Quasar - especially powerful
and distant active nucleus
galaxies. English
the term quasar is formed
from words quasistellar
("quasi-stellar" or "star-like") and
radio source
("radio source") and
literally means
"quasi-stellar
radio source. Quasars are one of
brightest objects in
Universe - them
radiation power
sometimes tens and hundreds
times the total power
all the stars are
galaxies like ours.
Traces of parental
galaxies around quasars
(and far from all) were found only
later. First
queue quasars were
identified as objects with
big red
displacement, having electromagnetic
radiation (including
radio waves and visible
light) and so small
angular dimensions, which
for several years after their discovery
could be distinguished from
"point sources"
- stars (on the contrary,
extended springs
more like galaxies). By their own
these properties
pseudostellar
radio sources are similar
to active nuclei
galaxies. Many astrophysicists believe that
the luminosity of these
objects
not supported
thermonuclear way.
The energy of quasars is gravitational energy,
which stands out for
catastrophic
compression that takes place in
the core of the galaxy. In addition to modern
definitions,
there was also
original: "Quasar
- celestial class
objects that are in the optical range
like a star, but
having a strong
radio emission and
extremely small
angular dimensions (less than 10″)”.
Initial
definition has developed
late 1950s, early
the 1960s when they were
the first quasars were discovered and their study is only
began. And in this
definition is nothing
wrong, for
exception
next fact. As it turned out, as
for 2004 powerful
radio emission have
maximum 10% of quasars.
And the other 90% don't.
emit strong radio waves. Such
astronomers objects
called
radio quiet
quasars. What are the largest quasars
popular on
present day
uses the hypothesis
according to which the quasar
is the largest black hole
draws in
surrounding
space. As
approaching black
hole, the particles accelerate,
clash between
itself - and this leads to
the most powerful
radio emission. If
black hole also has a magnetic field, then it
collects
particles into bundles
called jets.
that fly away from
poles. In other words, that radiance
which is observed
astronomers are all
remains of the galaxy
dead in a black hole.
According to other versions, quasars are young
galaxy, process
birth
which we are observing.
Some of the scientists
suggest that, yes, a quasar is a young
galaxy, but
devoured by a black hole.

Simply put, a billion years is not enough for something to become this big. "It's as weird as seeing a bunch of eggs that are bigger than the hen that laid them," Gezari says. We see a lot of supermassive black holes, but not enough time to get through them. They must have had very large seeds.

Just as a water main has a maximum capacity and therefore can only carry a certain amount of water per second, all black holes have a built-in "speed limit" that determines how fast they can collect matter. Sir Arthur Stanley Eddington first described this limit in the context of massive stars, long before black holes were finally known, but the concept applies to any body that exerts a strong gravitational field.

