I want to take another step back in perspective from the last post to say a few words about what the radial acceleration relation (RAR) means and what it doesn’t mean. Here it is again: This information was not available when the dark matter paradigm was developed. We observed excess motion, like flat rotation curves, … Continue reading Why’d it have to be MOND?

In the previous post, we discussed how lensing data extend the Radial Acceleration Relation (RAR) seen in galaxy kinematics to very low accelerations. Let’s zoom out now, and look at things at higher accelerations and from a historical perspective.

Flat rotation curves and the Baryonic Tully-Fisher relation (BTFR) both follow from the Radial Acceleration Relation (RAR). In Mistele et al. (2024b) we emphasize the exciting aspects of the former; these follow from the RAR in the Mistele et al. (2024a). It is worth understanding the connection.

Last time, we discussed the remarkable result that gravitational lensing extends the original remarkable result of flat rotation curves much farther out, as far as the data credibly probe. This corroborates and extends the result of Brouwer et al. They did a thorough job, but one thing they did not consider was Tully-Fisher.

That rotation curves become flat at large radii is one of the most famous results in extragalactic astronomy. This had been established by Vera Rubin and her collaborators by the late 1970s.

This is an update to a post from a few years ago, which itself was an update to a webpage I wrote in 2008, with many updates in between. At that time, the goalposts for detecting WIMPs had already moved repeatedly.

And pretty much everywhere else First, a pretty picture: The sun is nearing the peak of its eleven year sunspot cycle. That means lots of sunspots and associated activity. Solar prominences, visible to the naked eye during the eclipse, are bands of plasma entrained in the magnetic field connecting pairs of sunspots.

I have been spending a lot of time lately writing up a formal paper on high redshift galaxies, so haven’t had much time to write here. The paper is a lot more involved than I told you so, but yeah, I did. Repeatedly.

We will return to our usual programming shortly. But first, a few words on the eclipse experience last Monday. It. Was. Awesome . That’s a few words, so Mission Accomplished. That’s really all I had planned to say. However, I find I am still giddy from this momentous event, so will share my experience of the day, such as words can humbly convey.

Perhaps the most compelling astronomical phenomenon accessible to a naked-eye observer is a total eclipse of the sun. These rare events have always fascinated us, and often terrified us. It is abnormal and disturbing for the sun to be blotted from the sky! A solar eclipse will occur on Monday, 8 April 2024. A partial eclipse will be visible from nearly every part of North America.

I just got back from a visit to the Carnegie Institution of Washington where I gave a talk and saw some old friends. I was a postdoc at the Department of Terrestrial Magnetism (DTM) in the ’90s. DTM is so-named because in their early days they literally traveled the world mapping the magnetic field. When I was there, DTM ⁺ had a small extragalactic astronomy group including Vera Rubin*, Francois Schweizer, and John Graham.