4C +07.04 – tight QSO-galaxy pair

Clarke et al. (1966) associated Parkes catalog radio source PKS 0114+074 (4C +07.04) with a QSO (object 2 in figure 1). Lang et al. (1970) associated the radio source to a “faint red galaxy” (object 1) near the QSO. So did Hunstead & Jauncey (1970), Pauliny-Toth et al. (1972), and Shaffer et al. (1978). Agnew & Arp (1973) gave the redshift of z = 0.861 for the QSO but it had been measured by Bolton in 1970.

Previous studies had shown 4C +07.04 as double radio source, but Akujor (1987) detected three radio sources. The third source coincided with the position of the QSO, while the two previously known coincided with the galaxy. They then suggested that the system consists of either a galaxy + QSO or a galaxy + QSO + unidentified object. In their conclusion they mention:

The QSO and the galaxy are separated by 30 arcsec. If they are physically related, one must assume a noncosmological redshift in order to place a QSO (z = 0.861) and a galaxy with z ~ 0.2 at the same distance.

However, it is unclear where they got the estimate of z ~ 0.2 for the galaxy, but earlier they mentioned assuming a redshift of z = 0.2 for a 18 mag galaxy, so they might have estimated it from the magnitude of the galaxy. Akujor (1989) presented further radio observations of the system, and verified the three radio source structure. Akujor gave a chance projection probability of 10-3 for the QSO and galaxy, and mentioned that the galaxy has peculiar structure:

Indeed, this may be the first double radio source showing such a wide difference in spectrum between two components, and the first in which one component has a spectrum as flat as 0.45.

Note that here Akujor is talking about the double radio source of the galaxy, not about the radio source related to the QSO.

The redshift of the galaxy was given by Akujor & Jackson (1992). They found it to be z = 0.344. They also found that the spectrum of the galaxy showed a rare occurance of double extended emission line system. The two emission line systems differed from each other by about 400 km/s. They noted that only few cases were known with such wholescale splitting of nuclear emission lines. They discussed rotation as a possible source for emission line splitting but they noted that the usual velocity scale produced by rotation is smaller than 400 km/s observed in 4C +07.04. They also discussed a possibility of a radio jet causing an expanding cylinder of gas:

Because of the velocity field of this expanding cylinder of gas, we see split narrow emission lines as the gas cools. This model can also be applied to the case of 0114+074, although here the splitting occurs in the whole of the nuclear line.

So they didn’t seem very happy with that hypothesis either. Then they suggested a possibility of two active nuclei, but 4C +07.04 didn’t seem to show any double hotspot structure. They also were somewhat puzzled by their observations of the optical extended emission coinciding with radio lobe, and suggested it might be a sign of interaction taking place there.

4C_07_04
Figure 1. The objects with measured redshifts near 4C +07.04. Size of the image is 5 x 5 arcmin. Image is from Digitized Sky Survey (POSS2/UKSTU Blue).

Objects and their data

NBR NAME TYPE REDSHIFT MAG SEPARATION
1 4C +07.04 NED02 galaxy 0.343000 22.14 0
2 [HB89] 0114+074 QSO 0.858000 18 0.536

NED objects with available redshift within 10′ from 4C +07.04 NED02

References

Agnew & Arp, 1973, PASP, 85, 162, “A List of Quasi-Stellar Radio Sources and Quasi-Stellar Radio Source Candidates from the 3C and 4C Catalogs Between Declination -7° and +40°”

Akujor, 1987, AJ, 94, 867, “PKS 0114+074 – A QSO-galaxy association?”

Akujor, 1989, AJ, 98, 1226, “0114 + 074 – A very asymmetric galaxy in the field of an intermediate-redshift QSO”

Akujor & Jackson, 1992, AJ, 104, 546, “Double emission-line system in the radio galaxy 0114 + 074S”

Clarke et al., 1966, AuJPh, 19, 375, “Identification of extragalactic radio sources between declinations 0° and +20°”

Hunstead & Jauncey, 1970, MNRAS, 149, 91, “Observations of radio sources near 2 f.u. at 408 MHz”

Lang et al., 1970, ApJ, 160, 17, “Additional Occultation Studies of Weak Radio Sources at Arecibo Observatory: lIST 4”

Pauliny-Toth et al., 1972, AJ, 77, 265, “The NRAO 5-GHz radio source survey. II. The 140-ft “strong”, “intermediate”, and “deep” source surveys”

Shaffer et al., 1978, AJ, 83, 209, “Optical identifications of radio sources in the NRAO 5-GHz survey – The ‘S2’ and ‘intermediate’ surveys”

6dF J0406457-124421 – QSO pair at same redshift

Arp (1980) noted this system briefly:

Another pair of obviously related quasars is shown in Figure 6. Search of the Palomar Sky Survey reveals a galaxy just about midway between them.

