Magnetar SGR 1745-2900 By Christina Balanduk

SGR 1745-2900 SGR 1745-2900 was discovered to be a magnetar orbiting about 0.3 ly from SGR A*, the supermassive black hole at the center of the Milky Way.

So, what is a Magnetar? -Neutron star -Average diameter of about 20 km -Average density of about 10^17 kg/m^3 -Strongest known magnets in the universe -Powered by magnetic field

Formation -Type 2 supernova -May require a companion to form a Magnetar -Theory formed through observing star cluster Wunderlund 1 and Magnetar CXOU J164710.2-455216 “The rapid rotation created by mass transfer between the two stars appears necessary to generate the ultra-strong magnetic field, and then a second mass transfer phase allows the magnetar-to-be to slim down sufficiently so that it does not collapse into a black hole at the moment of its death.” Info from Astronomy Magazine

from Chandra x-ray observatory.

How SGR 1745-2900 was discovered -First observed in April 2013 -Discovered by many space telescopes including the Chandra X-ray Observatory. -Discovered as it was entering an outburst in the Radio and X-ray bands -Closest neutron star discovered to a supermassive black hole to date. from Chandra X-Ray Observatory

X-ray bursts -When matter is gravitationally pulled to an object it enters an accretion disk around the object as it orbits, continuously getting closer and closer to the object’s surface. -As additional mass eventually gets to the surface of a neutron star it heats up due to the additional pressure of more and more mass being added. -At some point this mass reaches high enough temperatures that hydrogen fusion turns on -Quick and high intensity batches of hydrogen fusion occur causing an X-ray burst! info from Astronomy Today

Simultaneous Multi-Band Radio & X-Ray Observations Article -Observed SGR 1745-2900 for 100 days after the initial discovery of this magnetar -Observed in X-ray and Radio band -Detected three separate bursts -Found Radio emission to be delayed after the detection of the X-ray burst -Something odd

X-Ray Outbursts Article -Found SGR 1745-2900 to have a higher temperature than non-magnetic models could predict -Slow radio flux decay (noted by both articles)

What have we learned about Magnetars from SGR 1745-2900? -We’ve learned that there’s something off about our model of crustal cooling in magnetars -More research and modeling needs to be done into the radio flux decay of magnetars

Bibliography Garching. 2014. Magnetar formation mystery solved? Astronomy Magazine, May 14 http://www.astronomy.com/news/2014/05/magnetar-formation-mystery-solved Chandra x-ray observatory. 2015. SGR 1745-2900: Magnetar Near Supermassive Black Hole Delivers Surprises http://chandra.harvard.edu/photo/2015/sgr1745/ Pennucci TT, Possenti A, Esposito P, Rea N, Haggard D, et al. 2015. simultaneous multi-band radio and x-ray observations of the galactic center magnetar SGR 1745-2900, ApJ. 808: 81-96 http://arxiv.org/pdf/1505.00836v2.pdf Coti Zelati F, Rea N, Papitto A, Viganò D, Pons JA, et al. 2015. the x-ray outburst of the galactic centre magnetar SGR J1745-2900 during the first 1.5 year 449: 2685-2699 http://arxiv.org/pdf/1503.01307v1.pdf Chaisson E, McMillan S. 2014. neutron stars and black holes. Astronomy today. Whilton N, Kenney L, Goodwin T. 8: 544-551