[et_pb_section fb_built=”1″ admin_label=”Section” _builder_version=”4.16″ _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″ admin_label=”Section” _builder_version=”4.16″ _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=”4.16″ _module_preset=”default” custom_padding=”||||false|false” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text admin_label=”Unitats de recerca” module_class=”ieec-orgs” _builder_version=”4.27.4″ _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” module_class=”ieec-title” _builder_version=”4.27.4″ _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” module_class=”ieec-summary” _builder_version=”4.27.4″ _module_preset=”default” text_font=”Source Sans Pro||on||||||” text_font_size=”24px” text_line_height=”1.1em” text_font_size_tablet=”22px” text_font_size_phone=”20px” text_font_size_last_edited=”on|phone” global_colors_info=”{}”]<\/p>\n
[\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row column_structure=”1_2,1_2″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”1_2″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_post_title title=”off” meta=”off” module_class=”ieec-img-container” _builder_version=”4.27.2″ _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 module_class=”ieec-img-footer” _builder_version=”4.27.4″ _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
Artist\u2019s illustration of a quasar.<\/p>\n
[\/et_pb_text][\/et_pb_column][et_pb_column type=”1_2″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text _builder_version=”4.27.4″ _module_preset=”default” link_font=”|700|||on||||” global_colors_info=”{}”]<\/p>\n
Of the many open questions that puzzle physicists today, there is one, most relevant to cosmologists that crystallises into a single number: <\/span>the Hubble constant<\/b> H<\/i>0<\/sub><\/i><\/strong>, which stands for the ratio between <\/span>how far a cosmic object is from us and how fast it moves away<\/b> from us due to the accelerating expansion of the Universe.\u00a0<\/span><\/p>\n The TDCOSMO international collaboration, including researchers from the <\/span>Institute of Space Studies of Catalonia<\/span><\/a> (IEEC \u2014 Institut d\u2019Estudis Espacials de Catalunya) at the <\/span>Institute of Cosmos Sciences of the University of Barcelona<\/span><\/a> (ICCUB), has presented new results on this parameter measuring the expansion rate of the Universe. Based on the study of quasars, extremely bright and active galactic nuclei, <\/span>the team has found confirmation of the so-called \u201cHubble tension\u201d,<\/b> the statistically significant discrepancy between the values of<\/span> H<\/span><\/i>0<\/sub><\/i>\u00a0depending on the method used to determine them.<\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text _builder_version=”4.27.4″ _module_preset=”default” link_font=”|700|||on||||” locked=”off” global_colors_info=”{}”]<\/p>\n The puzzle comes from the different measurement strategies: the traditional method, based on the observation of cosmic objects such as Cepheid variable stars and supernovae, or a more indirect approach that uses the cosmic microwave background as the starting point for inferring<\/span> H<\/span><\/i>0<\/sub><\/i>. If this Hubble tension is real, that is, if the differing values of <\/span>H<\/span><\/i>0<\/sub><\/i>\u00a0aren’t caused by yet-to-be-found systematic uncertainties in the measurements, this calls for <\/span>a<\/b> profound rethinking of what we believe we know about the evolution and composition of the Universe.<\/b><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text module_class=”section-title” _builder_version=”4.27.4″ _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=”4.27.4″ _module_preset=”default” link_font=”|700|||on||||” locked=”off” global_colors_info=”{}”]<\/p>\n The <\/span>TDCOSMO collaboration, which brings together researchers from about twenty research centres and universities<\/b>, documents their latest effort in pursuing an alternative path to the precise measurement of the Hubble constant in a paper just published in the journal Astronomy & Astrophysics.\u00a0<\/span><\/span><\/p>\n The team\u2019s results <\/span>further support the Hubble tension between late- and early-Universe measurements of<\/b> H<\/i>0<\/sub><\/i><\/strong>.<\/b> \u201cTo me, the lensing time delay method is pivotal in the tension resolution as it is fully independent of any other method and as it does not involve complicated calibrations,\u201d says Fr\u00e9d\u00e9ric Courbin, ICREA researcher from the IEEC at the ICCUB.\u00a0<\/span><\/span><\/p>\n This international collaboration uses a <\/span>technique known as<\/b> time-delay cosmography <\/b>to infer the value of the Hubble constant. In the paper, the team applies this method to a sample of cosmic probes known as strongly lensed quasars.