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Measuring the Universe's Expansion through Fast Radio Bursts

Fast radio bursts may help clarify the Hubble constant and its discrepancies.

Tsung-Ching Yang, Tetsuya Hashimoto, Tzu-Yin Hsu, Tomotsugu Goto, Chih-Teng Ling, Simon C. -C. Ho, Amos Y. -A. Chen, Ece Kilerci

― 8 min read


FRBs and the Hubble FRBs and the Hubble Constant measurement discrepancies. New methods using FRBs tackle cosmic
Table of Contents

Measuring how fast the universe is expanding is pretty important for our understanding of the cosmos. This measurement is known as the Hubble Constant, and it tells us the rate at which galaxies are moving away from us. Think of it like watching a bunch of balloons being released into the sky. The faster they float away, the more quickly the universe is stretching.

However, figuring out this rate is not as simple as it sounds. Scientists have used different methods to measure the Hubble constant, but they’re not all lining up. It’s like trying to agree on the correct recipe for a cookie – everyone has their own version, and the results vary quite a bit!

Fast Radio Bursts: The Mysterious Signals

Enter fast radio bursts (FRBs). These are intense flashes of radio waves that come from far, far away in the universe. They are super brief, lasting only about a millisecond, but they pack a punch. When scientists first discovered them, they were scratching their heads, wondering what could cause such brilliant bursts of energy.

One key part of FRBs is something called the Dispersion Measure (DM). Imagine you’re trying to listen to a friend’s voice through a crowded café – the noise and chatter interfere with clarity. Similarly, DM tells us how much interference the FRBs have encountered on their way to us. By measuring DM, we can learn more about the journey of these signals.

The Hubble Mystery Deepens

Now, here’s where it gets really interesting. The Hubble constant has been measured in various ways, like through Cosmic Microwave Background (CMB) measurements and local distance ladders, but there's a noticeable difference between the results. This discrepancy has raised eyebrows among scientists.

When comparing two different methods, it turns out there’s a difference of about 4 to 6 percent between them. It’s similar to two chefs arguing over whether to add chocolate chips to their cookie recipes. One says it’s essential, while the other thinks it ruins the whole batch!

FRBs to the Rescue?

So, could FRBs provide a way to clear up the confusion? By using DM from FRBs, scientists can get a better estimate of the Hubble constant. However, there’s a catch: separating the contributions of DM from various sources is tricky. It’s like trying to pinpoint which ingredient made your cookie turn out delicious – was it the sugar or the dash of cinnamon?

To tackle this challenge, researchers devised a method that looks at how FRB pulses scatter as they pass through the plasma of their host galaxies. This scatter can give us valuable information about DM, hence leading to a more precise estimation of the Hubble constant. Think of it as figuring out that the secret ingredient in your friend’s legendary cookies is actually a pinch of salt – who would’ve thought?

Testing the New Method

The researchers decided to put their new method to the test. They created mock FRB data to see how their approach compared with older methods. After generating 100 mock FRBs, the results showed that their new method significantly improved the systematic error in measuring the Hubble constant.

In fact, it reduced that error by about 9 percent! This reduction is crucial in the context of the Hubble Tension. That’s what scientists call the discrepancy between different measurement methods. It’s like finally finding the perfect balance of ingredients in that tricky cookie recipe.

Real-world Applications

With their new method in hand, the researchers applied it to 30 actual localized FRB sources. They gathered data to constrain the Hubble constant and found a value of 74 km/s/Mpc. This means that, on average, for every megaparsec (a unit of distance) away a galaxy is, it’s moving away at a speed of 74 kilometers per second.

Interestingly, this value leans toward the measurements derived from local sources rather than the CMB. It’s like realizing that your neighbor’s cookie recipe is better than the one from the famous celebrity chef!

What This Means for the Future

As more localized FRBs are discovered, this method could help clarify discrepancies surrounding the Hubble constant. Future instruments and telescopes are expected to uncover many more FRBs, potentially shining a light on this cosmic conundrum.

Imagine having a giant cookie jar filled with diverse cookie recipes. Each new recipe could help you perfect your ultimate cookie, similar to how more FRB data could help scientists nail down the true value of the Hubble constant.

Conclusion: A Cosmic Cookie Recipe

The quest to understand the universe and its expansion rate using FRBs is like trying to master the perfect cookie recipe. With various methods available, each new finding adds another layer of insight. Scientists are hopeful that by tapping into the mysteries of FRBs, they can finally settle the debate over the Hubble constant.

So the next time you bite into a cookie, remember the cosmic connections: just like ingredients blending together to create a delicious treat, discoveries in the universe are piecing together a clearer picture of how our vast cosmos works. The Hubble constant may finally find its sweet spot!

More About Fast Radio Bursts

Let’s take a moment to learn more about these fast radio bursts. They come from billions of light-years away, making them a sort of cosmic Morse code. Imagine them as mysterious postcards, each telling a different story about the universe.

These bursts are extremely rare, appearing randomly. For every thousand cosmic events, only a handful are FRBs. Once detected, they can be studied to piece together the histories of their host galaxies. It’s like finding a rare collectible toy in a pile of old stuff, and it’s exciting!

How Do Scientists Measure FRBs?

Detecting and measuring FRBs requires powerful and sensitive telescopes. These telescopes listen for the radio waves and measure the time and frequency of the bursts.

