ARP 175 – A tale of a tail

ARP 175 is a system where two galaxies at similar redshifts are seemingly interacting, and an interaction tail from those two is emerging and apparently connecting to a third galaxy. This third galaxy has much lower redshift than the two other galaxies, so in traditional view the apparent connection should be just a chance projection. This is one of the oldest discordant redshift systems known, most of the relevant things about this system were already discussed by Zwicky (1956).

Zwicky (1956) said:

These widely separated galaxies which were the first ones to be found interconnected by long luminous filaments of intergalactic matter also turned out to be some of the most remarkable in the sense of presenting astrophysics with some unsuspected and very puzzling problems.

Then he mentioned about magnitudes:

From the near equality of their apparent magnitudes and of their angular diameters one would off hand conclude that the two galaxies IC 3481 and IC 3483 are roughly at the same distance.

Magnitude is of course only very rough distance indicator, but, as Zwicky stated:

This first evaluation is of course greatly strengthened because of the apparent connection of the two galaxies with the smaller and fainter central nebula by faintly luminous bands of intergalactic matter.

See the plate II of Zwicky (1956) for an image of the connecting material. He also said that the apparent bridge seemed to be an extension of one of IC 3483’s spiral arms (see Fig. 1 of Zwicky, 1956). He then described the spectral measurements of the system and started by stating the initial attitude:

From the features discussed in the preceding, the writer and his colleagues felt certain that the three galaxies form a physical triple system and that within narrow limits they are located at the same distance. Under these circumstances the results of the spectral studies which Drs. R. MINKOWSKI and M. L. HUMASON undertook at the request of the writer came as a complete surprise.

The resulting redshifts were: IC 3481 cz = 7304 km/s, IC 3481A (which was called “Anon” by Zwicky) cz = 7278, and IC 3483 cz = 108 km/s. He noted that the redshift of the apparent bridge couldn’t be obtained.

Zwicky then stated three possible explanations for the situation:

1. IC 3483 is a foreground galaxy.
2. IC 3483 is at the same distance as the two other galaxies and its low value of Vs indicates a real radial velocity of about 7000 km/sec relative to two other members of the triple system.
3. IC 3483 is at the same distance as the two other galaxies, but the large value of Vs between IC 3481 and IC 3483 is caused by some differential effect on the frequency of light quanta travelling cosmic distances. The gravitational drag of light which was discussed by the writer (23) long ago as a possibility of explaining the universal redshift of light in a non-expanding universe would in some cases produce large differential shifts in the spectra of little separated galaxies.

He then proceeded to present some arguments relating to these options. He discussed the properties of IC 3483 if it would be a foreground galaxy. Based on the redshift, it would be part of Virgo cluster. However, Zwicky noted based on the properties of IC 3483:

If a member of the Virgo cluster, it therefore follows that IC 3483 is a most unusual dwarf nebula of distinct spiral structure and with a central surface brightness comparable to that of the giant spirals.

He then emphasized the situation with the apparent luminous connection, and noted that the measured amount of reddening of IC 3483 implies greater distance than Virgo cluster. He also mentioned that the situation with IC 3481 and IC 3481A would also be exceptional if IC 3483 would be foreground object:

Finally, if IC 3483 were a foreground nebula, the remaining systems of IC 3481 and Anon would be left as one of the most unusual interconnected galaxies in the sense that among thousands of similar double galaxies not a single one can be found where the “countertide”, as we propose to call it, does not constitute the exact tangential continuation of the bridge between the two nebulae in question.

Zwicky then cited a few examples where there are quite large velocity differences between objects, but not as large as in this system. So it didn’t seem very probable that all three would be at same distance and just having large velocities causing the redshift difference. Zwicky still considered it to be possible though. However, he noted a complication for that hypothesis:

On this interpretation there nevertheless arises another great difficulty. It is well known from astrophysical theory that two stellar systems devoid of gas and dust passing through each other in the process of a head-on collision hardly disturb each other, unless their relative velocity is very low.

