adH0cc

accurate determination of H0 with core-collapse supernovae

We aim to determine the current expansion rate of the Universe, the so-called Hubble constant H0. To this end, we measure distances to Type IIP supernovae in the Hubble flow using the Tailored Expanding Photosphere Method.

This project is based on the ESO-VLT Large Programme 1104.A-0380.

How it works

This is the basic principle how the Expanding Photosphere Method (EPM) works:


As usual, the devil is in the details, and this is what the adH0cc programme is about. We intend to obtain better distances than with classical EPM through tailored spectral modelling of the individual Type IIP supernovae in our sample.

Publications

adH0cc AstroNotes

To identify well suited Type IIP supernovae, adH0cc has to spectroscopically classify numerous transients. The outcomes of these classifications are reported in AstroNotes of the IAU Supernova Working Group. All adH0cc AstroNotes can be found here:

Cosmological distances of type II supernovae from radiative transfer modeling

There is a great need for independent accurate measurements of the Hubble constant (H0). We establish a new one-step method to determine H0 based on radiative transfer modeling of type II supernovae and demonstrate its utility in a proof-of-principle measurement. In this first-ever application of the tailored-expanding-photosphere method in the Hubble flow, we find H0 = 72.3 ± 2.9 km s-1 Mpc-1 in good agreement with state-of-the-art results.

Family dispute: do type IIP supernova siblings agree on their distance?

Type II supernovae that exploded in the same galaxy provide us with the exciting opportunity to measure the same distance twice and compare the results.

Reeling in the Whirlpool: the distance to M 51 clarified by Cepheids and the Type IIP SN 2005cs

In the Whirpool galaxy, we can directly compare distances from three state-of-the-art methods: the EPM applied to supernova 2005cs, the Cepheid period-luminosity relation, and the tip of the red giant branch.

Supernova observations

We aim to observe ~20 Type IIP supernovae in the redshift range from 0.04 to 0.10, i.e., the linear Hubble flow. We are using the 8.2 m VLT-UT1 telescope equipped with the FORS2 spectrograph, where we have been granted 150 hr of observing time through an ESO Large Programme.
VLT images cutouts of our current sample of supernovae are shown below.


We are collecting spectral time series for the first month of the evolution of Type IIP supernovae, since this period is ideal for accurate spectral modelling to determine the distances of the supernovae.


The spectra are reduced using the custom-made FORSify pipeline, which is based on PypeIt.

At the end of the adH0cc project, we will upload the fully reduced and calibrated data to the ESO archive and make them available to the community.

Spectral modelling


Radiative transfer calculations with our code TARDIS allow us to predict the luminosity and spectrum for a supernova model. To find a good model for an observed supernova, we adjust the parameters of our simulated supernova until the predicted spectrum matches the observation. In this step, we vary, for example, the temperature, the velocity, and the abundances of various chemical elements. Finally, the best fit model tells us the luminosity and therefore the distance to the observed supernova.

People

Finland

Rubina Kotak (Turku)

France

Stéphane Blondin (CNRS, LAM)

Germany

Wolfgang Hillebrandt (PI, MPA)
Bruno Leibundgut (PI, ESO)
Geza Csörnyei (MPA)
Gabi Cudmani (MPA / TUM)
Andreas Flörs (GSI)
Alexander Holas (ZAH / HITS)
Sabrina Kressierer (ESO / TUM)
Jason Spyromilio (ESO)
Sherry H. Suyu (MPA / TUM / ASIAA)
Stefan Taubenberger (MPA)
Christian Vogl (MPA)

Israel

Rachel Bruch (Weizmann)
Avishay Gal-Yam (Weizmann)

Switzerland

Cameron Lemon (EPFL)

United Kingdom

Stephen J. Smartt (QUB)

Contact

You want to learn more? Do not hesitate to contact us!
Wolfgang and Bruno are the PIs of adH0cc.

  • Address

    Bruno Leibundgut
    European Southern Observatory
    Karl-Schwarzschild-Str. 2
    D-85748 Garching
    Germany

  • Address

    Wolfgang Hillebrandt
    Max Planck Institute for Astrophysics
    Karl-Schwarzschild-Str. 1
    D-85748 Garching
    Germany