{
  "bibcode": "2019GCN.26243....1K",
  "body": "David Kaplan and John Friedman (University of Wisconsin-Milwaukee),\nand Jocelyn Read (CSU Fullerton, Caltech) report on behalf of the\nGROWTH collaboration:\n\nThe unmodelled GW burst S191110af (LVC, GCN 26222) consisted of a\nnarrow-band signal near 1781.72 Hz with duration 0.1 s.  This\nfrequency is consistent with the frequency of the fundamental\nquadrupole mode of a star with mass in the range of 1.2 to 1.45 Msun\nand radii within current estimates. We use Andersson & Kokkotas (1998,\nMNRAS, 299, 10591068) Eqs. (1), (5) and (8) for the frequency, damping\ntime, and effective amplitude of the quadrupole f mode.  In\nparticular, for a neutron star with mass 1.25 Msun, a frequency of\n1782 Hz corresponds to radius 13.3 km, and the damping time is then\n0.2 s, consistent with observations.  Similarly, the range of EOS\nconsidered in Chirenti et al. (2015, Phys. Rev. D 91, 044034) generate\nf-modes along a band in frequency and decay time that seems compatible\nwith this candidate.\n\nWhile we do not know the strain amplitude associated with this burst,\nwe can estimate a minimum detectable strain based on the observed\nfrequency, duration, and the LIGO noise properties.  At the observed\nfrequency we estimate a noise level of 1.5e-23 Hz**-0.5\n(https://www.gw-openscience.org/detector_status/day/20191110/).\nFollowing Eqs. (3) and (4) of Kokkotas et al. (2001, MNRAS, 320, 307)\nwe estimate that a signal with f=1782Hz and duration 0.15s will have\namplitude 5e-22, and SNR~10 in a detector with noise 1.5e-23 Hz**-0.5,\nfor a source at 1kpc emitting 2.5e-9 Msun c**2 of energy in\ngravitational waves. Comparably, in a physical model where similar\noscillations come from a pulsar triggered by a significant glitch,\nKeer & Jones (2015, MNRAS, 446, 865) estimate a stain of 3e-22 at a\ndistance of 1 kpc.\n\nMotivated by this, we searched for potential counterparts among known\npulsars (note that if such a signal originates with a neutron star it\nneed not be visible as a pulsar). Based on the amplitude estimates\nreferenced above, we restrict our search to Galactic pulsars and do\nnot consider significantly more distant objects.\n\nWe looked at the latest version (1.61) of the ATNF pulsar catalog\n(Manchester et al. 2005, AJ, 129, 1993;\nhttp://www.atnf.csiro.au/research/pulsar/psrcat) and computed the\nprobability of the GW sky map at the position of each pulsar.  The top\n3 pulsars ranked by probability are:\n\nPSR J0045-7042 1.6e-3\nPSR J0101-6422 2.4e-4\nPSR B2045-16   4.9e-5\n\nAll other pulsars have probabilities <3e-5, and do not stand out from\nthe rest of the population, with 394 other sources at probabilities\n>1e-6.\n\nFor these three pulsars:\n\nPSR J0045-7042 is a slow (0.6s period) pulsar in the Small Magellanic\nCloud, and would not appear to be sufficiently energetic or close\nenough to give rise to a significant GW signal.\n\nPSR J0101-6422 is a nearby (~1 kpc), energetic (rotational energy loss\n1.2e34 erg/s) millisecond pulsar in a 1.8d orbit, which is also a\nFermi gamma-ray source (Kerr et al. 2012, ApJ, 748, 2; Nolan et\nal. 2012, ApJS, 199, 31).\n\nPSR J2045-16 is a nearby (~0.8 kpc) slow (2.0s period) pulsar, which\ndoes not appear otherwise notable.\n\nUnfortunately, PSRs J0045-7042 and B2045-16 do not have sufficient\ntiming data to search for a recent glitch.  PSR J0101-6422 is timed\nregularly with the Fermi Large Area Telescope, but detecting a\nputative glitch will take weeks to months, depending on the magnitude\nof the glitch (M. Kerr and P.S. Ray, private communication).  As\nmentioned above, any or none of these sources could be the origin of\nthe possible gravitational wave emission, or the candidate could be\nterrestrial in origin.  It also may be worth searching for short GW\nbursts associated with known glitches, especially those from the Vela\npulsar (as in Abadie et al. 2011, PRD 83, 042001).\n\nWe thank Joe Swiggum, Sinead Walsh, Nils Andersson, and Cecilia\nChirenti for helpful conversations.  GROWTH is a worldwide\ncollaboration comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC,\nSweden; JSI/UMd, USA; U Washington, USA; DESY, Germany; MOST, Taiwan;\nUW Milwaukee, USA; LANL USA; Tokyo Tech, Japan; IIT-B, India; IIA,\nIndia; LJMU, UK; TTU USA and USyd, Australia. GROWTH acknowledges\ngenerous support of the NSF under PIRE Grant No 1545949.",
  "circularId": 26243,
  "createdOn": 1573673970000,
  "email": "kaplan@uwm.edu",
  "subject": "LIGO/Virgo S191110af: Potential pulsar counterparts",
  "submitter": "David Kaplan at UW-Milwaukee  <kaplan@uwm.edu>",
  "eventId": "LIGO/Virgo S191110af"
}