According to new research, a galaxy with a quasar in the middle is not a good place to grow up. As active galactic nuclei (AGN) evolve, they pass through a "quasar phase", where the accretion disk surrounding the central black hole blasts intense radiation into space. The quasar far outshines the entire host galaxy. After the quasar phase, when the party is over, it is as if there is no energy left and star formation stops.
AGN are the compact, active and bright central cores to active galaxies. The intense brightness from these active galactic cores is produced by the gravitationally driven accretion disk of hot matter spinning and falling into a supermassive black hole at the centre. During the lifetime of an AGN, the black hole/accretion disk combo will undergo a "quasar phase" where intense radiation is blasted from the superheated gases surrounding the black hole. Typically quasars are formed in young galaxies.
Although the quasar phase is highly energetic and tied with young galaxy formation, according to new results from the Sloan Digital Sky Survey, it also marks the end for any further star birth in the galaxy. These findings will be presented today (Friday 4th April) at the RAS National Astronomy Meeting in Belfast, Northern Ireland, by Paul Westoby having just completed a study of 360 000 galaxies in the local Universe. He carried out this research with Carole Mundell and Ivan Baldry from the Astrophysics Research Institute of Liverpool, John Moores University, UK. This study was proposed to understand the relationship between accreting black holes, the birth of stars in galactic cores and the evolution of galaxies as a whole. The results are astonishingly detailed.
By analysing so many galaxies, quite a detailed picture emerges. The primary result to come from this shows that as a young galactic core is dominated by a highly energetic quasar, star formation stops. After this phase in a galaxy's life, star formation is not possible; the remaining stars are left to evolve by themselves.
It is believed that all AGNs go through the quasar phase in their early galactic lives. It is also thought that most massive galaxies will have a supermassive black hole hiding inside their galactic cores passively, having already gone through the quasar phase. Westoby notes that some dormant supermassive black holes can be "reignited" into a secondary quasar phase, but the mechanisms behind this are sketchy.
"The starlight from the host galaxy can tell us much about how the galaxy has evolved
Hello Alokmohan
You said
You need to look at the evolution of galaxies and their varies forms and their relationship to the active core.
The quarsar is a reult of stars breaking up, once the so called black hole sucks matter, there comes a time that it activates a jet stream to eject matter deep into space and reforming the galaxy and in some cases reforming two galaxies. Where does it get the matter from, from the core.
You said
QUOTE
According to new research, a galaxy with a quasar in the middle is not a good place to grow up. As active galactic nuclei (AGN) evolve, they pass through a "quasar phase", where the accretion disk surrounding the central black hole blasts intense radiation into space. The quasar far outshines the entire host galaxy. After the quasar phase, when the party is over, it is as if there is no energy left and star formation stops.
You need to look at the evolution of galaxies and their varies forms and their relationship to the active core.
The quarsar is a reult of stars breaking up, once the so called black hole sucks matter, there comes a time that it activates a jet stream to eject matter deep into space and reforming the galaxy and in some cases reforming two galaxies. Where does it get the matter from, from the core.
Harry,the quasar is too large a thing.Your explanation seems oversimplification.
Hello Alokmohan
What do you mean?
What do you mean?
Harry quasars are enigmatic.I keep wondering what they are really.
Hello Alokmohan
Quarsar is a star like body.
You have them at varies sizes and their method of production.
The large quarsars surround black holes, these can be thousands of light years across.
Micro-quarsar is a star like body ejected from a black hole.
Quasars: Near Versus Far
http://metaresearch.org/cosmology/QuasarsNearVersusFar.asp
New Picture of Quasar Emerges
http://www.physorg.com/news73057202.html
Microquasars: disk–jet coupling in stellar-mass black holes
http://journals.cambridge.org/action/displ...ine&aid=1026420
Hubble Space Telescope images
http://www.sns.ias.edu/~jnb/HST/hstimages.html
Quasars
http://csep10.phys.utk.edu/astr162/lect/active/quasars.html
Not quite true: I will expand on this later.
