HXMT Telescope Satellite——The Smartest "Eyes" in Space

Recently, my country's Insight-HXMT team discovered a cyclotron absorption line with an energy of up to 146 keV in a neutron star X-ray binary numbered Swift J0243.6+6124, and the corresponding neutron star surface magnetic field strength exceeds 1.6 billion Tesla. Scientists said that this is the second time that the Insight-HXMT satellite has significantly refreshed the world record for the highest energy cyclotron absorption line and the direct measurement of the strongest magnetic field in the universe, following the direct measurement of the strongest magnetic field in the universe of about 1 billion Tesla in 2020.

Artistic image of the Insight-HXMT satellite observing an accreting pulsar

(Image source: Institute of High Energy Physics, Chinese Academy of Sciences)

Why did the Insight-HXMT satellite break the world record? Why did we build it? What are its features and breakthroughs compared with other astronomical satellites? Let's go and find out today.

1. What is the Insight-HXMT satellite?

In order to study the basic physical properties of high-energy compact objects such as black holes and neutron stars and their impact on the surrounding space and time, the Institute of High Energy Physics of the Chinese Academy of Sciences and the Fifth Academy of China Aerospace Science and Technology Corporation developed my country's first space X-ray astronomical satellite, the Insight Hard X-ray Modulation Telescope (HXMT) satellite. This is China's first space X-ray astronomical satellite, which was launched on June 15, 2017.

HXMT launch site (Photo source: Insight—HXMT)

It is mainly composed of a satellite platform and a payload, with a total weight of about 2,500 kg, and will operate in a near-Earth circular orbit at an altitude of 550 kilometers and an inclination of 43 degrees. It carries three space telescopes, including a high-energy X-ray telescope, a medium-energy X-ray telescope, and a low-energy X-ray telescope.

2. Why build the Insight-HXMT satellite?

Space telescopes have actually opened up a window for human beings to explore the universe. After opening up this field, humans have launched various astronomical satellites, including the Hubble satellite that we are very familiar with. As a major space power, China hopes to use its own strength to promote science in the field of aerospace and conduct basic research in space. The Insight Hard X-ray Modulation Telescope (HXMT) satellite came into being and became a breakthrough for Chinese people to explore the universe.

Hubble Telescope (Image credit: NASA)

In the universe, when matter is captured by the gravity of a dense celestial body, it will fall toward the central celestial body in a spiral motion, with increasing speed and temperature, and finally emit strong hard X-rays with higher energy than ordinary X-rays. Although X-rays have strong penetrating power, they cannot penetrate the Earth's atmosphere, so we must go outside the Earth's atmosphere to detect X-rays from celestial bodies.

The purpose of the HXMT satellite is to receive X-rays from celestial bodies, which can be neutron stars or black holes. Scientists hope to find black holes and neutron stars that have not yet been discovered, and at the same time, observe and study the known ones, so as to expand our knowledge of black holes and neutron stars.

3. What are the strengths of the Insight-HXMT satellite?

The Hard X-ray Modulation Telescope (HXMT) satellite has obvious comprehensive advantages in terms of energy coverage, detection area and energy resolution . It will provide a large amount of high-quality observation data for scientists at home and abroad, enabling China to reach the international advanced level in the fields of high-sensitivity rapid surveys of large sky areas, research on rapid light variations of hard X-rays of celestial bodies such as black holes and neutron stars, and monitoring of violent high-energy explosion phenomena.

1. Wide energy coverage area. First of all, the X-ray instrument has a relatively wide coverage range, from 1kev to about 300kev, which is basically 300 times the energy coverage range. If we add the detection capability of gamma-ray bursts, up to 3000kev, the coverage range will be 3000 times. There are very few satellites that can have such a wide photon coverage range.

2. The instrument has a large geometric area. For example, the geometric area of ​​the high-energy instrument reaches 5,000 square centimeters, which is the largest area in this energy range.

3. The telescope has a wide field of view. For example, we will conduct very high statistical and high-band studies on neutron stars and black holes, which is difficult to do with previous astronomical telescopes or X-ray telescopes. Since the field of view is relatively wide and the area is relatively large, we will be more sensitive to some weaker source changes in the Milky Way, so we will survey the Milky Way to search for such faint objects that change over time. This is very important for our understanding of neutron stars and black holes in the Milky Way, and is suitable for astrophysical research.

Compared with foreign X-ray satellites, the Insight-HXMT satellite has advantages in many of the above aspects. It has opened a new window for observing the rapid light changes and energy spectrum of black holes and neutron stars. At the same time, we also hope that there will be more unexpected gains in the subsequent scientific research, and we look forward to HXMT bringing us more unexpected surprises.

Produced by: Science Popularization China

Author: China Science Expo

Producer: China Science Expo