<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0185-1101</journal-id>
<journal-title><![CDATA[Revista mexicana de astronomía y astrofísica]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. mex. astron. astrofis]]></abbrev-journal-title>
<issn>0185-1101</issn>
<publisher>
<publisher-name><![CDATA[Universidad Nacional Autónoma de México, Instituto de Astronomía]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0185-11012023000200389</article-id>
<article-id pub-id-type="doi">10.22201/ia.01851101p.2023.59.02.15</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Late accelerated expansion of the universe in diffusive scenarios]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Piratova Moreno]]></surname>
<given-names><![CDATA[Eduard Fernando]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[García]]></surname>
<given-names><![CDATA[Luz Ángela]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Fundación Universitaria Los Libertadores  ]]></institution>
<addr-line><![CDATA[Bogotá ]]></addr-line>
<country>Colombia</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad ECCI  ]]></institution>
<addr-line><![CDATA[Bogotá ]]></addr-line>
<country>Colombia</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>00</month>
<year>2023</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>00</month>
<year>2023</year>
</pub-date>
<volume>59</volume>
<numero>2</numero>
<fpage>389</fpage>
<lpage>399</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0185-11012023000200389&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0185-11012023000200389&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0185-11012023000200389&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[ABSTRACT We present a diffusion model in a cosmological framework to describe the accelerated expansion of the Universe at late times. We first introduce a scalar field in Einstein&#8217;s field equations to account for the effect of diffusion as the driver of today&#8217;s expansion. We also study a second option for the diffusion source: a perfect fluid with a barotropic equation of state. We establish the equations that relate the fluid evolution with the cosmic budget and find analytical solutions of the field equations with different diffusion coefficients: constant, redshift-dependent, and &#963; proportional to the Hubble parameter. Our main finding is that diffusive processes in the Universe are viable scenarios to effectively describe the expansion dynamics once the model&#8217;s free parameters are gauged. The choice of the diffusion coefficient and the equation of state of the cosmic fluid determines the solutions of the density fractions and the transition to an accelerated expansion of the Universe at present.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[RESUMEN Presentamos un modelo de difusión en un marco cosmológico para describir la expansión acelerada del Universo en la época actual. Primero exploramos un campo escalar en las ecuaciones de campo para explicar el efecto de la difusión como el generador de la expansión actual. Además, estudiamos el efecto de un fluido perfecto con una ecuación de estado barotrópica, y encontramos las soluciones de las ecuaciones de campo para coeficientes de difusión: constante, dependiente del redshift y &#963; proporcional al parámetro de Hubble. Nuestro principal hallazgo es que procesos de difusión en el Universo son escenarios viables para describir la dinámica de la expansión una vez que los parámetros libres del modelo son calibrados. La elección del coeficiente de difusión con corrimiento al rojo y la ecuación de estado del fluido cósmico determinan la forma de las soluciones de las fracciones de densidad y la transición a una expansión acelerada del Universo en la actualidad.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[cosmology: theory]]></kwd>
<kwd lng="en"><![CDATA[dark energy]]></kwd>
<kwd lng="en"><![CDATA[diffusion]]></kwd>
</kwd-group>
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