83 research outputs found
The FLASHES Survey I: Integral Field Spectroscopy of the CGM around 48 QSOs
We present the pilot study component of the Fluorescent Lyman-Alpha
Structures in High-z Environments (FLASHES) Survey; the largest integral-field
spectroscopy survey to date of the circumgalactic medium at . We
observed 48 quasar fields between 2015 and 2018 with the Palomar Cosmic Web
Imager (Matuszewski et al. 2010). Extended HI Lyman- emission
is discovered around 42/48 of the observed quasars, ranging in projected,
flux-weighted radius from 21-71 proper kiloparsecs (pkpc), with 26 nebulae
exceeding in effective diameter. The circularly averaged
surface brightness radial profile peaks at a maximum of
( adjusted for
cosmological dimming) and luminosities range from
to
. The emission appears to have a highly
eccentric morphology and a maximum covering factor of ( for giant
nebulae). On average, the nebular spectra are red-shifted with respect to both
the systemic redshift and Ly peak of the quasar spectrum. The
integrated spectra of the nebulae mostly have single or double-peaked line
shapes with global dispersions ranging from to
, though the individual (Gaussian) components of lines
with complex shapes mostly appear to have dispersions
, and the flux-weighted velocity centroids of the lines
vary by thousands of with respect to the systemic QSO
redshifts. Finally, the root-mean-square velocities of the nebulae are found to
be consistent with gravitational motions expected in dark matter halos of mass
. We compare these results to existing
surveys at both higher and lower redshift
Design of a precision calibration unit for Keck NIRC2 AO instrument
High-precision astrometry has the potential to address questions in planet formation, black hole science, Galactic structure, and more. However, in order to achieve a precision of sub-milli arcseconds (mas), we need a calibration method better than the current techniques such as on-sky calibration using calibrated stellar or stellar cluster systems, which have a precision of ~1 mas. Precision calibration unit with a regular grid of photo-lithographically manufactured pinholes combined with self-calibration techniques, on the other hand, is a new and innovative way to potentially achieve a precision of sub-mas over the entire field of view. This technique is beneficial to adaptive optic (AO) instruments for future telescopes like the Thirty Meter Telescope (TMT). In this work, we present our design for a new astrometric calibration unit to feed the NIRC2 AO instrument at the W. M. Keck Observatory. It allows calibration over a large field of view of 47" x 47"
Design of a precision calibration unit for Keck NIRC2 AO instrument
High-precision astrometry has the potential to address questions in planet formation, black hole science, Galactic structure, and more. However, in order to achieve a precision of sub-milli arcseconds (mas), we need a calibration method better than the current techniques such as on-sky calibration using calibrated stellar or stellar cluster systems, which have a precision of ~1 mas. Precision calibration unit with a regular grid of photo-lithographically manufactured pinholes combined with self-calibration techniques, on the other hand, is a new and innovative way to potentially achieve a precision of sub-mas over the entire field of view. This technique is beneficial to adaptive optic (AO) instruments for future telescopes like the Thirty Meter Telescope (TMT). In this work, we present our design for a new astrometric calibration unit to feed the NIRC2 AO instrument at the W. M. Keck Observatory. It allows calibration over a large field of view of 47" x 47"
FLASHES Survey. I. Integral Field Spectroscopy of the CGM around 48 z â 2.3â3.1 QSOs
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 = 2.3â3.1. We observed 48 quasar fields with the Palomar Cosmic Web Imager to an average (2Ï) limiting surface brightness of 6 Ă 10â»Âčâž erg sâ»Âč cmâ»ÂČ arcsecâ»ÂČ (in a 1'' aperture and ~20 Ă
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 Ă 10â»Âčâ” erg sâ»Âč cmâ»ÂČ arcsecâ»ÂČ at Râ„ ~ 20 pkpc and integrated luminosities range from 0.4 to 9.4 Ă 10âŽÂł erg sâ»Âč. The emission appears to have an eccentric morphology and an average covering factor of ~30%â40% 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 sâ»Âč, though the individual Gaussian components of lines with complex shapes mostly have dispersions â€400 km sâ»Âč, and the flux-weighted velocity centroids of the lines vary by thousands of km sâ»Âč 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 Logââ(M_h[Mâ]) â 12.2^(+0.7)_(-1.2). We compare these results to existing surveys at higher and lower redshift
FIREBall-2: flight preparation of a proven balloon payload to image the intermediate redshift circumgalactic medium
FIREBall-2 is a stratospheric balloon-borne 1-m telescope coupled to a UV
multi-object slit spectrograph designed to map the faint UV emission
surrounding z~0.7 galaxies and quasars through their Lyman-alpha line emission.
This spectro-imager had its first launch on September 22nd 2018 out of Ft.
Sumner, NM, USA. Because the balloon was punctured, the flight was abruptly
interrupted. Instead of the nominal 8 hours above 32 km altitude, the
instrument could only perform science acquisition for 45 minutes at this
altitude. In addition, the shape of the deflated balloon, combined with a full
Moon, revealed a severe off-axis scattered light path, directly into the UV
science detector and about 100 times larger than expected. In preparation for
the next flight, and in addition to describing FIREBall-2's upgrade, this paper
discusses the exposure time calculator (ETC) that has been designed to analyze
the instrument's optimal performance (explore the instrument's limitations and
subtle trade-offs)
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