Galaxy Zoo Starburst Talk

Unusual Peak in spectrum

  • Johanson69 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

  • JeanTate 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

  • Johanson69 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

  • JeanTate 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