Does the Milky have a QSO? What is the observational evidence concerning QSOs?

Evidence for Gamma Ray Jets in the Milky Way
Although accretion onto supermassive black holes in other galaxies is seen to produce powerful jets in X-ray and radio, no convincing detection has ever been made of a kpc-scale jet in the Milky Way. The recently discovered pair of 10 kpc tall gamma-ray bubbles in our Galaxy may be signs of earlier jet activity from the central black hole. In this paper, we identify a gamma-ray cocoon feature in the southern bubble, a jet-like feature along the cocoon’s axis of symmetry, and another directly opposite the Galactic center in the north. Both the cocoon and jet-like feature have a hard spectrum with spectral index _ −2 from 1 to 100 GeV, with a cocoon total luminosity of (5.5 ± 0.45) × 10^35 and luminosity of the jet-like feature of (1.8 ± 0.35) × 10^35 erg/s at 1 − 100 GeV. If confirmed, these jets are the first resolved gamma-ray jets ever seen.

The mechanism by which jets turn on and off is one of the major puzzles in high energy astrophysics, and may be connected to star formation (Antonuccio-Delogu & Silk 2008). The relativistic jets inject significant amounts of energy into the medium within which they propagate, creating an extended, under-dense and hot cocoon. After decades of study, we still lack a complete understanding of the main mechanism launching, accelerating, and collimating jets, with limited knowledge of the energy content, the composition, and the particle acceleration mechanisms of the jets (Blandford & Znajek 1977; Blandford & Payne 1982)....

...The SMBH at the center of the Milky Way (MW) is surrounded by clusters of young stars and giant molecular clouds (Morris & Serabyn 1996). Although there are indications of past activity (Sunyaev et al. 1993), the SMBH is currently in a quiescent state. Despite the abundant observational evidence of large-scale jets in other galaxies, it was not expected that the Milky Way’s SMBH would produce such a relativistic collimated structure, given its current quiescence. However, the MW must have undergone phases of nuclear activity in the past in order for the SMBH to grow, and it is plausible that signs of past activity are still visible.

There is a confusing article in the August, 2012 Scientific America concerning the recent discovery of a massive gamma radiation emission from the Milky Way galaxy, from the very recent past. As our solar system is one of the many members of the Milky Way this is an interesting subject.

If viewed from a distance galaxy, say M31, this massive gamma radiation emission would appear to be a Quasar, a QSO, a quasi-stellar object. As there are no QSOs in the local universe this presents an interesting puzzle. Why are there no QSOs in the local universe and how the heck can there be a QSO in the Milky Way?

Quasars are active galactic nuclei (AGN's). The nucleus of the Milky Way is not currently active. We do see the jets from previous activity, however.

I believe it is generally expected that the nuclei of galaxies become active when they first form, and when the galaxy undergoes a large disruption such as a merger with another galaxy.

And by the way, there are quite a few AGN's that are relatively close-by. The nearest is the nucleus of Centaurus-A, a mere 10-16 million light years away.

• Why have the masses of the observed central BHs decreased during cosmic epochs, from initial . 10^9.5 M⊙ to their present-day 10^7M⊙, as shown by the statistics of the SDSSurvey (fig.4, Vestergaard et al 2008)? • How could some of the most massive ones already form within . 0.8 Gyr after the Big Bang? • Why do their masses scale as 10^−2.85 times their bulge masses (Marconi and Hunt 2003)? • How do they blow their gigantic winds, and why have those winds the chemistry of ashes from excessive nuclear burning, being & 10^2-fold metal enriched (upto Fe)? • How do they generate their extremely hard spectra, (occasionally) peaking at &TeV energies, even recorded (from PKS 2155-304) as minute-sharp, hour-scale bursts (Weekes 2007), whilst accreting black holes radiating at their Eddington rates are predicted to shine with blackbody temperatures of KeV(M⊙/M)1/4? • Why are some of them distinctly underluminous? • Why does their high g -ray compactness not prevent them from forming jets, in the (10%) cases of their radio-loud subpopulation, via inverse-Compton losses?

