[et_pb_section fb_built=”1″ _builder_version=”4.14.8″ _module_preset=”default” background_image=”https:\/\/www.ieec.cat\/wp-content\/uploads\/2022\/02\/slider-comunicacio.jpg” max_height=”130px” custom_padding=”0px||0px||false|false” da_disable_devices=”off|off|off” global_colors_info=”{}” da_is_popup=”off” da_exit_intent=”off” da_has_close=”on” da_alt_close=”off” da_dark_close=”off” da_not_modal=”on” da_is_singular=”off” da_with_loader=”off” da_has_shadow=”on”][\/et_pb_section][et_pb_section fb_built=”1″ _builder_version=”4.14.8″ _module_preset=”default” custom_padding=”24px||11px|||” da_disable_devices=”off|off|off” global_colors_info=”{}” da_is_popup=”off” da_exit_intent=”off” da_has_close=”on” da_alt_close=”off” da_dark_close=”off” da_not_modal=”on” da_is_singular=”off” da_with_loader=”off” da_has_shadow=”on”][et_pb_row _builder_version=”4.14.8″ _module_preset=”default” custom_padding=”||||false|false” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.14.8″ _module_preset=”default” global_colors_info=”{}”][et_pb_text admin_label=”Unitats de recerca” _builder_version=”4.14.8″ _dynamic_attributes=”content” _module_preset=”default” text_font=”|700||on|||||” text_font_size=”16px” header_font=”|700|||||||” custom_margin=”||10px||false|false” header_font_size_tablet=”28px” header_font_size_phone=”26px” header_font_size_last_edited=”on|phone” global_colors_info=”{}”]@ET-DC@eyJkeW5hbWljIjp0cnVlLCJjb250ZW50IjoiY3VzdG9tX21ldGFfb3JnYW5pemFjaW9uZXMiLCJzZXR0aW5ncyI6eyJiZWZvcmUiOiIiLCJhZnRlciI6IiIsImVuYWJsZV9odG1sIjoib2ZmIn19@[\/et_pb_text][et_pb_post_title author=”off” categories=”off” comments=”off” featured_image=”off” admin_label=”T\u00edtol i data” _builder_version=”4.14.8″ _module_preset=”default” title_font=”Cairo|300|||||||” title_font_size=”40px” meta_font=”||on||||||” meta_font_size=”16px” title_font_size_tablet=”35px” title_font_size_phone=”30px” title_font_size_last_edited=”on|desktop” global_colors_info=”{}”][\/et_pb_post_title][et_pb_text admin_label=”Subt\u00edtols” _builder_version=”4.14.8″ _module_preset=”default” text_font=”Source Sans Pro||on||||||” text_font_size=”24px” text_line_height=”1.1em” hover_enabled=”0″ text_font_size_tablet=”22px” text_font_size_phone=”20px” text_font_size_last_edited=”on|phone” global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n
[\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row column_structure=”1_2,1_2″ _builder_version=”4.14.8″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”1_2″ _builder_version=”4.14.8″ _module_preset=”default” global_colors_info=”{}”][et_pb_post_title title=”off” meta=”off” _builder_version=”4.14.8″ _module_preset=”default” custom_margin=”||0px||false|false” border_width_top=”10px” border_color_top=”#406fda” global_colors_info=”{}”][\/et_pb_post_title][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” text_font=”||||||||” text_font_size=”15px” text_line_height=”1.1em” background_color=”rgba(64,111,218,0.15)” custom_margin=”0px||||false|false” custom_padding=”30px|20px|30px|20px|true|true” global_colors_info=”{}”]<\/p>\n
Caption:<\/strong> An artist’s impression of a neutron star, shown as a bright blue and red sphere with spark-like features flying off it. Several blue magnetic field lines loop connect the sphere’s two poles. [\/et_pb_text][\/et_pb_column][et_pb_column type=”1_2″ _builder_version=”4.14.8″ _module_preset=”default” global_colors_info=”{}”][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” link_font=”|700|||on||||” global_colors_info=”{}”]<\/p>\n The European Space Agency\u2019s (ESA) <\/span>XMM-Newton<\/span><\/a> and NASA\u2019s <\/span>Chandra<\/span><\/a> spacecraft have detected <\/span>three young neutron stars that are unusually cold<\/b> for their age. By comparing their properties to different neutron star models, a team of astronomers from the <\/span>Institute of Space Studies of Catalonia<\/span><\/a> (IEEC \u2014 Institut d\u2019Estudis Espacials de Catalunya) at the <\/span>Institute of Space Sciences<\/span><\/a> (ICE-CSIC), in collaboration with the <\/span>University of Alicante<\/span><\/a>, concludes on a study published in <\/span>Nature Astronomy<\/span><\/i> that the oddballs\u2019 low temperatures disqualify around 75% of known models. This is a big step towards uncovering the one neutron star \u2018equation of state\u2019 that rules them all, with important implications for the fundamental laws of the Universe.