infers that Δμ/μ = (2.2 ± 0.4 stat ± 0.3 sys ) × 10 −8 . If only a conservative upper bound is considered, then the maximum offset between ammonia and the other molecules is |ΔV| ≤ 30 m s −1 . This provides the most accurate reference point at z = 0 for Δμ/μ of |Δμ/μ| ≤ 3 × 10 −8 .

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Detecting chameleons: The astronomical polarization produced by chameleonlike scalar fields

Cited by 90 publications

References 111 publications

Beyond the cosmological standard model

Beyond the cosmological standard model

Searching for chameleon-like scalar fields with the ammonia method

Searching for chameleon-like scalar fields with the ammonia method

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