Cross-Correlating Astrophysical and Cosmological Gravitational Wave Backgrounds with the Cosmic Microwave Background

Ricciardone, Angelo; Dall'Armi, Lorenzo Valbusa; Bartolo, N.; Bertacca, Daniele; Liguori, M.; Matarrese, S.

doi:10.1103/physrevlett.127.271301

Cited by 37 publications

(63 citation statements)

References 86 publications

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“…The LISA sensitivity and angular resolution will allow to detect the anisotropies of the SGWB, opening the possibility to use them in the process of characterization of the SGWB, and also to study their correlation to other cosmological tracers such as the Cosmic Microwave Background [102,110,112,120] and galaxies as tracers of the Large-Scale Structure [210][211][212][213][214]. This represents an exciting possibility to use LISA to explore our universe in a completely new perspective.…”

Section: Discussionmentioning

confidence: 99%

“…We refer the interested reader to the literature in [102,103,110,112,120] for a thorough treatment of the topic. We find it worthwhile to briefly mention the following notion.…”

Section: Inflationmentioning

confidence: 99%

“…This naturally induces a crosscorrelation among these two messengers. Recently, the cross-correlation between CMB and SGWB anisotropies induced during the propagation has been studied in [110,120], and focusing on the initial anisotropy in [102,103]. All these studies have shown that such a cross correlation signal will be within the reach of the LISA detector, and it will be extremely useful to extract information on cosmological parameters, pre-recombination physics and the non-linear parameter f N L to measure primordial non-Gaussianity.…”

Section: Propagation Effectsmentioning

confidence: 99%

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Probing Anisotropies of the Stochastic Gravitational Wave Background with LISA

Bartolo¹,

Bertacca²,

Caldwell³

et al. 2022

Preprint

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We investigate the sensitivity of the Laser Interferometer Space Antenna (LISA) to the anisotropies of the Stochastic Gravitational Wave Background (SGWB). We first discuss the main astrophysical and cosmological sources of SGWB which are characterized by anisotropies in the GW energy density, and we build a Signal-to-Noise estimator to quantify the sensitivity of LISA to different multipoles. We then perform a Fisher matrix analysis of the prospects of detectability of anisotropic features with LISA for individual multipoles, focusing on a SGWB with a power-law frequency profile. We compute the noise angular spectrum taking into account the specific scan strategy of the LISA detector. We analyze the case of the kinematic dipole and quadrupole generated by Doppler boosting an isotropic SGWB. We find that β Ω GW ∼ 2 × 10 −11 is required to observe a dipolar signal with LISA. The detector response to the quadrupole has a factor ∼ 10 3 β relative to that of the dipole. The characterization of the anisotropies, both from a theoretical perspective and from a map-making point of view, allows us to extract information that can be used to understand the origin of the SGWB, and to discriminate among distinct superimposed SGWB sources.

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Section: Discussionmentioning

confidence: 99%

“…We refer the interested reader to the literature in [102,103,110,112,120] for a thorough treatment of the topic. We find it worthwhile to briefly mention the following notion.…”

Section: Inflationmentioning

confidence: 99%

Section: Propagation Effectsmentioning

confidence: 99%

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Probing Anisotropies of the Stochastic Gravitational Wave Background with LISA

Bartolo¹,

Bertacca²,

Caldwell³

et al. 2022

Preprint

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“…Thus we see that this cross-correlation decays sharply with due to the factor (r lss /d) , as also pointed out in Refs. [41,51]. This suppression arises from the fact that the time when the gravitons begin their free streaming η in is different from that of the CMB photons η lss , thus r lss /d < 1 (recall that d = η 0 −η in for the short mode k so η in corresponds to a conformal time deep within radiation domination, whereas r lss = η 0 − η lss ).…”

Section: Cross-correlations With Induced Anisotropiesmentioning

confidence: 99%

“…Since the properties of the astrophysical background depend strongly on the distribution of the large scale structure, it will have cross-correlations with probes like galaxy clustering and weak lensing [65,67,[86][87][88][89]. As for cross-correlation of the AGWB anisotropies with the CMB, this is a direction which is being actively investigated [51]. Interestingly, the findings of [51] suggest that cross-correlating the CMB with the cosmological SGWB provides a stronger signal 13 .…”

Section: Astrophysical Foregroundsmentioning

confidence: 99%

Testing the Early Universe with Anisotropies of the Gravitational Wave Background

Dimastrogiovanni,

Fasiello,

Malhotra

et al. 2021

Preprint

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In this work we analyse in detail the possibility of using small and intermediatescale gravitational wave anisotropies to constrain the inflationary particle content. First, we develop a phenomenological approach focusing on anisotropies generated by primordial tensor-tensor-scalar and purely gravitational non-Gaussianities. We highlight the quantities that play a key role in determining the detectability of the signal. To amplify the power of anisotropies as a probe of early universe physics, we consider cross-correlations with CMB temperature anisotropies. We assess the size of the signal from inflationary interactions against so-called induced anisotropies. In order to arrive at realistic estimates, we obtain the projected constraints on the non-linear primordial parameter F NL for several upcoming gravitational wave probes in the presence of the astrophysical gravitational wave background. We further illustrate our findings by considering a concrete inflationary realisation and use it to underscore a few subtleties in the phenomenological analysis.

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Primordial gravitational waves from excited states

Fumagalli

Palma

Renaux‐Petel

et al. 2022

J. High Energ. Phys.

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We show that a scalar excited state with large occupation numbers during inflation leads to an enhancement of tensor modes and a characteristic pattern of order-one oscillations in the associated stochastic gravitational wave background (SGWB) sourced during inflation. An effective excited state, i.e. a departure from the Bunch-Davies vacuum, can emerge dynamically as the result of a transient non-adiabatic evolution, e.g. a sharp feature along the inflationary history. We provide an explicit example in a multifield context where the sharp feature triggering the excited state is identified with a strong turn in the inflationary trajectory. En passant, we derive a universal expression for the tensor power spectrum sourced at second order by an arbitrary number of scalar degrees of freedom during inflation, crucially taking into account the nontrivial structure of the Hilbert space in multifield setups. The SGWB sourced during inflation can overcome the standard scalar-induced SGWB sourced at horizon re-entry of the fluctuations after inflation, while being less constrained by perturbativity and backreaction bounds. In addition, one may entertain the possibility of detecting both since they peak at different frequencies exhibiting oscillations with distinct periods.

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Cross-Correlating Astrophysical and Cosmological Gravitational Wave Backgrounds with the Cosmic Microwave Background

Cited by 37 publications

References 86 publications

Probing Anisotropies of the Stochastic Gravitational Wave Background with LISA

Probing Anisotropies of the Stochastic Gravitational Wave Background with LISA

Testing the Early Universe with Anisotropies of the Gravitational Wave Background

Primordial gravitational waves from excited states

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