[\/vc_column_text]
Interested to join our group ?<\/h3>\n[vc_cta_button2 h2=”” h4=”PhD positions available in the field of X-ray and gamma-ray astronomy.” title=”Apply” link=”url:http%3A%2F%2Fwww.clemson.edu%2Fscience%2Fdepartments%2Fphysics-astro%2Facademics%2Fgraduate%2Fprospective.html||”][\/vc_cta_button2][vc_cta_button2 h2=”” h4=”Post-doc position available ” title=”Contact” link=”url:https%3A%2F%2Fscience.clemson.edu%2Fcosmicorigins%2Fcontact-info%2F|title:Contact%20me|”][\/vc_cta_button2][\/vc_column_inner][vc_column_inner width=”1\/3″]Interests<\/h2>\n- Evolution of massive black holes and galaxies<\/li>
- The Extragalactic Background Light<\/li>
- Very High-energy Sources<\/li>
- The Extragalactic Gamma-ray Background<\/li>
- The Cosmic X-ray Background<\/li>
- The MeV Background<\/li>
- High-energy Transients<\/li><\/ul>[\/vc_column_inner][\/vc_row_inner][\/vc_column][\/vc_row][vc_row][vc_column]
- \n\t\t\t\t
<\/i><\/div><\/div><\/div>Active Galactic Nuclei and Blazars<\/h3>
Every galaxy hosts at its center a massive, not always dormant, black hole<\/p><\/div><\/div><\/div>\n\t\t
\n\t\t\tNature has provided us with spectacular particle accelerators called active galactic nuclei, or AGN. These are galaxies that host tremendously large black holes at their centers, some of which are known to be a million times heavier than our sun. These distant celestial laboratories allow researchers to study physics at energies orders of magnitude greater than what can be generated by the most powerful manmade accelerators on Earth.<\/p>\n
The gravity in the vicinity of a black hole is so intense that even light cannot escape.\u00a0 Those black holes grow by swallowing, or “accreting” galactic gas from their vicinity, and can reach a mass equivalent to millions or even a billion times more than our Sun.\u00a0But before such gas falls into the black hole, it heats up, and can generate a vast amount of electromagnetic radiation:\u00a0 those are known as active galactic nuclei.\u00a0 In some cases, some modest fraction of the material falling onto the black hole is sent off away from the black hole, along the axis of its rotation, in a form of great outflows, or \u201cjets,” moving with speed\u00a0 close to the speed of light.\u00a0 Such jets produce additional radiation, usually seen as intense radio waves, X-rays, and gamma-rays.\u00a0 The most luminous of such active nuclei might vastly exceed all light produced by all ordinary stars in the entire galaxy – even though that light is generated in a region with a size comparable to our Solar system.<\/p>\n
Dr. Ajello and his group are heavily involved in the study of AGN and blazars. They try to answer questions like: how and when did they form ? what triggers their activity ? how do they evolve and finally what powers them ? To do so they rely on data from the\u00a0Fermi<\/em> Large Area Telescope (LAT), the\u00a0Swift<\/em> satellite and\u00a0NuSTAR.<\/em><\/p>\n\n\t\t<\/div> <\/li><\/ul>[\/vc_column][\/vc_row][vc_row][vc_column]- \n\t\t\t\t
<\/i><\/div><\/div><\/div>Very High Energy Sources<\/h3>
The cosmos is full of interesting astrophysical objects. Some of them are able to emit light that is 100 billion times more energetic than the Sun light. These are sources of very high energy photons. At Clemson we discover new ones and we study how their engines work.<\/p><\/div><\/div><\/div><\/li><\/ul>[\/vc_column][\/vc_row][vc_row][vc_column]
- \n\t\t\t\t
- Evolution of massive black holes and galaxies<\/li>
- The Extragalactic Background Light<\/li>
- Very High-energy Sources<\/li>
- The Extragalactic Gamma-ray Background<\/li>
- The Cosmic X-ray Background<\/li>
- The MeV Background<\/li>
- High-energy Transients<\/li><\/ul>[\/vc_column_inner][\/vc_row_inner][\/vc_column][\/vc_row][vc_row][vc_column]
- \n\t\t\t\t<\/i><\/div><\/div><\/div>
Active Galactic Nuclei and Blazars<\/h3>
Every galaxy hosts at its center a massive, not always dormant, black hole<\/p><\/div><\/div><\/div>\n\t\t
\n\t\t\tNature has provided us with spectacular particle accelerators called active galactic nuclei, or AGN. These are galaxies that host tremendously large black holes at their centers, some of which are known to be a million times heavier than our sun. These distant celestial laboratories allow researchers to study physics at energies orders of magnitude greater than what can be generated by the most powerful manmade accelerators on Earth.<\/p>\n
The gravity in the vicinity of a black hole is so intense that even light cannot escape.\u00a0 Those black holes grow by swallowing, or “accreting” galactic gas from their vicinity, and can reach a mass equivalent to millions or even a billion times more than our Sun.\u00a0But before such gas falls into the black hole, it heats up, and can generate a vast amount of electromagnetic radiation:\u00a0 those are known as active galactic nuclei.\u00a0 In some cases, some modest fraction of the material falling onto the black hole is sent off away from the black hole, along the axis of its rotation, in a form of great outflows, or \u201cjets,” moving with speed\u00a0 close to the speed of light.\u00a0 Such jets produce additional radiation, usually seen as intense radio waves, X-rays, and gamma-rays.\u00a0 The most luminous of such active nuclei might vastly exceed all light produced by all ordinary stars in the entire galaxy – even though that light is generated in a region with a size comparable to our Solar system.<\/p>\n
Dr. Ajello and his group are heavily involved in the study of AGN and blazars. They try to answer questions like: how and when did they form ? what triggers their activity ? how do they evolve and finally what powers them ? To do so they rely on data from the\u00a0Fermi<\/em> Large Area Telescope (LAT), the\u00a0Swift<\/em> satellite and\u00a0NuSTAR.<\/em><\/p>\n\n\t\t<\/div> <\/li><\/ul>[\/vc_column][\/vc_row][vc_row][vc_column]
- \n\t\t\t\t<\/i><\/div><\/div><\/div>
Very High Energy Sources<\/h3>
The cosmos is full of interesting astrophysical objects. Some of them are able to emit light that is 100 billion times more energetic than the Sun light. These are sources of very high energy photons. At Clemson we discover new ones and we study how their engines work.<\/p><\/div><\/div><\/div><\/li><\/ul>[\/vc_column][\/vc_row][vc_row][vc_column]
- \n\t\t\t\t