• And, if all the astrophysical jet sources are generated by a universal type of engine – whose powerhouses are newly forming stars (like our Sun, in its past), forming (binary)white dwarfs, binary neutron stars, and AGN – this universal type of engine looks like a rotating magnet, not like a BH (Kundt and Krishna 2004).


FIGURE 4. (Estimated) mass distribution of 14,584 quasar central engines (CEs) with z ≥ 0.2, as functions of redshift z, from the Sloan Digital Sky Survey Data Release 3, within an effective sky area of 1644 deg2, taken from Vestergaard et al (2008). Squares denote median masses in each redshift bin. The dashed curve indicates faint SDSS flux limits.

An independent signature of the BD character of Sgr A* is its gigantic wind, seen to blow radial tails from the windzones of & 8 nearby stars, at distances . lyr, and mapped in the redshifted light of extended Br, and in the blueshifted light of Br, of mass rate some 10−2.5M⊙/yr, and speed . 103Km/s, (Kundt 1990). No hole can expel more matter than you dump on it.

On the non-evolution of the dependence of black hole masses on bolometric luminosities for QSOs

The main conclusion of our analysis is that both the mass and the Eddington ratio of the black holes for a QSO with a given luminosity do not evolve with redshift. Or in other words, the luminosity of a QSO does not evolve with redshift for a given mass. More precisely and considering systematic uncertainties _ 0:2􀀀0:3 dex in the estimation of masses and luminosities, we conclude that the evolution in redshift, if any, is very small compared to the change in mean luminosity of the population of QSOs at low redshift with respect to such a population at high redshifts.

This implies an important result on the nature of QSOs, i.e. local QSOs are intrinsically less massive than QSOs at high redshift. Labita et al. (2009a) derived that the maximum mass of a black hole in a QSO is a function of the redshift: log10MBH = (0:34z + 8:99) M_ up to redshift 1.9, or proportional to (1 + z)^1:64 if extended up to a redshift of 4 (Labita et al. 2009b). This lack of the signature of active massive AGN black holes in the local Universe cannot be related with a possible decline in the rate of formation of QSOs (this would affect the density of QSOs but not their average mass; and indeed there is evidence for the change in the comoving density of QSOs of a given mass; Steinhardt & Elvis 2011, fig. 3), but because of some mechanism for the formation of huge black holes which took place in the past in the Universe, which is absent in the present Universe.

NOTE: Do not confuse the non-evolution of the black hole mass-luminosity ratio (the result of this paper) with the non-evolution of mechanisms which produce such black holes. Evidently, as said in the introduction, some evolution in the birth of new QSOs must take place in order to explain the absence of very bright QSOs at low redshift.

The existence of very massive black holes is only at high z. Perhaps it could be related with the higher ratio of mergers and then star formation in the past. We wonder whether it might have something to do with the excess of very massive galaxies at high-z, which is still not completely understood within semianalytical hierarchical _CDM models (e.g., Fontana et al. 2009). Indeed, the mass of the black hole has remained proportional to the stellar mass of their host galaxies for at least the last 9 Gyr (Jahnke et al. 2009). Or perhaps it has something to do with the larger average density of the Universe, or the angular momentum of some components of the galaxies (at high z, the black holes rotate faster; Netzer
2010).

However, where are the black holes with masses larger than 10^10 M_ which were frequent in the past? We do not know any mechanism by which black holes can reduce its mass.

These are the papers I was thinking of. High luminosity quasars are no longer found in the local universe. This was assumed to be due to a difference in the feeding of the quasar due to a change in the environment from high redshift to the present.

As these two papers indicate. That belief is not correct.

Yes it is quite correct. The supposed discrepancies claimed by these papers are pretty trivially explained by two effects:
1. Selection: extremely massive black holes are going to be most visible when they are most luminous, i.e. at high redshift.
2. Volume: there is vastly more observable universe at high redshift than at low redshift, so that any exceptional regions in the universe are more likely to be at high redshift than low redshift.