One point about these two quasars is their similar redshift. The centering galaxy is brightest in the nearby field, according to Arp.

Marr & Spinrad (1985) found a faint galaxy (object 4 in the object table below) near object 3, at redshift of z = 0.568. They said:

The nominal velocity difference between the two objects is only 900 km s-1 in the quasar’s rest frame, clearly consistent (within the galaxy redshift uncertainty) with a cluster velocity dispersion.

There are some studies of absorption lines in the spectrum of object 3, and their possible correlation with nearby galaxy distribution. Williger et al. (2006) is an example of such study.

Notes

There are lot of objects with available redshift in the field, but only the centering galaxy and the two quasars are shown in Fig. 1. Nearest objects with available redshift to 6dF J0406457-124421 are about at 8 – 10 arcmin angular distance, and as the photographed field in Fig. 1 is only 5 x 5 arcmin, those objects are not shown.

There are 15 objects having redshifts between z = 0.55 and 0.60 within 40 arcmin from 6dF J0406457-124421. The two aligned across 6dF J0406457-124421 are clearly brightest of them.

6dF0406
Figure 1. The field of 6dF J0406457-124421 with the two quasars. Size of the photograph section of the image is 5 x 5 arcmin. Image is from Digitized Sky Survey (POSS2/UKSTU blue).

Objects and their data

NBR NAME TYPE REDSHIFT (cz) MAG SEPARATION
1 6dF J0406457-124421 galaxy 0.032621 (9780 km/s) 16.11 0
2 [HB89] 0403-132 QSO, HPQ 0.570550 17.17 29.555
3 [HB89] 0405-123 QSO, blazar, Sy1.2 0.572590 14.82 36.169
4 G1 galaxy 0.568 20 0.22

NED page for object 1
NED page for object 2
NED page for object 3

References

Arp, 1980, ApJ, 236, 63, “Ultraviolet excess objects in the region of a companion galaxy to NGC 2639”

Marr & Spinrad, 1985, PASP, 97, 684, “An emission-line companion galaxy to the quasar PKS 0405-123”

Williger et al., 2006, ApJ, 636, 631, “The Low-Redshift Lyα Forest toward PKS 0405-123”

Edward Fath – early spectroscopy of galaxies

Although I’m concentrating on Fath’s extragalactic work, I’ll mention a paper among his early works as a curiosity; Steppins & Fath (1906), titled “The Use of Astronomical Telescopes in Determining the Speeds of Migrating Birds”.

Fath (1909) measured spectra of spiral galaxies, but he wasn’t able to determine their redshifts. He noted that by that time, general concensus was that spiral galaxies have continuous spectrum and that there were only two studies casting doubt on that. Both of them were inconclusive according to Fath. Fath then discussed the spectra of individual objects. He noted on the Andromeda galaxy (M31):

It contains little more than the spectrum of nucleus, which is not of a stellar character.

Some other objects he measured were NGC 1068 (of which there seemed to be a debate ongoing if it even is a spiral galaxy, or “spiral nebula” as they were called back then), NGC 3031 and NGC 4736. On NGC 5194, he said:

Photographically it is faint. Because of this it is not a promising object for spectrographic analysis, but it seemed best to make an attempt. … The plate showed nothing.

Well, you can’t succeed every time… He summed up his research on the question of the spectrum of spiral galaxies:

No spiral nebula investigated has a truly continuous spectrum.

Fath then proceeded to interesting discussion on the possible explanation for the spectrum of spiral galaxies. He notes that the spectrum usually comes only from the nuclei of spiral galaxies and resembles stellar spectrum, then he says:

The hypothesis that the central portion of a nebula like the famous one in Andromeda is a single star may be rejected at once unless we wish to modify greatly the commonly accepted ideas as to what constitutes a star.

He says that a possible explanation would be a star cluster at the center but asks:

Is it reasonable to assume that in a condensed cluster we should have stars of one spectral type strongly predominating?

He mentioned that there weren’t enough spectral measurements of star clusters to determine the answer to this question, so he proceeded to measure a few star clusters himself. He found out that one spectral type can predominate strongly. He then considered a parallax measurement of Andromeda galaxy and noted that the value of the parallax leads to the impossibly small sizes of hypothesized star cluster members. So, Fath is left with a hypothesis that to his knowledge is only one that can explain the spectrum, but other evidence rather conclusively show that the hypothesis is not likely to be valid.

Fath (1910) discussed some aspects of the distribution of spiral galaxies in the sky. Fath (1911) continued with spiral galaxy spectra. He gave some new spectral information on individual objects, and then suggested a preliminary spectral type division for all nebulae. Fath (1913) was his third paper on the subject, and here he only discussed individual objects.

