GW151226, the second event

 

The GW151226 event

On December 26, 2015 at 03:38:53 UTC, the LIGO and Virgo scientists have observed gravitational waves for the second time. The second event, labeled GW151226, was detected by the twin Laser Interferometer Gravitational-Wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA.

As for the first event, GW150914, this one is consistent with the merger of two black holes. However, in this event the black hole masses are slightly smaller – 14 and 8 solar masses, producing a more massive black hole of 21 solar masses.

Gravity Waves StillImage

Image credit: LIGO/T. Pyle
This illustration shows the merger of two black holes and the gravitational waves that ripple outward as the black holes spiral toward each other. The black holes—which represent those detected by LIGO on Dec. 26, 2015—were 14 and 8 times the mass of the sun, until they merged, forming a single black hole 21 times the mass of the sun. In reality, the area near the black holes would appear highly warped, and the gravitational waves would be difficult to see directly.

 

This means that during the merger, which occurred approximately 1.4 billion years ago, mass roughly equivalent to the Sun was converted into gravitational waves. The signal comes from the last 27 orbits of the black holes before they merged.  The signal arrived in the Livingston detector about 1.1 milliseconds before reaching the Hanford detector: in this way the position of the source is roughly determined.

Here below we collect some useful resources about GW151226

Discovery Paper on Physical Review Letters:

http://link.aps.org/doi/10.1103/PhysRevLett.116.241103

Full “Observation Run 1” (September 2015 -> January 2016) binary black hole search:

Binary Black Hole Mergers in the first Advanced LIGO Observing Run (posted on arXiv)

VIRGO-related Press Releases

Webcast of the June 15, 2016 LIGO-Virgo press conference

Link to LIGO Press material

Press Review related to GW151226

Here is a selection of articles and stories appeared in Europe about the second announcement:

France:
http://www.lefigaro.fr/sciences/2016/06/15/01008-20160615ARTFIG00295-de-nouvelles-ondes-gravitationnelles-detectees.php
http://www.lemonde.fr/sciences/article/2016/06/15/les-ondes-gravitationnelles-frappent-une-deuxieme-fois_4951224_1650684.html
http://www.leparisien.fr/sciences/ondes-gravitationnelles-einstein-a-encore-raison-15-06-2016-5887735.php
http://www.futura-sciences.com/magazines/espace/infos/actu/d/ondes-gravitationnelles-ondes-gravitationnelles-deuxieme-detection-fusion-trous-noirs-63170/
http://www.pourlascience.fr/ewb_pages/a/actu-ondes-gravitationnelles-un-deuxihttps://lejournal.cnrs.fr/articles/ondes-gravitationnelles-et-trous-noirs-acte-2
http://www.lexpress.fr/actualite/sciences/deuxieme-detection-directe-des-ondes-gravitationnelles-d-einstein_1802781.html
https://fr.sputniknews.com/sci_tech/201606151025871398-ondes-gravitationnelles-nouveau-detectees/
http://www.clubic.com/mag/sciences/actualite-809404-ondes-gravitationnelles-second-signal-detecte.html

Italy:
http://www.nationalgeographic.it/scienza/spazio/2016/06/15/news/nuove_onde_gravitazionali-3127488/
http://www.repubblica.it/scienze/2016/06/15/news/seconda_rivelazione_di_onde_gravitazionali-142010034/
http://www.lescienze.it/news/2016/06/15/news/seconda_volta_ligo_onde_gravitazionali-3126554/
http://www.ilfattoquotidiano.it/2016/06/15/onde-gravitazionali-catturato-nuovo-segnale-emesso-da-fusione-tra-buchi-neri-abbiamo-iniziato-a-studiare-linvisibile/2829237/
http://www.ansa.it/scienza/notizie/rubriche/tecnologie/2016/06/15/onde-gravitazionali-rilevato-il-secondo-segnale_b26db43e-8af3-412e-bcb7-73f198a7f164.html
http://www.focus.it/scienza/spazio/ligo-buchi-neri-e-nuove-rilevazioni-di-onde-gravitazionali
http://www.lastampa.it/2016/06/15/scienza/onde-gravitazionali-rilevate-per-la-seconda-volta-0pKuQ4NPU5At0d1hT9SH1O/pagina.html
http://www.tgcom24.mediaset.it/tgtech/onde-gravitazionali-rilevato-il-secondo-segnale_3014579-201602a.shtml
http://www.wired.it/scienza/spazio/2016/06/15/ligo-altre-onde-gravitazionali/
http://www.ilmessaggero.it/tecnologia/scienza/onde_gravitazionali_rilevato_secondo_segnale-1798518.html
http://www.ilsole24ore.com/art/notizie/2016-06-15/onde-gravitazionali-rilevato-nuovo-segnale-ecco-soffio-dell-universo–164419.shtml?uuid=ADdrHec
http://www.meteoweb.eu/2016/06/onde-gravitazionali-cosa-le-increspature-spazio-tempo-raccontano-luniverso/703713/
http://www.huffingtonpost.it/2016/06/16/onde-gravitazionali_n_10497758.html

