Daniel Lenz

This afternoon, I worked on a model implementation of the scale-dependent bias, following the ansatz of De Putter & Doré (2014, their Eq. 1). The goal is to constrain the fNL parameter which quantifies the amplitude of the primordial non-Gaussianity. These primordial density fluctuations are very Gaussian, but a small departure from this Gaussianity or limits on … Continue reading First look into the scale-dependent bias and non-Gaussianity →

Last week, I started to re-visited quickspeck, a python package by Duncan Hanson that allows to create angular power spectra for cosmic fields under the Limber approximation (see this paper for a nice overview and an extension). In light of the upcoming CMB lensing workshop at Stanford and our ongoing work on the cross correlation between … Continue reading Python packaging, astropy, and Travis CI →

I have recently been working on the cross-correlation of CIB intensity and CMB lensing from the Planck data. I've had a few hiccups with the format of the lensing data and thus decided to document this properly in a notebook, just in case others ran into similar issues. The notebook with the calculations and examples … Continue reading Power spectra of Planck CMB lensing maps →

I've been working on the problem of computed the angular power spectrum for quite some time now, and nothing quite satisfied my needs. The problem is as follows: For a given map in the HEALPix format (Gorski+ 2005), the angular power spectrum of a map (or the cross power between two maps) needs to be … Continue reading The final take on angular power spectra in HEALPix? →

I just painfully became aware of the importance of adding the different profiles (.bashrc, .bash_profile, .ipython, etc.) to version control. To ignore all but a few relevant files in the home directory, I'd use following as .gitignore: * !*/ !.gitignore !.bash_profile !.jupyter/ !.ipython/ Moreover, I started to experiment a bit with extensions to jupyter through … Continue reading git for .profiles and nbviewer extensions →

The PyCon took place a few weeks ago in Portland, and I have yet to attend this conference for the first time. However, I found the slides very helpful and the videos and great to watch. In particular, I can recommend: The Keynote and python visualization landscape by Jake VanderPlas, who gave two great talks Introduction … Continue reading PyCon videos →

tl;dr: Link to paper & data at the bottom Over the past few months, Brandon Hensley, Olivier Doré, and myself have revisited the correlation between interstellar reddening by dust grains and the atomic neutral hydrogen column density. The basic idea is that HI and dust grains are well-mixed in the ISM and thus that HI can … Continue reading A new, large scale map of interstellar reddening →

This morning, my attention was brought to the new release of the Wisconsin H-Alpha Mapper Sky Survey (WHAM-SS), now covering the full sky at approximately 1 deg resolution, with velocities of +- 100 km/s and ~10 km/s spectral resolution. This first data release is only the start to further post-processing of the data, which will … Continue reading New WHAM-SS release →

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