338 research outputs found
Galactic Scale Feedback Observed in the 3C 298 Quasar Host Galaxy
We present high angular resolution multi-wavelength data of the 3C 298
radio-loud quasar host galaxy (z=1.439) taken using the W.M. Keck Observatory
OSIRIS integral field spectrograph with adaptive optics, Atacama Large
Millimeter/submillimeter Array (ALMA), Hubble Space Telescope (HST) WFC3, and
the Very Large Array (VLA). Extended emission is detected in the rest-frame
optical nebular emission lines H, [OIII], H, [NII], and [SII],
as well as molecular lines CO (J=3-2) and (J=5-4). Along the path of 3C 298's
relativistic jets we detect conical outflows of ionized gas with velocities up
to 1700 km s and outflow rate of 450-1500 Myr. Near the
spatial center of the conical outflow, CO (J=3-2) emission shows a molecular
gas disc with a total molecular mass () of
6.6M. On the molecular disc's blueshifted side
we observe a molecular outflow with a rate of 2300 Myr and
depletion time scale of 3 Myr. We detect no narrow H emission in the
outflow regions, suggesting a limit on star formation of 0.3
Myrkpc. Quasar driven winds are evacuating the molecular
gas reservoir thereby directly impacting star formation in the host galaxy. The
observed mass of the supermassive black hole is M and
we determine a dynamical bulge mass of 1-1.7
M. The bulge mass of 3C 298 resides 2-2.5 orders of magnitude below
the expected value from the local M relationship. A second
galactic disc observed in nebular emission is offset from the quasar by 9 kpc
suggesting the system is an intermediate stage merger. These results show that
galactic scale negative feedback is occurring early in the merger phase of 3C
298, well before the coalescence of the galactic nuclei and assembly on the
local relationship.Comment: 23 pages, 11 figures, 4 tables, Accepted for publication in the
Astrophysical Journa
Providing stringent star formation rate limits of z2 QSO host galaxies at high angular resolution
We present integral field spectrograph (IFS) with laser guide star adaptive
optics (LGS-AO) observations of z=2 quasi-stellar objects (QSOs) designed to
resolve extended nebular line emission from the host galaxy. Our data was
obtained with W. M. Keck and Gemini-North Observatories using OSIRIS and NIFS
coupled with the LGS-AO systems. We have conducted a pilot survey of five QSOs,
three observed with NIFS+AO and two observed with OSIRIS+AO at an average
redshift of z=2.15. We demonstrate that the combination of AO and IFS provides
the necessary spatial and spectral resolutions required to separate QSO
emission from its host. We present our technique for generating a PSF from the
broad-line region of the QSO and performing PSF subtraction of the QSO emission
to detect the host galaxy. We detect H and [NII] for two sources, SDSS
J1029+6510 and SDSS J0925+06 that have both star formation and extended
narrow-line emission. Assuming that the majority of narrow-line H is
from star formation, we infer a star formation rate for SDSS J1029+6510 of 78.4
Myr originating from a compact region that is kinematically
offset by 290 - 350 km/s. For SDSS J0925+06 we infer a star formation rate of
29 Myr distributed over three clumps that are spatially offset
by 7 kpc. The null detections on three of the QSOs are used to infer
surface brightness limits and we find that at 1.4 kpc distance from the QSO
that the un-reddened star formation limit is 0.3
Myrkpc. If we assume a typical extinction values for z=2
type-1 QSOs, the dereddened star formation rate for our null detections would
be 0.6 Myrkpc. These IFS observations indicate that
if star formation is present in the host it would have to occur diffusely with
significant extinction and not in compact, clumpy regions.Comment: 17 pages, 7 figures, 7 tables, Accepted to Ap
The InfraRed Imaging Spectrograph (IRIS) for TMT: latest science cases and simulations
The Thirty Meter Telescope (TMT) first light instrument IRIS (Infrared Imaging Spectrograph) will complete its preliminary design phase in 2016. The IRIS instrument design includes a near-infrared (0.85 - 2.4 micron) integral field spectrograph (IFS) and imager that are able to conduct simultaneous diffraction-limited observations behind the advanced adaptive optics system NFIRAOS. The IRIS science cases have continued to be developed and new science studies have been investigated to aid in technical performance and design requirements. In this development phase, the IRIS science team has paid particular attention to the selection of filters, gratings, sensitivities of the entire system, and science cases that will benefit from the parallel mode of the IFS and imaging camera. We present new science cases for IRIS using the latest end-to-end data simulator on the following topics: Solar System bodies, the Galactic center, active galactic nuclei (AGN), and distant gravitationally-lensed galaxies. We then briefly discuss the necessity of an advanced data management system and data reduction pipeline
Detector Characterization of a Near-Infrared Discrete Avalanche Photodiode 5x5 Array for Astrophysical Observations
We present detector characterization of a state-of-the-art near-infrared
(950nm - 1650 nm) Discrete Avalanche Photodiode detector (NIRDAPD) 5x5 array.
