Finding AGN at high(er) redshifts
This paper describes a new diagnostic that separates galaxies from AGN at much higher redshifts than the traditional BPT diagram.
A New Class of Quasar?
In this paper, the authors describe a new class of quasar which pushes the boundaries of our current understanding of black hole physiology.
A zoo of dusty ellipticals provides evidence for merging galaxies
With the help of citizen science through Galaxy Zoo, this paper’s authors collect a large sample of dusty elliptical galaxies, which allows them to investigate the connection between gas-rich mergers, starbursts, and AGN activity.
Catching Galaxies in the Act: A Confirmed Dual AGN
While there are many examples of AGN pairs with relatively large separations, there are (including the object discussed in this paper) currently only six known closely separated pairs. Unless there are many more undiscovered closely separated AGN pairs, something must be seriously wrong with our theoretical understanding of galaxy mergers and black hole growth.
Simulating Galaxies for Fun and Profit
Title: Galaxy Formation with Self-consistently Modeled Stars and Massive Black Holes. I: Feedback-regulated Star Formation and Black Hole Growth Authors: Ji-Hoon Kim, John H. Wise, Marcelo A. Alvarez, Tom Abel First Author’s Institution: Kavli Institute for Particle Astrophysics and Cosmology; Stanford UniversityIn previous astrobites posts, we’ve talked about how black holes eat gas and the relationship between black hole growth and galaxy evolution. We know that galaxies and black holes grow during their evolution and that something must couple the growth of galaxies and black holes to produce the observed M-σ relation between the mass of supermassive black holes and the typical velocities in galactic bulges. Today, we’ll discuss a new attempt to understand the coupled growth of galaxies and supermassive black holes by directly simulating the growth of a high redshift disk galaxy and its central black hole.Using the cosmological hydrodynamics code enzo, the authors have come up with novel prescriptions for simulating the birth of stars and the feedback of black holes. In this simulation, molecular clouds form when gas cools and collapses. Molecular clouds in turn slowly convert a small fraction of their mass into stars, which can then explode in supernovae, supplying kinetic energy for turbulent gas motions. This is in contrast with previous simulations where gas is converted directly into stars and is more consistent with observations of star formation in the Milky Way and nearby galaxies.The black hole can ionize, heat, and exert forces on the gas in its surroundings via both radiation pressure and by ejecting a collimated jet. This is also a significant improvement compared to previous work in which only thermal feedback was included by dumping an...
When photons talk to each other
Photons do not normally talk to each other – but put GeV gamma-rays into a high enough background radiation field, and eventually one will break the ice.