The KBSS-KCWI Survey: The connection between extended Ly$\alpha$ halos and galaxy azimuthal angle at $z\sim 2-3$

Abstract

We present the first statistical analysis of kinematically-resolved, spatially-extended Ly$\alpha$ emission around $z=2-3$ galaxies in the Keck Baryonic Structure Survey (KBSS) using the Keck Cosmic Web Imager (KCWI). Our sample of 59 star-forming galaxies ($z_{\mathrm{med}}=2.29$) comprises the subset with typical KCWI integration times of ~5 hours and with existing imaging data from the Hubble Space Telescope and/or adaptive optics-assisted integral field spectroscopy. The high resolution images were used to evaluate the azimuthal dependence of the diffuse Ly$\alpha$ emission with respect to the stellar continuum within projected galactocentric distances of $\lesssim 30$ proper kpc. We introduce cylindrically-projected 2D spectra (CP2D) that map the averaged Ly$\alpha$ spectral profile over a specified range of azimuthal angle, as a function of impact parameter around galaxies. The averaged CP2D spectrum of all galaxies shows clear signatures of Ly$\alpha$ resonant scattering by outflowing gas. We stacked the CP2D spectra of individual galaxies over ranges of azimuthal angle with respect to their major axes. The extended Ly$\alpha$ emission along the galaxy principal axes are statistically indistinguishable, with residual asymmetry of $\le$ 2% ($\sim 2\sigma$) of the integrated Ly$\alpha$ emission. The symmetry implies that the Ly$\alpha$ scattering medium is dominated by outflows in all directions within 30 kpc. Meanwhile, we find that the blueshifted component of Ly$\alpha$ emission is marginally stronger along galaxy minor axes for galaxies with relatively weak Ly$\alpha$ emission. We speculate that this weak directional dependence of Ly$\alpha$ emission becomes discernible only when the Ly$\alpha$ escape fraction is low. These discoveries highlight the need for similar analyses in simulations with Ly$\alpha$ radiative transfer modeling.

25 pages, 24 figures, 2 tables, accepted by MNRAS

References in corpus (30)

• Array Programming with NumPy
• The Circumgalactic Medium
• The MUSE second-generation VLT instrument
• Constraining the Low-Mass Slope of the Star Formation Sequence at 0.5<z<2.5
• Strong Nebular Line Ratios in the Spectra of z~2-3 Star-forming Galaxies: First Results from KBSS-MOSFIRE
• 3D Lyman-alpha radiation transfer. I. Understanding Lyman-alpha line profile morphologies
• The MUSE Hubble Ultra Deep Field Survey: I. Survey description, data reduction and source detection
• Lyman Alpha Emitting Galaxies as a Probe of Reionization
• Nebular Emission Line Ratios in z~2-3 Star-Forming Galaxies with KBSS-MOSFIRE: Exploring the Impact of Ionization, Excitation, and Nitrogen-to-Oxygen Ratio
• Observations of the Lyman-$\alpha$ Universe
• Diffuse Lyman-alpha Halos around Galaxies at z=2.2-6.6: Implications for Galaxy Formation and Cosmic Reionization
• Integral Field Spectroscopy of High-Redshift Star Forming Galaxies with Laser Guided Adaptive Optics: Evidence for Dispersion-Dominated Kinematics
• The Lyman-alpha Reference Sample: I. Survey outline and first results for Markarian 259
• Quasars Probing Galaxies: I. Signatures of Gas Accretion at Redshift Approximately 0.2
• Evolution of the Cool Gas in the Circumgalactic Medium (CGM) of Massive Halos -- A Keck Cosmic Web Imager (KCWI) Survey of Ly$\alpha$ Emission around QSOs at $z\approx 2$
• An uncontaminated measurement of the escaping Lyman continuum at $z\sim 3$
• Predictions for the Angular Dependence of Gas Mass Flow Rate and Metallicity in the Circumgalactic Medium
• The Rest-Frame Optical Spectroscopic Properties of Ly$\alpha$-Emitters at $z\sim 2.5$: The Physical Origins of Strong Ly$\alpha$ Emission
• Kinematics of Circumgalactic Gas: Feeding Galaxies and Feedback
• From Mirrors to Windows: Lyman-Alpha Radiative Transfer in a Very Clumpy Medium
• The Keck Baryonic Structure Survey: Using foreground/background galaxy pairs to trace the structure and kinematics of circumgalactic neutral hydrogen at $z\sim 2$
• The MUSE Hubble Ultra Deep Field Survey VIII : Extended Lyman-alpha haloes around high-redshift star-forming galaxies
• Modeling $237$ Lyman-$\alpha$ spectra of the MUSE-Wide survey
• Illuminating gas in-/outflows in the MUSE deepest fields: discovery of Ly-alpha nebulae around forming galaxies at z~3.3
• On the Diffuse Lyman-alpha Halo Around Lyman-alpha Emitting Galaxies
• The Lyman alpha reference sample: IV. Morphology at low and high redshift
• Morphologies of Galaxies in and around a Protocluster at z=2.300
• Lyman-alpha radiative transfer: Modeling spectrum and surface brightness profile of Lyman-alpha emitting galaxies at z=3-6
• Resolved galactic superwinds reconstructed around their host galaxies at z>3
• CWITools: A Python3 Data Analysis Pipeline for the Cosmic Web Imager Instruments

