Cosmological implications of DESI DR2 BAO measurements in light of the latest ACT DR6 CMB data
Bibliographic record
Abstract
We report cosmological results from the Dark Energy Spectroscopic Instrument (DESI) measurements of baryon acoustic oscillations (BAO) when combined with recent data from the Atacama Cosmology Telescope (ACT). By jointly analyzing ACT and data and applying conservative cuts to overlapping multipole ranges, we assess how different <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:mi>P</a:mi> <a:mi>l</a:mi> <a:mi>a</a:mi> <a:mi>n</a:mi> <a:mi>c</a:mi> <a:mi>k</a:mi> <a:mo>+</a:mo> <a:mi>ACT</a:mi> </a:mrow> </a:math> dataset combinations affect consistency with DESI. While ACT alone exhibits a tension with DESI exceeding <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mrow> <c:mn>3</c:mn> <c:mi>σ</c:mi> </c:mrow> </c:math> within the <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mi mathvariant="normal">Λ</e:mi> <e:mi>CDM</e:mi> </e:math> model, this discrepancy is reduced when ACT is analyzed in combination with . For our baseline DESI DR2 <h:math xmlns:h="http://www.w3.org/1998/Math/MathML" display="inline"> <h:mrow> <h:mi>BAO</h:mi> <h:mo>+</h:mo> <h:mi>P</h:mi> <h:mi>l</h:mi> <h:mi>a</h:mi> <h:mi>n</h:mi> <h:mi>c</h:mi> <h:mi>k</h:mi> </h:mrow> </h:math> <j:math xmlns:j="http://www.w3.org/1998/Math/MathML" display="inline"> <j:mrow> <j:mi mathvariant="normal">P</j:mi> <j:mrow> <j:mi mathvariant="normal">R</j:mi> <j:mn>4</j:mn> <j:mo>+</j:mo> <j:mi>ACT</j:mi> </j:mrow> </j:mrow> </j:math> likelihood combination, the preference for evolving dark energy over a cosmological constant is about <n:math xmlns:n="http://www.w3.org/1998/Math/MathML" display="inline"> <n:mrow> <n:mn>3</n:mn> <n:mi>σ</n:mi> </n:mrow> </n:math> , increasing to over <p:math xmlns:p="http://www.w3.org/1998/Math/MathML" display="inline"> <p:mrow> <p:mn>4</p:mn> <p:mi>σ</p:mi> </p:mrow> </p:math> with the inclusion of type Ia supernova data. While the dark energy results remain quite consistent across various combinations of and ACT likelihoods with those obtained by the DESI collaboration, the constraints on neutrino mass are more sensitive, ranging from <r:math xmlns:r="http://www.w3.org/1998/Math/MathML" display="inline"> <r:mrow> <r:mo>∑</r:mo> <r:msub> <r:mrow> <r:mi>m</r:mi> </r:mrow> <r:mrow> <r:mi>ν</r:mi> </r:mrow> </r:msub> <r:mo><</r:mo> <r:mn>0.061</r:mn> <r:mtext> </r:mtext> <r:mtext> </r:mtext> <r:mi>eV</r:mi> </r:mrow> </r:math> in our baseline analysis, to <t:math xmlns:t="http://www.w3.org/1998/Math/MathML" display="inline"> <t:mo>∑</t:mo> <t:msub> <t:mi>m</t:mi> <t:mi>ν</t:mi> </t:msub> <t:mo><</t:mo> <t:mn>0.077</t:mn> <t:mtext> </t:mtext> <t:mtext> </t:mtext> <t:mi>eV</t:mi> </t:math> (95% confidence level) in the CMB likelihood combination chosen by ACT when imposing the physical prior <v:math xmlns:v="http://www.w3.org/1998/Math/MathML" display="inline"> <v:mo>∑</v:mo> <v:msub> <v:mi>m</v:mi> <v:mi>ν</v:mi> </v:msub> <v:mo>></v:mo> <v:mn>0</v:mn> <v:mtext> </v:mtext> <v:mtext> </v:mtext> <v:mi>eV</v:mi> </v:math> .
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".