Alexander Harvey Nitz

A photo of some slides being presented at a scientific conference.

Looking for multiband gravitational-wave sources in #LISA data - a needle in a haystack problem!
Shichao Wu presented a search for stellar origin binary black hole signals in LISA & next generation ground-based detectors (LISA+3G) with pyCBC.
#GR26Amaldi16
Find out more: arxiv.org/abs/2506.01898

YouTube video by Syracuse Gravity Gravitational Wave Timeline of Observations

In honor of the 10th anniversary of observing gravitational waves, I assembled this little video showing the observations over time. Come give a listen to the sound of the Universe!

www.youtube.com/watch?v=z7t8...

One can infer a bit about the masses of the black hole and neutron star already. The chirp mass would be something near ~ 1.96 solar masses. That's a particular combination of the two object masses, so if the NS were 1.4 solar masses that would mean the black hole is ~ 3.8 solar masses.

The localization of this event is somewhat large and it is over a billion light years away. However, the mass of this merger might allow for the neutron star to be torn apart and produce detectable light.

Fun gravitational-wave news!

An neutron star - black hole merger was potentially just observed! ⚫⚪ The false alarm rate is ~ 1 per 25 years, so this will need further investigation. With luck, there may be electromagnetic emission from the collision.

gracedb.ligo.org/superevents/...

Interested in a postdoctoral position helping to design the next-generation of US gravitational-wave observatories? There is still time to apply! Please consider doing so or share with someone who may be interested.

www.sujobopps.com/postings/107...

Yes, absolutely! He's retired now, but he was the senior faculty of the group at Syracuse when I was a PhD student.

Congratulations!

Postdoctoral Scholar - Gravitational Wave Detector Design The Physics Department at Syracuse University invites applications for a postdoctoral position to work on the design of the Open Control and Analysis Architecture for Cosmic Explorer, the planned U.S....

We are hiring! Work on the design of the Open Control and Analysis Architecture for Cosmic Explorer, the U.S. next-generation gravitational-wave observatory. Candidates will be considered at the postdoctoral level or as research assistant professor with suitable experience.

tinyurl.com/5n8t6n7y

So CE/ET, LISA, and PTAs will be sensitive to different types of sources (or in different parts of their evolution), but CE/ET will be an order of magnitude (or more) more sensitive than current LIGO/Virgo.

How does this related to say LISA or pulsar timing? Both of these use arm lengths much longer than ground-based observatories. However, their ability to measure displacements is actually *much* worse. LISA's design will be sensitive to 10^-4 -> 10^-1 H, while Pulsar timing focusing on ~ 10^-8 Hz.

In many ways a CE facility is endgame for gravitational-wave astronomy on the ground. There is the potential for upgrading the detectors within the facilities, but there would likely not be an effort for an even larger observatory on the ground.

You can't build much longer than 40km (say 400 km) on the earth due to civil engineering problems (we need actually arms not following earth curvature) and issues with designing and controlling a cavity. The returns would not be as high as you'd hope even if you could solve the engineering issues.

Ground based detectors because they are fixed in place, use resonant cavities for their arms to store the laser light. This increases the "effective" arm length by orders of magnitude (or conversely allows them to measure very small displacements because they average the measurement of many photons)

If you could ignore all other considerations, longer arms are better because the gravitational wave causes a larger displacement, however, in practice you can't ignore how you actually measure this displacement itself.

Great question with a lot to unpack. The short answer is that what matters is the combination of measurement method/technology + arm length. CE is the sweet spot for what you can build on the Earth and will have strictly better sensitivity than current ground based detectors at all frequencies.

Interested in the future of gravitational-wave astronomy?

Cosmic Explorer, the proposed US 40 km gravitational-wave observatories will observe millions of compact-binary mergers throughout the Universe and cosmic time.

CE will hopefully be joined by the Einstein Telescope and space-based LISA.

I guess all the scientists are moving over here? I don't really talk about much besides science.

Look out for updates on gravitational waves from me and my fantastic students. We study neutron stars and black holes with LIGO and are building tools for Cosmic Explorer and LISA.

First Targeted Search for Gravitational Waves from Highly Spinning... Searches for gravitational waves from compact-binary mergers, which to date have reported nearly 100 observations, have previously ignored binaries whose components are both light ($< 2 M_\odot$)...

What if there are highly spinning solar-mass scale binaries?

We report a search for gravitational waves from these unusual binaries, which might include unusual neutron stars, quark stars, hierarchical merger of primordial black holes, or other exotic scenarios.

arxiv.org/abs/2308.16173

Then what do we call the sum of everything else?