25 research outputs found
Evidence for shock-heated gas in the Taffy Galaxies and Bridge from Optical Emission-Line IFU spectroscopy
We present optical IFU observations of the Taffy system (UGC 12914/15); named
for the radio emission that stretches between the two galaxies. Given that
these gas rich galaxies are believed to have recently collided head-on, the
pair exhibits a surprisingly normal total (sub-LIRG) IR luminosity
( L). Previous observations
have demonstrated that a large quantity of molecular and neutral gas have been
drawn out of the galaxies into a massive multi-phase bridge. We present, for
the first time, spatially resolved spectroscopy of the ionized gas in the
system. The results show that the ionized gas is highly disturbed
kinematically, with gas spread in two main filaments between the two galaxies.
The line profiles exhibit widespread double components in both the bridge and
parts of the disks of the galaxies. We investigate the spatial distribution of
the excitation properties of the ionized gas using emission-line diagnostic
diagrams, and conclude that large quantities (up to 40) of the emission
from the entire system is consistent with gas heated in 200 \kms\ shocks.
While the shocked gas is mainly associated with the bridge, there is a
significant amount of shocked gas associated with both galaxies. Confirming
other multi-wavelength indicators, the results suggest that the effects of
shocks and turbulence can continue to be felt in a high-speed galaxy collision
long after the collision has occurred. The persistence of shocks in the Taffy
system may explain the relatively low current star formation rates in the
system as a whole.Comment: 19 pages, 13 figures. Accepted for publication in Ap
FIGS -- Faint Infrared Grism Survey: Description and Data Reduction
The Faint Infrared Grism Survey (FIGS) is a deep Hubble Space Telescope (HST)
WFC3/IR (Wide Field Camera 3 Infrared) slitless spectroscopic survey of four
deep fields. Two fields are located in the Great Observatories Origins Deep
Survey-North (GOODS-N) area and two fields are located in the Great
Observatories Origins Deep Survey-South (GOODS-S) area. One of the southern
fields selected is the Hubble Ultra Deep Field. Each of these four fields were
observed using the WFC3/G102 grism (0.8-1.15 continuous coverage)
with a total exposure time of 40 orbits (~ 100 kilo-seconds) per field. This
reaches a 3 sigma continuum depth of ~26 AB magnitudes and probes emission
lines to . This paper details the four
FIGS fields and the overall observational strategy of the project. A detailed
description of the Simulation Based Extraction (SBE) method used to extract and
combine over 10000 spectra of over 2000 distinct sources brighter than
m_F105W=26.5 mag is provided. High fidelity simulations of the observations is
shown to significantly improve the background subtraction process, the spectral
contamination estimates, and the final flux calibration. This allows for the
combination of multiple spectra to produce a final high quality, deep,
1D-spectra for each object in the survey.Comment: 21 Pages. 17 Figures. To appear in Ap
Evidence for Shock-heated Gas in the Taffy Galaxies and Bridge from Optical Emission-line IFU Spectroscopy
We present optical integral field unit observations of the Taffy system (UGC 12914/15), named for the radio emission that stretches between the two galaxies. Given that these gas-rich galaxies are believed to have recently collided head-on, the pair exhibits a surprisingly normal total (sub-LIRG) IR luminosity (L_(FIR) ~ 4.5 × 10^(10) L_⊙). Previous observations have demonstrated that a large quantity of molecular and neutral gas has been drawn out of the galaxies into a massive multiphase bridge. We present, for the first time, spatially resolved spectroscopy of the ionized gas in the system. The results show that the ionized gas is highly disturbed kinematically, with gas spread in two main filaments between the two galaxies. The line profiles exhibit widespread double components in both the bridge and parts of the disks of the galaxies. We investigate the spatial distribution of the excitation properties of the ionized gas using emission-line diagnostic diagrams and conclude that a large quantity (up to 40%) of the emission from the entire system is consistent with gas heated in ~200 km s^(−1) shocks. While the shocked gas is mainly associated with the bridge, there is a significant amount of shocked gas associated with both galaxies. Confirming other multiwavelength indicators, the results suggest that the effects of shocks and turbulence can continue to be felt in a high-speed galaxy collision long after the collision has occurred. The persistence of shocks in the Taffy system may explain the relatively low current star formation rates in the system as a whole
Science Impacts of the SPHEREx All-Sky Optical to Near-Infrared Spectral Survey: Report of a Community Workshop Examining Extragalactic, Galactic, Stellar and Planetary Science
SPHEREx is a proposed SMEX mission selected for Phase A. SPHEREx will carry
out the first all-sky spectral survey and provide for every 6.2" pixel a
spectra between 0.75 and 4.18 m [with R41.4] and 4.18 and 5.00
m [with R135]. The SPHEREx team has proposed three specific science
investigations to be carried out with this unique data set: cosmic inflation,
interstellar and circumstellar ices, and the extra-galactic background light.
