Radio Galaxy Zoo Talk

ARG0000bpf

  • Dolorous_Edd by Dolorous_Edd

    Well, I have seen things, but IMO SDSS J105452.02+552112.2 takes the cake, it is HUGE for z_sp = 0.468 object ( your mileage may vary, though )

    enter image description here

    Is it a single object or my eyes deceiving me?

    Posted

  • ivywong by ivywong scientist, admin

    Hi @DolorousEdd,

    Yes, stellar population modelling results from DR10 actually place this galaxy at log (Stellar mass) ~ 12.0. So you're right, this is a very large galaxy!!

    cheers,
    Ivy

    Refs:

    http://skyserver.sdss.org/dr10/en/tools/explore/ex_sql.aspx?cmd=select+*+from+stellarMassStarformingPort+where+specObjId=1021245406266288128&name=stellarMassStarFormingPort&tab=V&id=1237657220949869202&spec=1021245406266288128&apid=

    http://skyserver.sdss.org/dr10/en/tools/explore/ex_sql.aspx?cmd=select+*+from+stellarMassPassivePort+where+specObjId=1021245406266288128&name=stellarMassPassivePort&tab=V&id=1237657220949869202&spec=1021245406266288128&apid=

    Posted

  • Dolorous_Edd by Dolorous_Edd in response to ivywong's comment.

    Thanks!

    Curious, if there any example of similar sized galaxy in "local" universe? Just to get the idea of the scale.

    Posted

  • Dolorous_Edd by Dolorous_Edd

    Found a similiar galaxy

    enter image description here

    http://radiotalk.galaxyzoo.org/#/subjects/ARG0001j1j

    Posted

  • ivywong by ivywong scientist, admin in response to Dolorous Edd's comment.

    You're welcome.

    Not a spiral that I can think of. The largest nearby galaxy I can think of is M87, the central elliptical in the Virgo Cluster. Recent stellar mass estimates put it at ~ 7x10^11 solar masses so it's close but not quite (Ref: http://arxiv.org/abs/1112.1884)

    Posted

  • Dolorous_Edd by Dolorous_Edd

    Offtopic, just don't want to create a separate thread, but seriusly what is wrong with this galaxy? It is like an eye!

    Superposition of star ( M dwarf ) + galaxy , or artifact? or z ~0.4 ~0.5 ETG

    enter image description here

    SDSS J134346.72+425608.3

    Posted

  • JeanTate by JeanTate

    FWIW, back when the GZ forum was working, I had a big - 'on my own' - independent research project, which I called 'Hudsmania' (Huge distant spirals). Here is a GZ forum thread on it (there are others): Seeing Is Believing (Or Is It?).

    Back then, Zooiverse Letters looked like it was going to live up the hype hopes of zkKevin and Meg, and I wrote several Letters on what I'd found: Discovery of Four Giant, Distant Spirals, Six SDSS 0.30 < z < 0.32 Huds (of the Eos Kind), and Physical Properties of the First Four HUDS. It's a project that's on the back-burner right now - along with my work on SDRAGNs - and I don't recall exactly what I found (but have not yet written up); hovvever ... at z_sp =0.468, SDSS J105452.02+552112.2 is indeed humongous; the other one, not so much.

    In terms of estimated log (stellar) masses, the first four Huds are not quite 12.0 ... in Table 6 (of my third Letter) I report they range from 11.6 to 11.8, which makes them comparable to that of M87 (per Ivy). Are the HUDS with log(stellar mass) > 12.0, in the SDSS footprint? Almost certainly. 😃 Ain't astronomy fun! 😄

    Posted

  • JeanTate by JeanTate in response to Dolorous Edd's comment.

    My totally non-expert SWAG: it's got an optically bright AGN, and that's messing the apparent SDSS colors (there are a lot of Eos, or near-Eos examples, here in RGZ, with bright nuclei causing changes in the apparent SDSS colors, and a lot more in the GZ forum).