This argument would suggest that the connecting luminous bridge would not form if the redshift differences were due velocity differences in an interacting system. Zwicky then concluded that the third possibility should not be discarded lightly:

It will in this case be quite possible that the redshift is not a function of the distance alone but depends also on the particular constellations of matter surrounding any individual cosmic trajectory of a quantum of light.

Other studies

ARP 175 (VV 043) system was included in a study by Humason et al. (1956). They noted briefly:

Zwicky believes IC3483 also connected with this pair. The discrepancy in the velocities, however, indicates that 3483 is a member of the Virgo Cl and not physically connected with this pair.

Vorontsov-Velyaminov (1959) included the system in his catalog (as #43), and published the image of the system shown in Figure 1.


Figure 1. Image of ARP 175 system from Vorontsov-Velyaminov (1959). Image is linked from NED.

Burbidge & Burbidge (1961) noted about this system:

However, Zwicky (1958 and earlier references given there) has argued that all three galaxies are connected by luminous bridges and must therefore be a physical group (IC 3481 and 3483 also are of about the same luminosity and diameter). The presence of many galaxies nearby, since the system lies in the field of the Virgo Cluster increases the probability that in this case IC 3483 is not a member of the small group.

In another paper, Burbidge & Burbidge (1961b) mentioned that sometimes there are long extensions from interacting galaxies ending to empty space, so in this case that might be a possibility.

The system was briefly mentioned by Vorontsov-Velyaminov (1962). Arp (1966) included the system in his Atlas of Peculiar Galaxies (as #175), and published the image of the system shown in Figure 2.


Figure 2. Image of ARP 175 system from Arp (1966). Image is linked from NED.

Toomre & Toomre (1972) commented on ARP 175 system:

…the Zwicky triplet (= ARP 175) has often been cited (e.g., Hoyle and Narlikar 1971; Arp 1971b) as a possible example of a bridge connecting galaxies with very disparate redshifts. Yet now even the shape of that “bridge” warns of an impostor: Such a long, broad, curving crescent seems much more characteristic of a tail emanating from the anonymous galaxy [= IC 3481A] solely as the result of an encounter with IC 3481. This makes IC 3483 presumably just a foreground galaxy.

I haven’t read the mentioned Hoyle & Narlikar (1971) and Arp (1971) because I don’t have access to them, but I’ll give links to them in the reference section anyway in case some readers with access wish to read them. The system was also briefly discussed in Jaakkola (1973) and in Burbidge (1973).

Katsiyannis et al. (1998) published new images in the system. They noted that the halo of the foreground star near IC 3483 (the object right above object 1 in Figure 3) hides the details of the connection of the tail to IC 3483. They conclude that visually IC 3483 appears to be interacting with IC 3481/IC 3481A, but that according to redshift IC 3483 is a foreground galaxy. By the way, Katsiyannis et al. say that Arp (1966) was the first to note the possible interaction between the three galaxies in this system, but as we have seen above, that’s not true. Katsiyannis et al. (2001) gives the same images of the system, and the discussion there is also the same.

Pérez Grana et al. (2009) discuss the interaction between OC 3481 and IC 3481A, but I don’t know what they say about IC 3483 because I don’t have access to the paper.

arp175
Figure 3. The objects with measured redshifts near IC 3483. Size of the image is 15 x 15 arcmin. Image is from Digitized Sky Survey (POSS2/UKSTU Blue).

Few notes

There’s a higher redshift galaxy, SDSS J123301.88+112301.9 (object 4 in Figure 3) between IC 3481A (object 3) and IC 3483 (object 1). It appears to coincide with the bulge of the bridge seen at the center in the image of the system published in Vorontsov-Velyaminov (1959), as shown in Figure 1.

