“Astronomy compels the soul to look upward, and leads us from this world to another,,

Plato

Welcome to my website!

My name is Ilaria Caiazzo and I am an astrophysicist. I am a Burke Prize Fellow at the California Institute of Technology, in Pasadena. I am a theorist, and I am interested in stars, in their lives and in their afterlives. I am interested in stellar evolution and dynamics, in particular in star clusters, and in the remnants of stellar deaths: white dwarfs, neutron stars and black holes. In my research page you can find more about my projects. See the latest research news below.

I am also a writer and movie producer. The latest movie I produced, The Recycling Man, is currently screening at several festivals. If you are interested, you can watch it on YouTube (link at the bottom of the page). You can also see our progress at The Recycling Man Facebook page, with all the latest news.

Latest News

Magnetars are neutron stars with ultrastrong magnetic fields, which can be observed in x-rays. Polarization measurements could provide information on their magnetic fields and surface properties. We observed polarized x-rays from the magnetar 4U 0142+61 using the Imaging X-ray Polarimetry Explorer and found a linear polarization degree of 13.5 ± 0.8% averaged over the 2– to 8–kilo–electron volt band. The polarization changes with energy: The degree is 15.0 ± 1.0% at 2 to 4 kilo–electron volts, drops below the instrumental sensitivity ~4 to 5 kilo–electron volts, and rises to 35.2 ± 7.1% at 5.5 to 8 kilo–electron volts. The polarization angle also changes by 90° at ~4 to 5 kilo–electron volts. These results are consistent with a model in which thermal radiation from the magnetar surface is reprocessed by scattering off charged particles in the magnetosphere.

You can see the paper here.

JWST observed 47 Tucanae, one of the richest and most carefully observed clusters in our Galaxy, for our program “Brown Dwarfs, White Dwarfs and Planetary Disks in an Ancient Stellar System” and the images are beautiful. The goal is to observe for the first time the cooling brown-dwarf sequence in the cluster and to hunt for ancient planetary systems around white dwarfs.

You can see the abstract here and the full list of approved programs for Cycle 1 here.

The first IXPE observations are coming in and they are beautiful!

At the IXPE splinter session at the summer AAS in Pasadena, members of the IXPE collaboration presented the first result of IXPE. I was invited to present the first observations of  the accreting X-ray pulsar Hercules X-1.

The Imaging X-ray Polarimetry Explorer was launched on December 9th from the Kennedy Space Center in Florida at 1 a.m. Eastern. The launch was just picture perfect! Congratulations to the team!
You can watch a replay here. And here is an article on the launch from the New York Times, for which I was interviewed.

IXPE will open a new window on the Universe: for the first time, we will be able to study the polarization of X-ray light coming from the densest and hottest places of all, neutron stars and black holes. With my collaborators, we developed theoretical models for the polarization of magnetars and of X-ray pulsars, and I look forward to be able to test them with real data:
Probing magnetar emission mechanisms with spectropolarimetry
Polarization of accreting X-ray pulsars. I. A new model
Polarization of accreting X-ray pulsars – II. Hercules X-1

We recently submitted to the arXiv several papers connected to our search for massive white dwarfs in open clusters. Our goal is to find massive white dwarfs close to the maximum limit, or Chandrasekhar limit, to understand the relation between the mass of the progenitor star and the final mass of the white dwarf (initial-final mass relation) and find the maximum mass for a star to produce a white dwarf (and not explode in a supernova). And we are finding the most massive white dwarfs known in clusters with the most massive progenitor stars!

In order to find white dwarfs that escaped from the clusters, we also developed a method to find members that escaped in the past and reconstruct the history of open clusters using the European mission Gaia.

Reconstructing the Pleiades with Gaia EDR3
Reconstructing Nearby Young Clusters with Gaia EDR3
The Ultramassive White Dwarfs of the Alpha Persei Cluster

Our proposed program on the Hubble Space Telescope, called “The radius and magnetic field structure of the smallest white dwarf”, has been awarded 10 obits. We will observe the extreme white dwarf ZTF J1901+1458 with UV spectroscopy to understand its unusual properties.

You can find the list of approved programs for Cycle 29 here.
Using the Zwicky Transient Facility, we discovered a white dwarf, ZTF J1901+1458, that is extreme in every regard: it shows a rotation period of 7 minutes, one of the shortest among isolated white dwarfs, a magnetic field of roughly 800 megaGauss (more than a billion times the magnetic field of the Earth), and a stellar radius of 2100 km, close to that of the moon (usually white dwarfs are much larger, with radii similar to that of the Earth). Such a small radius implies that the white dwarf’s mass is the closest ever detected to the maximum mass for a white dwarf. In fact, the white dwarf is so dense that, as it cools and its composition stratifies, it may become unstable and collapse due to electron capture, exploding into a thermonuclear supernova or collapsing into a neutron star.

We published our discovery on the journal Nature: A highly magnetized and rapidly rotating white dwarf as small as the Moon. The discovery has been widely reported in the press around the world and I’m listing here just a few articles: Forbes, NBC News, Smithsonian Magazine, CBC News, India Today, News Fr-24, El Mundo, DailyMail, Reuters, La Repubblica.

The popular YouTube Channel PBS Spacetime dedicated an episode to the white dwarf.
You can see it here.

Our proposed JWST program, with the title “Brown Dwarfs, White Dwarfs and Planetary Disks in an Ancient Stellar System”, has been awarded 20.6 hours of telescope time. We will observe the globular cluster 47 Tucanae, one of the richest and most carefully observed clusters in our Galaxy, to observe for the first time the cooling brown-dwarf sequence and to hunt for ancient planetary systems around white dwarfs.

You can see the abstract here and the full list of approved programs for Cycle 1 here.

The Recycling Man

Here is The Recycling Man, the latest short film that I produced. Enjoy!
(It’s 13 minutes long and not suitable for children, click settings for HQ)