Constraints on chameleon f(R)-gravity from galaxy rotation curves of the SPARC sample

Naik, Aneesh P.; Puchwein, Ewald; Davis, Anne-Christine; Sijacki, Debora; Desmond, Harry

doi:10.1093/mnras/stz2131

Cited by 33 publications

(27 citation statements)

References 74 publications

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“…Empirical searches for these are growing in sophistication [e.g. 43,66,67], with several indications that they may in fact be of use in accounting for certain astrophysical phenomena [68][69][70][71][72].…”

Section: Introductionmentioning

confidence: 99%

Local resolution of the Hubble tension: The impact of screened fifth forces on the cosmic distance ladder

2019

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The discrepancy between the values of the Hubble constant H 0 derived from the local distance ladder and the Cosmic Microwave Background provides a tantalising hint of new physics. We explore a potential resolution involving screened fifth forces in the local Universe, which alter the Cepheid calibration of supernova distances. In particular, if the Cepheids with direct distance measurements from parallax or water masers are screened but a significant fraction of those in other galaxies are not, neglecting the difference between their underlying period-luminosity relations biases the local H 0 measurement high. This difference derives from a reduction in the Cepheid pulsation period and possible increase in luminosity under a fifth force. We quantify the internal and environmental gravitational properties of the Riess et al. distance ladder galaxies to assess their degrees of screening under a range of phenomenological models, and propagate this information into the H 0 posterior as a function of fifth force strength. We consider well-studied screening models in scalar-tensor gravity theories such as chameleon, K-mouflage and Vainshtein, along with a recently-proposed mechanism based on baryon-dark matter interactions in which screening is governed by the local dark matter density. We find that a fifth force strength ∼ 5 − 30% that of gravity can alleviate the H 0 tension in many scenarios, around the sensitivity level at which tests based on other distance ladder data can constrain this strength. Our most successful models achieve consistency with Planck at the ∼1.5σ level. Although our analysis is exploratory and based on screening models that are not necessarily realised in full theories, our results demonstrate that new physics-based local resolutions of the H 0 tension are possible, supplementing those already known in the pre-recombination era. * harry.desmond@physics.ox.ac.uk

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Section: Introductionmentioning

confidence: 99%

Local resolution of the Hubble tension: The impact of screened fifth forces on the cosmic distance ladder

2019

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“…For the most massive dwarf spheroidals, like Sagittarius or Fornax, the criterion given in Eq. (29) suggests values of β 2 ≳ 10 −3 can be probed. For the smallest dwarf spheroidals such as Segue 1 with a mass of 6 × 10 5 M ⊙ , then values of β 2 ≳ 10 −4 are in principle accessible.…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, Baker et al [27] identify a "desert" in modified gravity parameter space accessible only to galaxy-scale probes and have launched the "novel probes" project, aimed at connecting theorists with observers in order to devise tests to probe this region. Accordingly, several recent works [28][29][30][31][32][33] have studied imprints of screened modified gravity on galaxy scales.…”

Section: Introductionmentioning

confidence: 99%

Stellar streams in chameleon gravity

et al. 2020

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Theories of gravity that incorporate new scalar degrees of freedom typically require "screening mechanisms" to ensure consistency with Solar System tests. One widely studied mechanism-the chameleon mechanism-can lead to violations of the equivalence principle (EP), as screened and unscreened objects fall differently. If the stars are screened but the surrounding dark matter is not, EP violation can lead to asymmetry between leading and trailing streams from tidally disrupted dwarf galaxies in the Milky Way halo. We provide analytic estimates of the magnitude of this effect for realistic Galactic mass distributions, demonstrating that it is an even more sensitive probe than suggested previously. Using a restricted N-body code, we simulate four satellites with a range of masses and orbits, together with a variety of strengths of the fifth force and screening levels of the Milky Way and satellite. The ratio of the cumulative number function of stars in the leading and trailing stream as a function of longitude from the satellite is computable from simulations and measurable from the stellar data and can provide a direct test of chameleon gravity. We forecast constraints for streams at large Galactocentric distances, which probe deeper into chameleon parameter space, using the specific example case of Hu-Sawicki fðRÞ gravity. Streams in the outer reaches of the Milky Way halo (with apocenters between 100 and 200 kpc) provide easily attainable constraints at the level of jf R0 j ¼ 10 −7. Still more stringent constraints at the level of 10 −7.5 or even 10 −8 are plausible provided the environmental screening of the satellite is accounted for, and screening of the Milky Way's outer halo by the Local Group is not yet triggered in this range. These would be among the tightest astrophysical constraints to date. We note three further signatures of chameleon gravity: (i) the trailing stellar stream may become detached from the dark matter progenitor if all the stars are lost, (ii) in the extreme fifth force regime, striations in the stellar trailing tail may develop from material liberated at successive pericentric passages, and (iii) if the satellite is fully screened, its orbital frequency is lower than that of the associated dark matter, which is preferentially liberated into the leading tidal tail.

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“…In the presence of thin-shell screening, the fifth force in the galactic outskirts can make a cuspy matter distribution appear more corelike when reconstructed using Newtonian dynamics because one infers more mass in the outer regions (Lombriser and Peñarrubia, 2015;Naik et al, 2019). This could make an underlying NFW profile consistent with observations of the central regions of dwarf galaxies that suggest cores, thereby ameliorating the long-standing "cusp-core problem" (de Blok, 2010).…”

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confidence: 99%

“…This inference is limited by the small sample size. Naik et al (2019) analyzed the rotation curves of 85 galaxies from the SPARC sample under an fðRÞ model, finding evidence for f R0 ≃ 10 −7 if halos are assumed to have a NFW profile, but no evidence for modified gravity if halos are instead assumed to have a cored profile as predicted by some hydrodynamical simulations. This test is limited mainly by uncertainty in the dark matter distributions.…”

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confidence: 99%