<\/span><\/p>\n After stellar mass black holes, neutron stars are the densest objects in the Universe<\/b>. Each neutron star is the compressed core of a giant star, left behind after the star exploded in a supernova. After running out of fuel, the star’s core implodes under the force of gravity while its outer layers are blasted outward into space.<\/span><\/span><\/span><\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.14.8″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.14.8″ _module_preset=”default” global_colors_info=”{}”][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” link_font=”|700|||on||||” locked=”off” global_colors_info=”{}”]<\/p>\n Matter in the centre of a neutron star is squeezed so hard that scientists still don\u2019t know what form it takes. Neutron stars get their name from the fact that under this immense pressure, even atoms collapse: electrons merge with atomic cores, turning protons into neutrons. But it might get even weirder, as the extreme heat and pressure may stabilise more exotic particles that don\u2019t survive anywhere else, or possibly melt particles together into a swirling soup of their constituent quarks.\u00a0<\/span><\/p>\n What happens inside a neutron star is described by the so-called \u2018equation of state\u2019, a theoretical model that describes what physical processes can occur inside a neutron star. The problem is, <\/span>scientists don\u2019t yet know which of the hundreds of possible equation of state models is correct<\/b>. While the behaviour of individual neutron stars may depend on properties like their mass or how fast they spin, all neutron stars must obey the same equation of state. <\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.14.8″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.14.8″ _module_preset=”default” global_colors_info=”{}”][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” header_2_font=”|700|||||||” header_2_font_size=”25px” header_2_font_size_tablet=”23px” header_2_font_size_phone=”23px” header_2_font_size_last_edited=”on|phone” global_colors_info=”{}”]<\/p>\n [\/et_pb_text][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” link_font=”|700|||on||||” locked=”off” global_colors_info=”{}”]<\/p>\n Digging into data from ESA\u2019s XMM-Newton and NASA\u2019s Chandra missions, scientists discovered three exceptionally young and cold neutron stars that are 10\u2013100 times colder than their peers of the same age. By comparing their properties to the cooling rates predicted by different models, the researchers conclude that <\/span>the existence of these three oddballs rules out most proposed equations of state<\/b>.\u00a0<\/span><\/p>\n \u201cThe young age and the cold surface temperature of these three neutron stars can only be explained by invoking a fast cooling mechanism. Since enhanced cooling can be activated only by certain equations of state, this allows us to exclude a significant portion of the possible models,\u201d explains astrophysicist <\/span>Nanda Rea<\/b>, whose research group at the ICE-CSIC and the IEEC led the investigation.<\/span><\/p>\n [\/et_pb_text][et_pb_image src=”https:\/\/www.ieec.cat\/wp-content\/uploads\/2024\/06\/NeutronStar_Final2.jpg” _builder_version=”4.14.8″ _module_preset=”default” custom_margin=”||2px|||” global_colors_info=”{}”][\/et_pb_image][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” text_font=”||||||||” text_font_size=”15px” text_line_height=”1.1em” background_color=”rgba(64,111,218,0.15)” custom_margin=”0px||||false|false” custom_padding=”30px|20px|30px|20px|true|true” global_colors_info=”{}”]<\/p>\n Caption:<\/strong> Quick-cooling oddballs rewrite neutron star physics. [\/et_pb_text][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” link_font=”|700|||on||||” locked=”off” global_colors_info=”{}”]<\/p>\n Uncovering the true neutron star equation of state also has important implications for the fundamental laws of the Universe. Physicists famously don\u2019t yet know how to stitch together the theory of general relativity (which describes the effects of gravity over large scales) with quantum mechanics (which describes what happens at the level of particles). Neutron stars are the best testing ground for this as they have densities and gravitation far beyond anything we can create on Earth. <\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.14.8″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.14.8″ _module_preset=”default” global_colors_info=”{}”][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” header_2_font=”|700|||||||” header_2_font_size=”25px” header_2_font_size_tablet=”23px” header_2_font_size_phone=”23px” header_2_font_size_last_edited=”on|phone” global_colors_info=”{}”]<\/p>\n [\/et_pb_text][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” link_font=”|700|||on||||” locked=”off” global_colors_info=”{}”]<\/p>\n The three oddball neutron stars being so cold makes them too dim for most X-ray observatories to see. \u201cThe superb sensitivity of XMM-Newton and Chandra made it possible not only to detect these neutron stars, but to collect enough light to determine their temperatures and other properties,\u201d says <\/span>Camille Diez<\/b>, ESA research fellow who works on XMM-Newton data.\u00a0<\/span><\/p>\n However, the sensitive measurements were only the first step towards being able to draw conclusions about what these oddballs mean for the neutron star equation of state. To this end, Nanda Rea\u2019s research team at ICE-CSIC combined the complementary expertise of Alessio Marino, Clara Dehman and Konstantinos Kovlakas, as well as Daniele Vigan\u00f2, co-author of the magnetic field simulation code.<\/span><\/p>\n IEEC postdoctoral researcher at the ICE-CSIC and first author of the paper <\/span>Alessio Marino<\/b> led on determining the physical properties of the neutron stars. \u201cThree of these neutron stars are much cooler than the others at similar ages. This was a big clue that something weird might be going on inside these objects, which we need to understand,\u201d he says. The team could deduce the temperatures of the neutron stars from the X-rays sent out from their surfaces, while the sizes and speeds of the surrounding supernova remnants gave an accurate indication of their ages. <\/span><\/p>\n [\/et_pb_text][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” text_text_color=”#FFFFFF” text_font_size=”21px” text_line_height=”1.1em” background_color=”#406fda” text_orientation=”center” width=”70%” width_tablet=”70%” width_phone=”70%” width_last_edited=”on|desktop” module_alignment=”center” custom_padding=”40px|50px|40px|50px|true|true” custom_padding_tablet=”40px|50px|40px|50px|true|true” custom_padding_phone=”30px|20px|30px|20px|true|true” custom_padding_last_edited=”on|phone” text_font_size_tablet=”21px” text_font_size_phone=”19px” text_font_size_last_edited=”on|desktop” global_colors_info=”{}”]<\/p>\n \u201cThree of these neutron stars are much cooler than the others at similar ages. This was a big clue that something weird might be going on inside these objects,\u201d says Alessio Marino. [\/et_pb_text][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” link_font=”|700|||on||||” locked=”off” global_colors_info=”{}”]<\/p>\n Next, <\/span>Clara Dehman<\/b>,<\/span> postdoctoral researcher at the <\/span>University of Alicante,<\/span> took the lead on computing neutron star \u2018cooling curves\u2019 for equations of state that incorporate different cooling mechanisms. This entails plotting what each model predicts for how a neutron star\u2019s luminosity\u2014a characteristic directly related to its temperature\u2014changes over time. The shape of these curves depends on several different properties of a neutron star, not all of which can be determined accurately from observations. For this reason, the team computed the cooling curves for a range of possible neutron star masses and magnetic field strengths.<\/span><\/p>\n \u201cBecause more massive neutron stars have more particles, special processes that cause neutron stars to cool more rapidly might be triggered,\u201d says co-author Dehman, who worked in this study while doing her PhD thesis at ICE-CSIC. \u201cIt\u2019s like having early answers filled in on a crossword puzzle \u2013 it makes filling in the rest of the answers much easier.\u201d, she adds.<\/span><\/p>\n Finally, a statistical analysis led by <\/span>Konstantinos Kovlakas, <\/b>IEEC researcher at the ICE-CSIC,<\/span> brought it all together. Using machine learning to determine how well the simulated cooling curves align with the oddballs\u2019 properties showed that equations of state without a fast cooling mechanism have zero chance of matching the data.\u00a0<\/span><\/p>\n \u201cIf we are able to eliminate some of the possibilities about what is inside a neutron star, then the next question we have to ask is, what is left?