<?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>0035-001X</journal-id>
<journal-title><![CDATA[Revista mexicana de física]]></journal-title>
<abbrev-journal-title><![CDATA[Rev. mex. fis.]]></abbrev-journal-title>
<issn>0035-001X</issn>
<publisher>
<publisher-name><![CDATA[Sociedad Mexicana de Física]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0035-001X2007001000005</article-id>
<title-group>
<article-title xml:lang="es"><![CDATA[Materia y energía oscuras, ¿que son?]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Caldera-Cabral]]></surname>
<given-names><![CDATA[G.A]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Ureña-López]]></surname>
<given-names><![CDATA[L.A]]></given-names>
</name>
<xref ref-type="aff" rid="A01"/>
</contrib>
</contrib-group>
<aff id="A01">
<institution><![CDATA[,Universidad de Guanajuato Instituto de Física ]]></institution>
<addr-line><![CDATA[León Guanajuato]]></addr-line>
<country>México</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>08</month>
<year>2007</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>08</month>
<year>2007</year>
</pub-date>
<volume>53</volume>
<fpage>17</fpage>
<lpage>21</lpage>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0035-001X2007001000005&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0035-001X2007001000005&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0035-001X2007001000005&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="es"><p><![CDATA[Uno de los problemas más importantes de la cosmología actual es el determinar la naturaleza de la materia oscura y la energía oscura. Presentaremos un resumen de las evidencias observacionales de la existencia de la materia oscura, y se revisaran algunos de los posibles candidatos propuestos en la literatura. De igual manera, describiremos modelos dinámicos de energía oscura como Quintessence y Phantom.]]></p></abstract>
<abstract abstract-type="short" xml:lang="en"><p><![CDATA[One of the most important problems in modern cosmology is the determination of the nature of dark matter and dark energy. We present a summary of the observational evidence for the existence of dark matter, and we make a revision of some of the candidates that appear in the literature. Likewise, we describe dynamical models for dark energy in the case of Quintessence and Phantom energy.]]></p></abstract>
<kwd-group>
<kwd lng="es"><![CDATA[Cosmología]]></kwd>
<kwd lng="es"><![CDATA[materia oscura]]></kwd>
<kwd lng="es"><![CDATA[energía oscura]]></kwd>
<kwd lng="en"><![CDATA[Cosmology]]></kwd>
<kwd lng="en"><![CDATA[dark matter]]></kwd>
<kwd lng="en"><![CDATA[dark energy]]></kwd>
</kwd-group>
</article-meta>
</front><body><![CDATA[ <p align="center"><font face="verdana" size="4"><b>Materia y energ&iacute;a oscuras, &iquest;que son?</b></font></p>     <p align="center"><font face="verdana" size="2">&nbsp;</font></p>     <p align="center"><font face="verdana" size="2"><b>G.A. Caldera&#150;Cabral y L.A. Ure&ntilde;a&#150;L&oacute;pez </b></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><i>Instituto de F&iacute;sica, Universidad de Guanajuato, </i><i>Le&oacute;n, Guanajuato, 37150 M&eacute;xico, e&#150;mail: <a href="mailto:gcaldera@fisica.ugto.mx" target="_blank">gcaldera@fisica.ugto.mx</a>, <a href="mailto:lurena@fisica.ugto.mx" target="_blank">lurena@fisica.ugto.mx</a></i></font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">Recibido el 1 de mayo de 2006    <br>   Aceptado el 1 de noviembre de 2006</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Resumen</b></font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2">Uno de los problemas m&aacute;s importantes de la cosmolog&iacute;a actual es el determinar la naturaleza de la materia oscura y la energ&iacute;a oscura. Presentaremos un resumen de las evidencias observacionales de la existencia de la materia oscura, y se revisaran algunos de los posibles candidatos propuestos en la literatura. De igual manera, describiremos modelos din&aacute;micos de energ&iacute;a oscura como Quintessence y Phantom.</font></p>     <p align="justify"><font face="verdana" size="2"><b>Descriptores: </b>Cosmolog&iacute;a; materia oscura; energ&iacute;a oscura.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Abstract</b></font></p>     <p align="justify"><font face="verdana" size="2">One of the most important problems in modern cosmology is the determination of the nature of dark matter and dark energy. We present a summary of the observational evidence for the existence of dark matter, and we make a revision of some of the candidates that appear in the literature. Likewise, we describe dynamical models for dark energy in the case of Quintessence and Phantom energy.</font></p>     <p align="justify"><font face="verdana" size="2"><b>Keywords: </b>Cosmology; dark matter; dark energy.</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2">PACS:  98.80.&#150;k; 95.35.+d; 95.36.+x</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><a href="/pdf/rmf/v53s4/v53s4a5.pdf">DESCARGAR ART&Iacute;CULO EN FORMATO PDF</a></font></p>     ]]></body>
<body><![CDATA[<p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>Acknowledgments</b></font></p>     <p align="justify"><font face="verdana" size="2">GC agradece la beca de maestr&iacute;a otorgada por CONACYT. Otros apoyos parciales para este trabajo son los: proyectos CONACYT (42748, 46195 y 47641), CONCYTEG (05&#150;16&#150;K1 17&#150;032), PROMEP (UGTO&#150;CA&#150;3) y DINPO (00085).</font></p>     <p align="justify"><font face="verdana" size="2">&nbsp;</font></p>     <p align="justify"><font face="verdana" size="2"><b>References</b></font></p>     <!-- ref --><p align="justify"><font face="verdana" size="2">1. C.L. 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Ure&ntilde;a&#150;Lopez, <i>JCAP </i><b>0509 </b>(2005) 013, astro&#150;ph/0507350.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8342293&pid=S0035-001X200700100000500020&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">21. Llamaremos en general materia (M) al total de componentes del universo capaces de formar estructuras ligadas gravitatoriamente. <i>Rev. Mex. F&iacute;s. S </i><b>53 </b>(4) (2007) 17&#150;21</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8342294&pid=S0035-001X200700100000500021&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">22.  En sentido estricto, Zwicky se refer&iacute;a a materiano&#150;luminosa, lo        que no implicaba que fuera materia de tipo no&#150;bari&oacute;nico, como se cree actualmente.</font>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;[&#160;<a href="javascript:void(0);" onclick="javascript: window.open('/scielo.php?script=sci_nlinks&ref=8342295&pid=S0035-001X200700100000500022&lng=','','width=640,height=500,resizable=yes,scrollbars=1,menubar=yes,');">Links</a>&#160;]<!-- end-ref --><!-- ref --><p align="justify"><font face="verdana" size="2">23. 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