We designed an experimental setup to characterize the NIRDAPD dark count rate,
photon detection efficiency (PDE), and non-linearity. The NIRDAPD array was
illuminated using a 1050 nm light-emitting diode (LED) as well as 980 nm, 1310
nm, and 1550 nm laser diodes. We find a dark count rate of 3.3x10 cps,
saturation at 1.2x10 photons per second, a photon detection efficiency of
14.8% at 1050 nm, and pulse detection at 1 GHz. We characterized this NIRDAPD
array for a future astrophysical program that will search for technosignatures
and other fast (>1 Ghz) astrophysical transients as part of the Pulsed All-sky
Near-infrared Optical Search for Extraterrestrial Intelligence (PANOSETI)
project. The PANOSETI program will consist of an all-sky optical (350 - 800 nm)
observatory capable of observing the entire northern hemisphere instantaneously
and a wide-field NIR (950 - 1650 nm) component capable of drift scanning the
entire sky in 230 clear nights. PANOSETI aims to be the first wide-field
fast-time response near-infrared transient search.Comment: 8 pages, 7 figures, 1 tabl
The infrared imaging spectrograph (IRIS) for TMT: sensitivities and simulations
We present sensitivity estimates for point and resolved astronomical sources
for the current design of the InfraRed Imaging Spectrograph (IRIS) on the
future Thirty Meter Telescope (TMT). IRIS, with TMT's adaptive optics system,
will achieve unprecedented point source sensitivities in the near-infrared
(0.84 - 2.45 {\mu}m) when compared to systems on current 8-10m ground based
telescopes. The IRIS imager, in 5 hours of total integration, will be able to
perform a few percent photometry on 26 - 29 magnitude (AB) point sources in the
near-infrared broadband filters (Z, Y, J, H, K). The integral field
spectrograph, with a range of scales and filters, will achieve good
signal-to-noise on 22 - 26 magnitude (AB) point sources with a spectral
resolution of R=4,000 in 5 hours of total integration time. We also present
simulated 3D IRIS data of resolved high-redshift star forming galaxies (1 < z <
5), illustrating the extraordinary potential of this instrument to probe the
dynamics, assembly, and chemical abundances of galaxies in the early universe.