\u00a0<\/span><\/p>\n A quasar is a distant, extremely bright object produced by an accretion disk of gas and dust falling into a supermassive black hole at the centre of a galaxy. When a massive object, such as a galaxy, stands between an observer and a quasar, an effect known as gravitational lensing produces multiple images of the quasar<\/b>. This is because the so-called lens galaxy, also referred to as the deflector, acts a bit like an optical lens placed on the path of a light beam: it warps space and, as a result, bends and magnifies the light coming from a background object. In the case of a quasar, the light’s deflection produces bright, distorted lensed images around the lens galaxy..<\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row column_structure=”1_2,1_2″ _builder_version=”4.27.4″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”1_2″ _builder_version=”4.27.4″ _module_preset=”default” global_colors_info=”{}”][et_pb_text _builder_version=”4.27.4″ _module_preset=”default” global_colors_info=”{}”]<\/p>\n Crucially, the signature of gravitational lensing on an observed quasar is not just spatial, but temporal too. If the intensity of the radiation emitted by a quasar varies over time, the light rays coming from multiple images of one lensed quasar reach us with temporal delays. Time-delay cosmography allows researchers to measure what is known as time-delay distance. Provided the gravitational potential of the lens galaxy is sufficiently well known, scientists can infer <\/span>H<\/span><\/i>0<\/sub><\/i>\u00a0from the time-delay distance and the light’s redshift caused by the expanding Universe.<\/span><\/p>\n To obtain the new value of <\/span>H<\/span><\/i>0<\/sub><\/i>, <\/span>the TDCOSMO team used previously collected as well as new data on eight strongly lensed quasars <\/b>and took advantage of improved analysis methods. For six out of eight lens galaxies, the data related to stellar kinematics were made accessible by the NIRSpec spectrograph on the James Webb Space Telescope.These data refer to the motion of stars in a galaxy: they’re especially important to address a major source of error when determining <\/span>H<\/span><\/i>0<\/sub><\/i>\u00a0with time-delay cosmography. Other data were collected with the Multi Unit Spectroscopic Explorer (MUSE) spectrograph at the Very Large Telescope of the European Southern Observatory (ESO) in Chile and with the Keck Cosmic Web Imager (KCWI) at the Keck Observatory in Hawaii.<\/span><\/p>\n [\/et_pb_text][\/et_pb_column][et_pb_column type=”1_2″ _builder_version=”4.27.4″ _module_preset=”default” global_colors_info=”{}”][et_pb_image src=”https:\/\/www.ieec.cat\/wp-content\/uploads\/2025\/12\/PR_TDCOSMO.jpg” _builder_version=”4.27.4″ _module_preset=”default” custom_margin=”||3px|||” global_colors_info=”{}”][\/et_pb_image][et_pb_text module_class=”ieec-img-footer” _builder_version=”4.27.4″ _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 Montage of the eight lensed quasar systems in the TDCOSMO-2025 sample. The image for DES J0408\u22125354 is adapted from Shajib et al. (2020), HE 0435\u22121223, B1608+656, and WFI 2033\u22124723 from Suyu et al. (2017), PG 1115+080 and SDSS J1206+4332 from Wong et al. (2020), RX J1131\u22121231 from Shajib et al. (2024, credits: NASA\/ESA\/Chandra), and WGD 2038\u22124008 from Shajib et al. (2022).<\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_text module_class=”section-title” _builder_version=”4.27.4″ _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=”4.27.4″ _module_preset=”default” link_font=”|700|||on||||” locked=”off” global_colors_info=”{}”]<\/p>\n The latest findings from the TDCOSMO collaboration underscore the critical role of international research networks and sustained investment in science. Thanks to the support of the <\/span>Swiss National Science Foundation<\/span><\/a> (SNSF), researchers were able to collect two decades of time-delay measurements of lensed quasars using the Swiss Leonhard Euler Telescope at ESO. This long-term effort was further strengthened by European funding through the ERC Advanced Grant COSMICLENS, a project with Courbin as principal investigator.<\/span><\/p>\n Highlighting the significance of this research, the European Commission<\/b> has recently awarded a \u20ac12 million Synergy Grant to tackle the Hubble tension through <\/span>the RedH0T project<\/span><\/a>, co-led by researchers Licia Verde (ICREA-ICCUB) and Fr\u00e9d\u00e9ric Courbin.<\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.16″ _module_preset=”default” custom_margin=”30px||||false|false” locked=”off” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_divider color=”#406fda” _builder_version=”4.16″ _module_preset=”default” custom_margin=”||10px||false|false” global_colors_info=”{}”][\/et_pb_divider][et_pb_text admin_label=”M\u00e9s informaci\u00f3” module_class=”ieec-sub-title” _builder_version=”4.27.4″ _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 module_class=”ieec-sub-text” _builder_version=”4.27.4″ _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 This research is presented in a paper entitled \u201c<\/span>TDCOSMO 2025: Cosmological constraints from strong lensing time delays<\/span><\/a>\u201d, by <\/span>Birrer, S. <\/span>et al.<\/span><\/i>, to appear in the journal Astronomy & Astrophysics on 5 December 2025.