Whatever it was,
astrophysicists are very closely
bind
the existence of quasars
and the fate of galaxies.
The first quasar, 3C 48, was discovered at the end
1950s by Alan
Sandage and Thomas
Matthews during
radio survey of the sky. In 1963
5 quasars were already known. In the same
dutch
astronomer Martin Schmidt
proved that the lines
spectra of quasars
heavily redshifted.
Taking what it is
redshift
caused by the effect
cosmological
redshift resulting from
removing quasars,
distance to them
determined by law
Hubble. Last
time it is assumed that the source
radiation is
accretion disk
supermassive black
hole located in
center of the galaxy, and therefore red
displacement of quasars
more
cosmological on
value
gravitational displacement,
predicted A.
Einstein in general
theory of relativity.
Very difficult
determine the exact number of
present day
quasars. it
explained, on the one hand
hand, permanent
discovery of new quasars, and on the other hand,
lack of a clear
boundaries between
quasars and others
types of active
galaxies. Published in 1987
year of Hewitt's list -
Burbridge number
quasars 3594. In 2005
a group of astronomers
used data in their study.
already about 195,000 quasars.
One of the nearest and
the brightest quasar
3C 273 has red
offset z = 0.158 (corresponding to
a distance of about 3 billion
St. years). The most distant
quasars, thanks to
its gigantic
luminosity exceeding hundreds
times the luminosity of ordinary
galaxies,
registered with
help
radio telescopes at a distance of more than 12
billion St. years. July
2011 the most
remote quasar (ULAS
J112001.48+064124.3)
located at a distance of about 13 billion sv. years from
Earth. Irregular
brightness variability
quasars on temporary
less than a day
indicates that the area of ​​their generation
radiation has a small
size comparable to
solar
systems.
In 1982 the Australian
discovered by astronomers
new quasar,
dubbed
PKS 200-330, which has
found a record for that time
redshift
Z==3.78. It means,
that spectral lines
moving away from us
astronomical object as a result
Doppler effect have
wavelength, 3.78 times
exceeding the value
stationary source
light emission. Distance to this
quasar visible in
optical telescope as
star nineteenth
values, is
12.8 billion light years .. In the second half of the 80s
years was
still recorded
some of the most
distant quasars,
the redshift value of which is already
exceeds 4.0. So
Thus, radio signals
sent by these
quasars when
ours has not yet been formed
galaxy, including
Solar system,
only possible today
register for
earth. And these rays overcome a huge
distance-more than 13
billion light years. These
following each other
other astronomical
discoveries were made during a competitive
scientific race
Australian
astronomers from
Observatory Siding-
Spring and their American colleagues from
Mount Observatory
Palomar in California.
Today is the most
object remote from us
- quasar PC 1158+4635 with redshift,
equal to 4.733.
Distance to it
is 13.2 billion
light years .. But in the same
Mount Observatory
Palomar through 5-
meter telescope
american star
explorers led by a brave hunter
quasars by M. Schmidt in
September 1991
finally
confirmed the rumors
existence more distant from us
astronomical
object. Value
redshift
record distant
quasar numbered PC 1247+3406 is
4,897. Seems to be further
already nowhere. Radiation
this quasar reaches
our planet in time
almost equal to the age of the universe.
Recent Observations
showed that
most quasars
are close
centers of huge elliptical galaxies.
Quasars are compared to
beacons of the universe. They are
visible from huge
distances, along them
explore the structure and evolution of the universe,
determine
substance distribution
on the line of sight: strong
spectral lines
absorption of hydrogen unfold in the forest
lines in red
displacement of absorbing
clouds. One quasar
shines brighter than
our entire galaxy, about 10,000 times.
Energy average, nothing
unremarkable
a quasar would be enough
to supply all
Earth electricity for several
billion years. BUT
some of the quasars
radiate energies of 60
thousand times more.
Bolometric (integrated over the entire
spectrum) luminosity
quasars can reach 10 46 - 1047 erg / s. The average quasar
produces about
10 trillion times
more energy in
second than ours
The sun (and a million times more energy than
most powerful known
star), and has
variability
radiation in all
wavelength ranges. Many quasars change
its luminosity in
short intervals
time. This is,
apparently one of
fundamental properties of quasars
(the shortest variation from
period t "1 h,
maximum
gloss changes - at 25
once). Since the dimensions of the variable in brightness
object cannot
exceed ct (c -
speed of light), dimensions
quasars cannot be
more than 4,000,000,000,000 m (less than the diameter
orbit of Uranus), and only
in the movement of matter
at a speed close to
the speed of light, these
sizes may be larger.

This velocity limit bears Eddington's name and is a balance between two competing forces: the gravitational pull towards the black hole and the external radiation pressure created by this process. It turns out that this is quite difficult. They should have grown at the Eddington limit throughout the early history of the universe.

Such a scenario is difficult to explain, in large part because it is difficult to model how a self-contained black hole can feed on enough matter to maintain the Eddington limit for that long time. So astronomers looked for other explanations. Perhaps supermassive black holes are by-products of galaxy formation, seeded with giant central stars that collapsed and formed smaller black holes. Sitting at the center of a young, turbulent host galaxy could provide such a "seed" with enough raw material to grow larger and quickly reach the Eddington limit.

Quasar(English) quasar) is a particularly powerful and distant active galactic nucleus. Quasars are one of the brightest objects in the universe. The radiation power of a quasar is sometimes tens and hundreds of times higher than the total power of all the stars in galaxies like ours.

Initially, quasars were identified as high redshift objects ( redshift- shift spectral lines chemical elements towards the red (long wavelength) side) and electromagnetic radiation with very small angular dimensions. For this reason, they could not be distinguished from stars for a long time, because. extended sources are more consistent with galaxies. And only later traces of parent galaxies were found around quasars.

Reynolds is undertaking black hole seeding modeling efforts as principal investigator at the Nationally funded science foundation project called "Theoretical and Computational Astrophysical Network". "We plan to model these huge balls of gas to see if they actually form supermassive black holes," explains Reynolds. This is not what they will do. high levels energies can inflate them. In fact, the process may go wrong.

Instead, an alternative theory suggests that small black holes formed by accretion at the centers of young galaxies a long time ago. Then some of these galaxies merged together, merging their central black holes to form large black holes. This process continued, resulting in a gradual increase in black holes, which eventually reached supermassive status.

Term quasar stands for "resembling a star". According to one theory, quasars are galaxies at the initial stage of development, in which a supermassive black hole absorbs the surrounding matter.

