Johannes R. Eskilt

He already gave a talk on the results! youtu.be/vvxSsnZivTQ?...

20.09.2025 13:11 — 👍 1    🔁 0    💬 0    📌 0

Currently at 4.6sigma, so we are not far from crossing it!

bsky.app/profile/joha...

20.09.2025 12:18 — 👍 2    🔁 0    💬 2    📌 0

Combining these results, we get 4.6 sigma. Getting close to 5 sigma!
Graph credit: E. Komatsu

20.09.2025 09:08 — 👍 6    🔁 0    💬 0    📌 1

In 2022, we were very excited to see 3.6sigma evidence of Cosmic Birefringence in Planck+WMAP. We've been waiting for confirmation from other experiments since, and now we are slowly getting it!

New paper is finding 2.9sigma evidence in ACT DR6. This is getting serious!
arxiv.org/abs/2509.13654

20.09.2025 09:07 — 👍 69    🔁 13    💬 8    📌 4

ACT's 2.5sigma cosmic birefringence measurement should not be viewed in isolation. Combining their measurement with previous WMAP+Planck result increases the significance to 4+ sigma (assuming Gaussian dist+independent measurements).

Graph credit: E. Komatsu

19.03.2025 14:23 — 👍 0    🔁 0    💬 0    📌 0

With Planck+WMAP, we reached 3.6 sigma. If another CMB experiment with different systematics and people doing the analysis reaches the same significance, I won't just be excited, I'll actually believe cosmic birefringence is real. But I might just be young and naive 😅

18.03.2025 20:01 — 👍 1    🔁 0    💬 1    📌 0

I would expect you to be more excited about their 2.5 sigma birefringence results! It's a bit hidden, but they find a birefringence angle of 0.20 \pm 0.08 deg (Eq 14 in act.princeton.edu/sites/g/file...). Very consistent with our Planck+WMAP results! arxiv.org/abs/2205.13962

18.03.2025 19:14 — 👍 3    🔁 0    💬 1    📌 0

Although #ACT DR6s headline is that LCDM is still king, they do find a 2.5 sigma of an unexplained polarization angle (aka cosmic birefringence)! I am amazed that people are not more excited by this! Their beta = 0.20 \pm 0.08 is very consistent with our Planck+WMAP results! arxiv.org/abs/2205.13962

18.03.2025 19:09 — 👍 6    🔁 1    💬 1    📌 1