Got to go
Quarsar is a star like body.
You have them at varies sizes and their method of production.
The large quarsars surround black holes, these can be thousands of light years across.
Micro-quarsar is a star like body ejected from a black hole.
Quasars: Near Versus Far
http://metaresearch.org/cosmology/QuasarsNearVersusFar.asp
New Picture of Quasar Emerges
http://www.physorg.com/news73057202.html
Microquasars: disk–jet coupling in stellar-mass black holes
http://journals.cambridge.org/action/displ...ine&aid=1026420
Hubble Space Telescope images
http://www.sns.ias.edu/~jnb/HST/hstimages.html
Quasars
http://csep10.phys.utk.edu/astr162/lect/active/quasars.html
QUOTE
Evolution of Quasars
The standard theory is that quasars turn on when there is matter to feed their supermassive black hole engines at the center and turn off when there is no longer fuel for the black hole. Recent Hubble Space Telescope observations indicate that quasars can occur in galaxies that are interacting with each other. This suggests the possibility that quasars that have turned off because they have consumed the fuel available in the original galaxy may turn back on if the galaxy hosting the quasar interacts with another galaxy in such a way to make more matter available to the black hole. Here is a recent survey of quasar host galaxies that sheds light on this issue.
Abundance of quasars as a function of the age of the Universe (Source: Bill Keel).
The standard theory is that quasars turn on when there is matter to feed their supermassive black hole engines at the center and turn off when there is no longer fuel for the black hole. Recent Hubble Space Telescope observations indicate that quasars can occur in galaxies that are interacting with each other. This suggests the possibility that quasars that have turned off because they have consumed the fuel available in the original galaxy may turn back on if the galaxy hosting the quasar interacts with another galaxy in such a way to make more matter available to the black hole. Here is a recent survey of quasar host galaxies that sheds light on this issue.
Abundance of quasars as a function of the age of the Universe (Source: Bill Keel).
Not quite true: I will expand on this later.
Got to go
Quasars are a region at the center of an AGN, where there is so much matter falling into the black holes located there, that it's like many constant GRBs.
QUOTE (Harry Costas+Apr 8 2008, 12:39 PM)
Micro-quarsar is a star like body ejected from a black hole.
No. The micro-quasar is a black hole surrounded by an accretion disk and perhaps jets. It just happens to be around a smaller black hole.
No. The micro-quasar is a black hole surrounded by an accretion disk and perhaps jets. It just happens to be around a smaller black hole.
QUOTE
barakn Posted on Today at 8:24 AM The micro-quasar is a black hole surrounded by an accretion disk and perhaps jets. It just happens to be around a smaller black hole.
the accretion can also occur around a neutron star as here http://www.universetoday.com/2005/07/08/mi...es-astronomers/
QUOTE (kjw+Apr 8 2008, 10:44 PM)
the accretion can also occur around a neutron star as here http://www.universetoday.com/2005/07/08/mi...es-astronomers/
Note they aren't sure if it's a neutron star or a black hole. And I don't think it invalidates my point - neutron stars being on the same end of the scale as small black holes.
Note they aren't sure if it's a neutron star or a black hole. And I don't think it invalidates my point - neutron stars being on the same end of the scale as small black holes.
QUOTE
barakn Posted: Today at 2:55 PM Note they aren't sure if it's a neutron star or a black hole.
agreed, it was not the best example.QUOTE (->
| QUOTE |
| barakn Posted: Today at 2:55 PM Note they aren't sure if it's a neutron star or a black hole. |
agreed, it was not the best example.
And I don't think it invalidates my point - neutron stars being on the same end of the scale as small black holes.
And I don't think it invalidates my point - neutron stars being on the same end of the scale as small black holes.
sorry i was not trying to invalidate your point, only to expand it to include neutron star powered microquasars.
