Unusual Peak in spectrum

• by Johanson69

  Referring to this object

  http://quench.galaxyzoo.org/#/examine/AGS00001w5

  Spectrum: http://skyserver.sdss3.org/dr9/en/get/specById.asp?id=2474728335851153408

  It has a (to me) unexplainable peak at ~583nm. At longer wavelengths the intensity appears to be increased when compared to shorter wavelengths.

  Has anybody an explanation for this?

  Posted July 18, 2013 11:34 PM

• by JeanTate in response to Johanson69's comment.

  It's a failure of the spectroscopic pipeline; specifically, it did not stitch the 'red' and 'blue' spectra together correctly. See BOSS Spectrograph for more details.

  Posted July 19, 2013 12:00 AM

• by Johanson69

  Now this clears up some confusion, thank you. Any information on how common this is? Is it possible that the error is large enough so that the determination of the redshift is way off or that no spectral lines can be assigned?

  Posted July 19, 2013 12:10 AM

• by JeanTate in response to Johanson69's comment.

  I don't know how common it is, but I've certainly come across quite a few ('oldbie' zooites like you flag these quite reliably, I'm sure, so perhaps it's more that few escape your ivy eagle eyes [1]). In this case, it has no effect on the redshift determination; the emission lines are screamingly obvious, and the pipeline did not assign anything to the spurious break.

  A more serious concern is that the continuum is - obviously - totally messed up across the red/blue break, so if this is a 'quenched' candidate, it's stellar mass estimate may be completely invalid (as I understand it, such estimates rely heavily on good continuum fits).

  [1] check out Ivy Wong's avatar; maybe it's just a seagull?

  Posted July 19, 2013 12:23 AM