Although Fath showed that the spectrum of spiral galaxies is not continuous but that it contains spectral lines, he didn’t discuss the possibility of measuring the redshifts of galaxies.

Links

Not much information is available on Edward Fath, but here’s at least something:

A Science Not Earthbound: A Brief History of Astronomy at Carleton College, page 11

References

Fath, 1909, LicOB, 5, 71, “The spectra of some spiral nebulae and globular star clusters”

Fath, 1910, PA, 18, 544, “The Distribution of Nebulae and Globular Star Clusters”

Fath, 1911, ApJ, 33, 58, “The spectra of spiral nebulae and globular star clusters”

Fath, 1913, ApJ, 37, 198, “The spectra of spiral nebulae and globular star clusters”

Stebbins & Fath, 1906, Sci, 24, 49, “The Use of Astronomical Telescopes in Determining the Speeds of Migrating Birds”

53W 080 – QSO triplet

Arp (1999) discussed a quasar triplet (objects 1, 13, and 14 in Figure 1) that was very similar to two previously known Arp/Hazard triplets. He first briefly described the Arp/Hazard triplets, and then said:

Now, in the Her I field, we have another, almost identical triplet configuration. Notice the remarkable close numerical similarity of the redshifts involved in all three of these examples

Numerical similarity here refers to the fact that all three triplets have similar redshift for all three objects: Two old ones have redshifts of 2.15 – 0.51 – 1.72 and 2.12 – 0.54 – 1.61, the new one has redshifts of 2.14 – 0.543 – 1.84. However, in the two old ones the highest redshift quasar was closer (in angular distance) to centering quasar but in this new one it isn’t.

Arp then argued that the centering object is in very active state, and that the oute, higher redshift quasars had been ejected from the centering quasar at opposite direction so that their velocity relative to us would correspond to redshift of z = 0.15, which is similar to the situation with Arp/Hazard triplets. Arp also studied the redshift quantization in new triplet:

If we average their [= the two outer quasars] redshifts to remove the component of ejection velocity, we obtain z = 1.99, very close to the major formula peak of z = 1.96. The central quasar is close to the formula peak of z = 0.60.

I must admit that I find this somewhat odd. Normal procedure has been to convert the redshifts to the reference frame of the parent object, the z = 0.543 quasar in this case. If we use Arp’s averaged value of z = 1.99, we get the intrinsic redshift of:

zi = (1 + zM)/(1 + zC) – 1 = (1 + 1.99)/(1 + 0.543) – 1 = 0.938

Which is close to the Karlsson redshift peak of z = 0.96. Similarily, individual values of the two outer quasars would result in intrinsic redshifts of zi = 0.84 (z = 1.84 quasar) and zi = 1.03 (z = 2.14 quasar). First of these is not particularly close to any Karlsson peak, but the latter is quite close to z = 0.96 peak.

Arp also presented a probability calculation for the chance alignment for this quasar triplet. The probability he got is 4 x 10-8.

Notes

This field has been thoroughly studied redshift-wise, so there’s too much objects to map the entire field covering the quasar triplet in question. Figure 1 presents a few closest objects with available redshifts and the two aligned quasars.

There’s little bit uncertainty about what exactly is the centering object Arp discussed, because there are two objects at z ~ 0.55, objects 1 and 7. But as Arp talks about quasar, the object 1 has been used as the centering object here.

Some rough alignments are seen in the nearby objects. Particularly noteworthy is the pair alignment of objects 4 and 6 across object 5, because objects 4 and 6 have almost the same redshift. Objects 10 and 11 are also aligned across object 5 but don’t have similar redshifts.

53W_080
Figure 1. The objects with measured redshifts near of NGC 0007. Size of the image is 15 x 15 arcmin. Image is from Digitized Sky Survey (POSS2/UKSTU blue), and it has been adjusted for brightness and contrast to bring out the faint objects in the field.

Objects and their data

NBR NAME TYPE REDSHIFT (cz) MAG SEPARATION
1 53W 080 QSO 0.543000 18.3 0
2 HERC-1:[MKK97] 309937 galaxy 0.155500 20.01 1.127
3 HERC-1:[MKK97] 309714 galaxy 0.496300 20.47 1.283
4 HERC-1:[MKK97] 310979 galaxy 0.323700 19.73 1.454
5 LEDA 167151 galaxy 0.155000 19.51 1.633
6 HERC-1:[MKK97] 310632 galaxy 0.323000 20.35 1.922
7 HERC-1:[MKK97] 310248 galaxy 0.545400 21.35 1.924
8 HERC-1:[MKK97] 309838 galaxy 0.087400 19.26 2.085
9 LEDA 167126 galaxy 0.155000 19.18 2.250
10 53W 081 QSO 2.060000 24.84 2.336
11 HERC-1:[MKK97] 310395 galaxy 0.490100 20.67 2.370
12 53W 085 QSO 1.350000 22.57 2.629
13 [HB89] 1719+500 QSO 1.840000 19.3 9.931
14 [HB89] 1721+498 QSO 2.140000 20.3 12.537