When a burst is detected, scientists analyze its DM, which helps them understand the properties of the medium through which it traveled. This measurement gives clues about the structure of the universe. It’s like using a metal detector to find buried treasure – the more signals you get, the more you uncover!

The Role of Scattering

Scattering is a key factor when it comes to measuring DM. When FRBs pass through various materials in space, like plasma and gas, they scatter. This scattering causes the radio waves to spread out, which can alter their arrival time.

By measuring the scattering, scientists can better understand the density of the material the waves passed through. This is critical for accurately calculating the Hubble constant. It’s similar to how knowing the type of flour used in cookies can affect their texture and flavor.

Why Does It Matter?

Understanding the Hubble constant is crucial for numerous reasons. It helps astronomers learn about the universe's fate. Is it continuing to expand forever, or will it eventually slow down and collapse?

Moreover, a precise value for the Hubble constant can inform us about the universe's age. The more we find out, the better we can understand how we got here.

The Hubble Tension Explained

The Hubble tension refers to the discrepancy in measurements of the Hubble constant. This tension has sparked numerous discussions and investigations in the scientific community.

Scope for improvement is abundant, and scientists are constantly searching for new methods to measure the constant more accurately. Think of it as a rivalry between two chefs, each convinced their cookie recipe is better than the other’s.

FRBs: A New Path to Clarity

FRBs present an exciting opportunity to tackle the Hubble tension. They could serve as reliable cosmic markers, much like GPS coordinates help us navigate our world.

As we gather more FRB data, researchers anticipate decreasing uncertainties in measuring the Hubble constant. It’s like finally obtaining a crystal-clear cookie recipe that everyone can follow.

Future Prospects in Astronomy

With advanced telescopes and radio arrays coming online, the future looks bright for FRB research. Each new FRB discovered can help refine our calculations and enhance our understanding of the universe.

The journey of discovery is filled with challenges, but it’s also immensely rewarding. As more FRBs are found and analyzed, we slowly decode the mysteries of our universe. Each breakthrough acts like a sprinkle of happiness in the cosmic cookie jar!

The Importance of Collaboration

Just like baking cookies can be a group activity, astronomy often requires collaboration. Scientists from around the globe share their findings and work together to solve complex questions about the universe.

This collaborative spirit accelerates progress and leads to significant discoveries. It emphasizes the idea that the pursuit of knowledge is best achieved when we come together – much like friends gathering to create the perfect batch of cookies!

Conclusion: The Cosmic Recipe

As we look to the future, the potential of using FRBs to measure the Hubble constant is immense. The journey of understanding the universe is akin to perfecting a cookie recipe – a blend of ingredients leading to a delightful outcome.

Through persistence, teamwork, and innovative methods, scientists hope to gain a clearer view of our expanding universe. And just like that perfect cookie, we may finally bake up a solution for the Hubble tension!

Remember, every new FRB is a step closer to understanding the vast cosmos, with each discovery illuminating our path forward. The universe is like the ultimate cookie jar, waiting for us to uncover its delicious secrets!

Original Source

Title: Constraining the Hubble constant with scattering in host galaxies of fast radio bursts

Abstract: Measuring the Hubble constant (H$_0$) is one of the most important missions in astronomy. Nevertheless, recent studies exhibit differences between the employed methods. Fast radio bursts (FRBs) are coherent radio transients with large dispersion measures (DM) with a duration of milliseconds. DM$_{\rm IGM}$, DM in the intergalactic medium (IGM), could open a new avenue for probing H$_0$. However, it has been challenging to separate DM contributions from different components (i.e., the IGM and the host galaxy plasma), and this hampers the accurate measurements of DM$_{\rm IGM}$ and hence H$_0$. We adopted a method to overcome this problem by using the temporal scattering of the FRB pulses due to the propagation effect through the host galaxy plasma (scattering time). The scattering-inferred DM in a host galaxy improves the estimate of DM$_{\rm IGM}$, which in turn leads to a better constraint on H$_0$. In previous studies, a certain value or distribution has conventionally been assumed of the dispersion measure in host galaxies (DM$_{\rm h}$). We compared this method with ours by generating 100 mock FRBs, and we found that our method reduces the systematic (statistical) error of H$_0$ by 9.1% (1%) compared to the previous method. We applied our method to 30 localized FRB sources with both scattering and spectroscopic redshift measurements to constrain H$_0$. Our result is H$_0$=74$_{-7.2}^{+7.5}$ km s$^{-1}$ Mpc$^{-1}$, where the central value prefers the value obtained from local measurements over the cosmic microwave background. We also measured DM$_{\rm h}$ with a median value of $103^{+68}_{-48}$ pc cm$^{-3}$. The reduction in systematic error is comparable to the Hubble tension ($\sim10$%). Combined with the fact that more localized FRBs will become available, our result indicates that our method can be used to address the Hubble tension using future FRB samples.

Authors: Tsung-Ching Yang, Tetsuya Hashimoto, Tzu-Yin Hsu, Tomotsugu Goto, Chih-Teng Ling, Simon C. -C. Ho, Amos Y. -A. Chen, Ece Kilerci

Last Update: 2024-11-04 00:00:00

Language: English

Source URL: https://arxiv.org/abs/2411.02249

Source PDF: https://arxiv.org/pdf/2411.02249

Licence: https://creativecommons.org/licenses/by/4.0/

Changes: This summary was created with assistance from AI and may have inaccuracies. For accurate information, please refer to the original source documents linked here.

Thank you to arxiv for use of its open access interoperability.

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