In this paper we analyse the pre-explosion spectrum of SN2015bh by performing radiative transfer simulations using the CMFGEN code .
This object has attracted significant attention due to its remarkable similarity to SN2009ip in both its pre- and post-explosion behaviour .
They seem to belong to a class of events for which the fate as a genuine core-collapse supernova or a non-terminal explosion is still under debate .
Our CMFGEN models suggest that the progenitor of SN2015bh had an effective temperature between 8700 and 10000 K , luminosity in the range \simeq 1.8 ~ { } - ~ { } 4.74 \times 10 ^ { 6 } ~ { } \mathit { L } _ { \odot } , contained at least 25 % H in mass at the surface , and half-solar Fe abundances .
The results also show that the progenitor of SN2015bh generated an extended wind with a mass-loss rate of \simeq 6 \times 10 ^ { -4 } to 1.5 \times 10 ^ { -3 } ~ { } \mathrm { M } _ { \odot } { yr } ^ { -1 } and a velocity of 1000 { km s ^ { -1 } } .
We determined that the wind extended to at least 2.57 \times 10 ^ { 14 } cm and lasted for at least 30 days prior to the observations , releasing 5 \times 10 ^ { -5 } ~ { } \mathrm { M } _ { \odot } into the circumstellar medium .
In analogy to 2009ip , we propose that this is the material that the explosive ejecta could interact at late epochs , perhaps producing observable signatures that can be probed with future observations .
We conclude that the progenitor of SN2015bh was most likely a warm luminous blue variable of at least 35 ~ { } \mathrm { M } _ { \odot } before the explosion .
Considering the high wind velocity , we can not exclude the possibility that the progenitor was a Wolf-Rayet star that inflated just before the 2013 eruption , similar to HD5980 during its 1994 episode .
If the star survived , late-time spectroscopy may reveal either a similar LBV or a Wolf-Rayet star , depending on the mass of the H envelope before the explosion .
If the star exploded as a genuine SN , 2015bh would be a remarkable case of a successful explosion after black-hole formation in a star with a possible minimum mass 35 ~ { } \mathrm { M } _ { \odot } at the pre-SN stage .