24
votes
Accepted
What happens when the quasar remnants reach Earth in 3 million years?
Probably nothing of practical interest. Keep in mind that the gas in the shock wave in question is much less dense than our Solar wind. The X-rays generated in the shock wave aren't much intense ...
- 2,869
22
votes
Accepted
How can the Sun block an X-ray telescope from observing a QPO galaxy "for several years"?
It is not that it is blocked by the Sun, but that the duration of time for which it can be continuously observed was too small to be useful for the investigations performed in the paper.
The object ...
- 158k
20
votes
What are optical counterparts?
Observations can be made using different parts of the electromagnetic spectrum. Many of them not within the range of the spectrum that can be made with optical telescopes. Other messengers than ...
- 371
13
votes
Accepted
Are these images of the same nebula?
Yes, sort of. But the Chandra image is of just a small portion at the centre of the Spitzer image.
Astronomical objects often have different appearances at different wavelengths.
In the case of the ...
- 158k
12
votes
What happens when the quasar remnants reach Earth in 3 million years?
In astronomy, we generally use observer time uncorrected for distance (because we usually don't know the distance very well). The 6 Mya is the time that the x-rays from the event arrived at Earth, so ...
- 2,607
9
votes
Accepted
Plot of best available resolution vs wavelength - radio through gamma rays?
After a bit of searching, I found this blog page, which has several charts about various observatories, including this one:
Image courtesy of Olaf Frohn under the Creative Commons Attribution-Share ...
- 37.3k
8
votes
Accepted
What are the curved lines in this X-ray image of the sky?
GIFs too big to post here directly: 1, 2
NICER is all about time resolution and energy resolution and is used to collect the time and energy-resolved X-ray spectra from pulsars. It isn't an imaging ...
- 30.6k
8
votes
Light curves for Chandra
PI files, or more commonly PHA files, are higher level data products derived by binning the (cleaned) event list by the registered PI/PHA channel of each event, which should correspond to their energy....
- 3,441
7
votes
Is there evidence of super-heavy elements in the x-ray and gamma-ray spectrums of neutron stars?
The crusts of neutron stars will contain "super-heavy", neutron-rich nuclei. This is an inevitable consequence of the high density material, the accompanying degenerate electrons (that block $\beta$-...
- 158k
7
votes
Accepted
Supernova remnant spectral lines
I would go to the AtomDB and then look for lines with high emissivity in a specific wavelength region.
So under "List lines in wavelength region:" select a not too wide energy band and play ...
- 3,441
6
votes
Accepted
Are X-ray rings around GRBs analogous to sun halos?
Imagine the X-ray pulse from the GRB travelling outwards like a spherical shell. If it then encounters a slab of dust on its way into our galaxy, then the intersection of the X-ray shell and the slab ...
- 158k
5
votes
After only one eclipse of its X-ray bright primary, how can astronomers estimate the first extragalactic exoplanet's period to be about 70 years?
If you go to the original article, you can see that it's something like this
They have a plausible size for the X-ray-emitting source (that is, the X-ray-bright part of the accretion disk): $R = 2.5 \...
- 18.1k
4
votes
Accepted
What does less than one count from an x-ray detector mean? (Swift BAT detector)
I think there is a missing piece of information. The BAT is a coded mask telescope. The imaging is done by photons passing through a mask and falling onto an array of 32768 detectors. http://swift....
- 158k
4
votes
After only one eclipse of its X-ray bright primary, how can astronomers estimate the first extragalactic exoplanet's period to be about 70 years?
The answer can be found in the "Methods" section of the original Nature paper (Stefano et. al). I will try to give a brief sketch of what they did:
First thing is, that the eclipsing object ...
- 3,441
4
votes
Accepted
Are X-ray telescopes with glancing angle surfaces basically "funny-looking" Cassegrain telescopes mathematically?
Short answer, yes, the x-ray grazing incidence mirrors set up like this still function like a Cassegrain to minimize off-axis aberration. However, it is still different in that a classical Cassegrain ...
- 619
4
votes
Supernova remnant spectral lines
In addition to AtomDB, another useful resource is the x-ray data booklet provided by LBNL. Specifically, this table has some common x-ray emission lines. My recommendation would be to fit the spectrum ...
