Cosmological Distance Indicators

Noebauer

et al. 2019

A&A

110

The upcoming Large Synoptic Survey Telescope (LSST) will detect many strongly lensed Type Ia supernovae (LSNe Ia) for timedelay cosmography. This will provide an independent and direct way for measuring the Hubble constant H 0 , which is necessary to address the current 4.4σ tension in H 0 between the local distance ladder and the early Universe measurements. We present a detailed analysis of different observing strategies (also referred to as cadence strategy) for the LSST, and quantify their impact on time-delay measurement between multiple images of LSNe Ia. For this, we simulated observations by using mock LSNe Ia for which we produced mock-LSST light curves that account for microlensing. Furthermore, we used the free-knot splines estimator from the software PyCS to measure the time delay from the simulated observations. We find that using only LSST data for time-delay cosmography is not ideal. Instead, we advocate using LSST as a discovery machine for LSNe Ia, enabling time delay measurements from follow-up observations from other instruments in order to increase the number of systems by a factor of 2 to 16 depending on the observing strategy. Furthermore, we find that LSST observing strategies, which provide a good sampling frequency (the mean inter-night gap is around two days) and high cumulative season length (ten seasons with a season length of around 170 days per season), are favored. Rolling cadences subdivide the survey and focus on different parts in different years; these observing strategies trade the number of seasons for better sampling frequency. In our investigation, this leads to half the number of systems in comparison to the best observing strategy. Therefore rolling cadences are disfavored because the gain from the increased sampling frequency cannot compensate for the shortened cumulative season length. We anticipate that the sample of lensed SNe Ia from our preferred LSST cadence strategies with rapid follow-up observations would yield an independent percent-level constraint on H 0 .

Section: Results: Cadence Strategies For Lsnementioning

confidence: 99%

Strongly lensed SNe Ia in the era of LSST: observing cadence for lens discoveries and time-delay measurements

Huber

Noebauer

et al. 2019

A&A

110

“…Joseph et al 2014;Agnello 2017;Petrillo et al 2017;Ostrovski et al 2017;Lanusse et al 2018;Spiniello et al 2018;Treu et al 2018;Avestruz et al 2019), and more are expected to be found with the Large Synoptic Survey Telescope (Oguri & Marshall 2010). Hence, a 1% H 0 measurement from time-delay cosmography is a realistic expectation in the near future (e.g., Jee et al 2015Jee et al , 2016de Grijs et al 2017;Suyu et al 2018;Shajib et al 2018, Jee et al 2019 if we can control the systematic effects to a sub-percent level (Dobler et al 2013;Liao et al 2015;Ding et al 2018).…”

Section: Distance Measurement From Time-delay Cosmographymentioning

confidence: 99%

“…In addition, a prior on the source size (Birrer et al 2016) or having a background source of known brightness (e.g., a lensed SN, Grillo et al 2018) can also put constraints on λ. We refer interested readers to Treu & Marshall (2016) and Suyu et al (2018) for more details.…”

Section: Time-delay Cosmographymentioning

confidence: 99%

A SHARP view of H0LiCOW: H0 from three time-delay gravitational lens systems with adaptive optics imaging

Chen

Fassnacht

Monthly Notices of the Royal Astronomical Society

et al. 2019

204

167

We present the measurement of the Hubble Constant, H 0 , with three strong gravitational lens systems. We describe a blind analysis of both PG 1115+080 and HE 0435−1223 as well as an extension of our previous analysis of RXJ 1131−1231. For each lens, we combine new adaptive optics (AO) imaging from the Keck Telescope, obtained as part of the SHARP AO effort, with Hubble Space Telescope (HST ) imaging, velocity dispersion measurements, and a description of the line-of-sight mass distribution to build an accurate and precise lens mass model. This mass model is then combined with the COSMOGRAIL measured time delays in these systems to determine H 0 . We do both an AO-only and an AO+HST analysis of the systems and find that AO and HST results are consistent. After unblinding, the AO-only analysis gives H 0 = 82.8 +9.4 −8.3 km s −1 Mpc −1 for PG 1115+080, H 0 = 70.1 +5.3 −4.5 km s −1 Mpc −1 for HE 0435−1223, and H 0 = 77.0 +4.0 −4.6 km s −1 Mpc −1 for RXJ 1131−1231. The joint AOonly result for the three lenses is H 0 = 75.6 +3.2 −3.3 km s −1 Mpc −1 . The joint result of the AO+HST analysis for the three lenses is H 0 = 76.8 +2.6−2.6 km s −1 Mpc −1 . All of the above results assume a flat Λ cold dark matter cosmology with a uniform prior on Ω m in [0.05, 0.5] and H 0 in [0, 150] km s −1 Mpc −1 . This work is a collaboration of the SHARP and H0LiCOW teams, and shows that AO data can be used as the high-resolution imaging component in lens-based measurements of H 0 . The full time-delay cosmography results from a total of six strongly lensed systems are presented in a companion paper.

“…The measurement of D d depends on (1), ( 2), and also the stellar velocity dispersion of the foreground deflector, but not on (3), as shown by Jee et al (2015Jee et al ( , 2019. Recent reviews on time-delay cosmography are provided by Treu & Marshall (2016), Suyu et al (2018), and Oguri (2019), for example.…”

Section: Forecasted Cosmological Constraints From Strongly Lensed Snementioning

confidence: 99%

Holismokes

Huber

Cañameras

et al. 2020

A&A

We present the HOLISMOKES programme on strong gravitational lensing of supernovae (SNe) as a probe of SN physics and cosmology. We investigate the effects of microlensing on early-phase SN Ia spectra using four different SN explosion models. We find that distortions of SN Ia spectra due to microlensing are typically negligible within ten rest-frame days after a SN explosion (< 1% distortion within the 1σ spread and ≲10% distortion within the 2σ spread). This shows the great prospects of using lensed SNe Ia to obtain intrinsic early-phase SN spectra for deciphering SN Ia progenitors. As a demonstration of the usefulness of lensed SNe Ia for cosmology, we simulate a sample of mock lensed SN Ia systems that are expected to have accurate and precise time-delay measurements in the era of the Rubin Observatory Legacy Survey of Space and Time (LSST). Adopting realistic yet conservative uncertainties on their time-delay distances and lens angular diameter distances, of 6.6% and 5%, respectively, we find that a sample of 20 lensed SNe Ia would allow us to constrain the Hubble constant (H0) with 1.3% uncertainty in the flat ΛCDM cosmology. We find a similar constraint on H0 in an open ΛCDM cosmology, while the constraint degrades to 3% in a flat wCDM cosmology. We anticipate lensed SNe to be an independent and powerful probe of SN physics and cosmology in the upcoming LSST era.