Primordial Gravitational Waves from Galaxy Intrinsic Alignments

Biagetti, Matteo; Orlando, Giorgio

doi:10.48550/arxiv.2001.05930

Cited by 7 publications

(8 citation statements)

References 142 publications

(200 reference statements)

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“…That distribution of the spin directions can be linked to different geometrical models of the universe (Campanelli et al, 2006), and can also be an indication of previously proposed theories of a rotating universe (Gödel, 1949;Ozsváth and Schücking, 1962;Ozsvath and Schücking, 2001). It has been also proposed that asymmetry between spin patterns of galaxies can be driven by parity-breaking gravitational waves (Biagetti and Orlando, 2020). While these cosmological models shift from the standard models, direct evidence of the existence of dark matter have not yet been reported, gradually reinforcing the need for models that are not necessarily based on the existence of dark matter.…”

Section: Discussionsupporting

confidence: 58%

Large‐scale asymmetry between clockwise and counterclockwise galaxies revisited

Shamir

2020

Astron Nachr

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The ability of digital sky surveys to collect and store very large amounts of data provides completely new ways to study the local universe. Perhaps one of the most provocative observations reported with such tools is the asymmetry between galaxies with clockwise and counterclockwise spin patterns. Here I use ∼ 1.7 · 10 5 spiral galaxies from SDSS and sort them by their spin patterns (clockwise or counterclockwise) to identify and profile a possible largescale pattern of the distribution of galaxy spin patterns as observed from Earth. The analysis shows asymmetry between the number of clockwise and counterclockwise spiral galaxies imaged by SDSS, and a dipole axis. These findings largely agree with previous reports using smaller datasets. The probability of the differences between the number of galaxies to occur by chance is (P < 4 · 10 −9 ), and the probability of an asymmetry axis to occur by mere chance is (P < 1.4 · 10 −5 ).

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Section: Discussionsupporting

confidence: 58%

Large‐scale asymmetry between clockwise and counterclockwise galaxies revisited

Shamir

2020

Astron Nachr

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“…In papers [4,5] we pointed out that measurements of galaxy angular momenta can be used to measure the sum of the neutrino masses and to probe primordial chirality violations. Beyond these applications, it seems possible to use galaxy spins to constrain primordial non-Gaussianity and gravitational waves, though detailed prospects for these measurements are currently unknown and under investigation (see [6,7] for similar efforts using intrinsic alignments). Measurements of galaxy spins can be also utilized to better constrain the initial conditions in the observed parts of the Universe [8,9], improving the reconstruction algorithms based on galaxy positions and velocities [10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Observational detection of correlation between galaxy spins and initial conditions

Motloch,

Yu,

Pen

et al. 2020

Preprint

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Galaxy spins can be predicted from the initial conditions in the early Universe through the tidal tensor twist. In simulations, their directions are well preserved through cosmic time, consistent with expectations of angular momentum conservation. We report a ∼ 3σ detection of correlation between observed oriented directions of galaxy angular momenta and their predictions based on the initial density field reconstructed from the positions of SDSS galaxies. The detection is driven by a group of spiral galaxies classified by the Galaxy Zoo as (anti-)clockwise, with a modest improvement from adding galaxies from MaNGA and SAMI surveys. This is the first such detection of the oriented galaxy spin direction, which opens a way to use measurements of galaxy spins to probe fundamental physics in the early Universe.*1 Not necessarily the amplitudes. *2 For brevity, we shorten "direction of angular momentum" to spin.

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“…Given the dCS-inflation dynamics, primordial power spectra, and degree of gravitational circular polarization, Eqs. (13)(14)(15)(16)(17)(18), we now move to our main calculation: the connected primordial scalar trispectrum due to graviton-exchange.…”

Section: Standard Dcs Inflationmentioning

confidence: 99%

“…[11][12][13] for applications of these ideas). In addition, LSS parity violation can be probed in any correlator that involves an odd number of galactic shear B modes, such as the galactic shear E/B cross-correlator [14,15] [or a non-zero curl component]. In the CMB, similar to the galactic shear, parity violation can be measured through correlators that involve an odd number of B modes [4,16,17], such as the E/B cross correlator, which can also measure a late-time cosmic birefringence signal [18], as well as both the CMB temperature and polarization trispectra [19,20].…”

Section: Introductionmentioning

confidence: 99%

Parity-Violating Trispectrum from Chern-Simons Gravity

Creque-Sarbinowski¹,

Alexander²,

Kamionkowski³

et al. 2023

Preprint

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A potential source for parity violation in the Universe is inflation. The simplest inflationary models have two fields: the inflaton and graviton, and the lowest-order parity-violating coupling between them is dynamical Chern-Simons (dCS) gravity with a decay constant f . Here, we show that dCS imprints a parity-violating signal in primordial scalar perturbations. Specifically, we find that, after dCS amplifies one graviton helicity due to a tachyonic instability, the graviton-mediated correlation between two pairs of scalars develops a parity-odd component. This correlation, the primordial scalar trispectrum, is then transferred to the corresponding curvature correlator and thus is imprinted in both large-scale structure (LSS) and the cosmic microwave background (CMB). We find that the parity-odd piece has roughly the same amplitude as its parity-even counterpart, scaled linearly by the degree of gravitational circular polarization Πcirc ∼ √ ε[H 2 /(M Pl f )] ≤ 1, with ε the slow-roll parameter, H the inflationary Hubble scale, and the upper bound saturated for purely circularlypolarized gravitons. We also find that, in the collapsed limit, the ratio of the two trispectra contains direct information about the graviton's spin. In models beyond standard inflationary dCS, e.g. those with multiple scalar fields or superluminal scalar sound speed, there can be a large enhancement factor F 10 6 to the trispectrum. We find that an LSS survey that contains N modes linear modes would place an nσ constraint on Πcircr of ∼ 0.04 (n/3)(10 6 /F )(10 6 /N modes ) 1/2 from the parity-odd galaxy trispectrum, for tensor-to-scalar ratio r. We also forecast for several spectroscopic and 21-cm surveys. This constraint implies that, for high-scale single-field inflation parameters, LSS can probe very large dCS decay constants f 4 × 10 9 GeV(3/n)(F/10 6 ) N modes /10 6 1/2 . Our result is the first example of a massless particle yielding a parity-odd scalar trispectrum through spin-exchange.

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Primordial Gravitational Waves from Galaxy Intrinsic Alignments

Cited by 7 publications

References 142 publications

Large‐scale asymmetry between clockwise and counterclockwise galaxies revisited

Large‐scale asymmetry between clockwise and counterclockwise galaxies revisited

Observational detection of correlation between galaxy spins and initial conditions

Parity-Violating Trispectrum from Chern-Simons Gravity

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