With its finest spatial scales, IRIS will be able to study luminous, massive,
high-redshift star forming galaxies (star formation rates ~ 10 - 100 M yr-1) at
~100 pc resolution. Utilizing the coarsest spatial scales, IRIS will be able to
observe fainter, less massive high-redshift galaxies, with integrated star
formation rates less than 1 M yr-1, yielding a factor of 3 to 10 gain in
sensitivity compared to current integral field spectrographs. The combination
of both fine and coarse spatial scales with the diffraction-limit of the TMT
will significantly advance our understanding of early galaxy formation
processes and their subsequent evolution into presentday galaxies.Comment: SPIE Astronomical Instrumentation 201
The Infrared Imaging Spectrograph (IRIS) for TMT: Volume phase holographic grating performance testing and discussion
Maximizing the grating efficiency is a key goal for the first light
instrument IRIS (Infrared Imaging Spectrograph) currently being designed to
sample the diffraction limit of the TMT (Thirty Meter Telescope). Volume Phase
Holographic (VPH) gratings have been shown to offer extremely high efficiencies
that approach 100% for high line frequencies (i.e., 600 to 6000l/mm), which has
been applicable for astronomical optical spectrographs. However, VPH gratings
have been less exploited in the near-infrared, particularly for gratings that
have lower line frequencies. Given their potential to offer high throughputs
and low scattered light, VPH gratings are being explored for IRIS as a
potential dispersing element in the spectrograph. Our team has procured
near-infrared gratings from two separate vendors. We have two gratings with the
specifications needed for IRIS current design: 1.51-1.82{\mu}m (H-band) to
produce a spectral resolution of 4000 and 1.19- 1.37 {\mu}m (J-band) to produce
a spectral resolution of 8000. The center wavelengths for each grating are
1.629{\mu}m and 1.27{\mu}m, and the groove densities are 177l/mm and 440l/mm
for H-band R=4000 and J-band R=8000, respectively. We directly measure the
efficiencies in the lab and find that the peak efficiencies of these two types
of gratings are quite good with a peak efficiency of ~88% at the Bragg angle in
both TM and TE modes at H-band, and 90.23% in TM mode, 79.91% in TE mode at
J-band for the best vendor. We determine the drop in efficiency off the Bragg
angle, with a 20-23% decrease in efficiency at H-band when 2.5 degree deviation
from the Bragg angle, and 25%-28% decrease at J-band when 5{\deg} deviation
from the Bragg angle.Comment: Proceedings of the SPIE, 9147-33
The InfraRed Imaging Spectrograph (IRIS) for TMT: Reflective ruled diffraction grating performance testing and discussion
We present the efficiency of near-infrared reflective ruled diffraction
gratings designed for the InfraRed Imaging Spectrograph (IRIS). IRIS is a first
light, integral field spectrograph and imager for the Thirty Meter Telescope
(TMT) and narrow field infrared adaptive optics system (NFIRAOS). We present
our experimental setup and analysis of the efficiency of selected reflective
diffraction gratings. These measurements are used as a comparison sample
against selected candidate Volume Phase Holographic (VPH) gratings (see Chen et
al., this conference). We investigate the efficiencies of five ruled gratings
designed for IRIS from two separate vendors. Three of the gratings accept a
bandpass of 1.19-1.37 {\mu}m (J band) with ideal spectral resolutions of R=4000
and R=8000, groove densities of 249 and 516 lines/mm, and blaze angles of 9.86
and 20.54 degrees, respectively. The other two gratings accept a bandpass of
1.51-1.82 {\mu}m (H Band) with an ideal spectral resolution of R=4000, groove
density of 141 lines/mm, and blaze angle of 9.86{\deg}. We measure the
efficiencies off blaze angle for all gratings and the efficiencies between the
polarization transverse magnetic (TM) and transverse electric (TE) states. The
peak reflective efficiencies are 98.90 +/- 3.36% (TM) and 84.99 +/- 2.74% (TM)
for the H-band R=4000 and J-band R=4000 respectively. The peak reflective
efficiency for the J-band R=8000 grating is 78.78 +/- 2.54% (TE). We find that
these ruled gratings do not exhibit a wide dependency on incident angle within
+/-3{\deg}. Our best-manufactured gratings were found to exhibit a dependency
on the polarization state of the incident beam with a ~10-20% deviation,
consistent with the theoretical efficiency predictions.Comment: Proceedings of the SPIE, 9147-34
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