The X-ray Universe Sarah Bank Presented July 22, 2004

Overview X-ray Production Mechanisms X-ray Production Mechanisms The Sun (in brief) The Sun (in brief) The Main Features The Main Features Supernovae (SNe), Supernova Remnants (SNRs), and Superbubbles Supernovae (SNe), Supernova Remnants (SNRs), and Superbubbles Active Galactic Nulcei Active Galactic Nulcei

X-ray Sources The three main sources of astrophysical x-rays The three main sources of astrophysical x-rays Thermal - bremsstrahlung and line emission Thermal - bremsstrahlung and line emission Synchrotron radiation from relativistic electrons Synchrotron radiation from relativistic electrons Inverse Compton Scattering Inverse Compton Scattering

Thermal Bremsstrahlung Thermal bremsstrahlung or free-free emission occurs when an e - is accelerated due to the strong electrical attraction of a positive ion in a plasma. Thermal bremsstrahlung or free-free emission occurs when an e - is accelerated due to the strong electrical attraction of a positive ion in a plasma. Temperatures above 10 5 K are necessary. Temperatures above 10 5 K are necessary.

Line Emission Heavy elements, not fully ionized, can have inner electrons collisionally excited to higher energy levels. Upon decay they emit an X-ray. Heavy elements, not fully ionized, can have inner electrons collisionally excited to higher energy levels. Upon decay they emit an X-ray.

Synchrotron/Relativistic e - Charged particles in a magnetic field are accelerated around field lines releasing radiation. Charged particles in a magnetic field are accelerated around field lines releasing radiation. If the particle is relativistic the radiation undergoes ‘beaming’ and the maximum E photon is then proportional to the field strength and inversely proportional to the particle’s momentum. If the particle is relativistic the radiation undergoes ‘beaming’ and the maximum E photon is then proportional to the field strength and inversely proportional to the particle’s momentum.

Inverse Compton Scattering A relativistic e - colliding with a low energy photon can impart energy resulting in an X- ray. A relativistic e - colliding with a low energy photon can impart energy resulting in an X- ray. Seen in SNe and AGN. Seen in SNe and AGN.

The Sun Turbulence in the convection zone amplifies magnetic fields to create loops conducting electric currents, thus heating the solar corona to X-ray temperatures. Turbulence in the convection zone amplifies magnetic fields to create loops conducting electric currents, thus heating the solar corona to X-ray temperatures. Solar Photosphere ≈ 6000K Solar Corona ≈ 10 6 K Charles & Seward, Exploring the X-ray Universe. Cambridge U. Press, Great Britain©1995

Solar Flare/Loop

The Main Features

The 1/4 keV (McCammon,D. et al. (Sept. 2002) ApJ. v.576, no.1,pt.1 p )

The 3/4 keV (McCammon,D. et al. (Sept. 2002) ApJ. v.576, no.1,pt.1 p )

The Features The Lockman Hole: a region where absorbing material, HI and dust, are sparse The Lockman Hole: a region where absorbing material, HI and dust, are sparse Draco Cloud: enhanced soft X-ray region due to a molecular cloud falling into the plane of the Galaxy Draco Cloud: enhanced soft X-ray region due to a molecular cloud falling into the plane of the Galaxy Cygnus Superbubble/Loop: nearby superbubble from the explosion of many Sne, 14 times the size (at 400 pc in diameter) of the Cynus Loop, a 20,000 year old SNR emitting thermal bremsstrahlung as soft x-rays. Cygnus Superbubble/Loop: nearby superbubble from the explosion of many Sne, 14 times the size (at 400 pc in diameter) of the Cynus Loop, a 20,000 year old SNR emitting thermal bremsstrahlung as soft x-rays. North Polar Spur (NPS)/Loop 1: The NPS is a bright region of the Loop 1 superbubble, a well- known radio feature. North Polar Spur (NPS)/Loop 1: The NPS is a bright region of the Loop 1 superbubble, a well- known radio feature.

More Features The Virgo Cluster: the cluster of galaxies at the center of the local supercluster The Virgo Cluster: the cluster of galaxies at the center of the local supercluster Galactic Bulge: not well understood, but definitely consists of some component beyond the NPS Galactic Bulge: not well understood, but definitely consists of some component beyond the NPS LMC: a nearby dwarf irregular galaxy LMC: a nearby dwarf irregular galaxy Vela/Puppis SNRs: Vela SNR ~ 1,500 ly away, 11,000 y old and 230 ly in diameter; whereas Puppis, superimposed on the Vela remnant is ~4 times farther away, but the brightest X-ray source between 0.5 and 1 keV Vela/Puppis SNRs: Vela SNR ~ 1,500 ly away, 11,000 y old and 230 ly in diameter; whereas Puppis, superimposed on the Vela remnant is ~4 times farther away, but the brightest X-ray source between 0.5 and 1 keV

Vela and Puppis

More Features Eridanus Enhancement: from the Orion superbubble, ~1200 ly across, being energized by stars in the Orion OB1 association Eridanus Enhancement: from the Orion superbubble, ~1200 ly across, being energized by stars in the Orion OB1 association Monogem Ring: a SNR in a low density region of the Galaxy, thus evolved into a low surface-brightness remnant Monogem Ring: a SNR in a low density region of the Galaxy, thus evolved into a low surface-brightness remnant The Crab: a SNR recorded in 1054 and now observed to contain a 33 ms pulsar The Crab: a SNR recorded in 1054 and now observed to contain a 33 ms pulsar

Supernova Remnants Type 1: mass transfer onto a white dwarf from a binary companion resulting in accretion beyond the Chandrasekhar limit. Type 1: mass transfer onto a white dwarf from a binary companion resulting in accretion beyond the Chandrasekhar limit. Type 2: core collapse of a massive star (~10 M solar ) that has formed an iron core. Type 2: core collapse of a massive star (~10 M solar ) that has formed an iron core. Most profuse X-ray emission during phases 1 & 2. Most profuse X-ray emission during phases 1 & 2. Thermal x-rays via line emission or bremsstrahlung. Thermal x-rays via line emission or bremsstrahlung. Charles & Seward, Exploring the X-ray Universe. Cambridge U. Press, Great Britain©1995

Superbubbles SN - Star Formation - SNe - Superbubble SN - Star Formation - SNe - Superbubble Not created by a single “super-supernova,” but by many such events over time. Not created by a single “super-supernova,” but by many such events over time. Dynamite vs. Digger analogy Dynamite vs. Digger analogy Charles & Seward, Exploring the X-ray Universe. Cambridge U. Press, Great Britain©1995

Active Galactic Nuclei The super massive Black Holes (BHs) at the centers of galaxies, actively accrete gas from the ISM, cannibalized galaxies, nearby stars. The super massive Black Holes (BHs) at the centers of galaxies, actively accrete gas from the ISM, cannibalized galaxies, nearby stars. An accretion disk forms, heating the material, as well as jets of relativistic matter at the poles of the MBH. An accretion disk forms, heating the material, as well as jets of relativistic matter at the poles of the MBH.