Kinematics of the SN Refsdal host revealed by MUSE: a regularly rotating spiral galaxy at z ≃ 1.5. Issue 1 (29th January 2018)

• Record Type: Journal Article
• Authors: Di Teodoro, E M; Grillo, C; Fraternali, F; Gobat, R; Karman, W; Mercurio, A; Rosati, P; Balestra, I; Caminha, G B; Caputi, K I; Lombardi, M; Suyu, S H; Treu, T; Vanzella, E
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 476:Issue 1(2018)
• Page Start: 804
• Page End: 813
• Publication Date: 2018-01-29
• Subjects: gravitational lensing: strong -- galaxies: clusters: individual: MACS J1149.5+2223298 -- galaxies: high-redshift -- galaxies: kinematics and dynamics; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty175
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract: We use Multi Unit Spectroscopic Explorer ( MUSE ) observations of the galaxy cluster MACS J1149.5+2223 to explore the kinematics of the grand-design spiral galaxy (Sp1149) hosting the supernova 'Refsdal'. Sp1149 lies at z ≃ 1.49, has a stellar mass M * ≃ 5 × 10 9 M⊙, has a star formation rate $\mathrm{(SFR)} \simeq 1\hbox{--}6 \, \, {\rm M_{\odot }\, \rm yr}^{-1}$, and represents a likely progenitor of a Milky Way-like galaxy. All the four multiple images of Sp1149 in our data show strong $\mathrm{[O\, \small {II}]}$ -line emissions pointing to a clear rotation pattern. We take advantage of the gravitational lensing magnification effect (≃4×) on the $\mathrm{[O\, \small {II}]}$ emission of the least distorted image to fit three-dimensional kinematic models to the MUSE data cube and derive the rotation curve and the velocity dispersion profile of Sp1149. We find that the rotation curve steeply rises, peaks at R ≃ 1 kpc, and then (initially) declines and flattens to an average ${V_\mathrm{flat}}= 128^{+29}_{-19}$ km s −1 . The shape of the rotation curve is well determined, but the actual value of V flat is quite uncertain because of the nearly face-on configuration of the galaxy. The intrinsic velocity dispersion due to gas turbulence is almost constant across the entire disc with an average of 27 ± 5 km s −1 . This value is consistent with z = 0 measurements in the ionized gas component and a factor of 2–4 lower than other estimates in different galaxies at similar redshifts. The average stellar-to-total mass fraction is of the order of one-fifth. Our kinematic analysis returns the picture of a regular star-forming, mildly turbulent, rotation-dominated ( V /σ ≃ 5) spiral galaxy in a 4-Gyr-old Universe.