CH 24 Blackholes and Curved Spacetime (NOTES)

what forms an accretion disk around white dwarf

accretion of mass from a companion

white dwarfs gradually increases or decreases from mass

increases

what forms an accretion disk around white dwarf

accretion of mass from a companion

white dwarfs gradually increases or decreases from mass

increases

what happens when white dwarf mass is bigger thyan the Chandrasekhar limit

leads to white dwarf supernova explosion

how can you easily distinguish from supernova that results from a masive star's death

bc white dwarf supernova has no hydrogren lines and a different light curve

how can u map the expansion of the universe

by calculating distances of luminous stars to their galaxies

the rate of universe expansion is accelerating or depleating

accelerating

how is a ball of neutrons created

collapse of high mass stars iron core in a massive star supernova

are neutron stars more massive than the sun

yes, typically 10km in radius

what are neutron stars made of

are like giant atomic nuclei made almost entirely of neutrons and held together by gravity

what do neutron stars and white dwarfs have in common

can resist the crush of gravity with the degeneracy pressure tha arises when particles are packed as closely as nature allows

what are closely packed in order for neutron degeneracy pressure is supporting the star

neutrons

neutron stars are found in ...

binary systems

what do neutron stars produce

bursts of fusion as gas overflowing from a companion star creates accretion disk

what does infalling matter release

great amounts of gravitational potential energy

what happens if you drop a brick on a neutron star

it would explode like an atomic bomb

in regards to special relativity, how many ythings in the universe are absolute

2

in regards to special relativity, laws of nature are the same or different for everyone ???

same, observers moving through space at different speeds would disagree abt laws of physics

in regards to special relativity, the speed of light is same or different for everyone?

same, we expect speeds to add and substract

ex. if someone shined light from a moving car, wed see it at the speed of light no matter how fast the car is going

are there any accelerations in special relativity ???

no

are there any inertial frames in special relativity ???

yes

what does general relativity describe

geoemtric theory of gravitation

what did Einstein propose as the foundation of the theory of general relativity

equivalence principle

what does the equivalence principle state

there is no way that anyone or anything in a sealed environment can distinguish between free fall and absence of gravity

In regards to Michelson Morley Experiment, what is the incorrect idea

the earth orbits around the sun , it must run through the ether, causing either wind, w, near the earth' surface blowing in the opposite direction of the earth's motion, u

in regards to Michelson Morley Experiment, what is does it measure? what effects were observed?

the extra time it took a light beam to travel "there and back"

no effect whatsoever was observed

due to the consequences of equivalence principle. einstein concluded that we live in a ..?

curved spacetime

how did einstein conclude that we lived in a curved space time ?

due to the conequences of equivalence principle

what determines curvature of spacetime

distribution of matter

other objects (even light) must follow what when entering the a region of spacetime?

spacetime's curvature

why must light change its path near a massive object

because spacetime is bent by gravity and the beam of light from a distance star going past an object will get the same curve from spacetime

explain rubber sheet experiment

- stretch rubber on four post- ant is used to represent how light travels in a straight path (ant was trained to walk straight)- begin with rubber sheet and ant, simulating empty space with no mass in it and ant walks in straight line- add more mass using paperweight (representing white dwarf of neutron star) to rubber that distorts the sheet and creates a big depression in the sheet, ant's path is altered dramatically as it walks where the sheet takes it- relates to Einstein's theory: light always follows the shortest path through spacetime but the mass associated with large concentration of matter distorts spacetime, and the shortest, most direct paths are no longer straight lines, but are curves

calculate shift of moving star from the curvature of a light path

1.75 arcsec

test of general relativity ???????

predictions of general relatibity in weak gravitational fields agree with newton's law of gravity preduction

what does general relativity predict

the stronger the gravitational force, the more slowly time runs

are general relativity tests accurate

yes, proven to be very accurate

light or radiation emerging from a compact smaller remnant such as white dwarf or neutron star, a gravitational redshift is shown due to the slowing of time ???

how do i make this a question

where did black holes originally come from

curiosity whether the gravity of such an object could be so strong that nothing, not even light, could escape its gravitational pull

theories suggested stars with stellar cores are how much bigger compared to the sun. What happens?

stars w/ stellar cores are 3x more massive than the sun, that exhaust their nuclear fuel, and collapse to become black holes

what is event horizon

the surface surrounding a black hole where the escape velocity = speed of light

speed of escape velocity from the earth

11km/s

how do you raise escape velocity

compacting earth while keeping its mass raises the escape velocity

how do you make escape velocity reach the speed of light

squeezing the earth? down to the size of a golf ball

what is schwarzschild radius

the radius of the black hole surface

nothing can escape through the ______ in a black hole

event horizon

strong observational evidence for black holes are formed by what

supernovae that comes from studies of xray binaries

what does general relativity tell us about gravity ? what happens when gravity increases?

- gravity is a curvature of spacetime

- as gravity increases, the curvature gets larger

what are evidence for black holes

best evidence of stellar mass black holes comes from binary star systems in which:

1. one star of the pair is not visible

2. the flickering xray emission is characteristic of an accretion disk around a compact object

3. orbit and characteristics of the visible star indicate that the mass of its invisible companion is greater than 3MSun

what kinds of black holes are found in thecenter of large galaxies

black holes with masses of millions to billions of solar masses

what can emit strong xray radiation

accretion disks around neutron stars in close binary systems > makes xray binary

why do accretion disk form

the neutron stars strong gravity gravity pulls in mass from the companion star

what should the black hole in a close binary system be surrounded by

hot, xray emitting accretion disk

what can an xray binary contain

a black hole OR a neutron star

how can we learn which type of corpse an xray binary??? may have (either black hole or neutron star??)

meauring object's mass

what does general relativity predict

the rearrangement of matter in space should product gravitational waves

where were the existence of gravitational waves first confirmed

observations of a pulsar in orbit around another neutron star whose orbits were spiraling closer and losing energy in the form of gravitational waves

in 2015, how did LIGO find gravitational waves? what happened since then?

by detecting the signal produced by the merger of two stellar mass black holes, opening a new window on the universe

since then, many other gravitational waves signals have been found, signaling mergers of both black holes and neutron stars

what does kneck adaptive optics do

help improve the quality and clarity when taking pictures

what is Sagittarius A and what is it's solar mass?

- it is a black hole

- 4Msun

where are more massive black holes located

milky way

what was the first black hole photographed

M87 star