Abstract
There is a supermassive black hole of mass 4 × 106 solar masses at the centre of the Milky Way1,2. A large reservoir of hot (107 kelvin) and cooler (102 to 104 kelvin) gas surrounds it within a few parsecs3. Although constraints on the amount of hot gas in the accretion zone of the black hole—that is, within 105 Schwarzschild radii (0.04 parsecs)—have been provided by X-ray observations4,5,6, the mass in cooler gas has been unconstrained. One possible way this cooler gas could be detected is by its emission in hydrogen recombination spectral lines7,8. Here we report imaging of a 104-kelvin ionized gas disk within 2 × 104 Schwarzschild radii, using the 1.3-millimetre recombination line H30α. This emission line is double-peaked, with full velocity linewidth of about 2,200 kilometres per second. The emission is centred on the radio source Sagittarius A*, but the redshifted side is displaced 0.11 arcsec (0.004 parsecs at a distance of 8 kiloparsecs) to the northeast and the blueshifted side is displaced a similar distance to the southwest. We interpret these observations in terms of a rotating disk of mass 10−5 to 10−4 solar masses and mean hydrogen density of about 105 to 106 per cubic centimetre, with the values being sensitive to the assumed geometry. The emission is stronger than expected, given the upper limit on the strength of the Brγ spectral line of hydrogen. We suggest that the H30α transition is enhanced by maser emission.
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Data availability
This paper makes use of the following ALMA data: ADS/JAO.ALMA #2015.1.00311.S. The data are publicly available from the ALMA archive at https://almascience.nrao.edu.
Code availability
We used the Common Astronomy Software Applications package (CASA) for the data reduction and analysis. We used Astropy, Python and Mathematica for plotting and data analysis. For the modelling of the spectra, we used the proprietary Code for AGN Reverberation and Modelling of Emission Lines (CARAMEL27). The key result presented in this paper is observational. The results of the CARAMEL modelling are not critical for interpretation of the observational data and therefore we are not releasing the code with this paper.
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Acknowledgements
We are grateful to N. Scoville for co-writing the observing proposal and his contribution to discussions of analysis and interpretation of the data and to J. Koda and J. Ott for discussing the data analysis, looking at the data and commenting on the paper. We are grateful to A. Ciurlo, A. Ghez, M. Morris and S. Gillessen for calculating the limit on Brγ and sharing it with us and discussions, and to E. Quataert, S. Ressler and J. Lu for bringing the Brγ non-detection to our attention and discussions. We thank Y. Levin, J. Cuadra, P. Goldreich, D. Lin, J. Guillochon, S. Naoz, G. Witzel, M. Coleman, S. Philippov, S. Tremaine, A. Loeb, Z. Haiman and J. Carlstrom for discussions and comments, and the North American ALMA Science Center scientists at the National Radio Astronomy Observatory, in particular A. Remijan, C. Vlahakis, M. Lacy, S. Stierwalt, A. Moullet, E. Keller and B. Kirk for their help and advice with the observational setups and data reduction. We also thank Z. Scoville for proofreading the manuscript. E.M.M. acknowledges the Bezos Fund for providing her stipend at the Institute for Advanced Study, D. and B. Groce for encouragement and for supporting her as a Groce Fellow at Caltech; and the NRAO Student Observational Support programme for supporting two years of her graduate studies. A.P. is supported by NASA through Einstein Postdoctoral Fellowship grant number PF5-160141 awarded by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for NASA under contract NAS8-03060. ALMA is a partnership of the ESO (representing its member states), the NSF (USA) and the NINS (Japan), together with the NRC (Canada) and the NSC and the ASIAA (Taiwan) and the KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by the ESO, the AUI/NRAO and the NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.
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E.M.M. was the principal investigator of the observing proposal, analysed the observational data, conducted theoretical calculations, produced the figures, and wrote most of the paper. E.S.P. conducted theoretical calculations and made major contributions to the interpretation of the observational results and to writing the paper. A.P. modelled the observed spectra, wrote the modelling section, and contributed to interpretation of the observational results. R.D.B. made a substantial contribution to the interpretation of the observational results. All co-authors commented on the manuscript.
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Murchikova, E.M., Phinney, E.S., Pancoast, A. et al. A cool accretion disk around the Galactic Centre black hole. Nature 570, 83–86 (2019). https://doi.org/10.1038/s41586-019-1242-z
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DOI: https://doi.org/10.1038/s41586-019-1242-z
Xinhang Shen
Dear Elena M. Murchikova, E. Sterl Phinney, Anna Pancoast & Roger D. Blandford as well as Nature Editors,
Black holes as singularities of spacetime do not exist in nature because there is no such thing called spacetime in nature. Spacetime is a concept derived from Einstein's relativity which has already been disproved for more than three years (see peer-reviewed published papers: https://www.researchgate.ne... and https://www.researchgate.ne... ). Here is a summary of the reasoning to disprove special relativity for your convenience:
Let's first look at the twin paradox which is designed to demonstrate that relative speed would generate time dilation as predicted by special relativity which claims that when the speed of a clock relative to an observer was close to the speed of light, the observer would see the clock slow down close to stop. But, as shown on Wikipedia, the final conclusion of the twin paradox becomes that, after a high speed space travel, it is the acceleration of the traveling twin (not his speed relative to his brother) that made him younger than his twin brother staying on the earth because both twins had experienced exactly the same speed relative to each other during the entire trip. Is it funny that the original argument that relative speed generates time dilation is completely lost, although relativists still think that the paradox has been solved? In fact, this conclusion simply tells us that relative speed won't generate time dilation and special relativity is wrong.
