51 research outputs found
The Deepest Supernova Search is Realized in the Hubble Ultra Deep Field Survey
The Hubble Ultra Deep Field Survey has not only provided the deepest optical
and near infrared views of universe, but has enabled a search for the most
distant supernovae to z~2.2. We have found four supernovae by searching spans
of integrations of the Ultra Deep Field and the Ultra Deep Field Parallels
taken with the Hubble Space Telescope paired with the Advanced Camera for
Surveys and the Near Infrared Multi Object Spectrometer. Interestingly, none of
these supernovae were at z>1.4, despite the substantially increased sensitivity
per unit area to such objects over the Great Observatories Origins Deep Survey.
We present the optical photometric data for the four supernovae. We also show
that the low frequency of Type Ia supernovae observed at z>1.4 is statistically
consistent with current estimates of the global star formation history combined
with the non-trivial assembly time of SN Ia progenitors.Comment: 24 pages (6 figures), submitted to the Astronomical Journa
Empirical Delay Time Distributions of Type Ia Supernovae From The Extended GOODS/HST Supernova Survey
Using the Hubble Space Telescope ACS imaging of the GOODS North and South
fields during Cycles 11, 12, and 13, we derive empirical constraints on the
delay-time distribution function for type Ia supernovae. We extend our previous
analysis to the three-year sample of 56 SNe Ia over the range 0.2<z<1.8, using
a Markov chain Monte Carlo to determine the best-fit unimodal delay-time
distribution function. The test, which ultimately compares the star formation
rate density history to the unbinned volumetric SN Ia rate history from the
GOODS/HST-SN survey, reveals a SN Ia delay-time distribution that is tightly
confined to 3-4 Gyrs (to >95% confidence). This result is difficult to resolve
with any intrinsic delay-time distribution function (bimodal or otherwise), in
which a substantial fraction (e.g., >10%) of events are ``prompt'', requiring
less than approximately 1 Gyr to develop from formation to explosion. The
result is, however, strongly motivated by the decline in the number of SNe Ia
at z>1.2. Sub-samples of the HST-SN data confined to lower redshifts (z<1) show
plausible delay-time distributions that are dominated by prompt events, which
is more consistent with results from low-redshift supernova samples and
supernova host galaxy properties. Scenarios in which a substantial fraction of
z>1.2 supernovae are extraordinarily obscured by dust may partly explain the
differences in low-z and high-z results. Other possible resolutions may include
environmental dependencies (such as gas-phase metallicity) that affect the
progenitor mechanism efficiency, especially in the early universe.Comment: 12 pages, 9 figures, accepted to the Astrophysical Journa
High Redshift Supernova Rates
We use a sample of 42 supernovae detected with the Advanced Camera for
Surveys on-board the Hubble Space Telescope as part of the Great Observatories
Origins Deep Survey to measure the rate of core collapse supernovae to z~0.7
and type Ia supernovae to z~1.6. This significantly increases the redshift
range where supernova rates have been estimated from observations.
The rate of core collapse supernovae can be used as an independent probe of
the cosmic star formation rate. Based on the observations of 17 core collapse
supernovae, we measure an increase in the core collapse supernova rate by a
factor of 1.6 in the range 0.3<z<0.7, and an overall increase by a factor of 7
to z~0.7 in comparison to the local core collapse supernova rate. The increase
in the rate in this redshift range in consistent with recent measurements of
the star formation rate derived from UV-luminosity densities and IR datasets.
