{"id":17672,"date":"2020-06-23T19:38:33","date_gmt":"2020-06-23T11:38:33","guid":{"rendered":"https:\/\/wp-productionenv-bjg9h2g2bgg5b8aa.southeastasia-01.azurewebsites.net\/news\/black-hole-or-neutron-star-gravitational-waves-bring-a-cosmic-conundrum-to-light\/"},"modified":"2020-06-23T19:38:33","modified_gmt":"2020-06-23T11:38:33","slug":"black-hole-or-neutron-star-gravitational-waves-bring-a-cosmic-conundrum-to-light","status":"publish","type":"post","link":"https:\/\/starpath.global\/news\/black-hole-or-neutron-star-gravitational-waves-bring-a-cosmic-conundrum-to-light\/","title":{"rendered":"Black hole or neutron star? Gravitational waves bring a cosmic conundrum to light"},"content":{"rendered":"<figure id=\"attachment_570461\" aria-describedby=\"caption-attachment-570461\" style=\"width: 620px\" class=\"wp-caption aligncenter\"><img fetchpriority=\"high\" decoding=\"async\" class=\"size-full wp-image-570461\" src=\"https:\/\/cdn.geekwire.com\/wp-content\/uploads\/2020\/05\/200623-merger.jpg\" alt=\"Black holes\" width=\"620\" height=\"327\"><figcaption data-nosnippet=\"\" id=\"caption-attachment-570461\" class=\"wp-caption-text\">An artist\u2019s conception shows the imminent merger of two mismatched black holes. The mystery object involved in the merger detected last year might have been an unexpectedly small black hole or an unexpectedly large neutron star. (Credit: N. Fischer, S. Ossokine, H. Pfeiffer, A. Buonanno \/ Max Planck Institute for Gravitational Physics \/ Simulating eXtreme Spacetimes Collaboration \/ SXS)<\/figcaption><\/figure>\n<p>Telltale ripples in the fabric of spacetime have revealed the existence of a cosmic object that scientists can\u2019t definitively classify.<\/p>\n<p>Whatever it is, the object was engulfed suddenly by a black hole weighing 23.2 times the mass of our sun, 800 million light-years away. The gravitational waves thrown off by that violent merger were picked up last August by the twin detectors of the Laser Interferometer Gravitational-Wave Observatory, or LIGO, and by the Virgo gravitational-wave detector in Italy.<\/p>\n<p>The gravitational-wave patterns revealed that the smaller object was 2.6 times as massive as our sun. And that\u2019s where the classification problem arises.<\/p>\n<p>Astronomers have cataloged black holes that are as light as five solar masses, and neutron stars that are as heavy as 2.5 solar masses. But this is the first time they\u2019ve found definitive evidence of anything that\u2019s in between those two limits.<\/p>\n<p>The newly reported detection, described today in a paper published in The Astrophysical Journal Letters, fills in what was thought to be a \u201cmass gap\u201d dictated by physics and stellar evolution.<\/p>\n<p>\u201cWe\u2019ve been waiting decades to solve this mystery,\u201d study co-author Vicky Kalogera, an astronomer at Northwestern University, said in a news release. \u201cWe don\u2019t know if this object is the heaviest known neutron star, or the lightest known black hole, but either way it breaks a record.\u201d<\/p>\n<p><iframe title=\"GW190814 Artistic Interpretation\" src=\"https:\/\/player.vimeo.com\/video\/413180380?dnt=1&amp;app_id=122963\" frameborder=\"0\" allow=\"autoplay; fullscreen; picture-in-picture; clipboard-write; encrypted-media; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" data-ratio=\"0.5625\" data-width=\"800\" data-height=\"450\" style=\"display: block; margin: 0px; width: 800px; height: 450px;\"><\/iframe><\/p>\n<p>Another co-author, Patrick Brady of the University of Wisconsin at Milwaukee, said the find is likely to change how scientists talk about neutron stars and black holes, two of the most exotic denizens of the celestial menagerie. \u201cThe mass gap may in fact not exist at all, but may have been due to limitations in observational capabilities,\u201d he said. \u201cTime and more observations will tell.\u201d<\/p>\n<p>LIGO and Virgo can detect titanic collisions involving black holes or neutron stars by measuring the slight spatial distortions created by the gravitational waves that are thrown off. Physicist Albert Einstein predicted that such waves should exist, based on his general theory of relativity, but they weren\u2019t directly observed until 2015 (which led to a Nobel Prize for LIGO\u2019s leaders).<\/p>\n<p>LIGO has a double dose of detectors in Hanford, Wash., and in Livingston, La., to guard against spurious signals that could be caused, for example, by seismic activity. Each detector consists of an L-shaped complex of tunnels, measuring 2.5 miles on a side. Inside the tunnels, laser beams are bounced back and forth, and differences in the light travel time can point to gravitational-wave disruptions. The instruments are sensitive enough to measure changes in distance that are 10,000 times smaller than a proton\u2019s width.<\/p>\n<p>Last year\u2019s big event, designated GW190814, occurred last Aug. 14 and was picked up by both of LIGO\u2019s detectors as well as Virgo\u2019s detector. Other astronomers were immediately alerted to look for flashes of light that might be associated with the event. Such coordinated observations were crucial in a case in 2017 that involved the merger of two neutron stars. If a neutron star was involved in last August\u2019s crash, there might have been a similar flash.