- 41
3
votes
Accepted
Could observation of GL or other image phenomena from system of 2 merging massive dense objects and of GW caused by their merge be connected?
It would be very interesting if it happened, but such an event would be very rare.
Black holes are relatively rare, and black hole binaries are rarer. All the black hole mergers that we have detected ...
- 127k
3
votes
Accepted
How does IXPE measure polarization, and why does it have three identical X-ray telescopes?
How does IXPE measure polarization?
Short answer: Electrons in the detector are preferential emitted in the direction of the polarization of the incident photon and then detected.
Quoting from NASA's ...
- 2,349
3
votes
Accepted
How is it determined that the X-ray and radio intensity come from a magnetic field bridge between two clusters of galaxies?
I think the answer is that it's primarily a matter of association on the sky, though there are some (weak) additional constraints.
The first thing to note is that there are three observations that ...
- 18.1k
3
votes
Accepted
How do neutron stars maintain inhomogeneous surfaces and migrating "hot spots"? (e.g. SGR 1830-0645)
It is almost certainly the strong magnetic fields. These contribute a magnetic pressure that allows charged/ionised material to flow readily along field lines, but not to cross them.
In the paper you ...
- 158k
3
votes
Accepted
Any active solar X-ray imager in orbit?
The Hinode satellite has an active x-ray telescope that is routinely used to image the sun. And the NuSTAR extreme x-ray telescope can also be used for sun imaging (although its main job is looking ...
- 127k
3
votes
Accepted
Why is there a density dropoff in the stellar winds of magnetic O-type stars?
Conservation of mass?
In a steady-state wind, the mass loss rate through each shell is the same.
$$ \frac{dM}{dt} = - 4\pi r^2 \rho(r) v(r),$$
where $\rho$ and $v$ would be the density and velocity ...
- 158k
2
votes
How to shift an AGN X-ray spectrum to rest frame
The frequency is related to the redshift by $$\frac{\nu_{\rm obs}}{\nu_{\rm emit}} = \frac{1}{1+z}$$
Another useful relation is the fact that, for any redshift,
$$\frac{I_{\nu}}{\nu^3} = {\rm ...
- 121
2
votes
If sun-rays also contain any X-rays why we can't see the inner organs of the human body through these rays?
X-Rays from the sun don't reach the Earth's surface, as our atmosphere is opaque to this kind of electromagnetic radiation.
This is why X-Ray observatories like the Chandra telescope have to be placed ...
- 9,849
2
votes
In Chromoscope, what is the X-ray source between Ophiuchus, Libra and Scorpius?
The source is Sco X-1. It is a point source of X-rays.
I'll have get back to you on why it looks that way in chromoscope, but it looks incorrect to me.
- 158k
2
votes
What is a hard spectral state vs. a soft spectral state?
Just to add an example to what has already been said by eshaya and Larz.Astro.
Here is the spectrum of the Black Hole binary Cygnus X-1 in its hard and its soft state.
The plot is taken from ...
- 3,441
2
votes
What are the main ways that pulsar "glitches" are noticed and documented? Do they have to be caught in the act of glitching to be catalogued?
The majority of pulsar glitches are detected via radio observations, but then again the majority of pulsar observations are conducted in the radio so this is not so surprising. X-ray and gamma-ray ...
- 76
2
votes
Accepted
What is in this soft x-ray image?
Looking at the image, it appeared to be a supernova remnant, and sure enough when I plugged the coordinates into SkyMap, it identified NGC 6960, the Veil Nebula. The interaction of the hot ionized ...
- 3,455
2
votes
Accepted
Is it possible to observe Lyman-continuum emission from extragalactic objects?
I think the short answer is "You can't observe $z=0$ LyC leakers, but you can observe $z\sim0$ LyC leakers."
No z = 0 leakers…
Measuring the Lyman continuum (LyC) — i.e. photons capable of ...
- 39.1k
2
votes
Accepted
What is the lifetime of an x-ray binary?
I am not an expert on the topic but probably you have to specify in your search which mass regime are you looking for (low or high mass x-ray binaries). Accretion time must be important and depends on ...
- 56
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