Based on 25 type Ia supernovae, we find a SN Ia rate that is a factor 3-5
higher at z~1 compared to earlier estimates at lower redshifts (z<0.5),
implying that the type Ia supernova rate traces a higher star formation rate at
redshifts z>1 compared to low redshift. At higher redshift (z>1), we find a
suggested decrease in the type Ia rate with redshift. This evolution of the Ia
rate with redshift is consistent with a type Ia progenitor model where there is
a substantial delay between the formation of the progenitor star and the
explosion of the supernova. Assuming that the type Ia progenitor stars have
initial main sequence masses 3-8 M_Sun, we find that 5-7% of the available
progenitors explode as type Ia supernovae.Comment: 16 pages, 3 figures, accepted for publication in the Astrophysical
Journa
The Extended Hubble Space Telescope Supernova Survey: The Rate of Core Collapse Supernovae to z~1
We use a sample of 45 core collapse supernovae detected with the Advanced
Camera for Surveys on-board the Hubble Space Telescope to derive the core
collapse supernova rate in the redshift range 0.1<z<1.3. In redshift bins
centered on =0.39, =0.73, and =1.11, we find rates 3.00
{+1.28}{-0.94}{+1.04}{-0.57}, 7.39 {+1.86}{-1.52}{+3.20}{-1.60}, and 9.57
{+3.76}{-2.80}{+4.96}{-2.80}, respectively, given in units yr^{-1} Mpc^{-3}
10^{-4} h_{70}^3. The rates have been corrected for host galaxy extinction,
including supernovae missed in highly dust enshrouded environments in infrared
bright galaxies. The first errors represent statistical while the second are
the estimated systematic errors. We perform a detailed discussion of possible
sources of systematic errors and note that these start to dominate over
statistical errors at z>0.5, emphasizing the need to better control the
systematic effects. For example, a better understanding of the amount of dust
extinction in the host galaxies and knowledge of the supernova luminosity
function, in particular the fraction of faint M > -15 supernovae, is needed to
better constrain the rates. When comparing our results with the core collapse
supernova rate based on the star formation rate, we find a good agreement,
consistent with the supernova rate following the star formation rate, as
expected.Comment: 12 pages, 4 figures, ApJ, replaced to match version in pres
New Hubble Space Telescope Discoveries of Type Ia Supernovae at z > 1: Narrowing Constraints on the Early Behavior of Dark Energy
We have discovered 21 new Type Ia supernovae (SNe Ia) with the Hubble Space
Telescope (HST) and have used them to trace the history of cosmic expansion
over the last 10 billion years. These objects, which include 13
spectroscopically confirmed SNe Ia at z > 1, were discovered during 14 epochs
of reimaging of the GOODS fields North and South over two years with the
Advanced Camera for Surveys on HST. Together with a recalibration of our
previous HST-discovered SNe Ia, the full sample of 23 SNe Ia at z > 1 provides
the highest-redshift sample known. Combined with previous SN Ia datasets, we
measured H(z) at discrete, uncorrelated epochs, reducing the uncertainty of
H(z>1) from 50% to under 20%, strengthening the evidence for a cosmic jerk--the
transition from deceleration in the past to acceleration in the present. The
unique leverage of the HST high-redshift SNe Ia provides the first meaningful
constraint on the dark energy equation-of-state parameter at z >1.
The result remains consistent with a cosmological constant (w(z)=-1), and
rules out rapidly evolving dark energy (dw/dz >>1). The defining property of
dark energy, its negative pressure, appears to be present at z>1, in the epoch
preceding acceleration, with ~98% confidence in our primary fit. Moreover, the
z>1 sample-averaged spectral energy distribution is consistent with that of the
typical SN Ia over the last 10 Gyr, indicating that any spectral evolution of
the properties of SNe Ia with redshift is still below our detection threshold.Comment: typos, references corrected, minor additions to exposition 82 pages,
17 figures, 6 tables. Data also available at:
http://braeburn.pha.jhu.edu/~ariess/R06. Accepted, Astrophysical Journal vol.
656 for March 10, 200
RELICS: Strong Lens Models for Five Galaxy Clusters From the Reionization Lensing Cluster Survey
Strong gravitational lensing by galaxy clusters magnifies background
galaxies, enhancing our ability to discover statistically significant samples
of galaxies at z>6, in order to constrain the high-redshift galaxy luminosity
functions. Here, we present the first five lens models out of the Reionization
Lensing Cluster Survey (RELICS) Hubble Treasury Program, based on new HST
WFC3/IR and ACS imaging of the clusters RXC J0142.9+4438, Abell 2537, Abell
2163, RXC J2211.7-0349, and ACT-CLJ0102-49151. The derived lensing
magnification is essential for estimating the intrinsic properties of
high-redshift galaxy candidates, and properly accounting for the survey volume.
We report on new spectroscopic redshifts of multiply imaged lensed galaxies
behind these clusters, which are used as constraints, and detail our strategy
to reduce systematic uncertainties due to lack of spectroscopic information. In
addition, we quantify the uncertainty on the lensing magnification due to
statistical and systematic errors related to the lens modeling process, and
find that in all but one cluster, the magnification is constrained to better
than 20% in at least 80% of the field of view, including statistical and
systematic uncertainties. The five clusters presented in this paper span the
range of masses and redshifts of the clusters in the RELICS program. We find
that they exhibit similar strong lensing efficiencies to the clusters targeted
by the Hubble Frontier Fields within the WFC3/IR field of view. Outputs of the
lens models are made available to the community through the Mikulski Archive
for Space TelescopesComment: Accepted to Ap
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