Hubble Cycle-26 TAC results

Thoughts on the Hubble Space Telescope Cycle-26 results.

The results on the HST cycle-26 are out and there has been a lot of hay made of the improvement in gender balance in the results. It made me think about how the decision process in groups goes. I was reading how in times of stress (say a <3 day decision making process) people fall back on “what everyone knows” and “common knowledge”.

The argument was that people let some rote or authoritarian argument sway them if they are overwhelmed. And I think that is a decisive factor in the imbalance in previous cycles. When overwhelmed, consciously or unconsciously, go with the team you’ve heard of. Not necessarily your mates etc but people you know.

So I think it’s great that the information is now not being passed on to the TAC. Other organizations are similarly exploring double blind evaluations. ESO did an experiment with crowd sourced TAC. Interesting and much improved feedback (in my experience). Though no double blind yet.

Oh and only if funding agencies would do the same. They still ask for massive amounts of personal information. Resume, letters, publication lists etc etc. why? Why not simply focus on the science? And just that? I would be *very* interested to see if that would change the gender balance of NASA, NSF and ERC rewards.

But I also want to see what the next Hubble TAC result looks like. This cycle was...a mess. An experiment...perhaps successful...but massively oversubscribed. The experiment needs confirmation.

z~8 galaxy sizes

Got sick of struggling with SED fits of dwarfs... so I worked on z~8 galaxy sizes. I had done *much* more that I remembered. The paper is 80% done?

And it was Robin's first day at work with UNAWE! woo!

Trip to Tucson is approved and booked. Only now to have a get my talk together.

All I so far is Scrat images... those will come in handy.

Clearing the hopper. Co-authors! C'mon. Going for a personal best

latest draft of a small paper on the link between morphology and normalized specific angular momentum with Danail. Email with Australia. so. 24hr cycle.

Trying to figure out what is going on with my SED fits of Brown Dwarfs in CANDELS.

Proofs of second-ever Supernova paper are in. Third supernova paper needs to go back to MNRAS.
(waiting for co-author).

Trip to Tucson is coming down to the wire. hope someone will book me a flight (likely to be through Novisibirsk at this rate...) soon...
I would like to give my first ever invited talk.

Preparing talk. So far I have a lot of images of Scrat.

How I thought of the Philae lander. Yeah that tweet got more retweets than *everything I've done before*. Go scrat...

IAU invite

Sooo. I got an invitation to speak at the IAU in Hawaii next year.
This is nice. I hear Hawaii is a nice place. All is good.

End of announcement. Back to paper writing.

4 years in the making...SNIa and their host extinction properties

Back in South Africa (a postdoc, a kid, two moves, a continent, and a lifetime ago) I worked with a summer student, Adam Reynolds, on the possibility of using the SDSS-III data to use Supernovea Type Ia (SNIa) as probes of the ISM. The idea worked in principle on the --then public-- SDSS-III data but to be really convincing, we'd need their final data-release.
This was a few years in the making but finally arrived in 2014 (huzzah!). I dug out Adam's report and converted it to a small paper (script everything folks...). My interest is of course the distribution of extinction values, could not give a fig about SNIa...

The results are interesting. SNIa effectively "see" a dust screen (inclination dependence is cos(i), nothing more fancy) and their distribution is roughly exponential. The latter is weird, based on everything I've seen (PHAT survey results, occulting galaxy pairs), one would expect a log-normal one. I suspect that is what it really is but right now an exponential is used in SNIa measurements.

The gist of the current paper is Host Galaxy Inclination Matters!

So constructing the next version of SNIa cosmology, should start by taking disk inclination into account as the first host observable to be included. My second guess is host mass. But that is the second paper (already submitted...)

After that, one would need to redo the lightcurves with different extinction priors. To provide the templates for that, I got my STARSMOG HST SNAP program. The ultimate goal is here to reduce the errors in SNIa to below 1%. That'll keep them competitive as a cosmological tool.