• Why do their masses (bezalel: Galaxy central BH mass) scale as 10^−2.85 times their bulge masses (Marconi and Hunt 2003)?

Chalnoth,

The explanation is not selection.

The mass of the central galactic BH can also be estimated by the size of the spiral galaxy bulge as there is a tight relation of the size of the spiral galaxy bulge to the mass of the central BH.

The anomaly is not only that high redshift quasars are more luminous.

The galaxy central BH get smaller with redshift (10^10 solar masses down to 10^7 solar masses). Downsizing of the central galaxy BH mass with redshift is anomalous, as there is no known mechanism by which a BH can lose significant mass. i.e. A 10^10 solar mass BH that formed at high redshift should be 10^10 or larger at in the local universe which is not observed. The 10^10 solar mass BH downsizes to 10^7 solar masses.

As the paper notes the spectral energy distribution of the quasar does not change with redshift which is also curious.

Metallicity also does not change with redshift which is also anomalous. One would expect metallicity should decrease with redshift. It does not.

Extrapolating a poorly-understood empirical relationship with substantial variance far beyond where it is empirically-measured is not convincing.

The spectral energy distribution of AGN's varies dramatically from AGN to AGN. And their emission also tends to vary in time rather rapidly. The take away is just that AGN's are extremely variable objects, so that any apparent evolution of AGN environments is buried in the noise.

And these statements also don't surprise me at all, considering that AGN's aren't going to form until there's been a good amount of star formation in the area first.

Evidence for Gamma Ray Jets in the Milky Way
Although accretion onto supermassive black holes in other galaxies is seen to produce powerful jets in X-ray and radio, no convincing detection has ever been made of a kpc-scale jet in the Milky Way. The recently discovered pair of 10 kpc tall gamma-ray bubbles in our Galaxy may be signs of earlier jet activity from the central black hole. In this paper, we identify a gamma-ray cocoon feature in the southern bubble, a jet-like feature along the cocoon’s axis of symmetry, and another directly opposite the Galactic center in the north. Both the cocoon and jet-like feature have a hard spectrum with spectral index _ −2 from 1 to 100 GeV, with a cocoon total luminosity of (5.5 ± 0.45) × 10^35 and luminosity of the jet-like feature of (1.8 ± 0.35) × 10^35 erg/s at 1 − 100 GeV. If confirmed, these jets are the first resolved gamma-ray jets ever seen.

The mechanism by which jets turn on and off is one of the major puzzles in high energy astrophysics, and may be connected to star formation (Antonuccio-Delogu & Silk 2008). The relativistic jets inject significant amounts of energy into the medium within which they propagate, creating an extended, under-dense and hot cocoon. After decades of study, we still lack a complete understanding of the main mechanism launching, accelerating, and collimating jets, with limited knowledge of the energy content, the composition, and the particle acceleration mechanisms of the jets (Blandford & Znajek 1977; Blandford & Payne 1982)....

...The SMBH at the center of the Milky Way (MW) is surrounded by clusters of young stars and giant molecular clouds (Morris & Serabyn 1996). Although there are indications of past activity (Sunyaev et al. 1993), the SMBH is currently in a quiescent state. Despite the abundant observational evidence of large-scale jets in other galaxies, it was not expected that the Milky Way’s SMBH would produce such a relativistic collimated structure, given its current quiescence. However, the MW must have undergone phases of nuclear activity in the past in order for the SMBH to grow, and it is plausible that signs of past activity are still visible.

• And, if all the astrophysical jet sources are generated by a universal type of engine – whose powerhouses are newly forming stars (like our Sun, in its past), forming (binary) white dwarfs, binary neutron stars, and AGN – this universal type of engine looks like a rotating magnet, not like a BH (Kundt and Krishna 2004).

