Frequently Asked Questions


Quick links: [ About our group || About the PI ]

About our group (and about being a student/postdoc in cosmology)

How long is a typical Ph.D. in your group?

The mode is 5 years; our experience is that this is enough time for a student to participate in several projects and become a proficient researcher by the time they apply for their next position (in the fall of the 5th year). Under some circumstances a 6th year may be warranted (including unexpected issues with projects, a unique opportunity where it makes sense to spend an extra year here, or personal reasons). Some students with substantial prior experience may complete the program in 4 years.

What are your group's former students and postdocs doing now? Of the 8 former students for whom I have been the primary advisor (Ph.D. years 2011 to present):

Of the 6 former postdoctoral scholars for whom I have been the primary mentor:

How often do you have regular meetings? What should I come to?

Every week, we have joint group meetings with David Weinberg's group (in astronomy), which is used for general updates and discussions with visitors. There is also a weekly cosmology paper discussion (with participants from other parts of CCAPP), which is sometimes more general but also can get into technical details if they are important for working in large-scale structure. We also have a weekly WFIRST-focused meeting.

Group members should come to a reasonable fraction of these meetings and the Tuesday CCAPP seminars -- they are an essential part of the training experience, but this needs to be balanced against the investment of time (coming to everything can add up). Interested first-year students may come to a few events to learn about what life is like in our group. More advanced students and postdocs will make an assessment of which events are most useful, and may increase or decrease their participation depending on other responsibilities (e.g., project or job applications). It is important for your intellectual development and breadth to attend each of the group events at least occasionally.

Do I need to take particular courses before starting a research project in your group?

We don't have a specific list -- if you did your undergraduate studies and are coming to OSU for graduate school, you have taken enough courses to get started in research. Almost always, students getting started in a research project find that they need to draw on some knowledge that wasn't covered in their classes. That is normal, it simply means that your research project is an opportunity to learn.

More advanced graduate courses such as general relativity, quantum field theory, or special topics classes are important for some sub-areas of our research. If you work in my group and haven't studied these subjects, you are encouraged to take a few of these classes -- but in parallel to, not before, your first research project. As a graduate student, you should start a research project no later than the end of your first year.

What programming languages and tools does your group use?

The majority of our projects are in C or Python (sometimes we use Perl wrappers). Many projects use Github repositories.

If you are not familiar with some of these tools, that's okay -- you are here to learn!

How much writing will I be doing if I join your group?

Writing is one of the most important activities in any research group. You need to write in order to:

I recommend starting to write near the beginning of a project, rather than at the end. This both maximizes the benefit to you (you will better understand the motivation for the project -- and hence your choices when you get into the details -- if you have been writing the introduction), and will give you a longer time window to improve your writing skills.

The most important aspect of writing is organizational -- taking all of your material and turning it into a sequence of individual elements (sentences, plots, etc.) that another human can absorb. The details differ by medium and audience (e.g., research paper, conference talk, status update for a project, etc.) but the underlying principle is the same.

If English is not your first language and you do not yet feel comfortable writing in English, then for your first paper other group members (including me) should be able to help out with grammar and sentence construction.

How often do your group members travel?

This varies. Students will typically go to a conference or summer school 1-2 times per year, as well as a job tour the fall of their final year. Postdocs will go to more. If you have a key role in a large collaboration, you will likely have to travel more often for working group meetings. Some collaborations (particularly WFIRST) have emphasized remote participation where possible and the travel needs are lower.

I understand that travel, especially to more distant locations, has a substantial impact on your time and your carbon footprint. There is an additional burden if you have family responsibilities or your destination requires a visa. If in doubt, you should discuss with me (and maybe your colleagues) what meetings are most useful for you to attend.

Normally, we will pay for student travel directly from our grants and budget this on a case-by-case basis. Postdocs are granted a research budget in their offer letter, which can be used for travel to conferences in addition to other expenses. If you have collaboration responsibilities that require frequent international travel, such that your travel budget will exceed the usual expectations for your career stage, then we should set aside a specific budget for that travel and identify an appropriate funding source.

Can (or should) I collaborate with other professors during my time at OSU?

Absolutely yes -- for at least two reasons:

  1. Working with another professor or group is an excellent way to experience another mode of doing research and learn something that I may not know or be able to teach you. You will have responsibilities in my group (so please make sure to communicate with me to avoid over-commitments), but your main reason for being at a university should be to learn and grow. This will also help you to develop research directions that are not continuations of my program.
  2. When you apply for your next position, you will need letters of recommendation. If you apply for a postdoc in academia, 3 is standard, and when you get to the faculty level there will be more. That means you want at least 2 additional letters (either from OSU, or someone else in a collaboration, or both) that can attest to what it is like working with you. The principle here is more general than letters: you want to be able to count on the support of more than one senior researcher.

What if I want to do pure theory and am not interested in data and statistics?

I have mixed feelings about this, because theory and observation are more interconnected than ever before.

Theories in cosmology are usually tested by forward modeling. A typical sequence is: we take a fundamental model (say, a Lagrangian for a scalar field model of dark energy); we derive the equations of motion; then we generate simulations of the Universe using those equations of motion; we project those simulations into what we would see on the sky; we simulate how the telescope and instrument see that sky; we run these simulations through the real data processing pipeline; and then we compare the statistical properties of the outputs to what we get from the real data. There are many variations in the implementation, but the point is that "theorists" are needed at all of these steps. It is important for junior theorists to develop expertise across a range of these areas, and I aim to build a group environment where this is the norm. More generally, experience with large data sets will open career opportunities for you (both in astrophysics and other fields).

It may happen while you are here that you find a specific opportunity in pure theory that you want to pursue as the majority of your Ph.D. thesis. If this happens then by all means you should pursue it! But you shouldn't do this as a way of avoiding dealing with "messy" data.

What are the funding sources for your group?

We are currently receiving or have received support from the federal government (NASA, the National Science Foundation, and the Department of Energy), and from private foundations (currently the Simons Foundation; previously this included the Sloan and Packard Foundations).


About the PI

[under construction]