Paper on Giant Radio Jets from a spiral just appeared on the preprint server yesterday.....

by 42jkb scientist, admin

Here is the link: http://arxiv.org/abs/1404.6889

Interesting find, will need to read the paper more thoroughly.

Posted September 16, 2014 3:00 AM
by JeanTate in response to 42jkb's comment.

That's the v2 preprint.

Zutopian started a thread on the v1 preprint, when it appeared in April: Paper: Spiral with jets discovery by Bagchi et al.. The system (galaxy, radio lobes) is also discussed in another thread, J2345-0449 - a spiral host of giant double-doublelobes.

By the way, Search will tell you these threads exist (if you search on "Bagchi"), but clicking on the link to the second one takes you nowhere! 😦 To actually find it, knowing it exists, is, um, cumbersome (or at least it was for me). Any chance we can get a decent search tool, for RGZ Talk?

Posted September 23, 2014 10:47 PM
by JeanTate in response to 42jkb's comment.

Here are my notes, taken while reading the v2 preprint (it's quite OK for you to go "tl;dr"):
- (intro) "Moreover, while both ellipticals and spirals may host
  radio-quiet quasars, radio-loud quasars are never found in spiral
  galaxies, but only in ellipticals" really?!?
- (p4) how can they tell the radio emission is "synchrotron"?
- (p5) presumably it's quite OK to infer "very steep spectral slope"
  because such giant structures are not significantly variable over ~a
  decade (flux calibration had better be good!)
- (p5) "NLSy1s"? aren't Sy1s NL, by definition? No, as I subsequently discovered. But the whole nomenclature etc on "Seyferts" seems to me (as a complete outsider) to be quite byzantine; how do astronomers manage to keep it all straight in their heads? 😮
- (p5) "Despite decades of extensive observations, only two previous
  reports exist of a disk galaxy ejecting large scale (>100 kpc)
  bipolar radio jets: the radio source J031552-190644 found in the
  galaxy cluster Abell 428 (Ledlow et al. 1998), and a recently
  reported Mpc-scale episodic radio source known as Speca (Hota et al.
  2011). In both these exceptionally rare objects, the galactic disk is
  viewed nearly edge-on, precluding a clear view of the putative spiral
  arms, and thus the evidence is still indirect." - until, that is, the triple discovered by Duffin+ ... and the, what? ~25 discovered by RGZ zooites! ;D
- (p5) "The present giant radio source J2345-0449 is not only the most
  unambiguous example of this extremely rare class, but its spiral host
  galaxy also displays a unique combination of several other remarkable
  properties (as discussed below). Extremely unusual objects like
  J2345-0449 strongly challenge the conventional ideas of black hole
  growth and radio jet formation in galactic nuclei, thus, they are of
  profound interest for models of the central engines of radio galaxies
  and quasars." So, almost unique (i.e. it's an SDRAGN), but also has
  unique features! I can, therefore, claim any 'spiral' which is host
  to a DRAGN (my choice of definition) is unique! 😮 There's something about the logic here I'm not getting ...
- (p6) finding any cluster membership/association for the higher-z
  SDRAGN candidates we have found will be difficult (I think)
- (p14) used GALFIT to model light; pseudobulge (n=1)
- (p16) "Such rapid disk rotation (Vrot ∼400 − 500 kms−1) is rare and
  has been reported earlier for just a few exceptionally massive
  spirals" Hmm ... I wonder what the 'disk rotation' values of my Huds are?
- (p16) "This places J2345-0449 amongst the brightest and most massive
  spirals known, having ∼ 7 times the mass of the Milky Way within an
  equivalent radius, using the Tully-Fisher relation." cf my Huds? I think J2345-0449 would be a wimp
- (p17) "If confirmed it would imply that J2345-0449 hosts a SMBH as
  massive as those found in giant elliptical galaxies, which is not
  expected for normal disk galaxies and is extremely unusual for a pure
  disk galaxy like J2345-0449." Interesting.
- (p18) a classic correlation (SMBH mass/bulge properties) does not
  apply to pseudobulges and barred spirals?
- (lots of meat in the Discussion section; hard to get a handle on how
  speculative it is)
Would any reader who has also read the Bagchi+ (2014) v2 preprint like to share their notes?

Posted September 23, 2014 11:03 PM
by raynorris scientist in response to JeanTate's comment.

Hi Jean

Sorry for my long absence fom this chat. I've been flat out the last few months but have now reorganised my work & life (resigned off lots of committees! 😃 ) so I have more time fro science and RGZ!