Hello All
Microquarsar
Chandra Discovers the X-ray Signature of a Powerful Wind from a Galactic Microquasar
http://chandra.harvard.edu/press/00_releas...0800quasar.html
Microquasar Fireworks
http://www.sciencemag.org/cgi/content/summ.../5591/73?ck=nck
Microquasars: disk–jet coupling in stellar-mass black holes
Microquasars: disk–jet coupling in stellar-mass black holes
Microquasars provide new insights into: 1) the physics of relativistic jets from black holes, 2) the connection between accretion and ejection, and 3) the physical mechanisms in the formation of stellar-mass black holes. Furthermore, the studies of microquasars in our Galaxy can provide in the future new insights on: 1) a large fraction of the ultraluminous X-ray sources in nearby galaxies, 2) gamma-ray bursts (GRBs) of long duration in distant galaxies, and 3) the physics in the jets of blazars. If jets in GRBs, microquasars and Active Galactic Nuclei (AGN) are due to a unique universal magnetohydrodynamic mechanism, synergy of the research on these three different classes of cosmic objects will lead to further progress in black hole physics and astrophysics.
MAGIC Telescope Finds Microquasar
http://www.physorg.com/news68824943.html
Microquasar in Motion
http://antwrp.gsfc.nasa.gov/apod/ap040916.html
Where a Black Hole Roams
http://antwrp.gsfc.nasa.gov/apod/ap010921.html
V4641 Sgr: The Closest Black Hole Candidate
http://antwrp.gsfc.nasa.gov/apod/ap000117.html
Microquarsar
Chandra Discovers the X-ray Signature of a Powerful Wind from a Galactic Microquasar
http://chandra.harvard.edu/press/00_releas...0800quasar.html
Microquasar Fireworks
http://www.sciencemag.org/cgi/content/summ.../5591/73?ck=nck
QUOTE
Microquasars--the smaller cousins of radio galaxies and quasars--are characterized by transient relativistic jets that move away from the central black hole. By analogy to these larger systems, researchers expected to see how the jets crash into the interstellar environment. But as Rupen explains in his Perspective, earlier studies found little sign of interactions of the jets with the interstellar medium. He highlights the study by Corbel et al., who report direct evidence for such interactions.
Microquasars: disk–jet coupling in stellar-mass black holes
QUOTE (->
| QUOTE |
| Microquasars--the smaller cousins of radio galaxies and quasars--are characterized by transient relativistic jets that move away from the central black hole. By analogy to these larger systems, researchers expected to see how the jets crash into the interstellar environment. But as Rupen explains in his Perspective, earlier studies found little sign of interactions of the jets with the interstellar medium. He highlights the study by Corbel et al., who report direct evidence for such interactions. |
Microquasars: disk–jet coupling in stellar-mass black holes
Microquasars provide new insights into: 1) the physics of relativistic jets from black holes, 2) the connection between accretion and ejection, and 3) the physical mechanisms in the formation of stellar-mass black holes. Furthermore, the studies of microquasars in our Galaxy can provide in the future new insights on: 1) a large fraction of the ultraluminous X-ray sources in nearby galaxies, 2) gamma-ray bursts (GRBs) of long duration in distant galaxies, and 3) the physics in the jets of blazars. If jets in GRBs, microquasars and Active Galactic Nuclei (AGN) are due to a unique universal magnetohydrodynamic mechanism, synergy of the research on these three different classes of cosmic objects will lead to further progress in black hole physics and astrophysics.
MAGIC Telescope Finds Microquasar
http://www.physorg.com/news68824943.html
Microquasar in Motion
http://antwrp.gsfc.nasa.gov/apod/ap040916.html
Where a Black Hole Roams
http://antwrp.gsfc.nasa.gov/apod/ap010921.html
V4641 Sgr: The Closest Black Hole Candidate
http://antwrp.gsfc.nasa.gov/apod/ap000117.html
Microquasar is latest star 
Hello Alokmohan
Quasar can be taken to be large or small star like body. Not actually the star itself.
Further Evidence that the Redshifts of AGN Galaxies May
Contain Intrinsic Components
http://www.citebase.org/fulltext?for...rg%3A0704.1631
Quasar can be taken to be large or small star like body. Not actually the star itself.