Cited by in corpus (24)

• The Identification of a Dusty Multiarm Spiral Galaxy at $z=3.06$ with JWST and ALMA
• The cold circumgalactic medium in emission: MgII halos in TNG50
• The MUSE eXtremely Deep Field: Individual detections of Lyα haloes around rest-frame UV-selected galaxies at z~2.9-4.4
• The Lensed Lyman-Alpha MUSE Arcs Sample (LLAMAS) : I. Characterisation of extended Lyman-alpha haloes and spatial offsets
• The connection between the escape of ionizing radiation and galaxy properties at z~3 in the Keck Lyman Continuum Spectroscopic Survey
• The Circumgalactic Medium of Extreme Emission Line Galaxies at z ~ 2: Resolved Spectroscopy and Radiative Transfer Modeling of Spatially Extended Lyman-alpha Emission in the KBSS-KCWI Survey
• Accurate Oxygen Abundance of Interstellar Gas in Mrk 71 from Optical and Infrared Spectra
• A Complex Multiphase DLA Associated with a Compact Group at z=2.431 Traces Accretion, Outflows, and Tidal Streams
• Probing the Inner Circumgalactic Medium and Quasar Illumination around the Reddest `Extremely Red Quasar' (ERQ)
• Directly tracing cool filamentary accretion over >100 kpc into the interstellar medium of a quasar host at z=1
• MUSE-ALMA Haloes VII: Survey Science Goals & Design, Data Processing and Final Catalogues
• Where Outflows Meet Inflows: Gas Kinematics in SSA22 Lyman-$\alpha$ Blob 2 Decoded by Advanced Radiative Transfer Modelling
• The MOSDEF-LRIS Survey: Connection between Galactic-scale Outflows and the Properties of $z$~2 star-forming Galaxies
• The Stellar Kinematics of Void Dwarf Galaxies Using KCWI
• SILVERRUSH. XI. Intensity Mapping for Lya Emission Extending over $100-1000$ comoving kpc around $z\sim 2-7$ LAEs with Subaru HSC-SSP and CHORUS Data
• On the evolution of the size of Lyman alpha halos across cosmic time: no change in the circumgalactic gas distribution when probed by line emission
• Characterizing the Circumgalactic Medium of Quasars at z $\sim$ 2.2 through H$\alpha$ and Ly$\alpha$ Emission
• Metal content of the circumgalactic medium around star-forming galaxies at z $\sim$ 2.6 as revealed by the VIMOS Ultra-Deep Survey
• Revealing the Nature of a Lyman-$\alpha$ Halo in a Strongly Lensed Interacting System at $z=2.92$
• UV & Ly$\alpha$ halos of Ly$\alpha$ emitters across environments at z=2.84
• An Extremely Luminous Flare Recorded from a Supermassive Black Hole
• KBSS-InCLOSE I: Design and First Results from the Inner CGM of QSO Line Of Sight Emitting Galaxies at z~2-3
• Modelling gas around galaxy pairs and groups using the Q0107 quasar triplet
• When Stars Mimic Monsters: Spectral Evidence for an $\eta$ Carinae-like Giant Eruption in SBS 0335$-$052 E