X-RAY LIGHTHOUSES OF THE HIGH-REDSHIFT UNIVERSE. II. FURTHER SNAPSHOT OBSERVATIONS OF THE MOST LUMINOUS Z ∼ > 4 QUASARS WITH Chandra
There is no indication of any significant evolution in the X-ray properties of quasars between redshifts zero and six, suggesting that the physical processes of accretion onto massive black holes have not changed over the bulk of cosmic time.

You may be confusing variation in quasar luminosity with distribution of quasar spectral energy by frequency. QSO luminosity does very quickly and cyclically however the QSO spectral energy distribution continues to follow a power law.

The X-ray spectrum of QSOs shows a very simple spectral shape in the form of a power law, S υ = υ^- α where α≈ 0.7. The pattern of the QSO spectral energy distribution vs frequency is how Hawkins has able to show that QSOs do not show time dilation with redshift. This is the third paper that Hawkins has published that shows that QSOs do not show time dilation with redshift.

One of the quasar puzzles is how to generate jets, x-rays and gamma radiation that has spectral energy vs frequency that follows a power law, from an accreting disk and how to get the jet, x-ray and gamma radiation mechanism to turn on and off.

This thread starts with the observation that the Milky Way super massive BH in the very recent past created gamma ray excited jets similar to this picture. The puzzle is the Milky Way is not merging with another galaxy. Why would the Milky Way in the recent past produce gamma ray exited jets?

As there are no QSOs in the local universe this presents an interesting puzzle. Why are there no QSOs in the local universe and how the heck can there be a QSO in the Milky Way?

One can compare the toy model for QSOs to the observations and see if the observations match what is observed.

The mass of the central galactic BH can also be estimated by the size of the spiral galaxy bulge as there is a tight relation of the size of the spiral galaxy bulge to the mass of the central BH.

As the paper notes the spectral energy distribution of the quasar does not change with redshift which is also curious.

Metallicity also does not change with redshift which is also anomalous. One would expect metallicity should decrease with redshift. It does not.

One of the quasar puzzles is how to generate jets, x-rays and gamma radiation that has spectral energy vs frequency that follows a power law, from an accreting disk and how to get the jet, x-ray and gamma radiation mechanism to turn on and off.

The puzzle is the Milky Way is not merging with another galaxy. Why would the Milky Way in the recent past produce gamma ray exited jets?

• And, if all the astrophysical jet sources are generated by a universal type of engine – whose powerhouses are newly forming stars (like our Sun, in its past), forming (binary) white dwarfs, binary neutron stars, and AGN – this universal type of engine looks like a rotating magnet, not like a BH (Kundt and Krishna 2004).

I don't see the puzzle here. There is a supermassive black hole in the middle of the Milky Way. At some earlier time, that massive black hole was getting matter dumped into into producing massive amounts of gamma and X-rays. Now that the black hole has eaten up most of the gas, there's nothing left to produce a quasar.

A quasar is just an early phase of a normal galaxy.

As far as I can tell, it fits pretty well. Young galaxies have massive amounts of gas and dust at the core. This generates a continuous stream of radiation. As the galaxy eats up the gas, the radiation goes down. At some relatively recent time, a gas cloud got dumped into the black hole in the Milky Way generating a "last gasp" of gamma rays.

I don't see the mystery.

Critical Thoughts on Cosmology Wolfgang Kundt

• Why have the masses of the observed central BHs decreased during cosmic epochs, from initial 10^9.5 M⊙ to their present-day 10^7M⊙, as shown by the statistics of the SDSSurvey (fig.4, Vestergaard et al 2008)?

• How could some of the most massive ones already form within 0.8 Gyr after the Big Bang?

• Why do their masses scale as 10^−2.85 times their bulge masses (Marconi and Hunt 2003)? Labita et al. (2009a) derived that the maximum mass of a black hole in a QSO is a function of the redshift: log10MBH = (0:34z + 8:99) M up to redshift 1.9, or proportional to (1 + z)1:64 if extended up to a redshift of 4 (Labita et al. 2009b). This lack of the signature of active massive AGN black holes in the local Universe cannot be related with a possible decline in the rate of formation of QSOs (this would affect the density of QSOs but not their average mass; and indeed there is evidence for the change in the comoving density of QSOs of a given mass; Steinhardt & Elvis 2011, fig. 3), but because of some mechanism for the formation of huge black holes which took place in the past in the Universe, which is absent in the present Universe.