Germany
https://www.mpg.de/10598226/gravitationswellen-zweite
http://www.zeit.de/wissen/2016-06/gravitationswellen-einstein-nachweis-cnrs
http://www.spiegel.de/wissenschaft/weltall/gravitationswellen-zum-zweiten-mal-nachgewiesen-a-1097733.html
http://www.welt.de/wissenschaft/article156261005/Erneuter-Nachweis-von-Gravitationswellen-gelungen.html
http://www.heise.de/newsticker/meldung/Wissenschaftler-spueren-erneut-Gravitationswellen-auf-3238589.html
http://science.orf.at/stories/2780396/
http://www.spektrum.de/news/erneut-gravitationswellen-nachgewiesen/1413640
http://www.handelsblatt.com/technik/medizin/gravitationswellen-nachweis-die-raumzeit-schwingt-schon-wieder/13738230.html
http://www.focus.de/wissen/videos/zweiter-beweis-fuer-einsteins-theorie-trotz-schwachem-signal-forscher-entdecken-erneut-gravitationswellen_id_5637583.html
http://www.astronews.com/news/artikel/2016/06/1606-022.shtml
http://www.ingenieur.de/Themen/Forschung/Forscher-weisen-erneut-Gravitationswellen

Hungary

http://www.origo.hu/tudomany/20160615-gravitacios-hullamok-ujabb-felfedezes-ligo-virgo-detektorok.html
http://index.hu/tudomany/2016/06/15/gravitacios_hullam_masodik_felfedezes_gw151226/
http://mta.hu/tudomany_hirei/ligo-gravitacius-hullam-2015-december-masodik-eszleles-frei-zsolt-mta-elte-lendulet-asztrofizikai-kutatocsoport-106615
http://444.hu/2016/06/15/masodszor-is-sikerult-gravitacios-hullamokat-eszlelni
http://eduline.hu/felsooktatas/2016/6/15/Ujabb_gravitacios_hullamokat_erzekeltek_0GD5MJ
http://www.hirado.hu/2016/06/15/masodszor-is-eszleltek-az-einstein-altal-megjosolt-gravitacios-hullamokat/
http://www.ma.hu/tudomany/283702/Masodszor_is_eszleltek_az_Einstein_altal_megjosolt_gravitacios_hullamokat
http://24.hu/tudomany/2016/06/15/masodszor-is-sikerult-eszlelni-a-gravitacios-hullamokat/
http://magyaridok.hu/kulfold/masodszor-gravitacios-hullamot-erzekeltek-az-amerikai-detektorok-755524/
http://mno.hu/tudomany/ujra-gravitacios-hullamokat-eszleltek-1347406
http://hirhatar.com/masodszor-is-eszleltek-az-einstein-altal-megjosolt-gravitacios-hullamokat/
http://magyaridok.hu/kulfold/masodszor-gravitacios-hullamot-erzekeltek-az-amerikai-detektorok-755524/
http://nepszava.hu/cikk/1097132-einsteinnek-igaza-lett—megint-eszleltek-a-gravitacios-hullamokat/
http://hvg.hu/instant_tudomany/20160615_Ujra_erzekeltek_az_Einsteint_igazolo_gravitacios_hullamokat#rss

Poland

http://naukawpolsce.pap.pl/aktualnosci/news,410135,naukowcy-ponownie-zaobserwowali-fale-grawitacyjne.html
http://www.newsweek.pl/naukowcy-ponownie-zaobserwowali-fale-grawitacyjne,artykuly,387407,1.html
http://www.newsweek.pl/czym-sa-fale-grawitacyjne-i-jak-udalo-sie-je-odkryc,artykuly,388066,1.html
https://forumakademickie.pl/aktualnosci/2016/6/16/3726/fale-grawitacyjne-ponownie-zaobserwowane/
http://www.dzienmezczyzny.pl/kosmiczne-fale/
http://www.kuchnia.politykafiskalna.pl/naukowcy-ponownie-zaobserwowali-fale-grawitacyjne

Spain
http://elpais.com/elpais/2016/06/15/ciencia/1466002634_401491.html
http://www.abc.es/ciencia/abci-cientificos-detectan-segunda-ondas-gravitacionales-predichas-einstein-201606151914_noticia.html
http://www.elmundo.es/ciencia/2016/06/15/57618572268e3e8a748b45cd.html
http://www.20minutos.es/noticia/2773757/0/ondas-gravitacionales-einstein-descubiertas/
http://www.lavozdegalicia.es/noticia/sociedad/2016/06/15/detectan-segunda-vez-ondas-gravitacionales-predijo-einstein/00031466012531640889128.htm

UK
http://www.bbc.com/news/science-environment-36540254
https://www.theguardian.com/science/2016/jun/15/gravitational-waves-detected-from-collision-of-second-set-of-black-holes-ligo

Netherlands
http://www.kijkmagazine.nl/space/zwaartekrachtsgolven-tweede-keer-gezien/
http://www.blikopnieuws.nl/wetenschap/242303/wetenschappers-detecteren-weer-zwaartekrachtsgolven-van-botsende-zwarte-gaten.html
http://www.dekennisvannu.nl/site/artikel/Wederom-zwaartekrachtsgolven-gedetecteerd/8277
http://nos.nl/artikel/2111338-weer-zwaartekrachtsgolven-waargenomen-einstein-had-echt-gelijk.html
http://www.kijkmagazine.nl/space/zwaartekrachtsgolven-tweede-keer-gezien
http://www.telegraaf.nl/buitenland/26014449/Mysterieuze_zwaartekrachtgolf.html
http://www.newscientist.nl/nieuws/ligo-meet-opnieuw-zwaartekrachtsgolven
http://www.nationalgeographic.nl/artikel/voor-de-tweede-keer-zwaartekrachtsgolven-gemeten-op-aarde

Austria
http://derstandard.at/2000039031754/Erneut-Gravitationswellen-am-LIGO-Observatorium-gemessen

Belgium
http://www.nieuwsblad.be/cnt/dmf20160614_02338816

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