Speak to most astronomers and they will tell you that "radio-loud quasars are never found in spiral galaxies," A select few of us, including you and me, know they're wrong, but actually they're only a bit wrong - the vast majority of radio-loud quasars (or, more broadly, active galactic nuclei - AGN) are NOT in spirals. Which is why fidning a pile of them in RGZ is so exciting.

Minnie Mao and I and our colleagues have just submitted a paper where we present a new Spiral DRAGN (i.e. a double-lobed radio AGN in a spiral galaxy, and discuss the Bagchi paper) . In that paper we go through the published claims of spiral DRAGNS and conclude that we know of only four bona-fide spirals with radio-loud double-lobed AGN.

As you probably know, papers are usually kept under wraps until they have been refereed (unless you're BICEPS, and you probably heard that's all ending in tears) but I'll see if Minnie is able to give you a copy of her draft paper in confidence.

You make some really good comments and questions. I think each of them might take about a page to answer (e.g. how do we know its synchrotron - well, we do ( think!) but its a long and complicated story. If its ok with you, I might take each of your points and address it in a longer post more broadly accessible than just the discussion of this paper.

All the best

Ray

Posted September 24, 2014 7:46 AM
by akapinska scientist in response to JeanTate's comment.

@JeanTate don't worry too much about the version number of the preprint. That is use the latest version, but my point here is that typically changes between the versions are minor, or at least should be (spelling, references, re-phrasing if something was ambiguous and so could be mis-understood etc). I wouldn't think there should be any drastic changes in the interpretation. ... but if there are - well.... I would make sure to remember that author's name for the next time 😉

Posted September 24, 2014 2:39 PM
by JeanTate

Thanks, raynorris and akapinska! 😃

From what I read in the Bagchi+ preprint and your notes, raynorris, I now have a considerably clearer idea of what - specifically - to look for in selecting SDRAGN candidates*; I wrote up my new understanding in this post.

In that paper we go through the published claims of spiral DRAGNS and conclude that we know of only four bona-fide spirals with radio-loud double-lobed AGN.

Cool! 😄 So the two Eos (PKS 0400-181 and Speca), J2345-0449 (the one Bagchi+ report on), and the Duffin+ (2014) find? If only ~5% of the e+g and fair candidate SDRAGNs RGZ zooites have found to date turn out to be true SDRAGNs, we will have doubled the known number ... and that's with under a year's worth of classifying! 😮

but I'll see if Minnie is able to give you a copy of her draft paper in confidence.

That would be very nice, thank you. (Personally I think the BICEP2 team's far bigger mistake was making very high profile public claims, starting with that press conference).

You make some really good comments and questions. I think each of them might take about a page to answer (e.g. how do we know its synchrotron - well, we do ( think!) but its a long and complicated story. If its ok with you, I might take each of your points and address it in a longer post more broadly accessible than just the discussion of this paper.

That's a terrific idea! I've already read your 'synchrotron' thread, and am preparing some questions (hope you don't mind).

@akapinska yeah, I wrote that more to indicate which version I was reading. Sadly, there is not a lot of discussion of the v1 preprint, in the two earlier threads on it, here in RGZ Talk; more sadly, 42jkb seems to have missed both those earlier threads entirely ... not due to any lack of diligence, certainly, but to the, um, difficulty of finding anything in Talk (unless it's on the main page). I hope the next iteration of Talk will be a great deal better ...

*I had been using these criteria: "does the radio emission extend beyond the optical boundary?" (detached doublelobes with no core emission is included here) If so, "how likely is it that the candidate galaxy is the host?" In parallel, "is the candidate host NOT a boring elliptical?"

Posted September 24, 2014 3:22 PM
by mini.mintaka scientist

ahhh the Bagchi paper 😃

It is a very cool source ! Yes, I will send JeanTate a copy of the paper! waves at Jean yes it is minnie 😃

My main point of contention is that the Bagchi paper reckon their host galaxy is a bulgeless spiral o.O ... NO...

... which makes their rapidly-spinning-BH-with-very-efficient-accretion model hard to believe/understand... (in reference to your p18 note) !

when you read the J1649+2635 paper you'll see that our main argument is that these things are found in "intermediate" density environments...

more later!

clear skies

minnie

Posted September 25, 2014 5:09 AM
by JeanTate in response to mini.mintaka's comment.

Hi minni, and thanks. I'm very much looking forward to reading the draft!