NOTE: Do not confuse the non-evolution of the black hole mass-luminosity ratio (the result of this paper) with the non-evolution of mechanisms which produce such black holes. Evidently, as said in the introduction, some evolution in the birth of new QSOs must take place in order to explain the absence of very bright QSOs at low redshift.

On time dilation in quasar light curves
In this paper we set out to measure time dilation in quasar light curves. In order to detect the effects of time dilation, sets of light curves from two monitoring programmes are used to construct Fourier power spectra covering time-scales from 50d to 28yr. Data from high- and low-redshift samples are compared to look for the changes expected from time dilation. The main result of the paper is that quasar light curves do not show the effects of time dilation. Several explanations are discussed, including the possibility that time dilation effects are exactly offset by an increase in time-scale of variation associated with black hole growth, or that the variations are caused by microlensing in which case time dilation would not be expected.

1 INTRODUCTION
Time dilation (the stretching of time by a factor of (1 + z)) is a fundamental property of an expanding universe. Given the success of the the currently accepted cosmological model, which certainly implies expansion, it is perhaps surprising that more attention has not been paid to making direct measures of time dilation. This must surely be due in part to the fact that measures of time dilation can tell little or nothing about cosmological parameters within the framework of a Big Bang universe, but only whether or not the Universe is expanding. Also, it turns out to be surprisingly hard to formulate a conclusive test for time dilation. What is needed is an event or fluctuation of known rest frame duration which can be observed at sufficiently high redshift with an accuracy which enables the predicted stretching by a factor of (1 + z) to be observed.

5 INTERPRETATION OF RESULTS
The results of Section 4 provide strong evidence that the effects of time dilation are not seen in quasar light curves. This clearly runs against expectations based on a conventional cosmological viewpoint, and so in this section we examine ways in which the results may be understood.

This is the link to the 2001 paper that noted that quasars do not exhibit time dilation.
http://arxiv.org/abs/1009.3265v2

The fact that this paper was never published and never cited should cause you pause (well, technically, it was cited once in a paper, but that appears to be a mistake because the reference in the text is no longer there).


There is no mention of time dilation here.

On time dilation in quasar light curves
In this paper we set out to measure time dilation in quasar light curves. In order to detect the effects of time dilation, sets of light curves from two monitoring programmes are used to construct Fourier power spectra covering time-scales from 50d to 28yr. Data from high- and low-redshift samples are compared to look for the changes expected from time dilation. The main result of the paper is that quasar light curves do not show the effects of time dilation. Several explanations are discussed, including the possibility that time dilation effects are exactly offset by an increase in time-scale of variation associated with black hole growth, or that the variations are caused by microlensing in which case time dilation would not be expected.

1 INTRODUCTION
Time dilation (the stretching of time by a factor of (1 + z)) is a fundamental property of an expanding universe. Given the success of the the currently accepted cosmological model, which certainly implies expansion, it is perhaps surprising that more attention has not been paid to making direct measures of time dilation. This must surely be due in part to the fact that measures of time dilation can tell little or nothing about cosmological parameters within the framework of a Big Bang universe, but only whether or not the Universe is expanding. Also, it turns out to be surprisingly hard to formulate a conclusive test for time dilation. What is needed is an event or fluctuation of known rest frame duration which can be observed at sufficiently high redshift with an accuracy which enables the predicted stretching by a factor of (1 + z) to be observed.


5 INTERPRETATION OF RESULTS
The results of Section 4 provide strong evidence that the effects of time dilation are not seen in quasar light curves. This clearly runs against expectations based on a conventional cosmological viewpoint, and so in this section we examine ways in which the results may be understood.