It is readily apparent, however, that many other questions in astrophysics and
planetary sciences could be addressed with the SPHEREx data. The SPHEREx team
convened a community workshop in February 2016, with the intent of enlisting
the aid of a larger group of scientists in defining these questions. This paper
summarizes the rich and varied menu of investigations that was laid out. It
includes studies of the composition of main belt and Trojan/Greek asteroids;
mapping the zodiacal light with unprecedented spatial and spectral resolution;
identifying and studying very low-metallicity stars; improving stellar
parameters in order to better characterize transiting exoplanets; studying
aliphatic and aromatic carbon-bearing molecules in the interstellar medium;
mapping star formation rates in nearby galaxies; determining the redshift of
clusters of galaxies; identifying high redshift quasars over the full sky; and
providing a NIR spectrum for most eROSITA X-ray sources. All of these
investigations, and others not listed here, can be carried out with the nominal
all-sky spectra to be produced by SPHEREx. In addition, the workshop defined
enhanced data products and user tools which would facilitate some of these
scientific studies. Finally, the workshop noted the high degrees of synergy
between SPHEREx and a number of other current or forthcoming programs,
including JWST, WFIRST, Euclid, GAIA, K2/Kepler, TESS, eROSITA and LSST.Comment: Report of the First SPHEREx Community Workshop,
http://spherex.caltech.edu/Workshop.html , 84 pages, 28 figure
A comprehensive study of H emitters at 0.62 in the DAWN survey: the need for deep and wide regions
We present new estimates of the luminosity function (LF) and star formation
rate density (SFRD) for an H selected sample at from the
Deep And Wide Narrow-band (DAWN) survey. Our results are based on a new
H sample in the extended COSMOS region (compared to Coughlin et al.
2018) with the inclusion of flanking fields, resulting in a total area coverage
of 1.5 deg. A total of 241 H emitters were selected based on
robust selection criteria using spectro-photometric redshifts and broadband
color-color classification. We explore the effect of different dust correction
prescriptions by calculating the LF and SFRD using a constant dust extinction
correction, A{} mag, a luminosity-dependent correction,
and a stellar-mass dependent correction. The resulting H LFs are well
fitted using Schechter functions with best-fit parameters: L erg
s, Mpc, for constant dust
correction, L erg s, Mpc,
for luminosity-dependent dust correction, and L
erg s, Mpc, , for stellar
mass-dependent dust correction. The deep and wide nature of the DAWN survey
effectively samples H emitters over a wide range of luminosities,
thereby providing better constraints on both the faint and bright end of the
LF. Also, the SFRD estimates
MyrMpc (constant dust correction),
MyrMpc
(luminosity-dependent dust correction), and
MyrMpc (stellar mass-dependent dust correction) are in
good agreement with the evolution of SFRD across redshifts () seen
from previous H surveys.Comment: 16 pages, 8 figures, Accepted for publication in Ap
Investigating Galaxy Evolution and Active Galactic Nucleus Feedback with the Sunyaev-Zel'dovich Effect
International audienceGalaxy formation is a complex process with aspects that are still very uncertain. A mechanism that has been used in simulations to successfully resolve several of these outstanding issues is active galactic nucleus (AGN) feedback, where a large amount of energy is driven outwards through a galaxy and the surrounding region by a central supermassive black hole. A promising method for directly measuring this energy is by looking at small increases in the energy of the cosmic microwave background (CMB) photons as they pass through hot gas, known as the thermal Sunyaev-Zel'dovich (tSZ) effect. I will present work done to measure the tSZ effect around a large number of 0.5 5x10^11 M_Sun), favor the Horizon-NoAGN results at more than a 6-sigma level. These results indicate that AGN feedback may be milder than often predicted, and they also highlight the promising nature of tSZ effect measurements and the need for further work using better data and more varied simulations
High-Precision Redshifts for Type Ia Supernovae with the Nancy Grace Roman Space Telescope P127 Prism
We present results from simulating slitless spectroscopic observations with
the Nancy Grace Roman Space Telescope's (Roman) Wide-Field Instrument (WFI)
P127 prism spanning 0.75 to 1.8 . We quantify the efficiency of
recovered Type Ia supernovae (SNe Ia) redshifts, as a function of P127 prism
exposure time, to guide planning for future observing programs with the Roman
prism. Generating the two-dimensional dispersed images and extracting
one-dimensional spectra is done with the slitless spectroscopy package pyLINEAR
along with custom-written software. From the analysis of 1698 simulated SN Ia
P127 prism spectra, we show the efficiency of recovering SN redshifts to
, highlighting the exceptional sensitivity of the Roman P127
prism. Redshift recovery is assessed by setting a requirement of . We find that 3 hr
exposures are sufficient for meeting this requirement, for of
the sample of mock SNe Ia at and within days of rest-frame
maximum light in the optical. We also show that a 1 hr integration of Roman can
achieve the same precision in completeness to a depth of AB mag
(or ). Implications for cosmological studies with Roman P127 prism
spectra of SNe Ia are also discussed.Comment: 17 pages, 10 figures. Submitted to AAS journals. Comments welcom
A Synthetic Roman Space Telescope High-Latitude Time-Domain Survey: Supernovae in the Deep Field
NASA will launch the Nancy Grace Roman Space Telescope (Roman) in the second
half of this decade, which will allow for a generation-defining measurement of
dark energy through multiple probes, including Type Ia supernovae (SNe Ia). To
improve decisions on survey strategy, we have created the first simulations of
realistic Roman images that include artificial SNe Ia injected as point sources
in the images. Our analysis combines work done on Roman simulations for weak
gravitational lensing studies as well as catalog-level simulations of SN
samples. We have created a time series of images over two years containing
1,050 SNe Ia, covering a 1 square degree subarea of a planned 5 square
degree deep survey. We have released these images publicly for community use
along with input catalogs of all injected sources. We create secondary products
from these images by generating coadded images and demonstrating recovery of
transient sources using image subtraction. We perform first-use analyses on
these images in order to measure galaxy-detection efficiency, point
source-detection efficiency, and host-galaxy association biases. The simulated
images can be found here:
https://roman.ipac.caltech.edu/sims/SN_Survey_Image_sim.html.Comment: 12 pages, 12 figures. Submitted to MNRAS. For simulated images see
https://roman.ipac.caltech.edu/sims/SN_Survey_Image_sim.htm