From ultraluminous X-ray to ultraluminous soft sources\: NGC 55 ULX novel study

In a recent work done with XMMNewton, we have discovered that ultraluminousXray sources (ULXs) have strong relativistic winds in agreement with thetheoretical predictions of high accretion rates. These winds can becomeoptically thick enough to block and reprocess the disk Xray photons, making thesource appear as a soft thermal emitter or ultraluminous supersoft Xray source(ULS). We want to test this hypothesis, by studying a ULX where the wind isalready causing significant absorption of the Xray continuum. NGC 55 ULX is theoptimal target, a transitional object between ULXs and ULSs, which exhibitsseveral strong blueshifted emission and absorption lines, and we propose toobserve it for 250 ks to determine the velocity structure and location of its strong relativistic wind. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]