SDSS has quite good image of the system. Playing with brightness and contrast of the image suggests that the tail from IC 3481/IC 3481A is not particularly well associated to IC 3483, it just seems that it happens to point generally to that direction, but I see no clear signs of any interaction between the tail and IC 3483. There also are not any clear signs of interaction between the tail and the above mentioned SDSS galaxy (object 4).

There are 5 objects in Figure 3 that have similar redshift as IC 3481 (object 2): Objects 3, 5, 7, 8, 9. IC 3481 is clearly the biggest of them, and hence the probable main galaxy of the group. IC 3481 also has lowest redshift of the group, so all the known nearby companions for IC 3481 have higher redshift than the redshift of IC 3481.

Objects 4 and 6 have almost same redshift. Objects 1, 2, 3, and 10 are aligned in a very straight line. Object 10 is the only object in Figure 3 that has non-discordant redshift to IC 3483, so object 10 is possible companion for IC 3483, IC 3483 seems to be bigger of the two. Redshift velocity of object 10 is about 600 km/s bigger than the redshift velocity of IC 3483.

Objects and their data

NBR NAME TYPE REDSHIFT MAG SEPARATION
1 IC 3483 SABb, pec 0.000430 15.7 0
2 IC 3481 SAB0, pec 0.023636 14.2 (g) 5.5
3 IC 3481A E, pec 0.024457 15.9 (g) 4.1
4 SDSS J123301.88+112301.9 galaxy 0.148379 18.4 (g) 3.0
5 SDSS J123320.91+112108.2 galaxy 0.024139 18.7 (g) 3.0
6 SDSS J123250.81+111910.3 galaxy 0.148931 18.1 (g) 5.0
7 SDSS J123244.54+111920.3 galaxy 0.024603 18.1 (g) 6.4
8 SDSS J123245.24+112313.8 galaxy 0.023796 18.6 (g) 6.5
9 SDSS J123241.40+112220.4 galaxy 0.025866 18.5 (g) 7.2
10 PGC 041723 S0? 0.002542 15.73 7.9

SDSS image centered on object 4.

References

Arp, 1966, ApJS, 14, 1, “Atlas of Peculiar Galaxies”

Arp, 1971, Sci, 174, 1189, “Observational Paradoxes in Extragalactic Astronomy”

Burbidge & Burbidge, 1961, ApJ, 134, 244, “A Further Investigation of Stephan’s Quintet”

Burbidge & Burbidge, 1961b, AJ, 66, 541, “Recent investigations of groups and clusters of galaxies”

Burbidge, 1973, MitAG, 34, 19, “The Riddle of the Redshifts”

Hoyle & Narlikar, 1971, Nature, 233, 41, “On the Nature of Mass”

Humason et al., 1956, AJ, 61, 97, “Redshifts and magnitudes of extragalactic nebulae”

Jaakkola, 1973, A&A, 27, 449, “The Relation between Redshift and Surface Brightness for Normal Galaxies in Systems of Galaxies”

Katsiyannis et al., 1998, A&AS, 132, 387, “Results of the digital co-addition of thirteen Schmidt films of the Virgo cluster of galaxies”

Katsiyannis et al., 2001, Ap&SS, 276, 733, “Faint Features of Interacting Galaxies Revealed by the Digital Coaddition of 13 Tech-Pan Films of the Virgo Cluster”

Pérez Grana et al., 2009, NewA, 14, 556, “The unusual interacting pair of galaxies IC 3481 and IC 3481A: An optical-NIR photometric and spectroscopic analysis”

Vorontsov-Velyaminov, 1959, Sternberg Institute, Moscow: Moscow State University, “Atlas and Catalog of Interacting Galaxies”

Vorontsov-Velyaminov, 1962, SvA, 6, 131, “Extragalactic Astronomy and Cosmogony at the 1961 Conferences in California. A Survey of the Outstanding Problems in 1961”

Zwicky, 1956, ErNW, 29, 344, “Multiple Galaxies”

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