Bozzo, E.E.BozzoBhalerao, V.V.BhaleraoPradhan, P.P.PradhanTomsick, J.J.TomsickROMANO, PatriziaPatriziaROMANOFerrigno, C.C.FerrignoChaty, S.S.ChatyOskinova, L.L.OskinovaManousakis, A.A.ManousakisWalter, R.R.WalterFalanga, M.M.FalangaCAMPANA, SergioSergioCAMPANAStella, L.L.StellaRamolla, M.M.RamollaChini, R.R.Chini2020-06-012020-06-0120160004-6361http://hdl.handle.net/20.500.12386/25870In this paper we report on a long multi-wavelength observational campaign of the supergiant fast X-ray transient prototype IGR J17544-2619. A 150 ks-long observation was carried out simultaneously with XMM-Newton and NuSTAR, catching the source in an initial faint X-ray state and then undergoing a bright X-ray outburst lasting approximately 7 ks. We studied the spectral variability during outburst and quiescence by using a thermal and bulk Comptonization model that is typically adopted to describe the X-ray spectral energy distribution of young pulsars in high mass X-ray binaries. Although the statistics of the collected X-ray data were relatively high, we could neither confirm the presence of a cyclotron line in the broad-band spectrum of the source (0.5-40 keV), nor detect any of the previously reported tentative detections of the source spin period. The monitoring carried out with Swift /XRT during the same orbit of the system observed by XMM-Newton and NuSTAR revealed that the source remained in a low emission state for most of the time, in agreement with the known property of all supergiant fast X-ray transients being significantly sub-luminous compared to other supergiant X-ray binaries. Optical and infrared observations were carried out for a total of a few thousand seconds during the quiescence state of the source detected by XMM-Newton and NuSTAR. The measured optical and infrared magnitudes were slightly lower than previous values reported in the literature, but compatible with the known micro-variability of supergiant stars. UV observations obtained with the UVOT telescope on-board Swift did not reveal significant changes in the magnitude of the source in this energy domain compared to previously reported values.STAMPAenArticle10.1051/0004-6361/2016293112-s2.0-84999648302000390797900099https://www.aanda.org/articles/aa/abs/2016/12/aa29311-16/aa29311-16.html2016A&A...596A..16BFIS/05 - ASTRONOMIA E ASTROFISICA