That'll keep me busy. All that from a side-interest...

you can find the paper here:

SNIa Host Galaxy Properties and the Dust Extinction Distribution

Supernovae Type Ia display a complex relation with their host galaxies. An important prior to the fit of the supernovae's lightcurve is the distribution of host galaxy extinction values that can be encountered. The SDSS-SN project has published light curve fits using both MLCS2k2 and SALT2. We use the former fits extinction parameter (AV) to map this distribution of extinction values.
We explore the dependence of this distribution on four observables; the inclination of the host galaxy disk, radial position of the supernova, redshift of the supernova and host, and the level of star-formation in the host galaxy. The distribution of AV values encountered by supernovae is typically characterised by: N0 e−AV/τ, with τ= 0.4 or 0.33.
We find that the inclination correction using an infinitely thin disk for the SNIa is sufficient, resulting in similar exponential AV distributions for high- and low-inclination disks. The AV distribution also depends on the radial position in the disk, consistent with previous results on the transparency of spiral disks. The distribution of AV values narrows with increased star-formation, possibly due to the destruction or dispersion of the dusty ISM by stellar winds prior to the ignition of the supernova.
In future supernova searches, certainly the inclination of the host galaxy disk, should be considered in the construction of the \av \ prior with τ=0.4/cos(i) as the most likely prior in each individual host galaxy's case.

ESO proposals in with time to spare

...and with time to spare I mean 7 min...

three went in. GAMA groups proposal was in first. occulting group one next. Then a KMOS high-redshift one last.

egads. working so close to a deadline is not my thing.

Fair use of Hubble Images

Hubble images, especially those pretty ones made available through the Hubble Heritage (link), are free to use by everyone. Sometimes by some kind-of-fringy people or plain astrologers. I have seen some professional astronomers lose their cool as their image got sued for a Astrology ad for example.

My attitude is: "Hey, the public paid for these images and everyone in that public gets to use them. Any and all of them. That's fair use."

So imagine my surprise when I got an email regarding my occulting galaxy image (the wallpaper of this blog etc etc) by an author of an alternative galaxy evolution model.

Here is the excerpt he sent me that talked about the overlapping pair:

Case Study of 2MASX J00482185-2507365.    You are on your own, Lil’ Doggy.

In the next illustration the secondarily formed nucleus is considerably smaller than the primary body.  A case of mitosis?  If it is, then a fragment or the tail end of a bar nucleus was dislocated and forcefully and speedily flung for some distance from the galaxy’s center.  It lodged there above the ‘mother’ galaxy, where it has begun to construct its own galaxy of stars.  So small, but it seems to have retained a preference for the bar shape. [Any suggested names for this ‘newbie’ galaxy?]  

  Image of 2MASX J00482185-2507365. Credit  NASA, ESA, and The Hubble Heritage Team STScI, AURA, B. Holwerda, Space Telescope Science Institute, J. Dalcanton U. of Washington

            Before reaching its present location this ‘offspring’ galaxy was a clump of heavy black holes. Perhaps less than 10% of the original nucleus, it still weighed as much as several hundred thousand Suns, perhaps millions.  As it soared through the inner most galaxy and partially through the spiral rings it caused some minor alteration of the star orbits in those areas, which is apparent in the image, minor effects because of its great speed.  Run-away stars and black holes have been well documented.  These are the losers of a gravity contest between two or more big boss bodies.  So, this junior galaxy quickly got to where it wanted to be, then slowed enough to start its own family of stars.  Again, runaways are slowed by the capture of dark matter and increasing weight.  Its present site is ideal for capturing inflowing dark matter.  (Dark matter is instrumental in star formation.)

[Someone want to calculate how long it took to reach the present location?] 

(It is asserted here that the Milky Way nucleus is preparing for a similar event.  See The Case of the Twisted Ring at the Center of the Milky Way, July 20, 2011.)

[Reminder:  Scientists state that no such action is possible because the nucleus is just one oversized black hole that never breaks up or decomposes.  (Except for some vague exceptions.)]

One of the characteristics that distinguish Mitosis from the more common merger of galaxies is the absence of gravitational or pressure waves.  The two entities do not interfere with each other.  Reasons given elsewhere.  

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I will not even pretend I understand the logic but I am flattered that someone got inspired by the picture I helped create (props really go to JD and the Hubble Heritage team) and I appreciate being told about its use.