Further Evidence that the Redshifts of AGN Galaxies May
Contain Intrinsic Components
http://www.citebase.org/fulltext?for...rg%3A0704.1631
QUOTE
Because the belief that the redshift of quasars is cosmological has become so entrenched, and the consequences now of it being wrong are so enormous, astronomers are very reluctant to consider other possibilities. However, there is increasing evidence that some galaxies may form around compact, seed objects ejected with a large intrinsic redshift component from the nuclei of mature active galaxies. In this model, as the intrinsic component decreases
the compact objects evolve into mature active galaxies in a time frame of a few times 108 yrs (Arp 1997, 1998, 1999; Bell 2002a,b,c,d, 2004, 2006; Bell and McDiarmid 2006, 2007; Burbidge 1999; Galianni et al. 2005; Lop´ez-Corredoira and Guti´errez 2006). In the DIR model radio galaxies represent the end of the AGN evolutionary sequence, where most of the intrinsic redshift component has disappeared and their luminosity has peaked. Only then can these objects be detected to large cosmological distances and can it be seen that they are good standard candles. There is every reason to assume that at each stage of their evolution (at each zi value) they will also be good standard candles.
the compact objects evolve into mature active galaxies in a time frame of a few times 108 yrs (Arp 1997, 1998, 1999; Bell 2002a,b,c,d, 2004, 2006; Bell and McDiarmid 2006, 2007; Burbidge 1999; Galianni et al. 2005; Lop´ez-Corredoira and Guti´errez 2006). In the DIR model radio galaxies represent the end of the AGN evolutionary sequence, where most of the intrinsic redshift component has disappeared and their luminosity has peaked. Only then can these objects be detected to large cosmological distances and can it be seen that they are good standard candles. There is every reason to assume that at each stage of their evolution (at each zi value) they will also be good standard candles.
Harry,do they have black hole at center?
Hello Alokmohan
The large quasars do have at least one black hole. Some have a swam of black holes such as our MilkyWay.
In the last few decades quasars have been defined in a number of different ways.
=======================================
Black holes are found throughout every galaxy in varies sizes, from stella 3 solar masses to 20 odd solar masses and you will get a few black holes with 1000 solar masses, but these are found closer to the centre. They somehow grow bigger in their travel towards the centre of the galaxy.
News Release - heic0809: Black hole found in enigmatic Omega Centauri
http://www.spacetelescope.org/news/html/heic0809.html
Milky Way
Galactic Center Radio Arc:
X-ray Gas Associated With Cold Gas Cloud and Galactic Center Radio Arc
http://chandra.harvard.edu/photo/2002/gradioarc/
APOD: 2004 November 6 - X-Rays from the Galactic Core
http://antwrp.gsfc.nasa.gov/apod/ap041106.html
APOD: 2006 July 29 - The Swarm
http://antwrp.gsfc.nasa.gov/apod/ap060729.html
The large quasars do have at least one black hole. Some have a swam of black holes such as our MilkyWay.
In the last few decades quasars have been defined in a number of different ways.
=======================================
Black holes are found throughout every galaxy in varies sizes, from stella 3 solar masses to 20 odd solar masses and you will get a few black holes with 1000 solar masses, but these are found closer to the centre. They somehow grow bigger in their travel towards the centre of the galaxy.
News Release - heic0809: Black hole found in enigmatic Omega Centauri
http://www.spacetelescope.org/news/html/heic0809.html
Milky Way
Galactic Center Radio Arc:
X-ray Gas Associated With Cold Gas Cloud and Galactic Center Radio Arc
http://chandra.harvard.edu/photo/2002/gradioarc/
APOD: 2004 November 6 - X-Rays from the Galactic Core
http://antwrp.gsfc.nasa.gov/apod/ap041106.html
APOD: 2006 July 29 - The Swarm
http://antwrp.gsfc.nasa.gov/apod/ap060729.html
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