The fatal mistake of Einstein’s relativity is that it uses Lorentz Transformation to redefine time and space and the newly defined time is no longer the physical time we measure with physical clocks. We know the physical time shown on any physical clock is T = tf/k where t is the theoretical time, f is the frequency of the clock and k is a reference frame independent calibration constant.
In Newton’s mechanics, f is a reference frame independent constant too. Therefore, we can set k = f to make the clock show the theoretical time i.e. the absolute Galilean time t: T = tf/k = tf/f = t.
But in special relativity, frequency f is a reference frame dependent variable and can’t be eliminated by setting k = f. Thus, T can never be relativistic time t: T = tf/k != t. Therefore, relativistic time t is never the clock time i.e. the physical time which we are using to observe all physical phenomena. On the other hand, when a clock is observed in another inertial reference frame, we have t’ = rt and f’ = f/r and T’ = t’f’/k = rt(f/r)/k = tf/k = T, where r = 1/sqrt(1 - v^2/c^2), which means that the physical time T won’t change with the change of the inertial reference frame, and is Lorentz invariant and absolute. That is, a clock still measures the absolute time in special relativity.
This absoluteness of the physical time can be more clearly illustrated by the following thought experiment:
There are a series of vertically standing candles with the same burning rate and moving at different constant horizontal velocities in an inertial reference frame of (x, y, z, t) where x, y, z, t are relativistic space coordinates and time. At any moment t of relativistic time, all candles have the same height H in the reference frame of (x, y, z, t) and the height has been calibrated as the physical time. Therefore, we have the simultaneous events measured in both relativistic time t and physical time H in the frame of (x, y, z, t): (Candle1, x1, y1, H, t), (candle2, x2, y2, H, t), ... (CandleN, xn, yn, H, t). When these events are observed in anther horizontally moving inertial reference frame (x', y', z', t'), according to special relativity, these events can be obtained through Lorentz Transformation: (Candle1, x'1, y'1, H, t'1), (Candle2, x'2, y'2, H, t'2), ... (CandleN, x'n, y'n, H, t'n) where t'1, t'2, ... and t'n are relativistic times of the events observed in the frame of (x', y', z', t'). It is seen these events have different relativistic times after Lorentz Transformation in the frame of (x', y', z', t'), i.e., they are no longer simultaneous measured with relativistic time in the frame of (x', y', z', t'), but the heights of the candles remain the same because the vertical heights here do not experience any Lorentz contraction. Since the heights of the candles are the measures of the physical time, we can see these events still have the same physical time, i.e., they are still simultaneous measured with the physical time. Therefore, the physical time is invariant of inertial reference frames and absolute, which is completely different from relativistic time.
As relativistic time is not the physical time we measure with physical clocks, all what special relativity describes is irrelevant to real physics.
The fact that the physical time (i.e. clock time) is absolute has been clearly confirmed by the physical evidence that all the atomic clocks on the GPS satellites are synchronized not only relative to the ground clocks but also relative to each other (i.e. they are synchronized relative to all reference frames) to show the same absolute physical time, which directly denies the claim of special relativity that clocks can never be synchronized relative to more than one inertial reference frame no matter how you correct them because "time is relative" i.e. "simultaneity is relative only to one inertial reference frame".
Some people argue that the atomic clocks are corrected according to both STR and GTR. Please be aware that the relativistic kinematic time dilation of an atomic clock on a GPS satellite is relative i.e. is different relative to different inertial reference frame, which you can't correct to make the clock show the same time of all other inertial reference frames. In fact, the correction of each clock is not relative but absolute (i.e. the same observed in all inertial reference frames) and thus it does not contain any of the relativistic kinematic time dilation. It seems that the correction of each clock is the lump sum of all the influences of the atomic clocks running in the environment of the GPS satellites including gravitation and its motion relative to aether - the medium of light which fills up the entire visible part of the universe. The correction is very similar to the correction for a mechanical pendulum clock with the pendulum exposed to the air, which is influenced by both gravitation and its motion relative to the air. Therefore, there is no relativistic kinematic time dilation existing in the atomic clocks on the GPS satellites at all.
Some people argue that Wikipedia about GPS is wrong and the atomic clocks are not synchronized relative to all reference frames, but only synchronized relative to the ground reference frame i.e. the atomic clock on a GPS satellite and a ground clock are synchronized only when they are observed on the ground but unsynchronized when they are observed on the satellite. If this was true, then the difference of the two clocks observed on the satellite would grow with the increase of the number of the trips of the satellite around the earth, while these two clocks were still synchronized observed on the ground. As there are only two clocks with two displays, where could the clocks keep such a growing difference observed on the satellite but have no difference observed on the ground? Obviously, no such a case can exist.
More mathematical proofs that in special relativity, the real speed of light still follows Newton's velocity addition law, and both time dilation and length contraction are simply illusions can be found in my peer-reviewed publications as shown above.
From the above reasoning, we have seen that Einstein's relativity is completely wrong. All so-called relativistic effects are just misinterpretations of effects of other things (e.g. aether). I think it is very inappropriate to ignore this discovery, continue wasting taxpayers' money on wrong researches and keep publishing wrong papers and articles to mislead the public.
If you find any error in my reasoning, please point it out and let's debate!
Sincerely,
Xinhang Shen