The first quasar, 3C 48, has been discovered in the late 1950s by Alan Sandage and Thomas Matthews during a radio survey of the sky. In 1963, 5 quasars were already known. In the same year, the Dutch astronomer Martin Schmidt proved that the lines in the spectra of quasars are strongly redshifted.

Combine that with the assumption that every galaxy has a black hole at its center and this scenario starts to make a lot of sense. "Small galaxies merge to form large ones, so it's reasonable to think that black holes will merge as well," Gezari says. "But as far as we know, there is only one supermassive black hole at the center of most galaxies, and finding evidence for two or more black holes is hard to come by."

If they are correct, this "black hole" of a black hole is most likely a The final stage mergers of galaxies. Black holes are very close to each other - closer than anyone has seen before, leading researchers to suspect that the two black holes are gravitationally bound to each other.

Recently, it is commonly believed that the source of radiation is the accretion disk of a supermassive black hole located in the center of the galaxy and, consequently, the redshift of quasars is greater than the cosmological one by the value of the gravitational displacement predicted by A. Einstein in the general theory of relativity (GR). To date, more than 200,000 quasars have been discovered. The redshift and brightness of a quasar determine the distance to it. For example, one of the nearest quasars and the brightest one, 3C 273, is at a distance about 3 billion light years. Recent observations show that most quasars are located near the centers of huge elliptical galaxies, and the irregular brightness variability of quasars on time scales of less than a day indicates that region of generation of their radiation has a small size, comparable to the size of the solar system.

If so, it is likely that the two giant black holes will soon merge to become one - perhaps within the next 20 years or so. Confirmation of black hole mergers would lend great weight to the idea that supermassive black holes form in the same way, from a series of black hole mergers beginning shortly after the Big Bang.

“Before, we could only see one picture of the system, instantly frozen in time, like a single snapshot,” explains Liu. Regardless of how they form, it is clear that supermassive black holes have a close relationship with their host galaxies. One of the newest and most interesting areas of black hole research aims to understand the exact nature of these relationships. It is very likely that these black black holes have a big impact, greatly changing the dynamics and evolution of the entire system.

On average, a quasar produces about 10 trillion times more energy per second than our Sun (and a million times more energy than the most powerful famous star), and has radiation variability in all wavelength ranges.

"Galaxies and supermassive black holes are all wrapped up together, like an ecosystem," Muschotky adds. "It's not something you can easily separate." One curious observation led to great results in research in this area: in almost every galaxy where a supermassive black hole has been observed, astronomers have observed a tight correlation between the mass of the black hole and the mass of the galaxy. The larger the galaxy, the more massive the black hole at its center.

Most likely, this is not a coincidence. The extreme energy output of a supermassive black hole would almost certainly have far-reaching consequences for the matter around it. Many quasars have been found firing powerful, concentrated jets of plasma from their centers that reach hundreds of light-years away from their home galaxies. Some of these jets are so bright that they can be detected billions of light-years away, but it's not entirely clear whether the jets can affect the galaxy.

The physical mechanism responsible for the generation of such powerful radiation in a relatively small volume is still not known for certain. The processes occurring in quasars are the subject of intense theoretical research.

Narrow absorption lines of hydrogen and ions of heavy elements have been found in the spectra of distant quasars. The nature of the narrow absorption lines remains unclear. The absorbing medium can be vast coronas of galaxies or individual clouds of cold gas in intergalactic space. It is possible that such clouds may be the remnants of a diffuse medium from which galaxies were formed.

Concentrated jets are not the only powerful bursts of energy created by quasars. We find that these winds are common. It was immediately clear that these winds were controlling Markarian's evolution and development, and it seemed clear that the supermassive black hole at the center of the galaxy was responsible. But the researchers wanted confirmation.

These winds, in turn, directly influence the wind of the galaxy, which cleans the galaxy of the source of star-forming gas. This is the first opportunity to see the connection between these two phenomena, continues Tombesi. "This is also one of the first pieces of evidence to support that supermassive black holes can affect the entire galaxy, including stars and the interstellar medium."

The study of quasars located at distances of billions of light years is very important for cosmological model reflecting the properties of the real universe. Perhaps the study of quasars will also provide important information about the evolution of the universe.

But this regime of constant, high-energy activity is not the only way to think that supermassive black holes control their host galaxies. The theory suggests that black holes can also be produced periodically in short bursts, thereby controlling the rate of star formation on a smaller scale. These pulses of galactic wind could clear enough stellar gas to bring the galaxy's mass balance back into line before shutting down again. Astronomers call this process "feedback."