Browsing by Author "Ledoux, Cédric"

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    Dissecting a 30 kpc galactic outflow at z 1.7
    (2023) Shaban, Ahmed; Bordoloi, Rongmon; Chisholm, John; Rigby, Jane R.; Sharma, Soniya; Sharon, Keren; Tejos, Nicolas; Bayliss, Matthew B.; Barrientos, Luis Felipe; López, Sebastian; Ledoux, Cédric; Gladders, Michael G.; Florian, Michael K.
    We present the spatially resolved measurements of a cool galactic outflow in the gravitationally lensed galaxy RCS0327 at z ≈ 1.703 using VLT/MUSE IFU observations. We probe the cool outflowing gas, traced by blueshifted Mg II and Fe II absorption lines, in 15 distinct regions of the same galaxy in its image-plane. Different physical regions, 5 to 7 kpc apart within the galaxy, drive the outflows at different velocities (Vout ~ -161 to -240 km s-1), and mass outflow rates ($\dot{M}_{out} \sim$ 183 to 527 M⊙ yr-1). The outflow velocities from different regions of the same galaxy vary by 80 km s-1, which is comparable to the variation seen in a large sample of star-burst galaxies in the local Universe. Using multiply lensed images of RCS0327, we probe the same star-forming region at different spatial scales (0.5 kpc2 -- 25 kpc2), we find that outflow velocities vary between ~ -120 to -242 km s-1, and the mass outflow rates vary between ~ 37 to 254 M⊙ yr-1. The outflow momentum flux in this galaxy is ≥ 100% of the momentum flux provided by star-formation in individual regions, and outflow energy flux is ≈ 10% of the total energy flux provided by star-formation. These estimates suggest that the outflow in RCS0327 is energy driven. This work shows the importance of small scale variations of outflow properties due to the variations of local stellar properties of the host galaxy in the context of galaxy evolution....
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    Spatially Resolved Circumgalactic Medium around a Star-forming Galaxy Driving a Galactic Outflow at z ≈ 0.8
    (2025) Shaban, Ahmed; Bordoloi, Rongmon; O’Meara, John M.; Sharon, Keren; Tejos, Nicolás; López, Sebastián; Ledoux, Cédric; Barrientos, Luis Felipe; Rigby, Jane R.
    We report the small-scale spatial variation in cool (T ∼ 104 K) Mg II absorption detected in the circumgalactic medium (CGM) of a star-forming galaxy at z ≈ 0.8. The CGM of this galaxy is probed by a spatially extended bright background gravitationally lensed arc at z = 2.76. The background arc continuously samples the CGM of the foreground galaxy at a range of impact parameters between 54 and 66 kpc. The Mg II absorption strengths vary by more than a factor of 2 within these ranges. A power-law fit to the fractional variation of absorption strengths yields a coherence length of 5.8 kpc within this range of impact parameters. This suggests a high degree of spatial coherence in the CGM of this galaxy. The host galaxy is driving a strong galactic outflow with a mean outflow velocity ≈ 179 km s−1 and mass outflow rate + M 64out 27 31 M⊙ yr−1 traced by blueshifted Mg II and Fe II absorption lines. The galaxy itself has a spatially extended emission halo with a maximum spatial extent of ≈33 kpc traced by [O II], [O III], and Hβ emission lines. The extended emission halo shows kinematic signatures of corotating halo gas with solar metallicity. Taken together, these observations suggest evidence of a baryon cycle that is recycling the outflowing gas to form the next generation of stars
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    Transverse clues on the kiloparsec-scale structure of the circumgalactic medium as traced by C IV absorption
    (2024) López, Sebastián; Afruni, A.; Zamora Hidalgo, Diego Amaro; Tejos, Nicolás; Ledoux, Cédric; Hernández Guajardo, Joaquín Alexis; Berg, Trystyn A. M.; Cortés Muñoz, Hugo R.; Urbina Jiménez, Francisco; Johnston, E. J.; Barrientos, Luis Felipe; Bayliss, M. B.; Cuellar, Rodrigo; Krogager, Jens-Kristian; Noterdaeme, Pasquier; Solimano, Manuel
    The kiloparsec-scale kinematics and density structure of the circumgalactic medium (CGM) is still poorly constrained observationally, which poses a problem for understanding the role of the baryon cycle in galaxy evolution. Here we present VLT/MUSE integral-field spectroscopy (R ≈ 1800) of four giant gravitational arcs exhibiting W0 ≳ 0.2 Å C IV absorption at eight intervening redshifts, zabs ≈ 2.0–2.5. We detected C IV absorption in a total of 222 adjacent and seeing-uncorrelated sight lines whose spectra sample beams of ("de-lensed") linear size ≈1 kpc. Our data show that (1) absorption velocities cluster at all probed transverse scales, Δr⊥ ≈ 0–15 kpc, depending on system; (2) the (transverse) velocity dispersion never exceeds the mean (line-of-sight) absorption spread; and (3) the (transverse) velocity autocorrelation function does not resolve kinematic patterns at the above spatial scales, but its velocity projection, ξarc(Δv), exhibits a similar shape to the known two-point correlation function toward quasars, ξQSO(Δv). An empirical kinematic model suggests that these results are a natural consequence of wide-beam observations of an unresolved clumpy medium. Our model recovers both the underlying velocity dispersion of the clumps (70–170 km s‑1) and the mean number of clumps per unit area (2–13 kpc‑2). The latter constrains the projected mean inter-clump distance to within ≈0.3–0.8 kpc, which we argue is a measure of clump size for a near-unity covering fraction. The model is also able to predict ξarc(Δv) from ξQSO(Δv), suggesting that the strong systems that shape ξarc(Δv) and the line-of-sight velocity components that define ξQSO(Δv) trace the same kinematic population. Consequently, the clumps must possess an internal density structure that generates both weak and strong components. We discuss how our interpretation is consistent with previous observations using background galaxies and multiple quasars as well as its implications for the connection between the small-scale kinematic structure of the CGM and galactic-scale accretion and feedback processes....