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| Main Authors: | , , , , |
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| Format: | Preprint |
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2025
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2506.08832 |
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| _version_ | 1866914613463875584 |
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| author | Hansen, Frode K. Lambas, Diego Garcia Ruiz, Andrés N. Toscano, Facundo Pereyra, Luis A. |
| author_facet | Hansen, Frode K. Lambas, Diego Garcia Ruiz, Andrés N. Toscano, Facundo Pereyra, Luis A. |
| contents | We find a significant CMB temperature excess in the direction of local underdensities within $z<0.03$. By contrast, less than $0.2\%$ of simulated CMB maps show a similarly significant temperature excess in nearby voids. Combined with earlier findings showing a $>5σ$ cooling of CMB photons in galactic filaments in the same redshift range, we now may have possible evidence for a negative Integrated Sachs-Wolfe (ISW) effect in the very recent Universe. In addition to having opposite sign, the observed amplitude is an order of magnitude larger than the predicted Rees-Sciama and ISW effects, pointing to an unknown physical process, possibly related with a non-standard model of dark energy. We discuss the results in light of the latest Data Release 2 results of the Dark Energy Spectroscopic Instrument (DESI) showing hints for dynamical dark energy. Removing the quadrupole, we find the CMB temperatures measured in nearby voids to a large degree uncorrelated with the temperature measured around nearby galaxies and the observed mean difference between these temperatures is almost $6.5σ$ larger than found in simulations. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2506_08832 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Evidence for a sign change of the ISW effect in the very recent universe? hot voids and cold overdensities at $z<0.03$ Hansen, Frode K. Lambas, Diego Garcia Ruiz, Andrés N. Toscano, Facundo Pereyra, Luis A. Cosmology and Nongalactic Astrophysics We find a significant CMB temperature excess in the direction of local underdensities within $z<0.03$. By contrast, less than $0.2\%$ of simulated CMB maps show a similarly significant temperature excess in nearby voids. Combined with earlier findings showing a $>5σ$ cooling of CMB photons in galactic filaments in the same redshift range, we now may have possible evidence for a negative Integrated Sachs-Wolfe (ISW) effect in the very recent Universe. In addition to having opposite sign, the observed amplitude is an order of magnitude larger than the predicted Rees-Sciama and ISW effects, pointing to an unknown physical process, possibly related with a non-standard model of dark energy. We discuss the results in light of the latest Data Release 2 results of the Dark Energy Spectroscopic Instrument (DESI) showing hints for dynamical dark energy. Removing the quadrupole, we find the CMB temperatures measured in nearby voids to a large degree uncorrelated with the temperature measured around nearby galaxies and the observed mean difference between these temperatures is almost $6.5σ$ larger than found in simulations. |
| title | Evidence for a sign change of the ISW effect in the very recent universe? hot voids and cold overdensities at $z<0.03$ |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2506.08832 |