Astronomy Research Team - Galactic Black Holes
How many fibers should you look at?
100 emission galaxies - this means 100 fibers that have emission lines (not absorption lines). These can be identified by SDSS as galaxies or qso BUT NOT STARS. We are taking the position that these may or may not be quasars or qsos. Remember a quasar or qso is another name for a black hole.
What makes a fiber a qso candidate?
Two Criteria have to be met
Criteria #1 - Look at the velocity
The velocity is one of columns with a calculated number (we use a formula). In order to be considered a qso, the object's velocity has to be more than 100 km/sec. If is 100 or less, then the object is just a galaxy without an identifiable black hole. Velocities of 10-20,000 are very rare, so if you get one check your math. If it's velocity is more than 100 km/sec than it might be a qso if it meets criteria #2.
Criteria #2 - Either one of the following relationships about flux has to be met to be a qso.
A. N2=1/2 H alpha **** Look at the stronger N2 line (usually the one with a longer wavelength). Is the N2 flux about 1/2 of H alpha's flux? If so, then it is a candidate for a qso
B. O3=H alpha ***** Look at the 5007 O3 line. Is the O3 line equal (or almost equal) to the H alpha line? If so, then it is a candidate for a qso
PROBLEM - H alpha is off the chart *** SOLUTION - Use the H beta line. H beta is always 1/3 of H alpha. This is a fixed ratio in the universe.
N2=1.5 H beta
O3=3 H beta
If Critieria #1 has been met and A or B from Criteria #2 has been met then your object is a qso candidate. Say that in one of your columns on your chart. Check with your Payton team then with the interschool team. Hopefully you will agree with some of them.
Tools
Plate Tool
******** Ms. Barge’s video with instructions Calculating FWHM is at min 7:40-10:50
AAS - go here to look up our poster in the online program
Things to Read
1. Berman, Bob; Astronomy 10/2014; Why everything you know about black holes might be wrong - in our google drive
2. Sky and Telescope's free ebook on black holes - you have to register with them. Or it is in our google drive.
3. Baldwin, J. A.; Phillips, M. M.; Terlevich, R.; Classification parameters for the emission-line spectra of extragalactic objects - Choose the pdf link at the top of page "Full Refereed Journal Article (PDF/Postscript)"
4. BPT Diagram definition ---- Nice BPT diagram explanation
5. York, Donald G.; Adelman, J.; Anderson, John E., Jr.; Anderson, Scott F.; Annis, James; Bahcall, Neta A.; Bakken, J. A.; Barkhouser, Robert; Bastian, Steven; Berman, Eileen; and 135 coauthors;
The Sloan Digital Sky Survey: Technical Summary - Choose the pdf link or the html link at the top of the page6. AGN Notes
ADS - Search page for astronomical articles; Just type in your topic
arXIV - Another search tool for astronomical articles
Question to Dr Don York - Why are there particular ratios such as N2 =1/2 H alpha? Don's answer: "Good question. I am glad the students asked this. We don't know why there are certain ratios. This is a property that we see when we look at these objects but we don't know why they are there. This is called an empirical relationship - something that comes from an observation in the universe, not derived from physics formulas. I hope one of your students will grow up to find the answer to this question." Maybe that will be you!