I've now finished looking at six objects reported in the literature (I had looked at Speca, J1649+2635 - the one reported in Duffin+ (2104) - and J2345-0449 ealier)*:
- PKS 0400-181, initially thought to be an SDRAGN, later a background elliptical identified as the more likely host
- PKS 1413+135, a radio-loud Eos, but a point source (nuclear?) rather than a DRAGN
- B2 0722+30, candidate host z_sp 0.019 SDSS J072537.22+295714.7, a highly inclined/edge-on disk galaxy
- PKS 0313-192, the original SDRAGN
- PKS 0131-36, a doublelobe source (DRAGN) associated with the lenticular NGC 612
- PKS 1814-637, another radio-loud Eos, also a point source (nuclear?) rather than a DRAGN
How you establish association (radio source with optical galaxy) with high confidence, and how you conclude 'spiral host', are questions I am very much looking forward to finding answers to! 😃 And beyond that, how you robustly establish the size and nature of the components of host spirals (i.e. disk, bulge, nucleus), and estimate values for parameters such as sSFR, SMBH mass, cold gas mass, stellar mass, and dust mass.

*the six are posted on p13 of the Hourglass sources associated with spiral galaxies thread; the other three on p9 (also on p9: NGC 5548, SDSS J084002.36+294902.6/FIRST J084000.8+294838, 3C 285, and FIRSTJ094010.1+600352/SDSS J094014.54+600443.5)

Posted September 27, 2014 6:39 PM
by JeanTate

Having now gotten a better understanding of radio luminosity - thanks to Ray Norris' What is radio luminosity? thread! - I have had a go at trying to reproduce the radio luminosity estimates for J2345-0449 presented in Bagchi+ (2014).

There are two (well, I found two; there may be more):
- (on p4): "The integrated flux density and radio luminosity at
  1.4 GHz are S_1.4 = 180.60±20.0 mJy and L_1.4 = 2.5(±0.3)×10³¹ erg s^-1 Hz^-1 respectively"
- (on p5): "The integrated flux density
  and radio luminosity at 330 MHz are S₃₃₀ = 3.60 ± 0.15 Jy and L₃₃₀ = 5.0(±0.2) × 10³²
  erg s^-1 Hz^-1 respectively"
Values for key parameters, and key definitions:
- (p2): "We adopt a ΛCDM cosmology model with H₀ = 70.5 km s⁻¹ Mpc⁻¹,
  Ω_M = 0.27 and Ω_Λ = 0.73, which results in a scale of 1.43 kpc arcsec⁻¹ for a redshift z = 0.0755. The radio
  spectral index α is defined as: flux density (S_ν) ∝ frequency (ν)^-α."
With these valules, CosmoCalc gives a scale of 1.425 kpc arcsec⁻¹ (good!). The luminosity distance is 339.9 Mpc.

Using the radio luminosity calculator in Ray's thread, I get:
- luminosity distance 341.0 Mpc
- L_1.4 = 2.51×10³¹ erg s^-1 Hz^-1
- L₃₃₀ = 5.01×10³² erg s^-1 Hz^-1
It would seem, then, that they did not apply the 1/(1+z^(1+α)) factor.

I wonder how common this is?

Posted October 7, 2014 7:29 PM
by JeanTate

J2345-0449 features in this conference poster, from just a couple of months' ago*:

6. The first optical spiral found to be a GRG

Until now at most four spirals were found to have double−lobed RG morphology, all of them smaller than ~500 kpc. Double−double lobed RGs (DDRG) are also very rare. We report one DDRG with LLS=1.5 Mpc. Its spiral arms are only seen on SDSS (not DSS) images, thus there may be more examples on SDSS or future optical surveys.

*my thanks to a fellow zooite who told me about this (happy to say who you are; your call!)

Posted October 7, 2014 8:04 PM
by JeanTate

Follow-on paper in arXiv today: "A deep Chandra observation of the hot gaseous halo around a rare, extremely massive and relativistic jet launching spiral galaxy", Walker+ (2014):

We present a deep Chandra observation of the extremely massive spiral galaxy 2MASX J23453268-0449256, the first X-ray observation of this very rare system which features the largest known relativistic jets from a spiral galaxy. We detect extended X-ray emission from the hot halo surrounding the galaxy, reaching out to 80 kpc in radius. The hot halo is elongated along the plane of the spiral galaxy, and one possibility is that the powerful relativistic jets have disrupted the hot halo gas located perpendicular to the disk. Extrapolating best fits to the hot halo out to the virial radius and including all other baryonic mass, we find a baryon fraction in the range 0.09-0.16, which is lower than the mean cosmic baryon fraction of 0.171. We also detect extended emission which appears to be associated with the inner and outer southern radio lobes, and is possibly the result of inverse Compton emission. Using the observed X-ray and radio luminosity of the central AGN, the fundamental plane of Gultekin et al. predicts a black hole mass of 5x10^8 M_solar, with a range of 1x10^8 - 3x10^9 M_solar when the scatter in the fundamental plane relation is taken into account.

Posted November 10, 2014 7:30 PM