astronomy

GW170814

GW170814 is a astronomy topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand GW170814 rather than just read about it. In short: GW170814 was a gravitational wave signal from two merging black holes, detected by the LIGO and Virgo observatories on 14 August 2017. On 27 September 2017, the LIGO and Virgo collaborations announced the observation of the signal, the fourth confirmed event after GW150914, GW151226 and GW170104.

Key takeaways

GW170814 belongs to astronomy; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect GW170814 to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of GW170814 from memory before moving on to harder problems.

Reference excerpt

GW170814 was a gravitational wave signal from two merging black holes, detected by the LIGO and Virgo observatories on 14 August 2017. On 27 September 2017, the LIGO and Virgo collaborations announced the observation of the signal, the fourth confirmed event after GW150914, GW151226 and GW170104. It was the first binary black hole merger detected by LIGO and Virgo together.

Event detection

The signal was detected at 10:30:43 UTC. The Livingston detector was the first to receive the signal, followed by the Hanford detector 8 milliseconds later and Virgo received the signal 14 milliseconds after Livingston. The detection in all three detectors lead to a very accurate estimate of the position of the source, with a 90% credible region of just 60 deg2, a factor 20 times more accurate than before.

Astrophysical origin Analysis indicated the signal resulted from the inspiral and merger of a pair of black holes (BBH) with 30.5+5.7−3.0 and 25.3+2.8−4.2 times the mass of the Sun, at a distance of 540+130−210 megaparsecs (1.8+0.4−0.7 billion light years) from Earth. The resulting black hole had a mass of 53.2+3.2−2.5 solar masses, 2.7+0.4−0.3 solar masses having been radiated away as gravitational energy. The peak luminosity of GW170814 was 3.7+0.5−0.5×1049 W.

Implications for general relativity General relativity predicts that gravitational waves have a tensor-like (spin-2) polarization. The detection in all three detectors led to strong experimental evidence for pure tensor polarization over pure scalar or pure vector polarizations.

See also Gravitational-wave astronomy List of gravitational wave observations

References

External links GW170814 – FactSheet Archived 23 December 2019 at the Wayback Machine – LIGO GW170814 – Gravitational-waves observed by Virgo & LIGO on YouTube

Illustrations

Worked examples

Example 1 — a first encounter with GW170814

Start with the simplest possible case. Write down what GW170814 claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In astronomy, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to GW170814 before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about GW170814 ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of GW170814

In research: GW170814 appears in astronomy research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses GW170814 in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: GW170814 is common in secondary-school and first-year university syllabi. It links to neighbouring topics 2017 in outer space, 2017 in science, August 2017, so understanding it makes those chapters shorter.
In everyday life: Look for GW170814 outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study GW170814 in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what GW170814 means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain GW170814 out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is GW170814 in simple terms?

Why does GW170814 matter?

Because it connects several astronomy ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study GW170814?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on GW170814.