<\/p>\n<p><iframe title=\"Gravitational-wave overtones emitted by a black-hole merger with large mass-ratio (GW190814)\" src=\"https:\/\/www.youtube.com\/embed\/p4xHz-If6kw?feature=oembed\" frameborder=\"0\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share\" referrerpolicy=\"strict-origin-when-cross-origin\" allowfullscreen=\"\" data-ratio=\"0.5625\" data-width=\"800\" data-height=\"450\" style=\"display: block; margin: 0px; width: 800px; height: 450px;\"><\/iframe><\/p>\n<p>No such flash was detected, and astronomers said there could be a range of explanations for that: One possibility is that the event was so far away that any flash would be too dim to be seen, even if the mystery object was a neutron star. Another possibility is that the black hole could have consumed the neutron star in one flashless gulp, like Pac-Man eating a video-game dot.<\/p>\n<p>If both of the objects were black holes, it\u2019s not likely there\u2019d ever be any light to see. But there were plenty of gravitational waves: Some of the mass of the two combined objects \u2014 amounting to about a fifth of the mass of our sun \u2014 was converted directly into energy, in accordance with Einstein\u2019s E=mc<sup>2<\/sup> equation. The pattern of the waves and their intensity is what provided researchers with the data about the objects that crashed together.<\/p>\n<p>Currently, there\u2019s not enough data to determine whether the mystery object was a black hole, a neutron star or something even more exotic. But there\u2019s a chance that future observations of other objects in the mass gap will reveal enough additional clues to solve the mystery.<\/p>\n<p>\u201cThe mass gap has been an interesting puzzle for decades, and now we\u2019ve detected an object that fits just inside it,\u201d said Pedro Marronetti, program director for gravitational physics at the National Science Foundation. \u201cThat cannot be explained without defying our understanding of extremely dense matter or what we know about the evolution of stars. This observation is yet another example of the transformative potential of the field of gravitational-wave astronomy.\u201d<\/p>\n<figure id=\"attachment_570463\" aria-describedby=\"caption-attachment-570463\" style=\"width: 630px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"size-full-width wp-image-570463\" src=\"https:\/\/cdn.geekwire.com\/wp-content\/uploads\/2020\/05\/200623-graveyard2-630x397.jpg\" alt=\"Black hole chart\" width=\"630\" height=\"397\" srcset=\"https:\/\/cdn.geekwire.com\/wp-content\/uploads\/2020\/05\/200623-graveyard2-630x397.jpg 630w, https:\/\/cdn.geekwire.com\/wp-content\/uploads\/2020\/05\/200623-graveyard2.jpg 645w\" sizes=\"auto, (max-width: 630px) 100vw, 630px\"><figcaption data-nosnippet=\"\" id=\"caption-attachment-570463\" class=\"wp-caption-text\">This graphic shows the masses for black holes detected through electromagnetic observations (purple), the black holes measured by gravitational-wave observations (blue), the neutron stars measured with electromagnetic observations (yellow), and the neutron stars detected through gravitational waves (orange). GW190814 is highlighted in the middle of the graphic as the merger of a black hole and a mystery object around 2.6 times the mass of the sun. (Credit: LIGO-Virgo \/ Frank Elavsky and Aaron Geller \/ Northwestern)<\/figcaption><\/figure>\n<p><em>LIGO is funded by the National Science Foundation and operated by Caltech and MIT. The LIGO-Virgo team has scheduled a one-hour Zoom webinar at 7 a.m. PT June 25 to provide a deeper dive into the latest results and other gravitational-wave research. The presentation, part of the LIGO-Virgo-KAGRA Webinar Series, is aimed at a scientific audience. To register, follow this link.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"<p>An artist\u2019s conception shows the imminent merger of two mismatched black holes. The mystery object involved in the merger detected last year might have been an unexpectedly small black hole or an unexpectedly large neutron star. (Credit: N. Fischer, S. Ossokine, H. Pfeiffer, A. Buonanno \/ Max Planck Institute for Gravitational Physics \/ Simulating eXtreme [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"inline_featured_image":false,"footnotes":"","_links_to":"","_links_to_target":""},"categories":[2],"tags":[4568,1975,1978,3150,4571],"class_list":["post-17672","post","type-post","status-publish","format-standard","hentry","category-news","tag-advanced-ligo","tag-black-holes","tag-gravitational-waves","tag-neutron-stars","tag-virgo"],"acf":[],"_links":{"self":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/17672"}],"collection":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/comments?post=17672"}],"version-history":[{"count":0,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/posts\/17672\/revisions"}],"wp:attachment":[{"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/media?parent=17672"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/categories?post=17672"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/starpath.global\/blog\/wp-json\/wp\/v2\/tags?post=17672"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}