SPECTER: An Instrument Concept for CMB Spectral Distortion Measurements with Enhanced Sensitivity
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| Format: | Preprint |
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2024
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| author | Sabyr, Alina Sierra, Carlos Hill, J. Colin McMahon, Jeffrey J. |
| author_facet | Sabyr, Alina Sierra, Carlos Hill, J. Colin McMahon, Jeffrey J. |
| contents | Deviations of the cosmic microwave background (CMB) energy spectrum from a perfect blackbody uniquely probe a wide range of physics, ranging from fundamental physics in the primordial Universe ($μ$-distortion) to late-time baryonic feedback processes ($y$-distortion). While the $y$-distortion can be detected with a moderate increase in sensitivity over that of COBE/FIRAS, the $Λ$CDM-predicted $μ$-distortion is roughly two orders of magnitude smaller and requires substantial improvements, with foregrounds presenting a serious obstacle. Within the standard model, the dominant contribution to $μ$ arises from energy injected via Silk damping, yielding sensitivity to the primordial power spectrum at wavenumbers $k \approx 1-10^{4}$ Mpc$^{-1}$. Here, we present a new instrument concept, SPECTER, with the goal of robustly detecting $μ$. The instrument technology is similar to that of LiteBIRD, but with an absolute temperature calibration system. Using a Fisher approach, we optimize the instrument's configuration to target $μ$ while marginalizing over foreground contaminants. Unlike Fourier-transform-spectrometer-based designs, the specific bands and their individual sensitivities can be independently set in this instrument, allowing significant flexibility. We forecast SPECTER to observe the $Λ$CDM-predicted $μ$-distortion at $\approx 5σ$ (10$σ$) assuming an observation time of 1 (4) year(s) (corresponding to mission duration of 2 (8) years), after foreground marginalization. Our optimized configuration includes 16 bands spanning 1-2000 GHz with $\sim$degree-scale angular resolution at $\sim150$ GHz and 1100 total detectors. SPECTER will additionally measure the $y$-distortion at sub-percent precision and its relativistic correction at percent-level precision, yielding tight constraints on the total thermal energy and mean temperature of ionized gas. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2409_12188 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | SPECTER: An Instrument Concept for CMB Spectral Distortion Measurements with Enhanced Sensitivity Sabyr, Alina Sierra, Carlos Hill, J. Colin McMahon, Jeffrey J. Cosmology and Nongalactic Astrophysics Instrumentation and Methods for Astrophysics Deviations of the cosmic microwave background (CMB) energy spectrum from a perfect blackbody uniquely probe a wide range of physics, ranging from fundamental physics in the primordial Universe ($μ$-distortion) to late-time baryonic feedback processes ($y$-distortion). While the $y$-distortion can be detected with a moderate increase in sensitivity over that of COBE/FIRAS, the $Λ$CDM-predicted $μ$-distortion is roughly two orders of magnitude smaller and requires substantial improvements, with foregrounds presenting a serious obstacle. Within the standard model, the dominant contribution to $μ$ arises from energy injected via Silk damping, yielding sensitivity to the primordial power spectrum at wavenumbers $k \approx 1-10^{4}$ Mpc$^{-1}$. Here, we present a new instrument concept, SPECTER, with the goal of robustly detecting $μ$. The instrument technology is similar to that of LiteBIRD, but with an absolute temperature calibration system. Using a Fisher approach, we optimize the instrument's configuration to target $μ$ while marginalizing over foreground contaminants. Unlike Fourier-transform-spectrometer-based designs, the specific bands and their individual sensitivities can be independently set in this instrument, allowing significant flexibility. We forecast SPECTER to observe the $Λ$CDM-predicted $μ$-distortion at $\approx 5σ$ (10$σ$) assuming an observation time of 1 (4) year(s) (corresponding to mission duration of 2 (8) years), after foreground marginalization. Our optimized configuration includes 16 bands spanning 1-2000 GHz with $\sim$degree-scale angular resolution at $\sim150$ GHz and 1100 total detectors. SPECTER will additionally measure the $y$-distortion at sub-percent precision and its relativistic correction at percent-level precision, yielding tight constraints on the total thermal energy and mean temperature of ionized gas. |
| title | SPECTER: An Instrument Concept for CMB Spectral Distortion Measurements with Enhanced Sensitivity |
| topic | Cosmology and Nongalactic Astrophysics Instrumentation and Methods for Astrophysics |
| url | https://arxiv.org/abs/2409.12188 |