Constraints on variation of fine structure constant from joint SPT-SZ and XMM-Newton observations. (arXiv:2008.10541v2 [astro-ph.CO] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Bora_K/0/1/0/all/0/1">Kamal Bora</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Desai_S/0/1/0/all/0/1">Shantanu Desai</a>

We search for a variation of the electromagnetic fine structure constant
($alpha equiv e^2/hbar c$) using a sample of 58 SZ selected clusters in the
redshift range ($0.2<z<1.5$) detected by the South Pole Telescope, along with
X-ray measurements using the XMM-Newton observatory. We use the ratio of the
integrated SZ Compto-ionization to its X-ray counterpart as our observable for
this search. We first obtain a model-independent constraint on $alpha$ of
about 0.7%, using the fact that the aforementioned ratio is constant as a
function of redshift. We then look for a logarithmic dependence of $alpha$ as
a function of redshift: $Delta alpha/alpha = -gamma ln(1+z)$, as this is
predicted by runaway dilaton models. We find that $gamma$ = $-0.046 pm 0.1$,
which indicates that there is no logarithmic variation of $alpha$ as a
function of redshift. We also search for a dipole variation of the fine
structure constant using the same cluster sample. We do not find any evidence
for such a spatial variation.

We search for a variation of the electromagnetic fine structure constant
($alpha equiv e^2/hbar c$) using a sample of 58 SZ selected clusters in the
redshift range ($0.2<z<1.5$) detected by the South Pole Telescope, along with
X-ray measurements using the XMM-Newton observatory. We use the ratio of the
integrated SZ Compto-ionization to its X-ray counterpart as our observable for
this search. We first obtain a model-independent constraint on $alpha$ of
about 0.7%, using the fact that the aforementioned ratio is constant as a
function of redshift. We then look for a logarithmic dependence of $alpha$ as
a function of redshift: $Delta alpha/alpha = -gamma ln(1+z)$, as this is
predicted by runaway dilaton models. We find that $gamma$ = $-0.046 pm 0.1$,
which indicates that there is no logarithmic variation of $alpha$ as a
function of redshift. We also search for a dipole variation of the fine
structure constant using the same cluster sample. We do not find any evidence
for such a spatial variation.

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