Evolution of CMB spectral distortion anisotropies and tests of primordial non-Gaussianity

Chluba, Jens; Dimastrogiovanni, Emanuela; Amin, Mustafa A.; Kamionkowski, Marc

doi:10.1093/mnras/stw3230

Cited by 41 publications

(76 citation statements)

References 57 publications

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“…The first value is close to the estimated detection limit of a PIXIElike experiment without considering foregrounds in more detail (Chluba et al 2017a). The last value, putting us into the large signal-to-noise regime, is mainly chosen to validate the method as it reaches the limits of perturbation theory.…”

Section: Correlated µ Distortion and Cmb Temperature Anisotropiessupporting

confidence: 79%

See 1 more Smart Citation

Extracting foreground-obscured μ-distortion anisotropies to constrain primordial non-Gaussianity

Remazeilles

Chluba

2018

Monthly Notices of the Royal Astronomical Society

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Correlations between cosmic microwave background (CMB) temperature, polarization and spectral distortion anisotropies can be used as a probe of primordial non-Gaussianity. Here, we perform a reconstruction of µ-distortion anisotropies in the presence of Galactic and extragalactic foregrounds, applying the so-called Constrained ILC component separation method to simulations of proposed CMB space missions (PIXIE, LiteBIRD, CORE, PICO). Our sky simulations include Galactic dust, Galactic synchrotron, Galactic free-free, thermal Sunyaev-Zeldovich effect, as well as primary CMB temperature and µ-distortion anisotropies, the latter being added as correlated field. The Constrained ILC method allows us to null the CMB temperature anisotropies in the reconstructed µ-map (and vice versa), in addition to mitigating the contaminations from astrophysical foregrounds and instrumental noise. We compute the cross-power spectrum between the reconstructed (CMB-free) µ-distortion map and the (µfree) CMB temperature map, after foreground removal and component separation. Since the cross-power spectrum is proportional to the primordial non-Gaussianity parameter, f NL , on scales k 740 Mpc −1 , this allows us to derive f NL -detection limits for the aforementioned future CMB experiments. Our analysis shows that foregrounds degrade the theoretical detection limits (based mostly on instrumental noise) by more than one order of magnitude, with PICO standing the best chance at placing upper limits on scale-dependent non-Gaussianity. We also discuss the dependence of the constraints on the channel sensitivities and chosen bands. Like for B-mode polarization measurements, extended coverage at frequencies ν 40 GHz and ν 400 GHz provides more leverage than increased channel sensitivity.

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Section: Correlated µ Distortion and Cmb Temperature Anisotropiessupporting

confidence: 79%

“…In the description of Chluba et al (2017a), the cross-power spectrum between µ-distortion anisotropies and CMB temperature anisotropies on angular scales 2 200 is then given by:…”

Section: Correlated µ Distortion and Cmb Temperature Anisotropiesmentioning

confidence: 99%

Extracting foreground-obscured μ-distortion anisotropies to constrain primordial non-Gaussianity

Remazeilles

Chluba

2018

Monthly Notices of the Royal Astronomical Society

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“…Indeed, with local non-Gaussianity we expect an angular cross-correlation between temperature anisotropies and fractional µ anisotropies given by −12f NL C T T [3,4]. 1 Much recent work has been devoted to better understand and model this mechanism as well as forecasting and measuring the constraining power of C µT for primordial non-Gaussianity [4,[8][9][10][11][12][13][14][15][16][17][18][19].…”

Section: Introduction and Main Resultsmentioning

confidence: 99%

“…(1.7) in [9], even though that was derived for sub-Hubble scales only. Notice that when the angle between the momenta in this window function is zero (which happens for instance upon taking an ensemble average of µ itself), this window function also matches the window function in [16]: however, this reference does not write the full window function including super-Hubble modes, which is essential to this work. Moreover, we stress that the spatial structure in our formula differs from [16] for generic momenta.…”

