# The Hubble Constant from Gravitational Lens Time Delays

@inproceedings{Kochanek2003TheHC, title={The Hubble Constant from Gravitational Lens Time Delays}, author={Christopher S. Kochanek and P. S'ari Harvard-Smithsonian Center for Astrophysics and Mit}, year={2003} }

There are now 10 firm time delay measurements in gravitational lenses. The physics of time delays is well understood, and the only important variable for interpreting the time delays to determine H_0 is the mean surface mass density(in units of the critical density for gravitational lensing) of the lens galaxy at the radius of the lensed images. More centrally concentrated mass distributions with lowerpredict higher Hubble constants, with H_0~1-to lowest order. While we cannot determinedirectly…

## 13 Citations

The rates and time-delay distribution of multiply imaged supernovae behind lensing clusters

- Physics
- 2012

Time delays of gravitationally lensed sources can be used to constrain the mass model of a deflector and determine cosmological parameters. We here present an analysis of the time-delay distribution…

The time delays in gravitationally lensed quasars

- Physics2017 IEEE International Young Scientists Forum on Applied Physics and Engineering (YSF)
- 2017

Estimation of time delays is necessary for many applications in astrophysics and cosmology, such as the determination of the Hubble constant, the study of matter distribution at different spatial…

The Hubble Constant

- Physics, MedicineLiving reviews in relativity
- 2015

The size of the remaining systematics indicate that accuracy rather than precision is the remaining problem in a good determination of the Hubble constant, which gives the length scale of the Universe by relating the expansion velocity of objects to their distance.

An optical time delay for the double gravitational lens system FBQ 0951+2635

- Physics
- 2005

We present optical R -band light curves of the double gravitationally lensed quasar FBQ 0951+2635 from observations obtained at the Nordic Optical Telescope between March 1999 and June 2001. A time…

Machine learning methods for delay estimation in gravitationally lensed signals

- Physics, Computer Science
- 2017

This thesis explores in detail a new approach based on kernel regression estimates, which is able to estimate a single time delay given several data sets for the same quasar, and proposes a delay estimation method in which a single latent nonhomogeneous Poisson process underlying the lensed photon streams is imposed.

Testing thermal reprocessing in active galactic nuclei accretion discs

- Physics
- 2007

The thermal reprocessing hypothesis in active galactic nuclei (AGN), where extreme ultraviolet/X-ray photons are reprocessed by the accretion disc into optical/UV photons, predicts…

Estimating time delays between irregularly sampled time series

- Computer Science
- 2007

Experimental results show that this kernel-based approach to estimating the time delay, inspired by kernel methods in the context of statistical and machine learning, is one of the most accurate methods for gaps (missing data) and distinct noise levels.

Redshift drift of gravitational lensing

- Physics
- 2017

We investigate the effect of the redshift drift in strong gravitational lensing. The redshift drift produces a time variation of $i)$ the apparent position of a lensed source and $ii)$ the time delay…

A Kernel-Based Approach to Estimating Phase Shifts Between Irregularly Sampled Time Series: An Application to Gravitational Lenses

- Mathematics, Computer ScienceECML
- 2006

A kernel-based method that directly models the underlying process via a linear combination of Gaussian kernels to estimate the phase shift between temporal variations, in the brightness of multiple images of the same distant gravitationally lensed quasar, from irregular but simultaneous observations of all images.

Data compression in the petascale astronomy era: A GERLUMPH case study

- Computer Science, PhysicsAstron. Comput.
- 2015

This case study investigates off-the-shelf and custom lossless compression algorithms as well as the lossy JPEG2000 compression format and suggests that JPEG2000 could be suitable for other numerical datasets stored as gridded data or volumetric data.