GO2LF: Creating a Square Degree of HST+Spitzer Fields from a Newly-Approved 612-hour Spitzer Program

It was wonderful to hear on Thursday that the 612-hour Spitzer/IRAC proposal led by my collaborators Mauro Stefanon and Gabe Brammer (co-PIs) was successful. The proposal — and now successful program — is to add Spitzer 3.6 and 4.5 micron data to ~250 fields with deep HST data in at least 3 bands, including both 1.2 micron and 1.6 micron channels. The proposal should allow us to search for z~9-11 galaxies and low-mass stars (T/Y dwarfs) using an additional ~1100 arcmin**2 area. This is even more area than impressive programs like CANDELS possess.

Props are due to both Mauro and Gabe. This is the second year in a row Mauro has successfully led (PI’d) a >500-hour program with Spitzer; Mauro has been doing absolutely amazing work as a postdoc and the next year could be his most impressive yet! Actually all three postdocs I’m working with in Leiden are amazing. And, as for Gabe’s role, not only did he work alongside Mauro to develop the proposal but he basically put together an entire archive with the full set of HST pointings that exist with 1.6 micron data… The total area is now > 3.5 square degrees! Without this archive Gabe put together, the proposal would not have been possible!

And finally should not forget the important role of Adam Burgasser and Benne Holwerda — who put together the very exciting science case for low-mass stars and convinced us to obtain 4.5 micron data over our fields! And also the role of Ivo Labbe — whose photometric code will facilitate photometry over the full set of hst (+now Spitzer) fields.


Building a Cross-Disciplinary Community for Early/Mid-Career Academics in the Leiden/Amsterdam Areas

I’m trying my hand at helping to create a community in the Leiden/Amsterdam Areas for Early/Mid-Career Academics. The goal would be to provide a forum for a broad spectrum of academics to regularly come together to share experiences and to make friends in different areas of study. Gatherings would be at a beautiful location, likely alternating between Leiden and Amsterdam.

I’m not sure how the experiment will go, but I think it would be very interesting to build a cross-disciplinary community / friendship circle in the academic sphere. Many academics often feel alone in the challenges they face, and so creating a community of support could be very useful to us all.

Those of you in the Leiden/Amsterdam area who are starting, associate, or even young full professors are encouraged to sign up.

As the initiative proceeds, I will provide some personal reflections on what transpires.


Early/mid-career academics in the Leiden/Amsterdam Areas

Leiden, NL
15 Young Academics

This is a meetup for early to mid-career academics in the Amsterdam and Leiden areas.  The aim of this group is to provide a space for young academics to make friends with sim…

Check out this Meetup Group →

Exploring the z>~7 Universe with ALMA

In just the past day, ALMA TAC announced the results of its cycle 6 call for telescope proposals.    The oversubscription of telescope time with the facility has been such that the vast majority of proposals are not going to be successful and only a small fraction of the proposals are approved for execution at an A-ranking, the highest priority.

Amazingly again this cycle, the proposals my collaborators and I submitted to pursue redshift z>~7 science received high ratings, and four were approved for execution in cycle 6, three with an A-rating and one with a B-rating.   This was an improvement over our proposal results the previous year, with one A-rated program and two B-rated programs.

Our recent proposal success has been in distinct contrast to our performance in cycles 1 through 4 and has clearly owed to the remarkable success of just 1 hour of observations from a C-ranked ALMA program in cycle 3 led by Renske Smit, a previous PhD student.

This program resulted in the detection of bright [CII] emission from two galaxies at z~7, allowing for the determination of the redshift for the two sources and a measurement of rotation in the two sources.   The result has been published this year in Nature, by lead author Renske Smit in a remarkable effort.

Amazingly, the [CII] lines seen in the Smit+2018 sources were more luminous than seen in any other normal z~7 galaxies, suggesting that we should follow up a much larger sample of galaxies to search for similar lines therefore probing the redshifts, kinematics, and other properties of z~7 galaxies.

In the past two cycles, our small collaboration — driven significantly by highly innovative work by Renske Smit — has won telescope time with a diverse set of scientific goals.   These have included (1) pursuing larger samples of z~7-8 galaxies with [CII] detections (yielding redshifts, [CII] luminosities, and rough dynamical masses) and dust constraints, (2) reobserving a bright z~7 source with a known [CII] line at higher spatial resolution (for a thorough, detailed probe of the kinematic structure), and (3) probing other lines (i.e., [OIII], [NII]) in bright z~7 galaxies.

It is remarkable how dramatically a team’s success with telescope proposals can be transformed by just a single hour of ALMA time.

Keck MOSFIRE Time!

Today I just received news that the NASA Keck proposal that a PhD student (Leindert Boogaard) and I collaborated on with Dominik Riechers was successful, and we will therefore be able to use 0.5 nights of time on the Keck telescope to observe sources over the Hubble Ultra Deep Field (HUDF).    This is exciting since it means that the PhD student I (together with Paul van der Werf) have in Leiden will have the opportunity to make use of the amazing capabilities of the MOSFIRE instrument to observe massive star-forming galaxies in the HUDF to determine both their redshifts and other physical properties.

As NASA Keck time is available to the entire scientific community in the United States, the time is extremely competitive, and will only be awarded to the best scientific projects.   Fortunately, Leindert and I were able to collaborate with Dominik Riechers to put together an extremely compelling proposal.    Our proposal leveraged an incredible allocation of 150 hours of ALMA time given to the ASPECS project (PIs: Fabian Walter, Manuel Aravena, and Chris Carilli), the first extragalactic large program approved for ALMA.   The major aim of that program was to conduct a blind search for molecular gas in the Hubble Ultra Deep Field by looking for CO rotational lines in ALMA bands 3 and 6, in addition to probing far-IR emission from dust in distant galaxies.

The goal of our proposal was to detect the [OIII] and Halpha emission lines from z~2-4 galaxies with MOSFIRE to obtain a precise determination of the systemic redshifts of the targeted galaxies.   With precise systemic redshift measurements, it becomes possible to look for very low S/N CO line emission from lower mass z~2-4 galaxies in the ALMA data and also to perform stacking studies.   At the same time, the line measurements allow us to probe other physical properties of distant galaxies, e.g., such as metallicities, star formation rates, velocity offsets, etc.   The new data should therefore be of use for Leindert in writing one or more scientific manuscripts and will add to the science that will be done with 10 hours of KMOS data we are obtaining on an overlapping samples of sources.

All in all, the success of this proposal is welcome news and just adds to the huge amount of success Leindert Boogaard has already enjoyed as a PhD student in Leiden.   Not only does Leindert already have an accepted Astronomy & Astrophysics manuscript on the galaxy star forming main sequence in lower-mass galaxies to z~1, but also Leindert was able to almost single-handedly write a successful ALMA proposal in his first year as a PhD student.

In just his first 2 years as a PhD student, Leindert now knows how to reduce and pursue science with MUSE, KMOS, HST grism, and ALMA data.   In addition, Leindert is now writing several of the central scientific manuscripts for the ASPECS project, working closely with Fabian Walter, Roberto Decarli, Manuel Aravena, and Jorge Gonzalez, and is increasingly internationally known.   Like my first student in Leiden Renske Smit, Leindert is showing  remarkable early potential to be a scientist at the highest levels, and it has truly been a pleasure to collaborate with Paul van der Werf on his supervision.   It is because of students like Leindert that being a professor (and other challenges) are truly worthwhile.