NED page for object 1
NED page for object 2
NED page for object 3
NED page for object 4
NED page for object 5
NED page for object 6
NED page for object 7
NED page for object 8
NED page for object 9
NED page for object 10
NED page for object 11
NED page for object 12
NED page for object 13
NED page for object 14

References

Arp, 1999, ApJ, 525, 594, “The Distribution of High-Redshift (z>~2) Quasars near Active Galaxies”

3C 343.1 – radio bridged QSO-galaxy pair

Spinrad et al. (1977) studied the 3C 343.1 system. They gave a (somewhat uncertain) redshift of z = 0.750 for the object they called a “faint galaxy”. They compared the isophotal diameter vs. redshift of 3C 343.1 to that of few other similar objects, and found out that the isophotal diameter of 3C 343.1 matches well with a galaxy of z = 0.75, supporting their redshift determination. They also noted that 3C 343.1 is bluer than similar objects usually are.

Fanti et al. (1985) made radio maps of radio sources, including this system (see their Fig. 11). Two more radio maps of the system was published by van Breugel et al. (1992, see their Fig. 23). Also, de Vries et al. (1997) published radio map and HST image of the system (see their Fig. 2.26). All these radio maps showed two apparently connected radio sources, and HST image also seems to show two objects. Tran et al. (1998) studied this system along with few other systems. They found out something interesting:

A most surprising finding, however, is that the redshift of the absorption lines is radically smaller (z = 0.344) than that of the nuclear AGN emission lines (z = 0.75)!

So they found out that the system has two very different redshift systems. They also noted that the lower redshift system shows some emission lines as well. They showed that lower redshift system is more extended than the higher redshift system, so they concluded that there must be two different objects in a chance alignment. They gave some basic properties for each object, and also discussed the possibility of gravitational lensing.

Arp et al. (2004) reviewed the system, and discussed it as an ejecting system where the QSO would have been ejected from the lower redshift galaxy. They calculated that the probability for the chance projection is 1 x 10-8 (or, one in a hundred million), and said that it is a conservative estimate. They also calculated the intrinsic redshift of the quasar, if it would be at the distance of the lower redshift galaxy, and found out that it is very close to one of the Karlsson redshift peaks.

Notes

For those who like to check out the presented calculations, there’s a minor mistake in the Arp et al. (2004) equation relating to the intrinsic redshift calculation (see their section 5), a square bracket is missing:

They showed it like this:

(1 + zi) = (1 + zq)/(1 + zg)(1 + zd) ] = 1 + 0.302

But it should be:

(1 + zi) = (1 + zq)/[ (1 + zg)(1 + zd) ] = 1 + 0.302

Figure 1 shows the field of 3C 343.1, but there’s no other objects with available redshifts within 10 arcmin, and 3C 343.1 itself doesn’t show very well in the image. See the referred papers for better images, especially de Vries et al. (1997).

3c343_1
Figure 1. The 3C 343.1 field. 3C 343.1 is at the center, but does not show very well. Size of the image is 5 x 5 arcmin. Image is from Digitized Sky Survey (POSS2/UKSTU Blue).

Objects and their data

NBR NAME TYPE REDSHIFT MAG SEPARATION
1 3C 343.1 galaxy 0.344 0
2 3C 343.1 NLRG, Sy2 0.750000 20.71 ~0.004

NED page for 3C 343.1.

References

Arp et al., 2004, A&A, 414, 37, “The double radio source 3C 343.1: A galaxy-QSO pair with very different redshifts”

de Vries et al., 1997, ApJS, 110, 191, “Hubble Space Telescope Imaging of Compact Steep-Spectrum Radio Sources”

Fanti et al., 1985, A&A, 143, 292, “Compact Steep Spectrum 3CR radio sources – VLBI observations at 18 CM”

Spinrad et al., 1977, ApJ, 216, 87, “Spectroscopy and photometry of the distant radio galaxy 3C 343.1”

Tran et al., 1998, ApJ, 500, 660, “Scattered Radiation from Obscured Quasars in Distant Radio Galaxies”

van Breugel et al., 1992, A&A, 256, 56, “Compact steep-spectrum 3 CR sources – VLA observations at 1.5, 15 and 22.5 GHz”