Galaxy Zoo Talk

Round blue blob is emission line galaxy?

  • Budgieye by Budgieye moderator

    Can we find more info on this blue blob?

    It is classified as an emission line galaxy in NED by ramberts 6 minutes ago

    enter image description here

    interesting.!. galaxy with small round blue blob, supernova?, star?, voorwerpje? by Budgieye MODERATOR 8 minutes ago

    EDIT:

    Blue blob: z=1.294 tools photoz 2.45

    Orange galaxy z=1.246

    Posted

  • Budgieye by Budgieye moderator

    I'll check Spectroscopic Study of the HST/ACS PEARS Emission-line Galaxies Xia, Lifang http://adsabs.harvard.edu/cgi-bin/bib_query?2011AJ....141...64X

    EDIT:

    "and one object, 72509, with redshift difference of 0.05. Object 72509 has a redshift of 1.246 and only the [O ii] 3727 is observed in the red end of the spectra. The ACS grism spectrum of this object is noisy and there are several peaks around 8400 Å which could be due to the contamination of sky line residuals."

    If the emission line is Oii, then the blue area is a starburst region, so a "pea"

    Posted

  • ramberts by ramberts

    From what I've read, correct me if I'm wrong, ELG's seem pretty common. They contain knots that they are studying a lot, "Here, we present a new methodology and results of a
    search for these ELGs in the PEARS observations of the Hubble Ultra Deep Field (HUDF) using a 2D detection method that utilizes the observation that many emission lines originate from clumpy knots within galaxies." (article below) Also sounds like a certain percentage of these ELG's are good candidates for finding AGN's (not terribly high percentage).

    I don't know how to copy and paste pictures from PDF articles so I'll just post a link. I am not sure if the knots are the same star forming regions we see a lot, but they can be blue, purple, greenish and pink. I am assuming they are not normal star forming regions because they did not circle some.
    http://iopscience.iop.org/1538-3881/138/4/1022/pdf/aj_138_4_1022.pdf

    Posted

  • Budgieye by Budgieye moderator

    Here is the computer readable link http://iopscience.iop.org/1538-3881/138/4/1022/article

    enter image description here

    looking for PEARS 072509

    Posted

  • ramberts by ramberts

    So I think the knots are from star forming regions, but not all star forming regions are line emitting knots.

    Posted

  • Budgieye by Budgieye moderator in response to Budgieye's comment.

    If the blue area is an area of star formation as seen by Oii production, then it is a "pea", a blue pea in Hubble! Nice to find one! So not a hot hydrogen event associated with black holes.

    Posted

  • ramberts by ramberts

    Interesting, it is also one of the farthest examples of ELG's they found so far as well.

    Posted

  • Budgieye by Budgieye moderator

    Two peas in two pods. Two similar galaxies with a "pea" in SDSS at z=0.003 and in Hubble at z=1.294

    enter image description here

    http://skyserver.sdss.org/dr8/en/tools/explore/obj.asp?id=1237665025445462051
    http://skyserver.sdss.org/dr8/en/tools/explore/obj.asp?id=1237665025445462053

    Spectral chart of SDSS object, showing emission peaks of hot oxygen from many large stars that that rapidly formed and exploded. http://skyserver.sdss.org/dr8/en/get/specById.asp?id=2258666322118338560

    Posted

  • Budgieye by Budgieye moderator

    The Hubble pea is about 200X further away than the SDSS pea

    __249,000,000,000,000,000,000 miles away SDSS pea

    52,800,000,000,000,000,000,000 miles away Hubble pea

    SDSS pea
    Lookback time
    http://www.wolframalpha.com/input/?i=redshift+z%3D0.003&a=FSelect_**LookbackTimeFromRedshift--
    distance 41.5 million light-years
    41,500,000 light-years x 6,000,000,000,000 (6 trillion miles in a light year)
    249,000,000,000,000,000,000 miles away

    Hubble pea
    http://www.wolframalpha.com/input/?i=redshift+z%3D1.294&a=FSelect_**LookbackTimeFromRedshift--
    distance 8.8 billion light-years
    8,800,000,000 light-years x 6,000,000,000,000
    52,800,000,000,000,000,000,000

    Posted

  • ramberts by ramberts

    A pea?

    http://www.galaxyzoo.org/#/examine/AGZ00084zv

    I think this could be an example of another blue pea + ELG knot from Hubble. So if I am understanding this right, an ELG can emit different gaseous waves, but peas emit OII, so a pea is always an ELG, but an ELG is not always a pea?

    Posted

  • Budgieye by Budgieye moderator

    I think you have summed it up correctly.

    Usually peas ( Oiii ) will have at least a small amount of Hα emission from an active nucleus.

    And usually an active nucleus will have at least a small amount of Oiii emission too, but not necessarily.

    And sometimes, a galaxy can have large amounts of both Oiii emission and Hα emission.

    see Re: Colours of Galaxies : Redshift chart: complicated examples http://www.galaxyzooforum.org/index.php?topic=277142.msg425867#msg425867 Some of the links need repair, which I am unable to do since the forum is locked. Just copy the 58............ number into ObjID to get the correct galaxy.

    Posted