Section: µ Production At Quadratic Ordermentioning

confidence: 99%

Spectral distortion anisotropies from single-field inflation

Cabass

Pajer²,

Woude³

2018

J. Cosmol. Astropart. Phys.

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Distortions of the Cosmic Microwave Background energy spectrum of the µ type are sensitive to the primordial power spectrum through the dissipation of curvature perturbations on scales k 50 -10 4 Mpc −1 . Their angular correlation with large-scale temperature anisotropies is then sensitive to the squeezed limit of the primordial bispectrum. For inflationary models obeying the single-field consistency relation, we show that the observed µT angular correlation that would correspond to the local shape vanishes exactly. All leading non-primordial contributions, including all non-linear production and projection effects, are of the "equilateral shape", namely suppressed by k 2 /H 2 f , where H f 10 −1 Mpc −1 is the Hubble radius at the end of the µ-era. Therefore, these non-primordial contributions are orthogonal to a potential local primordial signal (e.g. from multi-field inflation). Moreover, they are very small in amplitude. Our results strengthen the position of µ distortions as the ultimate probe of local primordial non-Gaussianity. arXiv:1805.08775v2 [astro-ph.CO] 25 Aug 2018 1 We will consider only local fNL in this work. Conventionally, it is defined in terms of the Newtonian potential during matter domination, i.e. BΦ(k1, k2, k3) = −2fNLPΦ(k1)PΦ(k2) + 2 perms., where ζ = − 5Φ 3 [5,6]. Notice also that we use the notation of [7] for the comoving curvature perturbation.2 We use the loose language of "equilateral shape" and "local shape" to refer to the dependence of C µT that would be generated by equilateral or local primordial non-Gaussianity.

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“…The spectral y-distortion is a deviation from the blackbody spectrum at second-order in the cosmological perturbations. From the photon Boltzmann equation at second-order, the y-distortion obeys [29,[33][34][35]…”

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confidence: 99%

Statistical anisotropy in CMB spectral distortions

Ota

2019

Physics Letters B

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Measurements of the cosmic microwave background (CMB) spectral y-distortion anisotropy offer a test for the statistical isotropy of the primordial density perturbations on 0.01 kMpc 1. We compute the 1-point ensemble averages of the y-distortion anisotropies which vanish for the statistically isotropic perturbations. For the quadrupole statistical anisotropy, we find 4π y2m = −6.8A2 × 10 −9 Y2m(d) with the quadruple Legendre coefficient of the anisotropic powerspectrum A2 and the = 2 spherical harmonics Y2m(d) for the preferred direction d. Also, we discuss the cosmic variance of the y-distortion anisotropy in the statistically anisotropic Universe.There exist 10 −5 of anisotropies in the cosmic microwave background (CMB), the fossil of the radiation emitted about 380,000 years after the Big Bang [1-3]. These fluctuations are random fields on top of the statistically isotropic background spacetime, and cosmic inflation can explain their origin as the quantum fluctuations in the very early stage of the expanding Universe [4][5][6]. However, such a rotational invariance is not a mandatory requirement. Indeed several inflationary models can break the rotational symmetry in the early Universe [7-10]. For example, a vector field during inflation leads to a preferred direction and produces the quadrupole asymmetry in the primordial powerspectrum of the density perturbations [8][9][10]. More generally, spinning particles imprint the multipole asymmetry of the primordial correlators [11][12][13], and hence the statistical asymmetries are sensitive to the matter contents during inflation. Thus, the statistical isotropy is an assumption to be tested through observations, and its probes have been discussed with the powerspectra of the CMB anisotropies, the 21cm lines and galaxies [14][15][16][17][18][19][20][21][22][23][24].In this Letter, we point out another way to link the primordial statistical anisotropy with a cosmological observable, i.e., a deviation of the CMB energy spectrum from the blackbody one. In particular, we discuss the sensitivity for the short wavelength (O(0.01) < kMpc < O(1.)) statistical anisotropy. We focus on the spectral y-distortion, a kinetic deviation from the Planck distribution due to the Compton scattering in the late epoch of the early Universe [25,26]. A typical source of the y-distortion is energy release from dissipation of acoustic waves on small scales. It produces the y-distortions at second-order in the cosmological perturbations, and hence the ensemble average of them is related to the short wavelength primordial powerspectrum [27][28][29]. In particular, the isotropic spectral distortion has been studied for the small-scale primordial powerspectrum. Here, we investigate imprints of the primordial statistical anisotropy on the y-distortion anisotropy. In contrast to Refs [30-32], we do not discuss the 2-or higher correlation func-tions of the spectral distortion anisotropy. Instead, we compute a simple 1-point ensemble average of the ydistortion anisotropy in an explicit way based on...

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Evolution of CMB spectral distortion anisotropies and tests of primordial non-Gaussianity

Cited by 41 publications

References 57 publications

Extracting foreground-obscured μ-distortion anisotropies to constrain primordial non-Gaussianity

Extracting foreground-obscured μ-distortion anisotropies to constrain primordial non-Gaussianity

Spectral distortion anisotropies from single-field inflation

Statistical anisotropy in CMB spectral distortions

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