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”

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: