A New Class of X-ray TransientsquestionMark Highly Luminous XMM Transients

Finding Xray counterparts to future LIGO/Virgo events requires an understandingof the transient sky at low redshift. We have identified 7 nearby (D < 300 Mpc)transients in the XMMNewton Slew Survey Catalog via a systematic comparisonwith the ROSAT All Sky Survey. These sources have unusual properties and so aredifficult to characterize. They are highly luminous (>1e42 erg/s), extremelyvariable, associated with galaxies within 300 Mpc, and lack optical AGNsignatures. We propose to observe these seven targets with XMMNewton in anattempt to identify their nature. The sources could prove to be tidal disruptionevents, GRB afterglows, very high energy ULXs, or some new class. This is thefirst study of Xray transients within the LIGO/Virgo horizon. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]