Question: What metro area is the city connected to the east of Southampton by rail a part of?

full_context: Document 1: Southampton: Southampton is also served by the rail network, which is used both by freight services to and from the docks and passenger services as part of the national rail system. The main station in the city is Southampton Central. Rail routes run east towards Portsmouth, north to Winchester, the Midlands and London, and westwards to Bournemouth, Poole, Dorchester, Weymouth, Salisbury, Bristol and Cardiff. The route to London was opened in 1840 by what was to become the London and South Western Railway Company. Both this and its successor the Southern Railway (UK) played a significant role in the creation of the modern port following their purchase and development of the town's docks.
Document 2: Southampton: Local train services operate in the central, southern and eastern sections of the city and are operated by South West Trains, with stations at Swaythling, St Denys, Millbrook, Redbridge, Bitterne, Sholing and Woolston. Plans were announced by Hampshire County Council in July 2009 for the introduction of tram-train running from Hythe (on what is now a freight-only line to Fawley) via Totton to Southampton Central Station and on to Fareham via St. Denys, and Swanwick. The proposal follows a failed plan to bring light rail to the Portsmouth and Gosport areas in 2005.
Document 3: Southampton: There are two main termini for bus services. As the biggest operator, First uses stops around Pound Tree Road. This leaves the other terminal of West Quay available for other operators. Uni-link passes West Quay in both directions, and Wilts & Dorset drop passengers off and pick them up there, terminating at a series of bus stands along the road. Certain Bluestar services also do this, while others stop at Bargate and some loop round West Quay, stopping at Hanover Buildings. There was a tram system from 1879 to 1949.
Document 4: Somerset: The usefulness of the canals was short-lived, though some have now been restored for recreation. The 19th century also saw the construction of railways to and through Somerset. The county was served by five pre-1923 Grouping railway companies: the Great Western Railway (GWR); a branch of the Midland Railway (MR) to Bath Green Park (and another one to Bristol); the Somerset and Dorset Joint Railway, and the London and South Western Railway (L&SWR). The former main lines of the GWR are still in use today, although many of its branch lines were scrapped under the notorious Beeching Axe. The former lines of the Somerset and Dorset Joint Railway closed completely, as has the branch of the Midland Railway to Bath Green Park (and to Bristol St Philips); however, the L&SWR survived as a part of the present West of England Main Line. None of these lines, in Somerset, are electrified. Two branch lines, the West and East Somerset Railways, were rescued and transferred back to private ownership as "heritage" lines. The fifth railway was a short-lived light railway, the Weston, Clevedon and Portishead Light Railway. The West Somerset Mineral Railway carried the iron ore from the Brendon Hills to Watchet.
Document 5: Southampton: In the 2001 census Southampton and Portsmouth were recorded as being parts of separate urban areas, however by the time of the 2011 census they had merged to become the sixth largest built-up area in England with a population of 855,569. This built-up area is part of the metropolitan area known as South Hampshire, which is also known as Solent City, particularly in the media when discussing local governance organisational changes. With a population of over 1.5 million this makes the region one of the United Kingdom's most populous metropolitan areas.
Document 6: Southampton: Southampton had an estimated 236,900 people living within the city boundary in 2011. There is a sizeable Polish population in the city, with estimates as high as 20,000.
Document 7: Southampton: Southampton's police service is provided by Hampshire Constabulary. The main base of the Southampton operation is a new, eight storey purpose-built building which cost £30 million to construct. The building, located on Southern Road, opened in 2011 and is near to Southampton Central railway station. Previously, the central Southampton operation was located within the west wing of the Civic Centre, however the ageing facilities and the plans of constructing a new museum in the old police station and magistrates court necessitated the move. There are additional police stations at Portswood, Banister Park, Bitterne, and Shirley as well as a British Transport Police station at Southampton Central railway station.
Document 8: Southampton: The city has a strong higher education sector. The University of Southampton and Southampton Solent University together have a student population of over 40,000.
Document 9: Southampton: The town experienced major expansion during the Victorian era. The Southampton Docks company had been formed in 1835. In October 1838 the foundation stone of the docks was laid and the first dock opened in 1842. The structural and economic development of docks continued for the next few decades. The railway link to London was fully opened in May 1840. Southampton subsequently became known as The Gateway to the Empire.
Document 10: Southampton: Southampton (i/saʊθˈæmptən, -hæmptən/) is the largest city in the ceremonial county of Hampshire on the south coast of England, and is situated 75 miles (121 km) south-west of London and 19 miles (31 km) north-west of Portsmouth. Southampton is a major port and the closest city to the New Forest. It lies at the northernmost point of Southampton Water at the confluence of the River Test and River Itchen, with the River Hamble joining to the south of the urban area. The city, which is a unitary authority, has an estimated population of 253,651. The city's name is sometimes abbreviated in writing to "So'ton" or "Soton", and a resident of Southampton is called a Sotonian.
Document 11: Southampton: Between 1996 and 2004, the population of the city increased by 4.9 per cent—the tenth biggest increase in England. In 2005 the Government Statistics stated that Southampton was the third most densely populated city in the country after London and Portsmouth respectively. Hampshire County Council expects the city's population to grow by around a further two per cent between 2006 and 2013, adding around another 4,200 to the total number of residents. The highest increases are expected among the elderly.
Document 12: Southampton Terminus railway station: Southampton Terminus railway station served the Port of Southampton and Southampton City Centre, England from 1839 until 1966. The station was authorised on 25 July 1834 and built as the terminus of the London and Southampton Railway, which later changed its name to the London and South Western Railway (LSWR). The station opened as "Southampton" on 10 June 1839, although it was not officially operational until 11 May 1840, due to the track not being fully linked between Winchester and Basingstoke.
Document 13: Southampton: The city has undergone many changes to its governance over the centuries and once again became administratively independent from Hampshire County as it was made into a unitary authority in a local government reorganisation on 1 April 1997, a result of the 1992 Local Government Act. The district remains part of the Hampshire ceremonial county.
Document 14: Southampton: Town Quay is the original public quay, and dates from the 13th century. Today's Eastern Docks were created in the 1830s by land reclamation of the mud flats between the Itchen & Test estuaries. The Western Docks date from the 1930s when the Southern Railway Company commissioned a major land reclamation and dredging programme. Most of the material used for reclamation came from dredging of Southampton Water, to ensure that the port can continue to handle large ships.
Document 15: Southampton: There are 119,500 males within the city and 117,400 females. The 20–24 age range is the most populous, with an estimated 32,300 people falling in this age range. Next largest is the 25–29 range with 24,700 people and then 30–34 years with 17,800. By population, Southampton is the largest monocentric city in the South East England region and the second largest on the South Coast after Plymouth.
ground_truth: South Hampshire
sub_queries: Heading east from Southampton, what city is connected by rail? Answer: Portsmouth
What metropolitan area is Portsmouth a part of? Answer: South Hampshire