\u201d, points out co-author Kovlakas.<\/span><\/p>\n \u201cNeutron star research crosses many scientific disciplines, spanning from particle physics to gravitational waves. The success of this work demonstrates how fundamental teamwork is to advancing our understanding of the Universe,\u201d concludes Nanda Rea.<\/span><\/p>\n <\/span><\/p>\n Press release prepared in collaboration with the Institute of Space Sciences.<\/span><\/em><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.14.8″ _module_preset=”default” custom_margin=”30px||||false|false” locked=”off” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.14.8″ _module_preset=”default” global_colors_info=”{}”][et_pb_divider color=”#406fda” _builder_version=”4.14.8″ _module_preset=”default” custom_margin=”||10px||false|false” global_colors_info=”{}”][\/et_pb_divider][et_pb_text admin_label=”M\u00e9s informaci\u00f3” _builder_version=”4.14.8″ _module_preset=”default” text_font=”Cairo|700|||||||” text_text_color=”#406fda” text_font_size=”20px” custom_margin=”||10px||false|false” global_colors_info=”{}”]<\/p>\n More information<\/p>\n [\/et_pb_text][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” text_font_size=”16px” text_line_height=”1.1em” link_font=”|700|||on||||” custom_margin=”20px||||false|false” global_colors_info=”{}”]<\/p>\n <\/span><\/span>This research is presented in a paper entitled \u201c<\/span>Constraints on the dense matter equation of state from young and cold isolated neutron stars<\/span><\/a>\u201d, by <\/span>Alessio Marino, Clara Dehman, Konstantinos Kovlakas, Nanda Rea, Jos\u00e9 A. Pons and Daniele Vigan\u00f2<\/span>, to appear in the journal Nature Astronomy on 20 June 2024. <\/span>DOI: <\/span>10.1038\/s41550-024-02291-y<\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.14.8″ _module_preset=”default” custom_margin=”||||false|false” locked=”off” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.14.8″ _module_preset=”default” global_colors_info=”{}”][et_pb_divider color=”#406fda” _builder_version=”4.14.8″ _module_preset=”default” custom_margin=”||10px||false|false” global_colors_info=”{}”][\/et_pb_divider][et_pb_text admin_label=”Enlla\u00e7os” _builder_version=”4.14.8″ _module_preset=”default” text_font=”Cairo|700|||||||” text_text_color=”#406fda” text_font_size=”20px” custom_margin=”||10px||false|false” global_colors_info=”{}”]<\/p>\n Links<\/p>\n [\/et_pb_text][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” text_font_size=”16px” text_line_height=”1.1em” link_font=”|700|||on|||#1a1140|” link_text_color=”#1a1140″ link_line_height=”1.4em” custom_margin=”20px||||false|false” global_colors_info=”{}”]<\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.14.8″ _module_preset=”default” custom_margin=”||||false|false” locked=”off” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.14.8″ _module_preset=”default” global_colors_info=”{}”][et_pb_divider color=”#406fda” _builder_version=”4.14.8″ _module_preset=”default” custom_margin=”||10px||false|false” global_colors_info=”{}”][\/et_pb_divider][et_pb_text admin_label=”Contactes” _builder_version=”4.14.8″ _module_preset=”default” text_font=”Cairo|700|||||||” text_text_color=”#406fda” text_font_size=”20px” custom_margin=”||10px||false|false” global_colors_info=”{}”]<\/p>\n Contacts<\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row column_structure=”2_5,3_5″ admin_label=”Row” _builder_version=”4.14.8″ _module_preset=”default” custom_margin=”0px||||false|false” custom_padding=”0px||||false|false” global_colors_info=”{}”][et_pb_column type=”2_5″ _builder_version=”4.14.8″ _module_preset=”default” custom_padding=”|||20px|false|false” border_width_left=”1px” border_color_left=”#406fda” global_colors_info=”{}”][et_pb_text _builder_version=”4.14.8″ _module_preset=”default” text_font_size=”16px” text_line_height=”1.1em” link_font=”|700|||on|||#1a1140|” link_text_color=”#1a1140″ link_line_height=”1.4em” header_4_font=”|700|||||||” header_4_text_color=”#1a1140″ custom_margin=”||||false|false” locked=”off” global_colors_info=”{}”]<\/p>\n
Credits:<\/strong> ICE-CSIC\/D. Futselaar\/Marino et al.
<\/span><\/p>\nToo cold<\/h2>\n
Credits:<\/strong> ESA. Acknowledgement: Work performed by ATG under contract for ESA. License: CC BY-SA 3.0 IGO or ESA Standard License.
<\/span><\/p>\nJoining forces: four steps to discovery<\/h2>\n
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