<\/span><\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row _builder_version=”4.16″ _module_preset=”default” custom_margin=”||||false|false” locked=”off” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_divider color=”#406fda” _builder_version=”4.16″ _module_preset=”default” custom_margin=”||10px||false|false” global_colors_info=”{}”][\/et_pb_divider][et_pb_text admin_label=”Enlla\u00e7os” module_class=”ieec-sub-title” _builder_version=”4.27.4″ _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 module_class=”ieec-sub-text” _builder_version=”4.27.4″ _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=”4.16″ _module_preset=”default” custom_margin=”||||false|false” locked=”off” global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” global_colors_info=”{}”][et_pb_divider color=”#406fda” _builder_version=”4.16″ _module_preset=”default” custom_margin=”||10px||false|false” global_colors_info=”{}”][\/et_pb_divider][et_pb_text admin_label=”Contactes” module_class=”ieec-sub-title” _builder_version=”4.27.4″ _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=”4.16″ _module_preset=”default” custom_margin=”0px||||false|false” custom_padding=”0px||||false|false” global_colors_info=”{}”][et_pb_column type=”2_5″ _builder_version=”4.16″ _module_preset=”default” custom_padding=”|||20px|false|false” border_width_left=”1px” border_color_left=”#406fda” global_colors_info=”{}”][et_pb_text _builder_version=”4.16″ _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 Castelldefels, Barcelona [\/et_pb_text][\/et_pb_column][et_pb_column type=”3_5″ _builder_version=”4.16″ _module_preset=”default” custom_padding=”|||20px|false|false” border_width_left=”1px” border_color_left=”#406fda” global_colors_info=”{}”][et_pb_text _builder_version=”4.27.4″ _module_preset=”default” text_font_size=”16px” text_line_height=”1em” link_font=”|700|||on||||” link_text_color=”#1a1140″ header_4_font=”|700|||||||” header_4_text_color=”#1a1140″ hover_enabled=”0″ global_colors_info=”{}” sticky_enabled=”0″]<\/p>\n Institute of Space Studies of Catalonia (IEEC) [\/et_pb_text][\/et_pb_column][\/et_pb_row][et_pb_row module_id=”ieec-about” module_class=”about-ieec” _builder_version=”4.27.4″ _module_preset=”default” background_color=”rgba(64,111,218,0.15)” global_module=”17324″ global_colors_info=”{}”][et_pb_column type=”4_4″ _builder_version=”4.16″ _module_preset=”default” custom_padding=”20px|50px|20px|50px|true|true” global_colors_info=”{}”][et_pb_text admin_label=”Sobre l’IEEC” _builder_version=”4.16″ _module_preset=”default” header_2_font=”|700|||||||” header_2_font_size=”25px” custom_margin=”||10px||false|false” header_2_font_size_tablet=”23px” header_2_font_size_phone=”23px” header_2_font_size_last_edited=”on|phone” locked=”off” global_colors_info=”{}”]<\/p>\n [\/et_pb_text][et_pb_text admin_label=”Text” _builder_version=”4.16″ _module_preset=”default” text_font=”||on||||||” link_font=”|700|||on||||” locked=”off” global_colors_info=”{}”]<\/p>\n The Institute of Space Studies of Catalonia (IEEC \u2014 Institut d\u2019Estudis Espacials de Catalunya) promotes and coordinates space research and technology development in Catalonia for the benefit of society. IEEC fosters collaborations both locally and worldwide and is an efficient agent of knowledge, innovation and technology transfer. As a result of more than 25 years of high-quality research, done in collaboration with major international organisations, IEEC ranks among the best international research centres, focusing on areas such as: astrophysics, cosmology, planetary science, and Earth Observation. IEEC\u2019s engineering division develops instrumentation for ground- and space-based projects, and has extensive experience in working with private or public organisations from the aerospace and other innovation sectors.<\/p>\n The IEEC is a non-profit public sector foundation that was established in February 1996. It has a Board of Trustees composed of the Generalitat de Catalunya, Universitat de Barcelona (UB), Universitat Aut\u00f2noma de Barcelona (UAB), Universitat Polit\u00e8cnica de Catalunya \u00b7 BarcelonaTech (UPC), and the Spanish Research Council (CSIC). The IEEC is also a CERCA centre.<\/p>\n [\/et_pb_text][\/et_pb_column][\/et_pb_row][\/et_pb_section]<\/p>\n","protected":false},"excerpt":{"rendered":" An international collaboration presents new results on the expansion rate of the Universe based on the study of extremely luminous active galactic nuclei known as quasars.<\/p>\n","protected":false},"author":5,"featured_media":41800,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"on","_et_pb_old_content":"","_et_gb_content_width":"2880","footnotes":""},"categories":[111,74,98],"tags":[],"class_list":["post-41813","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-highlighted-news-small","category-news","category-science"],"yoast_head":"\nMeasuring the Hubble constant<\/h2>\n
A key research for cosmology<\/h2>\n
\n
IEEC Communication Office<\/h4>\n
E-mail: comunicacio@ieec.cat<\/a><\/p>\nLead Researcher at the IEEC<\/h4>\n
Fr\u00e9d\u00e9ric Courbin<\/h4>\n
Institute of Cosmos Sciences (ICCUB)
E-mail: courbin@ieec.cat,<\/a> frederic.courbin@icc.ub.edu<\/a><\/p>\nAbout the IEEC<\/h2>\n