Search for ultralight dark matter in the SuperMAG high-fidelity dataset

Ultralight dark matter, such as kinetically mixed dark-photon dark matter (DPDM) or axion-like-particle dark matter (axion DM), can source an oscillating magnetic-field signal at Earth’s surface. Previous work searched for this signal in a publicly available dataset of global magnetometer measurements maintained by the SuperMAG collaboration. This “low-fidelity” dataset reported measurements with a 1-min time resolution, allowing the search to set leading direct constraints on DPDM and axion DM with Compton frequencies <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msub><a:mrow><a:mi>f</a:mi></a:mrow><a:mrow><a:mi>DM</a:mi></a:mrow></a:msub><a:mo>≤</a:mo><a:mn>1</a:mn><a:mo>/</a:mo><a:mo stretchy="false">(</a:mo><a:mn>1</a:mn><a:mtext> </a:mtext><a:mtext> </a:mtext><a:mi>min</a:mi><a:mo stretchy="false">)</a:mo></a:mrow></a:math> (corresponding to masses <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:mrow><e:msub><e:mrow><e:mi>m</e:mi></e:mrow><e:mrow><e:mi>DM</e:mi></e:mrow></e:msub><e:mo>≤</e:mo><e:mn>7</e:mn><e:mo>×</e:mo><e:msup><e:mrow><e:mn>10</e:mn></e:mrow><e:mrow><e:mo>−</e:mo><e:mn>17</e:mn></e:mrow></e:msup><e:mtext> </e:mtext><e:mtext> </e:mtext><e:mi>eV</e:mi></e:mrow></e:math>). More recently, a dedicated experiment undertaken by the SNIPE Hunt collaboration has also searched for this same signal at higher frequencies <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:mrow><g:msub><g:mrow><g:mi>f</g:mi></g:mrow><g:mrow><g:mi>DM</g:mi></g:mrow></g:msub><g:mo>≥</g:mo><g:mn>0.5</g:mn><g:mtext> </g:mtext><g:mtext> </g:mtext><g:mi>Hz</g:mi></g:mrow></g:math> (or <i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:mrow><i:msub><i:mrow><i:mi>m</i:mi></i:mrow><i:mrow><i:mi>DM</i:mi></i:mrow></i:msub><i:mo>≥</i:mo><i:mn>2</i:mn><i:mo>×</i:mo><i:msup><i:mrow><i:mn>10</i:mn></i:mrow><i:mrow><i:mo>−</i:mo><i:mn>15</i:mn></i:mrow></i:msup><i:mtext> </i:mtext><i:mtext> </i:mtext><i:mi>eV</i:mi></i:mrow></i:math>). In this work, we search for this signal of ultralight DM in the SuperMAG “high-fidelity” dataset, which features a 1-sec time resolution, allowing us to probe the gap in parameter space between the low-fidelity dataset and the SNIPE Hunt experiment. The high-fidelity dataset exhibits lower geomagnetic noise than the low-fidelity dataset and features more data than the SNIPE Hunt experiment, making it a powerful probe of ultralight DM. Our search finds no robust DPDM or axion DM candidates. We set constraints on DPDM and axion DM parameter space for <k:math xmlns:k="http://www.w3.org/1998/Math/MathML" display="inline"><k:mrow><k:msup><k:mrow><k:mn>10</k:mn></k:mrow><k:mrow><k:mo>−</k:mo><k:mn>3</k:mn></k:mrow></k:msup><k:mtext> </k:mtext><k:mtext> </k:mtext><k:mi>Hz</k:mi><k:mo>≤</k:mo><k:msub><k:mrow><k:mi>f</k:mi></k:mrow><k:mrow><k:mi>DM</k:mi></k:mrow></k:msub><k:mo>≤</k:mo><k:mn>0.98</k:mn><k:mtext> </k:mtext><k:mtext> </k:mtext><k:mi>Hz</k:mi></k:mrow></k:math> (or <m:math xmlns:m="http://www.w3.org/1998/Math/MathML" display="inline"><m:mrow><m:mn>4</m:mn><m:mo>×</m:mo><m:msup><m:mrow><m:mn>10</m:mn></m:mrow><m:mrow><m:mo>−</m:mo><m:mn>18</m:mn></m:mrow></m:msup><m:mtext> </m:mtext><m:mtext> </m:mtext><m:mi>eV</m:mi><m:mo>≤</m:mo><m:msub><m:mrow><m:mi>m</m:mi></m:mrow><m:mrow><m:mi>DM</m:mi></m:mrow></m:msub><m:mo>≤</m:mo><m:mn>4</m:mn><m:mo>×</m:mo><m:msup><m:mrow><m:mn>10</m:mn></m:mrow><m:mrow><m:mo>−</m:mo><m:mn>15</m:mn></m:mrow></m:msup><m:mtext> </m:mtext><m:mtext> </m:mtext><m:mi>eV</m:mi></m:mrow></m:math>). Our results are the leading direct constraints on both DPDM and axion DM in this mass range, and our DPDM constraint surpasses the leading astrophysical constraint in a narrow range around <o:math xmlns:o="http://www.w3.org/1998/Math/MathML" display="inline"><o:msub><o:mi>m</o:mi><o:msup><o:mi>A</o:mi><o:mo>′</o:mo></o:msup></o:msub><o:mo>≈</o:mo><o:mn>2</o:mn><o:mo>×</o:mo><o:msup><o:mn>10</o:mn><o:mrow><o:mo>−</o:mo><o:mn>15</o:mn></o:mrow></o:msup><o:mtext> </o:mtext><o:mtext> </o:mtext><o:mi>eV</o:mi></o:math>. Published by the American Physical Society 2024