    What's a bit different here is that the AGN isn't quite as point-like, and it's not white/yellow/pink/etc. That could be due to rather more dust than usual (there are bright-nuclei Eos with somewhat similar colors; being Eos you can be pretty sure there's lots of dust). Alternatively, and potentially much more exciting - the AGN could be a relatively low luminosity FeLoBAL QSO. Why exciting? Because, AFAIK, there are no FeLoBAL QSOs whose host galaxy is so clearly seen in an SDSS image (not least because such QSOs all have much higher redshifts).

    Want to do some independent research into these kinds of objects? I'd be more than happy to provide advice! 😃

    Posted

  • Dolorous_Edd by Dolorous_Edd in response to JeanTate's comment.

    I checked WISE and can say that it is clearly visible in bands 1&2 but not in 3&4

    To my understanding AGN or high level of dust would make it visible in 3&4, which is not the case

    Edit*

    NED gives photo_z = 0.389 ( 2010ApJS..191..254H )

    Posted

  • JeanTate by JeanTate

    To my understanding AGN or high level of dust would make it visible in 3&4, which is not the case

    I think this is true in general; however, band 4 in particular is sensitive to cool (cold?) dust; there are surely plenty of ~Eos galaxies with prominent dust lanes (esp at z>~0.3) which are not band 4 sources. AGN? Just as not every (optical) AGN is not an x-ray source, so too not every optical AGN is a WISE band 3 or 4 source, AFAIK. While I cannot recall a specific paper on this, I do recall reading papers which show optical/WISE matches, perhaps even ones which select for AGN; while the degree of position matching is high, it is not 100% (not to mention that position matching alone cannot identify chance alignments, and there are surely plenty of those).

    Posted

  • ivywong by ivywong scientist, admin

    Hi all,

    Nice discussion about mid-infrared (MIR) colours! So perhaps a useful spot to lay out some things we know about the various WISE bands. (Note that these are general statements)

    WISE Bands 1 & 2 are typically indicative of the old stellar population in a galaxy.
    WISE Band 3 : For low-z galaxies, this band typically is dominated by PAH emission (soot stuff you get from BBQs) from star-forming regions. However for higher-z galaxies, this emission will come from hot dust (reradiated from young stellar population) as the emission becomes redshifted.
    WISE Band 4: For low-z galaxies, this emission comes from hot dust (reradiated from young stellar population) so is typically only present in star-forming galaxies.

    The presence of AGN confuses this somewhat. Here is a link to the MIR color-color diagram from our early science paper: https://galaxyzooblog.files.wordpress.com/2015/03/blog_fig2.jpeg

    Posted

  • JeanTate by JeanTate in response to ivywong's comment.

    Nice, thanks Ivy! 😃

    I just posted Comparing narrow and broad-line AGNs, in a new diagnostic diagram for emission-line galaxies based on WISE data in the Journal Club; I wonder if it's possible to somehow combine the results, in a single plot? Sure, they do not use the same pairs of WISE/IR colors, but still ...

    Also, in the plot, I know what AGNs, QSOs/Seyferts, Ellipticals, and LIRGs (luminous infrared galaxies, right?) are, but have no idea what a "PRG" is! Anyone?

    Posted

  • ivywong by ivywong scientist, admin

    Looking back upon the blog post which contains the caption to the figure, PRG stands for "powerful radio galaxies" 😃

    http://blog.galaxyzoo.org/2015/03/02/first-radio-galaxy-zoo-paper-has-been-submitted/

    So this just means that they are AGN that are bright at radio frequencies 😃

    Posted

  • Dolorous_Edd by Dolorous_Edd

    found another such galaxy, though a bit smaller

    https://radiotalk.galaxyzoo.org/#/subjects/ARG0003nrz

    enter image description here

    SDSS J003339.21+024321.1 - 1237678434329166158

    Posted