The FLASHES Survey. I. Integral Field Spectroscopy of the CGM around 48 z ≃ 2.3–3.1 QSOs

Abstract

We present the pilot study of the Fluorescent Lyman-Alpha Structures in High-z Environments Survey; the largest integral field spectroscopy survey to date of the circumgalactic medium at z=2.3-3.1. We observed 48 quasar fields with the Palomar Cosmic Web Imager to an average (2σ) limiting surface brightness of 6× 10 −18 erg s −1 cm −2 arcsec −2 (in a 1″ aperture and ∼20 Å bandwidth). Extended H I Lyα emission is discovered around 37/48 of the observed quasars, ranging in projected radius from 14 to 55 proper kiloparsecs (pkpc), with one nebula exceeding 100 pkpc in effective diameter. The dimming-adjusted circularly averaged surface brightness profile peaks at 1×10 −15 erg s −1 cm −2 arcsec −2 at R ⊥ ∼20pkpc and integrated luminosities range from 0.4 to 9.4×10 43 erg s −1. The emission appears to have an eccentric morphology and an average covering factor of ∼30%-40% at small radii. On average, the nebular spectra are redshifted with respect to both the systemic redshift and Lyα peak of the quasar spectrum. The integrated spectra of the nebulae mostly have single-or double-peaked profiles with global dispersions ranging from 143 to 708 km s −1 , though the individual Gaussian components of lines with complex shapes mostly have dispersions 400 km s −1 , and the flux-weighted velocity centroids of the lines vary by thousands of km s −1 with respect to the QSO redshifts. Finally, the root-mean-square velocities of the nebulae are found to be consistent with those expected from gravitational motions in dark matter halos of mass ([ ])  -+ M M Log 12.2 10 h 1.2 0.7. We compare these results to existing surveys at higher and lower redshift.

Cool outflows in galaxies and their implications

“…Photoionization by internal or external energy sources is also an important factor when studying the cool CGM in line emission. For instance, CGM-scale Lyα nebulae have been detected around several high-z star-forming and active galaxies through stacking analyses (e.g., Steidel et al 2011;Momose et al 2016) and deep integralfield spectroscopy (e.g., Borisova et al 2016;Wisotzki et al 2016Wisotzki et al , 2018Erb et al 2018;Arrigoni Battaia et al 2019;Cai et al 2019;O'Sullivan et al 2019), but in most cases, these nebulae are photoionized by the central quasars or starbursts (e.g., Leibler et al 2018) or the cosmic UV background (e.g., Wisotzki et al 2018), and thus they trace largely the warm-ionized component of the CGM rather the cool neutralatomic gas phase. Moreover, the severe radiative transfer effects of this strong resonant line complicate the interpretation of the broad Lyα line profiles, making this line an ambiguous kinematic tracer of outflows in general (Sect.…”

End-to-end ground calibration and in-flight performance of the FIREBall-2 instrument

“…Concerning diffuse CGM emission, observations at higher redshift with MUSE 4 revealed some Lyα haloes at z ∼ 3 reaching 4″ (∼30 kpc) from the galaxy at their limiting surface brightness of ∼10 −19 erg s −1 cm 2 arcsec −2 . The discussion in the work by Sullivan et al 3 suggests that average Lyα surface brightness in the vicinity of QSOs might decrease with time (study from z ∼ 3 to z ∼ 2). With the assumed angular resolution of 5″ for the 2021 flight, the first FIREBall-2 resolution element after the center is already at ∼35 kpc at z ∼ 0.7.…”

“…1 Directly mapping the HI Lyman alpha (Lyα) emission from circumgalactic gas at high redshifts (z > 2) is an insightful alternative to absorption spectroscopy, providing a new perspective with a complete 2-D or 3-D mapping of the gas distribution. [2][3][4][5][6][7] Its importance notwithstanding, emission data are very scarce in the 10-billion-year span from z ∼ 2 to the present because of the difficulties inherent to vacuum UV observations. The Faint Intergalactic Redshifted Emission Balloon (FIREBall-2) instrument, jointly funded by CNES and NASA, has been developed to help fill this gap and pave the way for future orbital projects.…”

A meeting at z ∼ 3: Young massive galaxies and an AGN within 30 kpc of the luminous QSO LBQS 0302–0019

“…More details of the MUSE data processing can be found in Paper I. Narrow-band images were extracted from the QSO-subtracted data in Paper I, which revealed an extended Lyα nebula around LBQS 0302−0019, as commonly observed around highredshift QSOs (e.g. Heckman et al 1991;Borisova et al 2016;Arrigoni Battaia et al 2019;Drake et al 2019;Farina et al 2019;O'Sullivan et al 2020). In order to characterise the asymmetry of the nebula, we measured the asymmetry parameter, α = 0.55, as defined by Arrigoni and a displacement of the flux-weighted centroid of the Lyα nebula with respect to the QSO position of d QSO−Neb = 0 .…”